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Molec Bio Exam 1
Molecular Biology Chapters 1-4
181
Microbiology
Undergraduate 2
01/24/2012

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Term
What is an allele?
Definition
A gene for single trait comes in alternate forms called alleles. Alleles can be considered either dominant or recessive. The recessive will not show up unless the dominant is not present.
Term
Explain and define Mendel's principles
Definition
Bred 29,000 pea plants and studied how seven traits were passed on. Came to 2 conclusions and 2 principles
Term
Mendel's Conclusions
Definition
1. Always inherit a pair of genes that control a trait, one from each parent 2. A gene for a single trait comes in alternate forms called alleles- either dominant or recessive
Term
Dominant allele
Definition
An allele that will always be expressed if present. [uses capital letter(s)]
Term
Recessive allele
Definition
An allele that will only be expressed in the absence of the dominant allele. [uses lower case letter(s)]
Term
Define phenotype
Definition
The allele that is being expressed - what is seen.
Term
Define genotype
Definition
The alleles you possess for a given trait- three types: Homozygous dominant, Homozygous recessive, and heterozygous
Term
Homozygous Recessive
Definition
Having two recessive alleles for a trait
Term
Homozygous Dominant
Definition
Having two dominant alleles for a trait
Term
Heterozygous
Definition
Having one dominant and one recessive allele for a trait
Term
Law of Segregation (Mendel's 1st principle)
Definition
Two alleles of any gene are on homologs that separate from each other in Anaphase of meiosis. Half sex cells get one allele, and the other half get the other.
Term
Law of Independent Assortment (Mendel's 2nd principle)
Definition
Homolog arrangement in Metaphase I is random, passing a maternal allele from one homolog does not affect any other homologous pair
Term
Sex Linked Traits
Definition
A trait that is only present on the 23rd homologous pair- the X or the Y. If a Y linked trait- will always appear since there is only ever one Y in the 23rd homologous pair (Male=xy, Female= xx)
Term
Autosomal Dominant
Definition
Trait is dominant: phenotype appears every generation, affected individual has at least one affected parent, affects both male and female
Term
Autosomal Recessive
Definition
Trait is recessive: phenotype can skip a generation, affected individual can have unaffected parents, affects both male and female
Term
Complete Dominance
Definition
Punnett Square- Dominant trait is ALWAYS dominant
Term
Incomplete Dominance
Definition
Phenotype is a blend of dominant and recessive alleles - pink carnation
Term
Co-dominance
Definition
Phenotype is both alleles, but not blended- more blotchy. Is often ENVIRONMENTALLY influenced
Term
Multiple Alleles
Definition
A gene that has more than two possible alleles- you can only inherit two, even if there are more than two possibilities
Term
Pleiotropic
Definition
One gene controls multiple different traits (opposite of polygenic)
Term
Polygenic
Definition
Multiple genes control the same trait (opposite of pleiotropic)
Term
Chromatin
Definition
Makes up Chromatids- make up chromosomes: Made of histone protines with strands of DNA wrapped around them twice.
Term
DNA is a polymer made of ____ monomers
Definition
Nucleotides
Term
2 classes of nitrogenous bases
Definition
1. Purines 2. Pyramidines
Term
Purines
Definition
Adenine and Guanine
Term
Pyramidines
Definition
Cytosine and Thymine
Term
Railing of DNA made of...
Definition
Alternating Carbohydrates and phosphates
Term
Carbohydrates in "railing" of DNA is____ bonded to __
Definition
Covalently bonded to "rungs" of nitrogenous bases
Term
Rungs of DNA made of _____, ______ bonded
Definition
Two nitrogenous bases, hydrogen-bonded together
Term
Adenine always bonds with _____ (part of Chargoff's Rules)
Definition
Thymine
Term
Thymine always bonds with_____(part of Chargoff's Rules)
Definition
Adenine
Term
Guanine always bonds with _____(part of Chargoff's Rules)
Definition
Cytosine
Term
Cytosine always bonds with _____(part of Chargoff's Rules)
Definition
Guanine
Term
Chargoff's Rules say
Definition
Which nitrogenous bases will bond together. Purines are always double ringed, while pyramidines are single-ringed. Base pair of 1 purine and 1 pyramidine. (consistent width) [If you have 40% adenine you must have 40% thymine which leaves 20% to other bases- ten each.]
