1. The size of a molecule is on the order of __________, and the size of an average cell is on the order of ____________.

A. nanometer (nm), micrometer (μm)
B. nanometer (nm), millimeter (mm)
C. micrometer (μm), millimeter (mm)
D. picometer (pm), millimeter (mm)
E. micrometer (μm), nanometer (nm)

2. Which of these statements is incorrect?
A. 1 meter = 10-3 mm
B. 1 meter = 10-6 μm
C. 1 meter = 10-9 nm
D. All of the above are correct

E. None of the above are correct

Cells in a multicellular organism contain (nearly) identical copies of DNA, but turn on different sets of genes according to their developmental history and signals from outside the cell.

A. True
B. False

The light microscope allows us to resolve details as small as ____, and this level of detail is limited by ______________________.
A. 200 μm; the quality of the lenses
B. 200 μm; the wavelike nature of light
C. 200 nm; the quality of the lenses

D. 200 nm; the wavelike nature of light

Flourescent dyes absord light at one wavelength and emit at another, longer wavelength

A. True

B. False

A confocal microscope differs from a typical fluorescence microscope in that:
       A. Confocal microscopy scatters light off the surface of the specimen giving striking 3-dimensional images of the object surface
    B. Confocal microscopy requires the samples be stained with fluorescent dyes.

     C. Confocal microscopy is used to focus at different depths within the specimen allows a 3 dimensional fluorescent image to be constructed
     D. B & C
      E. All of the above

Which of the following is true regarding transmission electron microscopy (TEM)?
A. TEM is in principle similar to a light microscope, but uses a beam of electrons rather than a beam of light
B. TEM samples must be very thin
C. Contrast is usually introduced by staining with electron-dense heavy metals

D. TEM can resolve details as small as about 2mm
E. All of the above are true

 Which of the following is NOT true regarding scanning electron microscopy (SEM)?
A. SEM scatters electrons on the surface of the samples
B. Electrons are focused on the sample surface using electromagnetic coils that act as lenses
C. SEM samples are coated with a very thin film of a heavy metal
D. SEM is used to look at surface details with a resolution of ~3nm to 20nm

E. All of the above are true

Tissues are often chemically fixed and and cut into thin slices, or sections, for certain types of microscopy. This is done because:

A. Most tissues are not small enough or transparent enough
B. Most tissues require fixing for removal
C. Fluorescent dyes require fixation for microscopy
D. A and C
E. All of the above

What statement is NOT true about procaryotes?
A. Procaryotes use DNA to store their genetic information

B. Procaryotes store their genetic information in a nucleus.
C. Procaryotes vary widely in shape and size.
D. Procaryotes are mostly single-celled organisms, but some are multicellular.
E. All of the above are true about procaryotes

Bacteria can duplicate approximately every τ minutes. Assuming unabated growth with a doubling time of exactly τ minutes and 50 bacteria at time t=0, which equation correctly models the number of bacteria as a function of time (t) in minutes?
A. τ * 50 ^ (t / τ)
B. τ * 50 ^ (t)

C. 50 * 2 ^ (t / τ)
D. 50 * 2 ^ (t)
E. 50 ^ (t / τ)
F. 50 ^ (t)

C. 50 * 2 ^ (t / τ)

Which of the following are prokaryotes?
A. Plants and animals
B. Animals and archaea

C. Archaea and bacteria
D. Bacteria and fungi
E. None of the above

All of the DNA of a eukaryotic cell is contained within the nucleus.

(T/F)

What role is NOT performed by the cytoskeleton?
A. Pulling duplicated chromosomes to opposite poles in dividing cells
B. Transporting organelles and molecules from one place to another in the cytoplasm

C. Generating chemical energy
D. Controlling cell shape and cell movement
E. All of the above are performed by the cytoskeleton

Which of the following is NOT a model organism?
A. Escherichia coli
B. Arabidopsis thaliana
C. Drosophilia melanogaster
D. Schizosaccharomyces cerevisae
E. Caenorhabditis elegans

F. All of the above are model organisms

T/F

Mammals possess the largest genome of any known species

The human body consists of greater than 60% hydrogen atoms both as a total percentage of all atoms and also by mass.
a. True
b. False – hydrogen does NOT make up greater than 60% of all atoms

c. False – hydrogen does NOT make up greater than 60% by mass
d. False – hydrogen does NOT make up greater than 60% either by mass or by count

T/F

Bond length is directly proportional to bond length (i.e. a longer bond has a higher energy).

At room temperature, corn oils are fluid while butter and lard are solid. This is primarily due to:
a. Corn oils are derived from plants while butter and lard are derived from animals
b. Fatty acids in butter/lard form bilayers while fatty acids in corn oil form micelles
c. Corn oils contain a larger number of saturated fatty acids

d. Butter/lard contain a larger number of saturated fatty acids
e. None of the above

Which of the following is NOT true regarding disaccharides:
a. Are the simplest polysaccharides
b. Include maltose, lactose, and sucrose

c. Have the general chemical formula (CH2O)n
d. Are formed via a condensation reaction of two monosaccharides
e. All of the above are true

The difference between a DNA nucleotide and a RNA nucleotide:
a. Is in the sugar ring
b. Is in the pyrimidine compounds
c. Is in the purine compounds
d. Is in the phosphate group

e. A and B
f. A and C

In an amino acid, which of the following is covalently linked to the α-carbon?
a. The amino group (-NH2)
b. The carboxyl group (-COOH)
c. The side chain group (-R)

d. All of the above are covalently linked to the α-carbon
e. None of the above

Disulfide bonds can form between two _________ side chains.
a. Methionine
b. Isoleucine
c. Tyrosine

d. Cysteine
e. Glutamic acid

How do protein, nucleic acid, and polysaccharide molecules polymerize (grow)?

a. By condensation reactions
b. By hydrolysis reactions
c. By oxidation reactions
d. All of the above
e. None of the above

Which type of bond makes it possible for a macromolecule to interact with great specificity with just one out of the many thousands of different molecules present inside a cell?
a. Covalent bonds

b. Noncovalent bonds
c. Hydrogen bonds
d. Ionic bonds

The measure of disorder in a system is called ____________________.
a. Free energy
b. Oxidation

c. Entropy
d. Enthalpy
e. None of the above

Which of the following is NOT true regarding oxidation?

