Deck 6: Anatomy and Function of a Gene: Dissection Through Mutation

Question 1

A sequence of DNA that reads 5' ATGCCTGAATCAGCTTTA 3' should code for ____ amino acids after all the steps of conversion into protein are complete.

A) 5
B) 6
C) 7
D) 8
E) 9

Answer 1

B

Question 2

A(n)_____________ consists of proteins and small nuclear RNAs forming discrete particles that mediate splicing.

A) holoenzyme
B) spliceosome
C) nucleosome
D) ribosome
E) chromosome

Answer 2

B

Question 3

The sequences within mRNA that are spliced out (removed)are called

A) extremes.
B) exons.
C) inclusions.
D) introns.
E) UTRs.

Answer 3

D

Question 4

The retroviruses,including HIV,are unique because they do reverse

A) replication.
B) transcription.
C) splicing.
D) translation.
E) initiation.

Question 5

The scientists credited with postulating the basis for the genetic code are

A) Hershey and Chase.
B) Griffith and Avery.
C) Beadle and Tatum.
D) Cohen and Boyer.
E) Watson and Crick.

Question 6

Transcription occurs in the ________ and translation occurs in the __________ of prokaryotic cells.

A) nucleus;cytoplasm
B) cytoplasm;nucleus
C) nucleus;nucleus
D) nucleolus;nucleus
E) cytoplasm;cytoplasm

Question 7

The pattern or sequence in which a molecule of mRNA is deciphered by a ribosome is called the

A) synthesis platform.
B) code degeneration.
C) peptide transition.
D) reading frame.
E) strand polarity.

Question 8

There are ______________ usually found in the genetic code.

A) 3 start codons and 1 stop codon
B) 2 start codons and 2 stop codons
C) 4 start codons and 1 stop codon
D) 0 start codons and 4 stop codons
E) 1 start codon and 3 stop codons

Question 9

The (expressed)sequences within mRNA that code for gene products are called

A) extremes.
B) promoters.
C) inclusions.
D) introns.
E) exons.

Question 10

Nonsense codons are

A) codons that code for multiple amino acids.
B) codons that do not code for an amino acid.
C) codons that can be read forward or backward.
D) start codons.
E) codons that do not consist of DNA or RNA.

Question 11

The cellular organelle responsible for protein synthesis is the

A) nucleus.
B) mitochondria.
C) centrioles.
D) ribosome.
E) polymerase.

Question 12

A codon is a three-base sequence of

A) mRNA that codes for an amino acid.
B) rRNA that codes for an amino acid.
C) tRNA that codes for an amino acid.
D) DNA that codes for an amino acid.
E) amino acids.

Question 13

In the usual flow of genetic information (often called the Central Dogma),which of the following best represents the expression of genes?

A) Protein-RNA-DNA
B) DNA-RNA-Protein
C) RNA-DNA-Protein
D) DNA-Protein-RNA
E) RNA-Protein-DNA

Question 14

Transcription occurs in the ________ and translation occurs in the __________ of eukaryotic cells.

A) ribosome;nucleus
B) cytoplasm;nucleus
C) nucleus;nucleus
D) cytoplasm;cytoplasm
E) nucleus;cytoplasm

Question 15

Charles Yanofsky helped decipher the genetic code working with the _____ biosynthesis genes in _______.

A) leucine Salmonella enteritidis
B) phenylalanine Klebsiella pneumoniae
C) tryptophan Escherichia coli
D) glycine Serratia marcescens
E) lactose Escherichia coli

Question 16

Which of these terms is NOT a stop codon or a nickname for a stop codon?

A) UGA
B) UAG
C) opal
D) ochre
E) emerald

Question 17

How many different amino acids could be coded for using the synthetic mRNA sequence of (5' UGCUGCUGC 3')?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 18

Which of these is NOT a character of the genetic code?

A) All codons are the same length.
B) The code is used by nearly every living organism.
C) Some amino acids have multiple codons.
D) The code is degenerate.
E) There is the same number of codons as there are amino acids.

Question 19

Which of these is NOT a step in transcription?

A) replication
B) initiation
C) termination
D) elongation
E) unwinding

Question 20

RNA molecules that can act as enzymes and catalyze specific biochemical reactions are known as ________________.

A) donors
B) splice acceptors
C) ribozymes
D) tRNAs
E) restriction enzymes

Question 21

A mutation that changes a codon that originally coded for an amino acid into a stop codon is called a

A) frameshift mutation.
B) missense mutation.
C) silent mutation.
D) nonsense mutation.
E) dominant mutation.

Question 22

Which enzyme forms peptide bonds between adjacent amino acids during polypeptide synthesis?

A) RNA polymerase
B) phosphotransferase
C) peptidyl transferase
D) ribonuclease
E) protein polymerase

Question 23

A mutation that occurs when a base is inserted into or deleted from a DNA sequence,completely altering the subsequent amino acid sequence,is called a

A) frameshift mutation.
B) missense mutation.
C) silent mutation.
D) nonsense mutation.
E) dominant mutation.