Term
Order of pairs of nitrogenous bases in DNA
Definition
Variable- determines an individual's genetic code
Term
Explain Chromosomes: (beads on a string)
Definition
Parents physically pass on alleles for genes on chromosomes. Chromosomes are made of chromatin. Chromatin is comprised of nucleosomes. Clumps of histone proteins with strands of DNA wrapped around them twice.
Term
DNA Replication
Definition
In the S stage of interphase, enzyme helicase untwists/unzips DNA, therefore, breaking hydrogen bonds. Enzyme DNA polymerase attaches complimentary bases to each half of unzipped DNA and each new DNA strand is exact clone of original. Each chromosome has added a chromatid. (when you want to copy entire cookbook)
Term
The Central Dogma
Definition
DNA-->RNA -->Protein-->Phenotype.
Term
A gene
Definition
A section of DNA with a code to produce a single protein.
Term
Analogy
Definition
Cell's nucleus is a library, chromosomes are cookbooks, genes are the recipes (to make protein), alleles are different versions of the same recipe (to make a protein)
Term
What is so important about the proteins made?
Definition
It is the protein you make that gives your phenotype for any gene!!!
Term
Explain Translation
Definition
Translation is when proteins are produced. mRNA leaves the nucleus and travels to a ribosome with a list of amino acid ingredients it needs. Translated codon by codon, codon codes for amino acid. But mRNA can't actually grab them, so tRNA comes in to play. tRNA carries an amino acid on one end and an anticodon on the other.
Term
tRNA...
Definition
The molecule that transfers AA to mRNA is called the transferRNA. Each molecule carries a specific amino acid.
Term
Anticodon
Definition
An anticodon hydrogen bonds only with its mRNA complimentary codon. The codon/anticodon match ensures each mRNA only gets the AA it calls for. 3 bases at the end of tRNA is where the anticodon is- sticks to codon and delivers amino acid.
Term
Translation Continued
Definition
mRNA winds its way into a ribosome. A ribosome exposes one codon at a time. One by one, tRNA brings the proper AA to each codon of mRNA. The individual AA are connected through dehydration reactions to form a polypeptide. The polypeptide folds into 3D form and becomes a protein (which actually expresses your gene.)
Term
Promoters
Definition
Switches for your genes. If a gene is "on" RNA polymerase transcribes. There are start and stop switches. Two cells with exact same recipes may behave differently because of these promoters that start and stop/turn on and off at different times.
Term
Exons
Definition
*to remember: EX (as in EXpressed).* Exons are expressed- actually codes for a protein
Term
Introns
Definition
Introns is a section of DNA that does not code for anything.
Term
Where are proteins made in a cell?
Definition
Ribosomes!
Term
mRNA
Definition
A copy of the DNA's recipe that can travel to ribosomes. The mRNA is made in the process of transcription. mRNA is mobile and leaves the nucleus. mRNA is a small copy of a single gene. It has ribose sugar in its railing. mRNA is single stranded-it lacks base pairs. mRNA replaces thymine with a base called uracil.
Term
Transcription
Definition
Helicase unzips the section of DNA with the gene, breaking the hydrogen bonds. Though the strand is double, only one side of dna is important. An enzyme called RNA polymerase travels around the strand- taking free nucleoiteds (A to A etc.) and matching them up with complement. It does this until it reaches stop codon and mRNA is released, leaves nucleus and goes into cytosol.
Term
Helicase
Definition
Helicase untwists or unzips only the section of DNA that has the needed gene (recipe).
Term
Watson and Crick
Definition
Published short paper (groundbreaking). Walked around and picked up pieces of the puzzle (about DNA) and put it together as a model. They
Term
DNA Structure
Definition
Is a polymer. DNA is a double stranded helix comprised of paired nucleotide monomers. Railings are for support. Rungs made of two nitrogenous bases hydrogen-bonded together
Term
Rosalind Franklin's discoveries
Definition
Rosalind's images demonstrated a molecule with 2 strands twisted around each other and pairs of nucleotides stacked along the middle.