a. Oxidation refers to the addition of electrons
b. Oxidation and reduction, the converse reaction, always occur simultaneously
c. Cellular respiration involves the oxidation of carbon and hydrogen atoms to produce CO2 and H2O, respectively
d. As an organic molecule, such as methane, is being oxidized, the number of C-H bonds decreases
e. Oxidation of NADPH, and important carrier of electrons, results in NADP+
f. All of the above are true

Proteins called ___________ lower the activation energy of a biological reaction, the result is that ______________________________.
a. Substrates; the reaction proceeds with a lower overall free energy (DG)
b. Enzymes; the reaction proceeds with a lower overall free energy (DG)
c. Substrates; the reaction is more likely to proceed, but the overall free energy (DG) does NOT change

d. Enzymes; the reaction is more likely to proceed, but the overall free energy (DG) does NOT change
e. None of the above

Suppose for a simple reaction Y X that ΔG = 5 kcal/mol and [Y] = 1 mol and [X] = e10 mol. What is the approximate free-energy change, ΔG, for the reaction?
a. ΔG = 5e10 kcal/mol
b. ΔG = -5.6 kcal/mol
c. ΔG = 5.6 kcal/mol

d. ΔG = 11 kcal/mol
e. None of the above
f. Not enough information to calculate ΔG

The Δ G° of the hydrolysis reaction of ATP is -7.3 kcal/mole, but in a cell the actual Δ G is much more __________ , this is because _______________________________.
a. Positive, ATP is much higher in concentration than the products ADP and Pi.
b. Positive, ATP is much lower in concentration than the products ADP and Pi.

c. Negative, ATP is much higher in concentration than the products ADP and Pi.
d. Negative, ATP is much lower in concentration than the products ADP and Pi.

Which of the following statements is NOT true?
a. Vmax is the same for Reaction X and Reaction Y

b. Km is greater for Reaction X than for Reaction Y
c. The equation for the left plot is:
d. Reaction 1 corresponds to Reaction Y while Reaction 2 corresponds to Reaction X
e. All of the above are true

If the two reactions, Reaction 1 and 2, represent the same reaction with and without a competitive inhibitor, and the same is true for Reactions X and Y, which of the two reactions on each plot would be the one that contains the inhibitor?

a. Reaction 1 and Reaction Y contain the inhibitor
b. Reaction 1 and Reaction X contain the inhibitor
c. Reaction 2 and Reaction Y contain the inhibitor
d. Reaction 2 and Reaction X contain the inhibitor

Which of the following statements is NOT true?
a. NADPH is an activated carrier molecule that is usually used in biosynthetic reactions to build energy-rich molecules.

b. NADPH is an activated carrier molecule that is used primarily by plants.
c. NADH is an activated carrier molecule that is usually used in oxidation reactions to produce ATP.
d. NADH carries an extra proton and two high-energy electrons.
e. All of the above statements are true.

T/F

Synthesis of macromolecules, including DNA, RNA, polysaccharides and proteins requires an input of energy, often driven by energy from nucleoside triphosphate hydrolysis.

The amino acid sequence of a protein is always presented and read in the:

A. N to C direction
B. C to N direction
C. 5’ to 3’ direction
D. 3’ to 5’ direction

Which of the following does NOT stabilize the folded structure of a protein:
A. Covalent bonds
B. Backbone to backbone hydrogen bonds
C. Side chain to side chain hydrogen bonds
D. Disulfide bonds
E. Van der Waals attractions

F. All of the above contribute to protein structure

When exposed to high concentrations of urea, proteins become denatured. Which of the following is NOT true regarding protein denaturation using urea?
A. Urea is a small molecule

B. Urea acts as both a hydrogen bond acceptor (via –NH2 groups) and a hydrogen-bond donor (via –C=O group) to destabilize hydrogen bonds
C. Urea does NOT destabilize covalent bonds within a protein structure
D. Urea, at high concentrations, destabilizes the hydrogen-bonded network of water molecules thus diminishing hydrophobic forces within a protein structure
E. All of the above are true

T/F

The two regular folding patterns in proteins are the α-helix and β-sheet, both of which result from hydrogen bonds forming between backbone amine and carbonyl groups

In a α-helix, a hydrogen bond is formed between every ________ amino acid, and the helix completes a turn approximately every ________ amino acids.
A. Third; 3.6
B. Third; 4

C. Fourth; 3.6
D. Fourth; 4
E. None of the above

Some protein molecules contain an assembly of two different subunits. Hemoglobin contains two copies of α-globin and two copies of β-globin. The complete structure is called the ______________________.
A. Primary structure
B. Secondary structure
C. Tertiary structure

D. Quaternary structure
E. Quinary structure

In theory, a polypeptide chain with n residues has _____ different possible sequences and _______________ of these sequences adopt a single, stable conformation.
A. 20^n; nearly all

B. 20^n; very few
C. n^20; nearly all
D. n^20; very few
E. 20*n; nearly all
F. 20*n; very few

What is the name of the enzyme class responsible for catalyzing the rearrangement of bonds within a single molecule?
A. Nuclease
B. Protease

C. Isomerase
D. Synthase
E. Oxido-reductase

Which of the following statements regarding antibodies is NOT true?
A. An antibody is a protein ligand that binds a target protein with high affinity
B. Antibodies contain two identical binding sites, a result of two identical light chains and two identical heavy chains

C. Antibodies are produced by T cells
D. Antibodies can be coupled to fluorescent dyes for fluorescence microscopy or to gold particles for electron microscopy
E. Some assays require antibodies that bind to other antibodies
F. All of the above are true

T/F

Most drugs work by inhibiting enzymes

Hemoglobin binds four oxygen molecules. Suppose oxygen binding to the heme group (the subunit within hemoglobin) facilitates further oxygen binding. This is an example of:
A. Ligand binding
B. Allosteric regulation
C. Feedback inhibition

D. A and B
E. A, B and C

The attachment or removal of modifying groups to a protein can control what aspects of the protein?
A. Its behavior or activity
B. Its stability or its binding partners
C. Its location inside the cell
D. A and B
E. A and C

F. A, B and C

How do most motor proteins make their movements unidirectional (i.e., irreversible)?
A. They couple a conformational change to a thermodynamically unfavorable reaction.

B. They couple a conformational change to the hydrolysis of an ATP molecule.
C. They couple a conformational change to the formation of an ATP molecule from ADP and Pi.
D. They couple a conformational change to the formation of a GTP molecule from GDP and Pi.

