Shared Flashcard Set

Details

TEST II BIOCHEM
Multiple Choice Questions
86
Biochemistry
Undergraduate 4
06/03/2011

Additional Biochemistry Flashcards

 


 

Cards

Term
What is the start codon for prokaryotic mRNA translation?
Definition

AUG (Met)

 

Term
The promotor site is...
Definition
the site on DNA at which RNA ploymerase binds to initiate transcription
Term
Which end of prokaryotic mRNA are protected from degradation?
Definition
Neither end
Term
Restriction enzymes are useful for genetic recominant work for all reasons except...
Definition

They are all reasons they are useful...

They CAN cut DNA in the  middle of specific sequences

They can cut DNA independent of the source of DNA

They can generate single stranded tails "sticky ends"

There are a large variety of them commercially available

Term
Protein that makes proteins for degradation is called
Definition
Ubiquitin
Term
The appropriate order for the steps of protein synthesis are:
Definition

1) Binding of mRNA by the small subunit followed by association of a particular aminoacyl-tRNA that recognizes the first codon

2) The large ribosomal subunit joins the initiation complex, preparing for the elongation stage

3) The P site is occupied by peptidyl-tRNA carrying the growing polypeptide chain

4) The elongation reaction transfers the peptide chain from the peptidyl-tRNA in the P site to the aminoacyl-tRNA in the A site

5) The new, longer peptidyl-tRNA moves from the A site into the P site as the ribosome moves one codon further along the mRNA

Term
The Shine-Dalgarno sequence found in prokaryotic systems resides on the ___ end of ___ and is the ___ site.
Definition

5'

mRNA

ribosome binding

Term
In DNA sequencing, fragments to be analyzed are produced by...
Definition
selective interruption of DNA synthesis using ddNTPS
Term
Which of the following is not a structural motif encountered in DNA-binding proteins?
Definition
β-Barrel
Term
Which of the following nucleobases is a purine?
Definition
adenine or guanine
Term
One of the important ways that eukaryotic DNA differs from prokaryotic DNA is
Definition
Eukaryotic DNA is complexed to proteins as prokaryotic is not
Term
Repair of DNA is usually carried out by...
Definition
a cut and patch process
Term
Protein synthesis in prokaryotes always starts for with...
Definition
Formylmethionine residue (f-Met)
Term
The DNA ____ strand has the same nucleotide sequenced and direction as the RNA transcript with the ____ end of mRNA encoding the N-terminus of the protein
Definition

Coding

5'

Term
Which statement is/are true reguarding ribosomes?
Definition

They are found in the cytosol of all cells

Prokaryotic ribosomes consist of a 30S and a 50S subunit

Ribosomes consist both of protein and rRNA

The catalytic center of the large subunit is a peptidyl transferase

ALL OF THE ABOVE!!!!

 

Term

Which of the following is the best description of an operon?

 

Definition
A group of genes under the control of a common promoter.
Term
Protein biosynthesis in cells utilizes energy driving the assembly process provided by ___ hydrolysis.
Definition
GTP
Term
The molecule that interacts specifically with both nucleic acids and amino acids is
Definition
tRNA
Term
Which of the following activities of DNA Polymerase I is most important to the role of proofreading?
Definition
3'-5' exonuclease
Term
Each of the following statements is true regarding  ways in eukaryotic protein synthesis differes from prokaryotic protein synthesis except........
Definition

Prokayotic protein synthesis is initiated by f-Met while eukaryotic is initiated by Met

-Prokaryotes use a 30S small ribosomal subunit while eukaryotes use a 40S small ribosomal subunit

-prokaryotic and eukaryotic translation initiation differs slightly in mechanism and processes

-Prokaryotic termination requires 3 release factors while eukaryotic requires 1

ALL OF THE ABOVE ARE TRUE

Term

Forensic uses of DNA to identify victims or criminals exploit the following trait in DNA:

 

Definition
 Differences in sizes of DNA restriction fragments (RFLPs)
Term
Advantages of PCR (Polymerase Chain Reaction) include all except the following...
Definition

-The reaction is specific for certain sequeces in the DNA

-Only small amounts of template are needed

-Results can be obtained with DNA that is old or partially degraded

-All the products from a specific part of DNA will be the same size

-ALL OF THESE ARE ADVANTAGES OF PCR

Term
Migration of DNA during electrophoresis is based
Definition
Mostly on the size of the molecule, since the ratio of charge to mass is approximately the same, no matter how large the DNA is
Term
Semiconservative replication implies that
Definition
Each strand of new double stranded DNA molecules contains one of the original intact strands and  one completely new strand
Term
At what position on tRNA is the wobble base of the triplet anticodon?
Definition