Term
Nucleotides consist of (3 parts)
Definition
A phosphate group, a deoxyribose sugar, nitrogenous base
Term
How many nucleotides does each cell in your body, need?
Definition
6 billion
Term
Monohybrid Cross
Definition
When you are crossing one gene.
Term
Dyhybrid Cross
Definition
When you are crossing two genes. Four possibilities: sixteen box punett square
Term
In sex cells, how many alleles do you pass on for each gene?
Definition
In each sex cell you only pass on one allele for each gene.
Term
Protein Synthesis
Definition
DNA to RNA to protein. DNA cannot leave the nucleus so we make a copy of the recipe that can travel- called mRNA (made in transcription).
Term
When is DNA replication is used?
Definition
In meiosis and mitosis
Term
How many strands of chromatin are there in a human sperm cell?
Definition
23
Term
What is NOT a part of the nucleotide monomers that comprise DNA?
Definition
Protein
Term
If you are heterozygous for a trait, what are the odds of passing the recessive allele to your kids?
Definition
50.00000%
Term
Codons
Definition
Three bases in a row. Each is a code for a single ingredient in building a protein-amino acid. Possible 64 codons on a codon chart.
Term
Archibald Garrod
Definition
In 1902, described the first (recessive) human Mendelian genetic disorder, alkaptonuria. Disease caused by a lack of an enzyme, homogenistic acid oxidase
Term
Dominant trait
Definition
The trait that appears in the F1 progeny
Term
Recessive trait
Definition
The trait that does not appear in F1 progeny
Term
Phenotype
Definition
The appearance or physical structures of an individual.
Term
Genotype
Definition
The genetic composition of an individual.
Term
Homozygous
Definition
A gene pair in which both the maternal and paternal gnes are identical (e.g. RR or rr).
Term
Heterozygous
Definition
A gene pair in which the paternal and maternal genes are different (e.g. Rr)
Term
Gene
Definition
the basic unit capable of transmitting characteristics from one generation to the next. It consists of a specific sequence of DNA or RNA that occupies a fixed position locus on a chromosome.
Term
Allele
Definition
one of two or more alternative forms of a gene, occupying the same position locus on paired chromosomes and controlling the same inherited characteristic
Term
Mendel's First Law (The principle of independent segregation)
Definition
Genes occur in pairs and at the time of gamete formation, one of each pair enters the gametes. Inferred from F1 x F1 crosses.
Term
Mendel's Second Law (The principle of independent assortment)
Definition
One gene pair segregates (sorts) independent of another gene pair.
Term
Walter Flemming
Definition
Described mitosis in 1879
Term
Meiosis vs Mitosis
Definition
Mitosis Metaphase 1: line up linearly; one chromatid from each chromosome in daughter cells
Meiosis Metaphase 1: line up pairs and duplicated chromosomes separate; then 2nd mitotic-like cell division
Term
Alkaptonuria
Definition
Defective homogenistic acid oxidase enzyme which is responsible for tyrosine degradation. Leads to build up in blood and excess in urine, can result in kidney stones. It was the first recessive Mendelian genetic disorder found in humans.
Term
How is genetics about phenotype?
Definition
Mendel could only infer genotype by observation of phenotypic properties of progeny.
Term
F2 Phenotypic Ratio
Definition
9:3:3:1
Term
3 Scientists who independently confirmed Mendel's Work
Definition
Hugo DeVries, Karl Correns, and Erich von Tschermak
Term
Walter Sutton
Definition
1902-He came up with the chromosome theory of inheritance (genes are carried from parents to their offspring on chromosomes). He observed that segregation of chromosomes during meiosis matched segregation of Mendel's traits or factors.
Term
Beadle and Tatum
Definition
Their work on Neurospora led credence to the hypothesis that genes coded for enzymes. The thought at the time was that genes were composed of amino acids and that " one gene one enzyme".
Term
Fredrick Griffith
Definition
showed that DNA can carry genetic specificity with his work on virulent and nonvirulant strains of streptococcus pneumoniae. Heating cells up until they died showed that genetic components not only remain intact, but are able to transfer to nonvirulant strains and undergo genetic recombination.