The attachment or removal of modifying groups to a protein can control what aspects of the protein?
A. Its behavior or activity
B. Its stability or its binding partners
C. Its location inside the cell
D. A and B

E. A, B and C

Using mass spectrometry, proteins are selectively digested (using trypsin digestion, for example) and then separated based on their:
A. Mass to length ratio

B. Mass to charge ratio
C. Mass to hydrophobicity ratio
D. Mass to structure ratio
E. Radial distribution function

The large scale study of cellular proteins (studying the activities or structures of many proteins) is called what?

A. Proteomics
B. Genomics
C. Metabolomics
D. Bioinformatics
E. Electrophoresis

A cell homogenate (or cell extract) contains large and small molecules as well as membrane enclose organelles. Which of the following is NOT used for homogenization of cells or tissues?
A. High frequency sound
B. Mild detergents
C. High pressure
D. Shearing cells

E. Centrifugation

Density gradient centrifugation is used to separate cell components on the basis of their __________________.
A. Primary amino acid sequence
B. Mass and charge

C. Buoyant density
D. Sucrose content
E. Radial distribution function

In gel electrophoresis, what is the purpose of adding SDS to samples?
A. Solubilization of proteins
B. Breaking disulfide bonds
C. Covering proteins with the negatively charged detergent

D. A and C
E. B and C
F. A, B and C

The nucleotide sequence of one DNA strand of a DNA double helix is:
5’–GGATTTTTGTCCACAATCA–3’. What is the sequence of the complementary strand?
a. 3’ – TGATTGTGGACAAAAATCC - 5’

b. 5’ - TGATTGTGGACAAAAATCC - 3’
c. 5’ - CCTAAAAACAGGTGTTAGT - 3’
d. 3’ - GGATTTTTGTCCACAATCA - 5’
e. None of the above

Assume the following DNA sequences are bound to their complementary strands, which of the following DNA sequences would you expect to require the lowest temperature to break the two strands apart?
a. 5’- GATCCAGA -3’
b. 5’- GATCCAAA -3’

c. 5’- GATAAAGA -3’
d. 5’- GATCCAGG -3’
e. The strands are the same

The polarity in a DNA strand is indicated by referring to one end as the 5’ end and the other as the 3’ end. Which chemical moiety is located on the 3’ end?
a. Amine group
b. Carboxyl group
c. Phosphate group

d. Hydroxyl group
e. The moiety depends on the direction the DNA strand is being read

A gene is a segment of DNA that ultimately codes for a protein or a set of related proteins. Alternatively, some genes code for RNA molecules as their final product.

a. True
b. False

What does the term genome refer to?
a. All of the proteins expressed in an organism

b. The complete set of information in the DNA of an organism
c. The set of genes turned on in an organism, tissue, or cell
d. The observable character of a cell or organism
e. None of the above

Which of the following statements is NOT true regarding chromosomes?
a. Eukaryotic DNA is made up of linear, double-stranded DNA
b. Bacteria typically carry their genes on a single, circular DNA molecule

c. Sex chromosomes are non-homologous chromosomes with the Y chromosome maternally inherited and the X chromosome paternally inherited.
d. Abnormal chromosomes are associated with some genetic defects
e. All of the above are true

The structures that cap the ends of eucaryotic chromosomes are called ______________, and the structure that allows each duplicated eucaryotic chromosome to be pulled into a daughter cell is called a _______________.
a. Centromeres; telomere

b. Telomeres; centromere
c. Mitotic spindles; telomere
d. Centromeres; mitotic spindle

A cell can change its pattern of gene expression by:
a. Histone tail modification
b. Remodeling the chromatin
c. Condensing the chromatin into heterochromatin
d. Replicating the DNA yielding two identical copies

e. A, B, and C
f. All of the above

Consider the process that a cell uses to replicate its double-stranded DNA to make copies for daughter cells. Which statement describes the DNA in daughter cells?
a. The double helix in one daughter cell consists of two strands that were originally in the parent cell, while the double helix in the other daughter cell consists of two newly made strands.
b. The two strands of the double helices in both daughter cells consist of segments of new and parental DNA

c. The double helices in each daughter cell consist of one parental strand and one newly made strand.
d. The two strands of the double helices in both daughter cells consist of segments that were originally in the parental cell.

DNA synthesis begins at:
a. The telomeres
b. The centromere

c. The replication origins
d. The CpG islands

At the leading strand the DNA is synthesized ______________, and at the lagging strand the DNA is synthesized ________________.
a. Continuously; continuously

b. Continuously; discontinuously
c. Discontinuously; discontinuously
d. Discontinuously; continuously
e. None of the above

Replication origins typically consist of a small stretch of DNA that is relatively easy to open. Which statement is true?

a. Replication origins are rich in A and T nucleotides.
b. Replication origins are rich in G and C nucleotides.
c. Replication origins have equal numbers of A, C, G, and T nucleotides.

DNA is synthesized in the _________, and DNA is proofread in the _________.

a. 5’ to 3’ direction; 3’ to 5’ direction
b. 5’ to 3’ direction; 5’ to 3’ direction
c. 3’ to 5’ direction; 3’ to 5’ direction
d. 3’ to 5’ direction; 5’ to 3’ direction

Most cancers arise from cells that have accumulated only a single mutation.
a. True

b. False

Nearly half of the human genome is made up of copies of various mobile genetic elements.

a. True
b. False

Homologous recombination takes place only between two DNA molecules with an identical sequence.
a. True

b. False

Retroviruses like HIV:

a. Must copy their RNA genomes into DNA to replicate.
b. Must copy their DNA genomes into RNA to replicate.
c. Must copy the host’s genome to replicate.
d. Contain no genes of their own.