1st position

(5' letter)

Term
The subunit in the E. coli RNA polymerase which is required for recognition of the promoter sequence is
Definition
sigma σ
Term
The strands in the double helix...
Definition

have their 3'-5' directions opposed

they are antiparallel

Term
Prokaryotic chromesomes are typically ____, while eukaryotic chromesomes are ____.
Definition

-cricular

-linear, richly protein-associated

Term
Which peice of DNA will have a higher Tm, one with cytosine plus guanine content of 30%, or one with  a cytosine plus guanine content of 50% if both are heated under the same exprimental conditions
Definition
50% will have a higher Tm
Term
Chain termination (transcription) occurs in vivo when...
Definition
either a hairpin loop forms or rho (ρ) is involved.
Term
What happens when a stop codon is reached by a ribosome (in the A site)
Definition

a termination protein binds to the codon and it is used to release the growing peptide from the P site tRNA.

the ribosome is then likely to dissocitate

Term
The following enzyme is responsible for the bulk of DNA synthesis during replication (prokaryotic)
Definition
DNA Pol III
Term
Which ends of eukaryotic DNA are protected from degredation?
Definition
Both ends
Term
The primer for in vivo DNA replication is
Definition
a short peice of RNA
Term
Which of the following groups are not contained in nucelosides?
Definition
phosphates
Term
In recombinant DNA technology
Definition

-foreign DNA is frequently inserted into a bacterial plamid

-vectors are used as carriers for recombinant genes

-it is impossible to insert eukaryotic genes into prokaryotic DNA

-ALL OF THE ABOVE ARE CORRECT

Term
How do origins of replication differ in eukaryotes and prokaryotes?
Definition
eukaryotes have several origins while  prokaryotes typically have one.
Term
An aminoacyl-tRNA is bound to the ribosome
Definition
at the A site on the 50S subunit
Term
A transcription factor is
Definition
A protein other than RNA polymerase that is involved in transription
Term
The backbone of nucleic acids consists of
Definition
a phosphodiester bond between the 3' and 5' hydroxyl groups of neighboring sugars
Term
E. coli replication on the lagging strand
Definition
is initially synthesised as Okazaki fragments
Term
The direction of DNA synthesis is
Definition
from the 5' to 3' end on both strands
Term
The initial step in the formation of aminoacyl-tRNA is
Definition
activation of the amino acid by reaction with ATP
Term
Which of the following terms does not describe the DNA strand used to direct RNA synthesis?
Definition
Coding Strand
Term
A single operon
Definition
usually contains all the enzymes which are specific for synthesis of a special biomolecule
Term
A plasmid
Definition
A small circular DNA that is not part of a bacterial chromesome
Term
Which inhibitor of protein synthesis competes with aminoacyl-tRNAs for binding to the A-site of the ribosome?
Definition
puromycin
Term
Linear eukaryotic DNA molecules
Definition
have many origins of synthesis while circular prokaryotic DNA usually have only one.
Term
The majority of protein synthesis occurs in the
Definition
cytoplasm
Term
All are stages in transcription except
Definition
DNase I activity on the RNA polymerase/DNA complex
Term
All are components required for peptide chain initiation except
Definition

-mRNA

-30S and 50S ribosomal subunits

-initiation factors

-GTP and f-Met-tRNA

-ALL ARE REQUIRED

Term
The mRNA must contain the following to allow for initiation of protein synthesis in E. coli
Definition
a Shine-Delgarno Sequence
Term
Response elements
Definition
are enhancers of transcription activated by metabolic factors
Term
The DNA double helix is stabilized by
Definition
both hydrogen bonds between bases(base-pairing) and hydrophobic and van der waals between stacked bases
Term
Which of the following statements is/are true about restriction endonucleases?
Definition

-they typically recognize and cleave specific DNA base sequences (palindromic)