Term
Oswald Avery
Definition
Avery isolated DNA, showing that if it was added to R (rough nonvirulent) cells they would turn to S (smooth virulent) cells. The transforming ability of these fractions were stopped if deoxyribonuclease was added, while if ribonuclease or protease there was no difference in the fractions transforming ability.
Term
Hershey and Chase
Definition
Their work with radioactive phages (radioactive S in protein coat and P in DNA) confirmed that nucleic acids were the actual component of DNA.
Term
William Astbury
Definition
1938-Took the first x-ray diffraction of DNA.
Term
Williams and Franklin
Definition
1950s-High quality x-ray diffractions showed that DNA was a helical structure and composed of more than one polynucleotide chain.
Term
Alexander Todd
Definition
Showed that DNA was held together by 3' to 5' phosphodiester bonds.
Term
Linus Pauling
Definition
Showed that alpha helices of polypeptide chains provided the models for DNA structure.
Term
Crick and Watson
Definition
1953-Showed the complementary nature of DNA.
Term
Vernon Ingram
Definition
1956-Showed that sickle hemoglobin differs from normal hemoglobin by the change of one amino acid in the beta chain
Term
What causes sickle cell anemia?
Definition
At position 6, glutamic acid residue found in wild-type hemoglobin is replaced by valine on the S allele of the beta globin gene
Term
Meselson & Stahl
Definition
Showed that DNA replication is a semiconservative process in which the single strands of the double helix remain intact (conserved) during a replication process where one parental strand seperates into two daughter molecules, one original, and one new (semi).
Term
Meselson & Stahl Experiment
Definition
Used CsCl density gradient centrifugation in which the sedimentation forms bands. The density gradient seperated by heavy (bottom), hybrid (middle), light (top)
Term
What distinguishes RNA from DNA?
Definition
1) RNA contains ribose, which is identical to deoxyribose except for the presence of an additional OH (hydroxyl) group on the 2' carbon
2) RNA has no thymine but has the closely related pyrimidine uracil (has no methyl group CH3)
Term
Torbjorn Caspersson & Jean Brachet
Definition
Found that RNA is in same cellular compartment (cytoplasm) where protein synthesis occurs
Term
Adapter Hypothesis of Crick
Definition
Crick proposed that prior to incorporation into proteins, amino acids are first attached to specific adapter molecules, which possess unique surfaces that can bind specifically to bases on the RNA templates
Term
Paul Zamecnik (early years)
Definition
1953-developed cell free extracts for protein synthesis by using radioactive tagged amino acids to trace newly made proteins and then ultracentrifuged them for fractioning.
Term
Paul Zamecnik & Mahlon Hoagland
Definition
Discovered that prior to incorporation into proteins, amino acids are first attached to transfer RNA (tRNA)
Term
Arthur Kornberg
Definition
Showed that a specific polymerizing enzyme is needed to catalyze the linking of building-block precursors of DNA
Ultimately isolated DNA polymerase I, the enzyme used to replicate DNA
Term
DNA Polymerase I
Definition
Catalyzes the synthesis of new DNA strands
Removes the primers (RNA nucleotides) from 5' end and replaces them with DNA nucleotides
Requires DNA template to determine sequence of the DNA strand that it is synthesizing
Term
What evidence suggests that DNA cannot be the template that directly orders amino acids?
Definition
Protein synthesis occurs at sites where DNA is absent
a second information containing molecule is needed that obtains its genetic specificity from DNA
Term
Transfer RNA (tRNA)
Definition
A type of RNA that carries an amino acid from the cytoplasm to the ribosome for incorporation into a growing protein
Term
Ribosomal RNA (rRNA)
Definition
The most abundant type of RNA (85%)
Composed of two unequally sized units, that stick together or fall apart depending on ion concentration
Brings the tRNA-amino acid precursors into position where they can read of information provided by mRNA templates
Term
Messenger RNA (mRNA)
Definition
type of RNA that carries instructions from DNA in the nucleus to the ribosomal sites of Protein synthesis
can be read by several ribosomes
Term
Polyribosomes
Definition
A group of ribosomes translating the same mRNA
Term
Why was mRNA overlooked?