RNA and DNA differ in their chemical structure. Which of the following is true?
a. RNA and DNA differ in their sugar group
b. RNA and DNA differ in their phosphate group
c. RNA and DNA differ in their bases
d. RNA and DNA differ in their phosphodiester bond

e. A and C are true
f. B and D are true

Pictured to the right is a nucleic acid, which nucleic acid is this?
a. 5’, 2’ RNA
b. 5’, 2’ DNA

c. 5’, 3’ RNA
d. 5’, 3’ DNA
e. The DNA/RNA designation depends only on the “BASE” groups

RNA, as opposed to DNA, can fold into complex three-dimensional structures because it is single-stranded.

a. True
b. False

Which of the following statements is NOT true?

a. pRNAs code for proteins
b. rRNAs form the core of the ribosome and catalyze protein synthesis
c. tRNAs serve as adaptors between mRNA and amino acids during protein synthesis
d. miRNAs (or microRNAs) regulate gene expression
e. All of the above are true

In eucaryotes, what must assemble at a promoter before RNA polymerase can transcribe a gene?
a. Nucleotides required in transcription

b. General transcription factors
c. Sigma factor
d. An RNA primer
e. A and D

The assembly of general transcription factors to a eucaryotic promoter begins at what site in a promoter?
a. The assembly box

b. The TATA box
c. The GAGA box
d. The TFIID box
e. None of the above

In a eukaryotic gene, coding regions are known as _______ and non-coding regions are known as ________.
a. Exons; introns; prokaryotic genes have similar organization of coding regions
b. Introns; exons; prokaryotic genes have similar organization of coding regions

c. Exons; introns; prokaryotic genes do not contain introns
d. Introns; exons; prokaryotic genes do not contain introns

The three nucleotide codon can be arranged into ______ combinations, and ___________________________.
a. 43 = 64; each combination codes for a unique amino acid

b. 4^3 = 64; due to redundancy in the code, there are only 20 amino acids
c. 3^4 = 81; each combination codes for a unique amino acid
d. 3^4 = 81; due to redundancy in the code, there are only 20 amino acids
e. None of the above are true

Of the total mRNA that is synthesized, only a small fraction—the mature mRNA—is useful to the cell. The cell distinguishes between mature mRNA molecules and debris RNA molecules generated by RNA processing using RNA binding proteins (such as poly-A-binding brotein and cap-binding protein) that allow the mRNA to be transported out of the nucleus and into the cytosol.

a. True
b. False

The structure of the ribosome, which is made up of greater than 50% RNA by mass, confirms that the RNAs (not the proteins) are responsible for the structure and catalytic activity. Therefore the ribosome is actually a __________________.
a. RNAzyme
b. Protozyme

c. Ribozyme
d. Enzonucleic acid
e. None of the above

Within the ribosome, the formation of peptide bonds is catalyzed by:
a. Aminoacyl-tRNA synthetase.
b. The tRNA itself.

c. An RNA molecule in the large ribosomal subunit.
d. A peptidase in the small ribosomal subunit.

During translation at the ribosome, peptide bond formation forms when the N-terminal (upstream) tRNA is in the __________ and the C-terminal (downstream) tRNA is in the __________.
a. E-site; A-site
b. P-site; E-site
c. E-site; P-site

d. A-site; P-site
e. P-site; A-site

Discovered in the polio virus in 1988, the internal ribosomal entry site (IRES) is described as “distinct regions of RNA molecules that are able to attract the eukaryotic ribosome therefore allowing translation,” similar to those found in prokaryotic RNAs. In an experiment within eukaryotic cells, what advantage does the IRES yield?
a. Translation of a single mRNA molecule yielding many copies of the same protein

b. Translation of a single mRNA molecule yielding copies of several different proteins
c. Translation of multiple different RNA molecules yielding many copies of the same protein
d. Translation of multiple different RNA molecules yielding copies of several different proteins

Which of the following mutational changes would be most harmful to an organism?
a. Removal of a single nucleotide near the end of the coding sequence
b. Removal of a single nucleotide within an intron at the beginning of the sequence
c. Deletion of three consecutive nucleotides in the middle of the coding sequence

d. Removal of a single nucleotide near the beginning of the coding sequence
e. Substitution of one nucleotide for another in the middle of the coding sequence

Which of the following statements is NOT true about the differences between liver cells and kidney cells in the same organism?
a. They contain the same genes, but express them differently.

b. They contain different genes.
c. They contain different sets of proteins.
d. They contain different sets of RNAs
e. B and D

Although all of the steps involved in expressing a gene can in principle be regulated, for most genes the most important point of control is:

a. Transcription initiation
b. RNA processing
c. RNA transport and localization
d. mRNA degradation
e. mRNA translation

Which of the following is false?
a. Eucaryotic gene activator proteins stimulate transcription initiation by recruiting proteins that modify chromatin structure.
b. A: Eucaryotic gene activator proteins stimulate transcription initiation by aiding in the assembly of general transcription factors and RNA polymerase at the promoter.

c. Eucaryotic gene activator proteins stimulate transcription initiation by recruiting a DNA polymerase to the promoter.
d. Eukaryotic gene activator proteins, such as transcription regulators, bind either upstream or downstream of the gene itself
e. All of the above are true

DNA methylation is a ____________________, and the transmission from parent to daughter cell of the methylated pattern of DNA that effect protein expression without altering the DNA base pair sequence is known as ___________________________.
a. Post-transcriptional control mechanism; single nucleotide polymorphism
b. Post-transcriptional control mechanism; epigenetic inheritance
c. Post-translational control mechanism; single nucleotide polymorphism
d. Post-translational control mechanism; epigenetic polymorphism
e. Transcriptional control mechanism; single nucleotide polymorphism

f. Transcriptional control mechanism; epigenetic inheritance

What type of molecule triggers RNA interference (RNAi)?
a. Foreign, single-stranded DNA

b. Foreign, double-stranded RNA
c. Foreign DNA-RNA hybrids
d. All of the above

What is a riboswitch?
a. A small molecule that regulates the translation of specific mRNAs.
b. A gene regulatory protein that turns on the expression of ribosomal proteins.

c. An mRNA that can regulate its own transcription and translation.
d. RNAi that targets the ribosome
e. None of the above

Which of the following is NOT a source of genetic variation crucial in evolution?

a. Mutation within a gene

b. Mutation within the promoter of a gene

c. Exon Shuffling

d. Horizontal gene transfer

e. All of the above are sources of genetic variation

Many mutations are accumulated in an organisim over time. Of those mutations, the only mutations that are passed on to the next generation are those that occur in a ____________.

a. Somatic cell

b. Germ cell

c. Embryonic stem cell

d. Tumor cell

e. All of the above

Nucleotide point mutations that lead to no change in the amino acid sequence of any protein are known as silent, selectively neutral mutations and accumulate in the genome of a species over evolutionary time.