Question 24

A mutation that is characterized by a change in the DNA sequence,but no change in the resulting protein sequence,is called a

A) frameshift mutation.
B) missense mutation.
C) silent mutation.
D) nonsense mutation.
E) dominant mutation.

Question 25

An anticodon is a physical component of a/an _______ molecule.

A) tRNA
B) mRNA
C) rRNA
D) DNA
E) antisense rRNA

Question 26

In the modification of eukaryotic mRNA,a "cap" consisting of a/an _________ and a tail consisting of _______ are usually added to the transcript.

A) acetyl group;multiple cytosines
B) multiple guanines;methyl group
C) multiple thymines;acetyl group
D) methyl group;multiple adenines
E) lipopolysaccharide;polypeptide

Question 27

Ribosomes are composed of

A) tRNA and protein.
B) mRNA and protein.
C) rRNA and protein.
D) only proteins folded together.
E) only RNA molecules folded together.

Question 28

Mutations that abolish the function encoded by the wild-type allele are known as

A) null mutations.
B) hypomorphic mutations.
C) hypermorphic mutations.
D) conditional mutations.
E) neomorphic mutations.

Question 29

Which of these processes are coupled (linked)in prokaryotes but NOT in eukaryotes?

A) transcription and translation
B) replication and transcription
C) replication and translation
D) replication,transcription,and translation are not separate in prokaryotes.
E) reverse transcription and reverse translation

Question 30

A mutation that changes a codon sequence,and subsequently changes the amino acid that should have been placed at that point in the polypeptide chain,is called a

A) frameshift mutation.
B) missense mutation.
C) silent mutation.
D) nonsense mutation.
E) dominant mutation.

Question 31

A bacterial (prokaryotic)ribosome is composed of ______ subunits.

A) 20S and 40S
B) 30S and 50S
C) 40S and 60S
D) 50S and 70S
E) 60S and 70S

Question 32

A tRNA that recognizes a nonsense codon and inserts an amino acid where protein synthesis should have stopped is called a

A) nonsense tRNA.
B) alternate tRNA.
C) revertant tRNA.
D) excision tRNA.
E) suppressor tRNA.

Question 33

A tRNA molecule looks like a compact ____ when it is folded into its functional configuration.

A) G
B) L
C) C
D) P
E) W

Question 34

Mutations that result in much less of a protein or a protein with limited function are known as

A) null mutations.
B) hypomorphic mutations.
C) hypermorphic mutations.
D) conditional mutations.
E) neomorphic mutations.

Question 35

The appearance of a novel phenotype resulting from the substitution of a single base pair might be due to

A) change in the amino acid sequence only.
B) change in the amount of protein expressed.
C) alteration in a gene that codes for a nontranslated RNA.
D) change in the developmental time or location at which a gene is expressed.
E) All of the choices are possible consequences of a single base pair substitution.

Question 36

Drugs like AZT,ddC,or ddI work against the AIDS virus because they

A) destroy viral proteins.
B) prevent the formation of viral mRNA.
C) block the action of viral tRNA.
D) look like nitrogenous bases and block viral reverse transcriptase.
E) destroy viral membranes.

Question 37

Aminoacyl-tRNA synthetase is the enzyme that

A) folds tRNA molecules into their proper configuration.
B) causes tRNA molecules to bind to the aminoacyl site of a ribosome.
C) produces tRNA by "reading" DNA molecules.
D) adds the appropriate amino acid to an uncharged tRNA.
E) acetylates histones prior to their translation.

Question 38

RNA polymerase binds to a sequence called a/an ______________ before beginning transcription.

A) promoter
B) operator
C) structural gene
D) replication origin
E) initiator

Question 39

Protein synthesis begins with the amino acid ___________ as its codon is the one used as the "start codon" by nearly all organisms.

A) methionine
B) arginine
C) cysteine
D) leucine
E) alanine

Question 40

A neomorphic mutation results in an allele that

A) produces no gene product.
B) produces a nonfunctional gene product.
C) produces novel proteins or cause inappropriate expression resulting in a new phenotype.
D) produces proteins that aggregate with wild-type subunits,inactivating them.
E) produces an altered protein that results in a wild-type phenotype.

Question 41

Assume that for a given gene a mutation creates an allele that functions as a dominant negative.The gene codes for a protein that forms a trimer within the cell.If at least one of the subunits has the mutant structure the entire protein is inactivated.For a heterozygous individual,what percent of the trimers present in the cell will be inactive?

A) 100%
B) 25%
C) 50%
D) 6.25%
E) 12.5%

Question 42

Except in reverse transcription,RNA is synthesized in a 3' to 5' fashion.

Question 43

Capping enzyme and methyl transferases are needed to add a 5' cap on mRNA.