-their natural function in bacteria is to cleave foreing DNA

-they can cleave large peices of DNA into smaller fragments

-ALL OF THE ABOVE ARE TRUE

Term
The typical composition of a ribosome is about
Definition

65% rRNA

35% Protein

Term
The replication of DNA to form daugther strands is
Definition
semiconservative
Term
The 3'-5' exonuclease activity of DNA polymerase I bestows ____ capabilities to the enzyme
Definition
proofreading
Term
ethidium bromide and acridine orange are two types of biochemicals called ____ that can cause genetic mutations by their interactions with DNA
Definition
intercallating agents
Term
In eukaryotic ribosomes, the subunit particle sizes are ____, and combine to make a particle of ___.
Definition

40S, 60S

80S

Term
The term degeneracy refers to
Definition
the use of more than one codon to define certain amino acids
Term
what are the energy needs for protein synthesis
Definition
four phosphoanhydride bonds cleaved per amino acid residue
Term
in eukaryotic cells, proteins targeted for destruction are first marked by ____, and then degraded into organelles called _____.
Definition

ubiquitin

proteosomes

Term
which DNA polymerase is most responsible for elongation in E. coli?
Definition
DNA Pol III
Term
DNA polymerase requires _____ for synthesis of DNA to occur.
Definition

-DNA template

-RNA primer

-Free 3'-OH end of the DNA strand

-ALL OF THE ABOVE ARE NECESSARY

Term
Constitutive genes
Definition

-Have products that are maintained at constant levels

-are genes expressed by all cells

-are transcribed continously

-ALL OF THE ABOVE

Term
It is easier to melt DNA richer in A-T  than G-C base pairs because
Definition
there is one less hydrogen bond
Term
Why does E. coli need both DNA Pol I and DNA Pol III
Definition
DNA Pol III lacks the 3'-5' enxonuclease activity needed to remove RNA primers
Term
An operon is
Definition
a set of related genes whose transcription is controlled by  a singular promoter
Term
Sequences that are removed from the primary mRNA transcript in eukaryotes are called
Definition
introns
Term
Puromycin is an antibiotic that inhibits protein synthesis because
Definition
it looks like aminoacyl-tRNA and binds to the A site
Term
general steps in the generation of a recombinant DNA molecule in the lab includes:
Definition

-ligation of DNA segmnets

-cleavage of DNA into small fragments

-insertion of DNA fragments into a vector

-ALL OF THE ABOVE ARE INCLUDED

Term
_____ are small, circular double stranded DNA molecules used as vectors for cloning DNA fragments
Definition
Plasmids
Term
The general steps in DNA repair include
Definition
endonuclease cleavage, exonuclease removal of the mononucleotide, polymerase filling of  the gap and ligase action to close the gap
Term
which type of RNA is most abundant in living cells (by percent)
Definition
rRNA
Term
What is the effect of incubating a mixture of RNA and DNA with 0.1 M NaOH?
Definition
RNA is hydrolyzed to nucleoside monophosphates
Term
The RNA primer at the begining of each Okazaki fragment is removed by
Definition
DNA Pol I
Term
The template strand of DNA is copied by the RNA ploymerase from
Definition
3'-5' end
Term
The sequence of CCA usually occurs
Definition
at the 3'-end of the tRNA in both prokaryotic and eukaryotic cells
Term
at the end of the initiation step the ribosome has a vacant
Definition
A site
Term
Which of the following statements about DNA replication is untrue?
Definition
DNA ligase catalyzes bond formation between each arriving  nucleotide
Term
The polymerase chain reaction (PCR)is a(n)
Definition
series of reiterative DNA synthesis steps using olignucleotide primers
Term
List 4 functional characteristics of the genetic code
Definition

code is a triplet code=3 nucleotides on mRNA which code for a specific AA

-code is nonoverlapping= set of 3 adjacent bases marks a codon

-code uses no punctuation (no invervening bases=comas/interruptions)

-code is degenerate=a singe amino acid may have multiple codons

-code is universal=many of the same codons used in all living organisms

Term
Breifly list 3 major post-transcriptional modifications that eukaryotic mRNA udergoes before full functional operation.
Definition

Addition of N-methylGuanosine (G) Cap to 5' end of mRNA

-Addition of Poly-A tail to 3' end

Removal of noncoding sequences(introns) and rejoining of exons

-Methylation of selected ribose sugars

Term
Briefly describe the structure/composition of prokaryotic promoter
Definition

Rich in AT, conserved sequence on DNA which provide direction for RNA Pol during transcription.

-key components of core promoter include 1)transcription start site (+1 TSS) 2)-10 region (prinbow box) 3) the -35 region/element.

-Extended promoter will also include an upstream (UP element) -40 to -60 bases upstream

Supporting users have an ad free experience!