a. True

b. False

The two globin genes, α- and β- globin, that make up the hemoglobin molecule are a result of:

a. Gene duplication

b. Horizontal transfer

c. Gene mutation

d. A and B

e. A and C

Given the following phylogenetic tree, the arrow points in the direction of:

a. Increasing time before present

b. Decreasing time before present

c. Percentage nucleotide substitution

d. A and C

e. B and C

In our human ancestors, the enzyme lactase, which allows us to digest the milk sugar lactose, was produced only during infancy. Today, a portion of the adult population can digest lactose while other adults remain lactose intolerant. Which adults have point mutations in the regulatory DNA of their lactase genes?

a. Those who are lactose intolerant

b. Those who can digest lactose

Most of the genetic variation in human genome takes what form?

a. Single nucleotide polymorphism

b. DNA duplications or deletions

c. Chromosomal rearrangements

d. Exon shuffling

e. Intron shuffling

The human genome consists of approximately 3.2x10^9 nucleotide pairs, and only a few percent of that DNA codes for protein and for structural, regulatory, and catalytic RNAs.

a. True

b. False

An organism can produce far more proteins than it has genes. This is in  part due to the ability of cells to produce a range of related but distinct proteins from a single gene via unique RNA transcripts in a process called....

a. Alternative transcription

b. Alternative translation

c. Exon shuffling

d. Alternative splicing

e. Single nucleotide polymorphism

Which of the following statements regarding restriction nucleases ( restriction enzymes) is NOT true?

a. Restriction nucleases provide a bacterial defense mechanism against foreign DNA

b. Restriction nucleases cleave specific protein sequences typically between 4-8 residues

c. Restriction nucleases typically recognize and cleave palindromic sequences

d. A longer restriction nuclease target sequence is less likely to occur by random change

e. All of the above are true

Gel electrophoresis separates DNA based on____________ whereby ____________.

a. Fragment size; the smaller the molecule the faster the migration

b. Fragment size; the larger the molecule the faster the migration

c. Fragment sequence; the higher G/C content the faster the migration

d. Fragment sequence; the higher A/T content the faster teh migration

e. None of the above is correct

Because DNA is negatively charged, DNA fragments migrate toward a positive electrode.

a. True

b. False - DNA is positively charged and migrates toward a negative electrode

c. False - DNA is negatively charged and migrates toward a negative electrode

d. False - DNA migration requires the addition of SDS, an anionic surfactant, allowing DNA  to migrate toward a positive charge

e. False - DNA migration requires the addition of SDS, a cationic surfactant, allowing DNA to migrate toward negative charge

Which of the following enzymes allows scientists to join together DNA fragments?

a. DNA polymerase

b. DNA ligase

c. Restriction nuclease

d. DNA helicase

A DNA fragment, such as a vector, can be replicated inside ____________, and the process of introducing the fragment into the cell is a process called ____________.

a. Mammalian cells; Transformation

b. Mammalian cells; Recombination

c. Bacterial cells; Transformation

d. Bacterial cells; Recombination

e. None of the above

A bacterial plasmid that contains a viral promoter and a mammalian gene is an example of recombinant DNA.

a. True

b. False

Suppose two DNA fragments were cute by different restriction nucleases that recognize different target sequences but generate the same single-stranded overhang ("sticky-ends") -- an example, BamHI and BglII is shown. Which is true of the resulting DNA fragments?

a. The two fragment can NOT be ligated together

b. The two fragments can be ligated together, and the resulting, ligated DNA can be cut by either restriction nuclease
c. The two fragments can be ligated, and the resulting ligated DNA can be cut by only one of the original restriction nucleases

d. The two fragments can be ligated, and the resulting, ligated DNA is not recognized by either restriction nuclease

The process of making DNA from messenger RNA is known as______________ and the result is a ______________.

a. Reverse transcription; messenger DNA library

b. Reverse transcription; complementary DNA library
c. Reverse translation; messenger DNA library
d. Reverse translation; complementary DNA library
e. None of the above

The difference between cDNA and genomic DNA is:

a. cDNA lacks exons
b. cDNA lacks introns
c. cDNA is tissue specific while genomic DNA is the same in every tissue
d. A and C

e. B and C

The correct sequence of steps in polymerase chain reaction (PCR) is __________________   , and, assuming you start with one double-stranded DNA molecule, after N cycles the number of double-stranded DNA molecules is __________________.

a. Denaturation > Primer hybridization > DNA synthesis; N2
b. Denaturation > DNA synthesis > Primer hybridization; N2
c. Denaturation > DNA synthesis > Primer hybridization; 2N d. Denaturation > Primer hybridization > DNA synthesis; 2N
e. None of the above

In the dideoxy method of sequencing DNA, if the ration of deoxyribonucleotide triphosphates (dATP, dTTP, dCTP, dGTP) to dideoxyribonucleotide triphosphates (ddATP, ddTTP, ddCTP, ddGTP) is increased:

a. The strand polymerization terminates more frequently

b. The strand polymerization terminates less frequently
c. These conditions are favorable for determining short nucleotide sequences
d. A and C
e. B and C

Given the results for two plasma membranes (PM-I and PM-II) from fluorescence recovery after photobleaching (FRAP) shown to the right, which of the following statements is correct?
a. PM-I is more fluid than PM-II
b. PM-I may contain a higher percentage of lipids with unsaturated hydrocarbon tails
c. PM-I may contain more cholesterol than PM-II

d. A and B
e. All of the above are correct

Which of the following is NOT an important function of cell surface carbohydrates?
a. The carbohydrate layer protects the cell from mechanical damage.
b. The carbohydrate layer protects the cell from chemical damage.
c. Cell-surface carbohydrates play a role in cell adhesion.
d. Cell-surface carbohydrates play a role in cell-cell recognition.

e. All of the above are important functions of cell-surface carbohydrates.

Lipid bilayers are highly impermeable to:
a. Water

b. Na+ and Cl-
c. Oxygen
d. Ethanol
e. The bilayer is impermeable to all of the above
f. The bilayer is permeable to all of the above

In a typical animal cell, which of the following types of transport occur through a channel protein?
a. Movement of amino acids into a cell
b. Movement of Na+ out of a cell

c. Movement of Na+ into a cell
d. Movement of glucose into a starved cell
e. Movement of glucose out of a starved cell

Why is Na+ commonly used to drive coupled inward transport of nutrients in animal cells?
a. The chemical gradient drives Na+ into the cell
b. The electrical gradient drives Na+ into the cell

c. Both A and B
d. Neither A nor B

The high intracellular concentration of K+ in a resting animal cell is partly due to:
a. The K+ leak channels in the plasma membrane

b. The Na+-K+ pump in the plasma membrane
c. Voltage-gated K+ channels in the plasma membrane
d. Intracellular stores of K+ in the endoplasmic reticulum
e. The membrane potential

Which of the following statements is NOT true regarding the Nernst equation:
a. The Nernst equation can be used to calculate the resting potential of a membrane.

b. The Nernst equation does not depend on the charge of the ion.
c. The Nernst equation takes into account the electrical gradient.
d. The Nernst equation takes into account the chemical gradient.
e. All of the above are true.