Definition
Because only a small percent of total cellular RNA is mRNA
Term
Transcription
Definition
RNA synthesis
Process by which a DNA template is used to produce a single-stranded RNA molecule
Term
Translation
Definition
Protein synthesis
genetic information coded in messenger RNA directs formation of specific Protein at ribosome in cytoplasm
Starts and stops at internal positions
Term
Jerard Hurwitz & Samuel Weiss
Definition
Isolated the first RNA polymerase
Term
RNA polymerase
Definition
An enzyme that pulls the 2 strands of DNA apart and hooks together the RNA nucleotides as they base pair along the DNA template
Term
Which experiment confirmed movement of mRNA from nucleus to ribosome-containing cytoplasm?
Definition
Pulse labeling experiment
Term
Pulse Labeling Experiment
Definition
Briefly exposed cells to radiolabeled precursors, adding large excess of unlabeled nucleotides in which mRNA synthesized in short window of time
Study Showed that mRNA is synthesized in nucleus
Led to conclusion that direction of Protein synthesis from AA teminus to carboxyl terminus (new aa added to C terminus of growing poly chain)
Term
Charles Yanofsky & Sidney Brenner
Definition
1960 - Conducted a mutational analysis on bacterial proteins that showed colinearity exists
Term
Colinearity
Definition
Concept that a gene's DNA codon sequence is the same as the protein's amino acid sequence along a given polypeptide chain
Term
Brenner & Crick
Definition
1961 - First to establish that groups of three nucleotides are used to specify (code) individual amino acids
Term
Marshall Nirenberg & Heinrich Matthaei
Definition
1961 - addition of synthetic polynucleotide poly U (UUUU...) to cell-free system capable of making proteins lead to synth of polypeptide chains w/ only AA phenylalanine
Term
Har Gobind Khorana
Definition
Used polynucleotides like AGUAGU to complete the genetic code
Term
Completion of the Genetic Code revealed...
Definition
1966 - Revealed that 61 out of 64 possible groups correspond to amino acids, with most amino acids being encoded by more than one nucleotide triplet.
Term
Central Dogma
Definition
DNA --> A: Transcription --> RNA --> B: Translation --> Protein
Term
Synthetic Polynucleotides
Definition
Poly U = Phenyl Alanine
Poly A = Lysine
Poly C = Proline
Term
Nonsense codons
Definition
Three codons that do not direct the addition of a particular amino acid but instead serve as translational stop signals (aka stop codon)
UAA, UAG, UGA
Term
start codon
Definition
AUG codon (methionine) in eukaryotes
AUG or GCG in prokaryotes
signals ribosomes to begin translation
Codes for the first amino acid in polypeptide chain
Term
How does initiator AUG distinguish from an internal codon? Pro vs. Euk
Definition
prokaryotes - AUG codons start new polypeptide chains, preceded by specific purine-rich blocks of nucleotides - serve to attach mRNA to ribosomes
eukaryotes - position of AUG relative to beginning of mRNA is critical determinant, w/ first AUG always selected as start site of translation
Term
Comparative Genomics
Definition
Identification of conserved and non-conserved DNA sequences between species, compare new genome sequence to previously sequenced genomes
Potential to identify mutations that lead to disease
Term
what is a gene?
Definition
discrete units of inheritance (segments of DNA)
Term
what does a gene consist of?
Definition
specific sequence of nucleotides in DNA
Term
what is a chromosome?
Definition
a single piece of coiled DNA containing many genes
Term
what is DNA?
Definition
a double strand polymer of nucleotides
Term
3 main structures of DNA
Definition
phosphate
5 carbon sugar (deyoxribose)
nitrogen base
Term
what are the 4 different nitrogen bases of DNA?
Definition
Adenine
Guanine
Thymine
Cytosine
Term
Of the 4 nitrogen bases of DNA, which 2 are double ringed purines?
Definition
Adenine and Guanine
Term
of the 4 nitrogen bases of DNA, which 2 are single ringed pyrimidines
Definition
thymine and cytosine
Term
the phosphate and 5 carbon sugar combine to form what?