Question 44

The genetic code is absolutely universal.

Question 45

The restoration of gene function by one mutation canceling another in the same gene is known as intragenic suppression.

Question 46

What would happen if all of the snRNAs were removed from a cell?

A) Most proteins would be longer than normal,if the cell was prokaryotic
B) Most transcripts would be abnormal,if the cell was prokaryotic
C) No translation or transcription would occur,if the cell was prokaryotic
D) Most transcripts would be shorter than normal,if the cell was eukaryotic
E) Most proteins would be abnormal,if the cell was eukaryotic

Question 47

Ectopic expression is when a protein is produced outside of its normal place or time.

Question 48

Nonsense codon and stop codon are synonymous.

Question 49

What is a leading theory for the existence of introns?

A) Introns are produced by insertion of viral genomes.
B) Introns accelerate RNA translation.
C) Introns facilitate protein evolution and adaptation.
D) Introns accelerate RNA transcription.
E) Introns are inherited in evolution from prokaryotes.

Question 50

What would happen in a cell that completely lacked aminoacyl-tRNA synthetases?

A) No charged tRNAs would be present in the cell.
B) Transcription would initiate,but elongation would not occur.
C) Translation would be initiated,but elongation would not occur.
D) Peptide elongation would occur,but termination would not occur.
E) RNA elongation would occur,but termination would not occur.

Question 51

The genetic code is described as nearly universal,degenerate,and non-overlapping.Briefly describe what each of these properties refers to.

Question 52

In most splice donor sites a G U dinucleotide sequence is flanked by a couple of 5' and 3' purine bases.

Question 53

rRNA carries an anticodon,which is the complementary sequence to the mRNA codon that specifies a particular amino acid.

Question 54

In vitro translation allows the determination of protein sequence.

Question 55

Exons are excised from mRNA.

Question 56

A neomorphic dominant mutation in the Antennapedia (Antp)gene of Drosophila causes

A) kinks to form in their tails.
B) shortened tails.
C) total loss of colour vision.
D) failure to assemble microtubules during mitosis.
E) growth of a leg from the head region.

Question 57

Three short sequences found within the primary transcript that are required for splicing are splice donors,splice acceptors,and branch sites.

Question 58

The template and RNA-like DNA strand are equivalent.

Question 59

As compared to subunit vaccines,what is the main advantage of the "killed whole virus" HIV vaccine under development in Canada?

A) The whole virus is more stable than the subunit vaccine.
B) The whole virus is less expensive than the subunit vaccine.
C) The whole virus has fewer side effects than the subunit vaccine.
D) The immune system learns to recognize more viral proteins when exposed to the whole virus.
E) The subunit vaccine is only effective in individuals from certain ethnic backgrounds.

Question 60

Frameshift mutations occur when the number of bases inserted or deleted is not a multiple of three.

Question 61

Describe nonsense suppression.

Question 62

Describe how the "wobble" theory applies to protein synthesis.

Question 63

You are a graduate student working for a mentor whose research is top secret.You are asked to complete in vitro translation experiments using top-secret cell cultures to determine a genetic code for what you believe are cells isolated from extraterrestrial life.Given that you have determined that the nucleotides in the DNA are the same as on earth but the cells contain 10 unique amino acids,describe how you would definitively determine the genetic code of the "extraterrestrial" cells.

Question 64

Hypothetically speaking,a particular protein named GOTEAM is 1,000 amino acids and is known to be involved in the phenotype,"avid football fan." Some individuals have been genotyped and were found to have a deletion of 2 nucleotides near the 5' end of the GOTEAM gene.Other individuals have been found to have a deletion of 99 bases in the same region.What is the length of GOTEAM gene? Which mutation do you think would be more likely to be the most deleterious to the GOTEAM phenotype?

Question 65

Design an experiment to show that the amino acid carried by a tRNA does not influence the genetic code.

Question 66

What does reverse transcriptase do?

Question 67

What is a null mutation?

Question 68

How does compartmentalization of transcription and translation lead to differences between prokaryotes and eukaryotes?

Question 69

Outline the steps of translation in prokaryotes.

Question 70

In your studies of an unusual prokaryotic organism,you have cloned and sequenced an interesting gene and the protein that it codes.Although you have sequenced the gene several times,the start codon is always read as GTG instead of ATG.How do you interpret this result?

Question 71

What are silent,missense,and nonsense mutations? Compared to control wild-type samples,how would each mutation affect the outcome of Northern and Western analyses?

Question 72

What is alternative splicing and how does it occur?

Question 73

Distinguish between neomorphic,hypomorphic,and hypermorphic mutations.

Question 74

Why are the genes for rRNA,tRNA,and snRNAs transcribed but not translated?

Question 75

Briefly describe the events of transcription in a living cell.

Question 76

Describe the process of splicing in eukaryotic RNA molecules.