The patch-clamp technique can characterize the behavior of a single ion channel. The example shows a result for a particular cAMP-activated Cl- channel on the luminal membrane from frog skin. The units on the x-axis are ___________ and the units on the y-axis are ________________.
a. time; voltage
b. voltage; time
c. current; voltage
d. voltage; current

e. time; current
f. current; time
g. time; arbitrary units of science

Ion channels of the auditory hair cells are opened by _______________ and thus transmit an electrical to the auditory nerve and to the brain.
a. Ligand stimulus

b. Mechanical stimulus
c. Electrical stimulus
d. All of the above
e. None of the above

The action potential travels in one direction because:
a. The Na+-K+ pump restores the concentrations of Na+ and K+ to their original levels.
b. The K+ leak channels allow K+ to flow out, restoring the membrane to the resting potential.
c. Depolarization of the membrane causes voltage-gated K+ channels to open.

d. Voltage-gated Na+ channels adopt a transitory inactive conformation after being opened.
e. Voltage-gated Na+ channels spend less time in the open conformation when the membrane returns to the resting potential.

Which of the following is NOT a benefit of using a chain of neurons and chemical synapses rather than a direct connection between the site of stimulus and the site of response?
a. Each chemical synapse represents an opportunity for the organism to modify the signal being sent.

b. Diffusion of small molecules is more rapid than propagation of an electric signal, thus the signal is accelerated by having more synapses
c. Use of chemical synapses increases the variety of messages the presynaptic cell can sent to the post synaptic cell
d. Modification of different ion channels at synapses can be used to generate memory on the cellular level.
e. Chemical synapses allow neurons to receive and integrate input from more than one source.

The energy released by oxidizing glucose is saved in a high-energy bonds of:

a. ATP and other activated carrier molecules.

b. ADP and other activated carrier molecules.

c. GDP and other activated carrier molecules.

D. H2O and CO2

E. none of the above

Fermentation is a useful method for generating energy, however the usefulness is limited because the end products are toxic to the producer.

A. True
B. False

Yeast : Ethanol :: Muscle cells : _______________
A. Pyruvate
B. ATP
C. NADH

D. Lactate
E. None of the above

Fermentation results in the net production of:
A. 2 ethanol molecules
B. 2 ATP molecules
C. 2 NADH molecules

D. A and B
E. All of the above

A and B

Anaerobic respiration differs from fermentation in that it involves an electron-transport chain embedded within a membrane.

A. True
B. False

When fatty acids are oxidized to acetyl CoA, each cycle of the reaction removes how many carbon atoms from the fatty acid molecule?
A. 1

B. 2
C. 3
D. 4

The complete oxidation of glucose to H2O and CO2 produces how many ATP molecules per molecule of glucose?
A. 2
B. 4
C. 12
D. 20

E. 30

Glucose subunits are stored as glycogen in animals and as starch in plants; both animals and plants store fatty acids as fats.

A. True
B. False

Cells obtain most of their energy by a membrane-based mechanism.

A. True
B. False

Which of the following statements regarding the electron-transport chain is NOT true?
A. The transmembrane gradient of H+ serves as a source of energy to drive reactions such as ADP phosphorylation to generate ATP.
B. The final product of the transport chain is water

C. High-energy electrons, as they fall to lower energy states, drive protons across the membrane, from the inner mitochondrial compartment to the cytosol
D. The chain of electron carriers is embedded in the inner mitochondrial membrane in eukaryotic cells
E. The chain of electron carriers is embedded in the plasma membrane of bacteria.
F. All of the above are true

12. NADH donates its electrons to the electron transport chain and becomes NAD+. Which of the following statements regarding the conversion of NADH to NAD+ is NOT true?
A. Electrons are donated from NADH via oxidation
B. A hydride ion, having a negative charge, is donated from a methylene group within NADH
C. Upon donating the hydride ion, NADH forms a temporary, unstable isomer before rearranging its bonds such that the positive charge is transferred from a carbon (unstable) to a nitrogen (stable) forming NAD+

D. The hydride ion is made up of a hydrogen atom and two extra electrons, with the two electrons being donated to the electron transport chain
E. FADH2 carries its electrons in a similar way
F. All of the above are true

The total electrochemical potential of H+ across the inner mitochondrial membrane consists of a large force due to the membrane potential (DV) and a smaller force due to the H+ concentration gradient (DpH), with the electrochemical gradient driving H+ into the mitochondrial intermembrane space.
A. True

B. False

Identify the correct path for an electron through the electron transport chain:

I. cytochrome b-c1 complex
II. Oxygen
III. NADH
IV. cytochrome oxidase complex
V. NADH dehydrogenase complex
VI. Ubiquinone
VII. Cytochrome C

Which of the following statements regarding ATP synthase is NOT true?
A. ATP synthase is a mitochondrial membrane protein
B. ATP synthase utilizes the electrochemical gradient of H+ in the mitochondria to synthesize ATP
C. ATP synthase synthesizes ATP as H+ flows across the mitochondrial inner membrane into the mitochondrial matrix.
D. ATP synthase is a reversible device that can hydrolyze ATP to drive H+ against the electrochemical gradient back into the intermitochondrial space

E. All of the above are true

The standard redox potential is for a 1:1 mixture of the redox pair. The standard redox potential for NADH and NAD+ is -320mV, and _____________________________________.
A. This is unchanged with either excess NADH or NAD+

B. Electron transfer is more favorable with excess NADH, yielding a more negative redox potential
C. Electron transfer is more favorable with excess NADH, yielding a more positive redox potential
D. Electron transfer is more favorable with excess NAD+, yielding a more negative redox potential
E. Electron transfer is more favorable with excess NAD+, yielding a more positive redox potential

Ubiquinone has a redox potential of +30 mV, while cytochrome c has a redox potential of +230 mV. In the electron transport chain, electrons flow from:

A. Ubiquinone to cytochrome c.
B. Cytochrome c to ubiquinone.

Chlorophyll molecules absorb which color of light most strongly?

