Question 1

What two experimental procedures allowed deciphering of the ordered triplet assignments of the genetic code?

Accepted Answer

The answer of What two experimental procedures allowed deciphering of...

Question 2

There is some indication that the code is in some way ordered; a certain pattern exists.Describe an observation that supports this view.

Accepted Answer

The answer of There is some indication that the code...

Question 3

Describe the direction of information flow in living systems.Use appropriate,scientific terms in your description.

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The answer of Describe the direction of information flow in...

Question 4

Which of the following contains the three posttranscriptional modifications often seen in the maturation of mRNA in eukaryotes?

Accepted Answer

A) 5'-capping,3'-poly(
A) tail addition,splicing 
B) 3'-capping,5'-poly(
A) tail addition,splicing 
C) removal of exons,insertion of introns,capping 
D) 5'-poly(
A) tail addition,insertion of introns,capping 
E) heteroduplex formation,base modification,capping

Question 5

Sidney Brenner argued that the code was nonoverlapping because he considered that coding restrictions would occur if it were overlapping.A second major argument against an overlapping code involved the effect of a single nucleotide change.In an overlapping code,how many adjacent amino acids would be affected by a point mutation? In a nonoverlapping code,how many amino acid(s)would be affected?

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The answer of Sidney Brenner argued that the code was...

Question 6

When examining the genetic code,it is apparent that ________.

Accepted Answer

A) there can be more than one amino acid for a particular codon 
B) AUG is a terminating codon 
C) there can be more than one codon for a particular amino acid 
D) the code is ambiguous in that the same codon can code for two or more amino acids 
E) there are 44 stop codons because there are only 20 amino acids

Question 7

What is the initiator triplet in both prokaryotes and eukaryotes? Which amino acid does this triplet recruit?

Accepted Answer

A) UAA; no amino acid called in 
B) UAA or UGA; arginine 
C) AUG; arginine 
D) AUG; methionine 
E) UAA; methionine

Question 8

Which of the following two terms relate most closely to split genes?

Accepted Answer

A) 5'-cap,3'-poly-A tail 
B) introns,exons 
C) elongation,termination 
D) transcription,translation 
E) heteroduplex,homoduplex

Question 9

What is polycistronic mRNA?

Accepted Answer

The answer of What is polycistronic mRNA?...

Question 10

An intron is a section of ________.

Accepted Answer

A) protein that is clipped out posttranslationally 
B) RNA that is removed during RNA processing 
C) DNA that is removed during DNA processing 
D) transfer RNA that binds to the anticodon 
E) carbohydrate that serves as a signal for RNA transport

Question 11

Of the following three types of nucleic acids-DNA,mRNA,tRNA-which is most likely to contain modified bases?

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Question 12

From the late 1950s to the mid-1960s,numerous experiments using in vitro cell-free systems provided information on the nature of the genetic code.Briefly outline significant experiments in the determination of the genetic code.

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Question 13

Introns are known to contain termination codons (UAA,UGA,or UAG),yet these codons do not interrupt the coding of a particular protein.Why?

Accepted Answer

A) UAA,UGA,and UAG are initiator codons,not termination codons. 
B) Exons are spliced out of mRNA before translation. 
C) These triplets cause frameshift mutations,but not termination. 
D) More than one termination codon is needed to stop translation. 
E) Introns are removed from mRNA before translation.

Question 14

Describe how the sigma subunit (factor)of E.coli RNA polymerase participates in transcription.

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The answer of Describe how the sigma subunit (factor)of E.coli...

Question 15

The relationship between a gene and a messenger RNA is that ________.

Accepted Answer

A) genes are made from mRNAs 
B) mRNAs are made from genes 
C) mRNAs make proteins,which then code for genes 
D) genes are structurally identical to mRNAs 
E) mRNA is directly responsible for making Okazaki fragments

Question 16

When scientists were attempting to determine the structure of the genetic code,Crick and coworkers found that when three base additions or three base deletions occurred in a single gene,the wild-type phenotype was sometimes restored.These data supported the hypothesis that ________.

Accepted Answer

A) the code is triplet 
B) the code contains internal punctuation 
C) AUG is the initiating triplet 
D) the code is overlapping 
E) there are three amino acids per base

Question 17

When considering the initiation of transcription,one often finds consensus sequences located in the region of the DNA where RNA polymerase(s)binds.Which of the following is a common consensus sequence?

Accepted Answer

A) TATA 
B) GGTTC 
C) TTTTAAAA 
D) any trinucleotide repeat 
E) satellite DNAs

Question 18

A 3' poly-A tail and a 5'-cap are common components of prokaryotic RNAs.

Accepted Answer

A) True 
 B)False

Question 19

Suppose that in the use of polynucleotide phosphorylase,nucleotides A and C are added in a ratio of 1A:5C.What is the probability that an AAA sequence will occur?

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Question 20

It has been recently determined that the gene for Duchenne muscular dystrophy (DMD)is more than 2000 kb (kilobases)in length; however,the mRNA produced by this gene is only about 14 kb long.What is a likely cause of this discrepancy?

Accepted Answer

A) The exons have been spliced out during mRNA processing. 
B) The DNA represents a double-stranded structure,whereas the RNA is single-stranded. 
C) More amino acids are coded for by the DNA than by the mRNA. 
D) The introns have been spliced out during mRNA processing. 
E) When the mRNA is produced,it is highly folded and therefore less long.

Exam 12: The Genetic Code and Transcription