Definition
phosphate-sugar complex
Term
how are phosphate-sugar complexes bonded together?
Definition
covalent bonds
Term
how are the nitrogen bases bonded to the phosphate-sugar complexes?
Definition
covalent bonds
Term
How are the double strands of DNA bonded together?
Definition
hydrogen bonds via the nitrogen bases
Term
In DNA what nitrogen base always pairs with Adenine?
Definition
Thymine
Term
In DNA what nitrogen base always pairs with Cytosine?
Definition
Guanine
Term
In DNA what is the name for three successive bases on a DNA strand?
Definition
triplet
Term
Where does DNA replication take place?
Definition
in the nucleus
Term
Why does DNA replicate?
Definition
- to ensure continuity of hereditary traits
Term
What is semi-conservative DNA replication?
Definition
- conserves some of the old strand with the new strand
Term
Where does DNA unwind?
Definition
origin of replication
Term
What 2 enzymes cause the DNA to separate?
Definition
helicase
DNA nuclease
Term
How do helicase and DNA nuclease separate the DNA strands?
Definition
they break the hydrogen bonds
Term
In DNA replication what is the exposed strand called?
Definition
template strand
Term
In DNA replication what enzyme joins the new nucleotides to the template strand?
Definition
DNA polymerase
Term
In DNA replication what is formed when the new nucleotides join with the template strand?
Definition
complimentary strand
Term
What enzyme connects the new segments of DNA?
Definition
Ligase
Term
What is RNA
Definition
single strand polymer of nucleotides
Term
What are the 3 structures of RNA?
Definition
phosphate
5 carbon sugar (ribose)
nitrogen base
Term
What are the 4 possible nitrogen bases for RNA?
Definition
Adenine
Cytosine
Guanine
Uracil
Term
What are the 3 differences between DNA and RNA?
Definition
different sugars
DNA double strand/RNA single strand
DNA = thymine / RNA = uracil
Term
What are the 3 types of RNA involved in protein synthesis?
Definition
messenger RNA (mRNA)
transfer RNA (tRNA)
ribosomal RNA (rRNA)
Term
what is the function of mRNA?
Definition
carries code from DNA to ribosomes
Term
what is the function of tRNA?
Definition
carries amino acids to mRNA at ribosomes
Term
what is the function of rRNA?
Definition
responsible for peptide bond
Term
What is the name for 3 successive bases on mRNA
Definition
codon
Term
What is the name for 3 successive bases on tRNA
Definition
anticodon
Term
What happens in RNA transcription?
Definition
DNA information into a molecule of RNA
Term
What happens in RNA translation?
Definition
RNA to protein (or polypeptite chain)
Term
Where does RNA translation occur?
Definition
in the cytoplasm/ribosome
Term
Where does the RNA strand go after transcription?
Definition
out into the cytoplasm
Term
What are the 3 main steps of RNA translation?
Definition
initiation
polypeptide formation (elongation)
termination
Term
In the initiation of RNA translation, what does mRNA attach to?
Definition
ribosomal subunit
Term
in the initiation of RNA translation, what does tRNA attach to?
Definition
codon of mRNA
Term
In RNA elongation, a polypeptide bond is formed between what?
Definition
two amino acids
Term
What causes the termination of RNA translation?
Definition
stop codon
Term
What do ribosomes use to translate bases into amino acids?
Definition
use tRNA to attach to mRNA
Term
What is a DNA mutation?
Definition
a heritable change in the DNA
Term
what does heritable mean (in terms of DNA mutations)?
Definition
it can move from one line (generation) of cells to the next line of cells
Term
What are 3 common causes of DNA mutations?
Definition
radiation
viruses mutagenic chemicals
Term
T or F
The information from mutated DNA is NOT likely to be passed on to RNA
Definition
0
Term
what are the 2 major types of DNA mutation?
Definition
point mutations
frameshift mutations
Term
what is a point mutation?
Definition
a substitution of a base
Term
what is a frameshift mutation?
Definition
a deletion or insertion of a base
Term
what is a silent mutation?
Definition
when a change would not affect the amino acid produced
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