A. Red light
B. Green light
C. Blue light
D. UV light
E. Fluorescent light

Identify the correct path of an electron during the photosynthetic electron transport chain in the thylakoid membrane.

I. Photosystem I
II. Photosystem II
III. NADPH
IV. Ferredoxin-NADP reductase
V. Cytochrome b6-f complex
VI. H2O
VII. Plastoquinone

In photosynthesis, what drives ATP synthesis by ATP synthase?
A. Transfer of high energy electrons to ATP synthase
B. Phosphorylation of ATP synthase
C. The absorption of a photon of light by an adjacent chlorophyll molecule

D. A proton gradient across the thylakoid membrane

Which of the following is NOT a membrane-enclosed organelle in plant or animal cells?
a. Peroxisome
b. Nucleus
c. Endosome
d. Chloroplast

e. All of the above are membrane enclosed organelles

It is thought that eukaryotic cells developed membrane-enclosed organelles due to their:
a. High plasma membrane surface area to cellular volume ratio

b. Low plasma membrane surface area to cellular volume ratio
c. Neither A nor B

Start transfer sequences and stop transfer sequences are similar in that:

a. Both are hydrophobic
b. Both are hydrophilic
c. Both are cleaved by signal peptidase
d. A and C
e. B and C

In the process of translocating a polypeptide across the membrane of the endoplasmic reticulum, a stop transfer sequence halts the process. What eventually becomes of the stop transfer sequence?

a. It forms an α-helical membrane-spanning segment of the protein.
b. It forms a β-barrel membrane-spanning segment of the protein
c. It is cleaved from the protein.
d. It is translocated into the lumen of the endoplasmic reticulum.

Proteins in the cytosol that are destined for other organelles must first enter the:
a. The nucleus

b. The endoplasmic reticulum
c. The Golgi apparatus
d. The lysosomes
e. The plasma membrane

Clathrin is a protein that:
a. Coats vesicles budding from the golgi apparatus on the outward secretory pathway
b. Coats vesicles from the plasma membrane on the inward endocytic pathway

c. Both A and B
d. Neither A nor B

SNARE proteins are located on:
a. Transport vesicles
b. Target membranes

c. Both transport vesicles and target membranes
d. Neither transport vesicles nor target membranes

In the endoplasmic reticulum, individual sugars are added one by one to a protein to create an oligosaccharide side chain.
a. True

b. False – oligosaccharides are added as a whole via a specialized lipid
c. False – oligosaccharides are added as a whole via a specialized protein

Which type of protein binds to improperly folded or improperly assembled proteins in the ER, holding them there until proper folding occurs?
a. Tethering proteins
b. Glycosylating proteins
c. Antibody proteins
d. SNARE proteins

e. Chaperone proteins

Which mechanism is used for degrading entire organelles of a cell, such as a defective mitochondrion?

a. Autophagy
b. Apoptosis
c. Phagocytosis
d. Endocytosis
e. Ubiquitination

Which of these forms of cell-cell communication typically travels the longest distance from the originating cell to the target cell?
a. Contact-dependent communication
b. Paracrine communication

c. Endocrine communication
d. Neuronal communication

Which of the following statements about steroid hormones is NOT correct?
a. Steroid hormones include cortisol, estradiol, testosterone, and thyroxine
b. The majority of steroid hormones pass through the plasma membrane due to their hydrophobic nature
c. Steroid hormones bind intracellular hormone receptors which directly regulate transcriptional gene activation and repression
d. Each hormone binds a different hormone receptor and, in turn, activates and represses a unique set of target genes

e. All of the above are correct

Nitric oxide (NO) acts only on neighboring cells (as a local mediator in paracrine signaling) because:
a. So little is produced by the signaling cell.
b. It is rapidly washed away by the blood stream.
c. It is rapidly converted to nitrates and nitrites in the target cell.

d. It is rapidly converted to nitrates and nitrites in the extracellular fluid.

Which of the following is NOT one of the basic classes of cell-surface receptors?

a. Hormone receptors
b. G-protein-coupled receptors
c. Ion-channel-coupled receptors
d. Enzyme-coupled receptors

Which of the following statements about the inositol phospholipid signaling pathway is NOT true?

a. The inositol phospholipid pathway is activated by GPCRs which activate the phospholipase C, a signaling molecule that also happens to be a phospholipid
b. Phospholipase C cleaves the sugar-phosphate head off inositol phospholipid to generate IP3 and diacylglycerol (DAG)
c. DAG remains embedded in the plasma membrane where it recruits protein kinase C (PKC)
d. IP3 is released into the cytosol where it binds to and opens Ca2+ channels in the ER membrane
e. Binding of DAG to PKC requires cytosolic Ca2+
f. All of the above are true

The concentration of free Ca2+ in the cytosol of an unstimulated cell is kept low compared with its concentration in both the extracellular fluid and the endoplasmic reticulum. Which of the following does not help maintain this difference?
a. Membrane-bound Ca2+ pumps in the plasma membrane

b. Ca2+-destroying enzymes in the cytosol
c. Membrane-bound Ca2+ pumps in the ER membrane
d. Ca2+-binding proteins in the cytosol
e. All of the above maintain the concentration difference

Adaptation in signaling pathways allow a cell to remain sensitive to signals despite:
a. Having mutant downstream adaptor proteins that may or may not bind the signaling receptor
b. The slow speed of signal propagation upon stimulation
c. The rapid speed of signal propagation upon stimulation
d. The absence of second messengers

e. Experiencing a wide range of background levels of stimulation

The cytoplasm of a eukaryotic cell is supported and spatially organized by a cytoskeleton of intermediate filaments, microtubules, and actin filaments.

a. True
b. False

Put the following components of the cytoskeleton in order of increasing diameter.
a. Microtubules < Intermediate filaments < Actin filaments
b. Microtubules < Actin filaments < Intermediate filaments
c. Actin filaments < Microtubules < Intermediate filaments

d. Actin filaments < Intermediate filaments < Microtubules
e. Intermediate filaments < Actin filaments < Microtubules

Which of the following is the main function of intermediate filaments?
a. To provide tracks for guiding intracellular transport
b. To enable cells to crawl

c. To enable cells to withstand the mechanical stress that occurs when cells are stretched

At which level of the intermediate filament hierarchy is a covalent bond first found?
a. The coiled-coil dimers are held together via covalent bonding
b. The staggered tetramer of two coiled-coil dimers are held together via covalent bonding
c. Two tetramers pack together via covalent bonding
d. Eight tetramers twisted into a ropelike filament and are held together via covalent bonding

e. None of the above interactions contains a covalent bond

Which of the following types of intermediate filaments are found in all animal cells?
a. Keratins
b. Vimentin and vimentin-related filaments

c. Nuclear lamins
d. Neurofilaments

Microtubule growing and shrinking, a process called ______________, stems from the intrinsic capacity of tubulin molecules to hydrolyze ____.
a. Dynamic instability; ATP
b. Rapid reassembly; ATP

c. Dynamic instability; GTP
d. Rapid reassembly; GTP
e. Dynamic instability; either ATP or GTP

In a centrosome, which structures serve as nucleation sites for the formation of microtubules?
a. αβ-tubulin dimers
b. α- and β-tubulin monomers
c. Tubulin protofilaments

d. γ-tubulin rings

Taxol, a drug used both as a cancer chemotherapy as well as in coating stents to prevent restenosis (recurrent narrowing of the coronary artery), is a mitotic inhibitor that works by:
a. Binding to free tubulin molecules and preventing polymerization
b. Binding to microtubules and preventing polymerization
c. Binding to free tubulin and preventing de-polymerization

d. Binding to microtubules and preventing de-polymerization
e. None of the above

In eukaryotic cells, directed intracellular movements are generated by motor proteins which use energy derived from repeated cycles of ATP hydrolysis to travel steadily, in a single direction, along either actin filaments or microtubules.

a. True
b. False – they only travel along microtubules
c. False – they only travel along actin filaments

The membrane of the Golgi apparatus is pulled toward the cell center by interacting with the motor protein:
a. Dyneins that pull toward the plus end

b. Dyneins that pull toward the minus end
c. Kinesins that pull toward the minus end
d. Kinesins that pull toward the plus end
e. None of the above

The hydrolysis of bound ATP to ADP in an actin filament _____ the strength of binding between monomers in the filament.
a. Increases

b. Decreases
c. Has no effect on

Take the following figure where networks of microtubules (M.T.), actin filaments (A.F.), or intermediate filaments (I.F.) were exposed to a shear force and the resulting degree of stretch was measured. Which of the following statements is NOT true?
a. Microtubules networks are easily deformed but cannot withstand excessive force without rupture
b. Intermediate filaments are easily deformed and can withstand large stresses and strains without rupture

c. Actin filaments are less rigid than either microtubules or intermediate filaments
d. A, B, and C are all true

Which organelle sequesters Ca2+ inside muscle fibers?
a. The nucleus
b. Mitochondria

c. The sarcoplasmic reticulum
d. The Golgi apparatus
e. Lysosomes

Which is the correct order of the cell cycle?
a. S  G1  M  G2  S …
b. G1  M  G2  S  G1 …
c. G1  S  M  G2  G1 …
d. S  G1  G2  M  S …

e. None of the above

Given the cell cycle profile of proliferating, asynchronous cells as measured by flow cytometry, which of the following statements is NOT true?

a. Inhibition of DNA synthesis would cause cells to accumulate in stage II
b. Inhibition of mitosis would cause cells to accumulate in stage III
c. Stage I is the longest stage in the cell cycle
d. A, B, and C are correc

Different cyclin-dependent protein kinases (Cdks) trigger different stages of the cell cycle in part because:
a. Their concentrations increase at different stages of the cycle.

b. Their activities increase at different stages of the cycle due to cyclin concentrations
c. They are degraded at different stages of the cycle.
d. A and B
e. A, B and C

What is responsible for triggering DNA replication and ensuring that DNA replication is initiated only once per cell cycle?

a. S-Cdk
b. M-Cdk
c. p21
d. p53

DNA damage can arrest the cell at a checkpoint in G1 by activating an important checkpoint protein transcription factor known as __________ (which happens to be disrupted in ~50% of all cancer cases).
a. G1/S-Cdk
b. p21

c. p53
d. M-Cdk
e. Cdc25

The five stages of mitosis occur in what order?
a. anaphase  telophase  prometaphase  metaphase  prophase  cytokinesis

b. prophase  prometaphase  metaphase  anaphase  telophase  cytokinesis
c. telophase  anaphase  prophase  prometaphase  metaphase  cytokinesis
d. prophase  metaphase  prometaphase  telophase  anaphase  cytokinesis
e. anaphase  prometaphase  metaphase  telophase  prophase  cytokinesis

Microtubules bind to replicated chromosomes (sister chromatids) and segregate them during anaphase. The ____________________ are the microtubules responsible for binding chromosomes, and they attach via the ________________ structure on a mitotic chromosome ?
a. Aster microtubules; kinetochore

b. Kinetochore microtubules; kinetochore
c. Interpolar microtubules; kinetochore
d. Aster microtubule; spindle pole
e. Kinetochore microtubules; spindle pole

Which of the following is/are inherited randomly between daughter cells during cell division?
a. Chromosomes
b. Golgi

c. Soluble proteins
d. Both B and C are inherited randomly
e. None of the above are inherited randomly

Which of the following statements regarding apoptosis is NOT true?
a. Apoptosis involves activation of pro-caspases to active caspases, a family of proteases, and activation of caspases is primarily regulated by members of the Bcl-2 family
b. A cell undergoing apoptosis shrinks and condenses, and cellular DNA is broken into fragments

c. Apoptotic cells often spill their contents into the surrounding region triggering the inflammation response of nearby cells
d. An intracellular apoptotic stimulus can cause activation of pro-caspase-9 via the release of cytochrome c from the mitochondrial intermembrane space
e. Apoptotic cells alter their membrane to attract phagocytic cells, which engulf the apoptotic cell

Mitogens stimulate cell proliferation by:
a. Phosphorylating the Rb protein
b. Activating the Rb protein
c. Inactivating the Rb protein
d. A and B

e. A and C

In mature organisms, cell number is controlled as a result of cell proliferation and cell death. An imbalance in the rates of proliferation or cell death can result in disorders of excessive cell accumulation, such as cancer, or disorders of excessive cell loss, such as neurodegenerative diseases.

a. True
b. False