Deck 15: Genes and How They Work

Question 1

A codon is composed of how many bases?

A)one
B)two
C)three
D)four
E)64

Answer 1

C

Question 2

The connection that exists between genes and hereditary traits is based on using the information encoded in genes to synthesize

A)codons.
B)nucleotides.
C)proteins.
D)histones.
E)complementary bases.

Answer 2

C

Question 3

Gene expression involves two phases,________ and translation.

A)replication
B)transcription
C)initiation
D)condensation

Answer 3

B

Question 4

During transcription of mRNA in eukaryotes,some sequences are cut out of the primary transcript and the remaining sequences are joined together.This processing of mRNA is called ________.

A)termination
B)translation
C)splicing
D)capping
E)elongation

Question 5

During translation,amino acids are carried to the ribosome by

A)mRNA.
B)tRNA.
C)snRNA.
D)rRNA.
E)miRNA.

Question 6

Most eukaryotic genes contain noncoding sequences called ________ that are interspersed with the coding sequences.

A)introns
B)exons
C)codons
D)spacers
E)spliceosomes

Question 7

The polypeptide-making organelles,which consist of protein combined with RNA,are called

A)ribosomes.
B)Golgi bodies.
C)lysosomes.
D)centrosomes.
E)mitochondria.

Question 8

During ________,RNA polymerase synthesizes a molecule of RNA using DNA as a template.

A)mRNA splicing
B)translation
C)transcription
D)gene sequencing
E)termination

Question 9

DNA affects the traits of an organism by providing the instructions for synthesizing _______.

A)proteins
B)nucleotides
C)codons
D)amino acids

Question 10

Which base in an anticodon will pair with the base adenine in a codon?

A)thymine
B)cytosine
C)guanine
D)uracil

Question 11

Crick and his colleagues proposed that the genetic code consists of a series of blocks of information,called ________,each corresponding to one amino acid in an encoded protein.

A)alleles
B)codons
C)genes
D)polypeptides

Question 12

Messenger RNA molecules contain information that is used to synthesize ________.

A)nucleotides
B)amino acids
C)polypeptides
D)fatty acids

Question 13

During ________,a ribosome assembles a polypeptide whose amino acid sequence is specified by the nucleotide sequence in a molecule of mRNA.

A)transcription
B)translation
C)replication
D)posttranscriptional modification

Question 14

Both DNA and RNA are made up of building blocks known as

A)nucleotides.
B)nucleic acids.
C)amino acids.
D)genes.
E)codons.

Question 15

The "one-gene/one-enzyme" hypothesis was proposed by

A)Watson and Crick.
B)Griffith.
C)Garrod.
D)Franklin.
E)Beadle and Tatum.

Question 16

Gene ________ refers to the combined processes of transcription and translation.

A)expression
B)replication
C)modification
D)regulation

Question 17

The strand of DNA that is not transcribed is called the ________ strand.

A)coding
B)noncoding
C)template
D)complementary

Question 18

The sequence of nucleotides in a DNA molecule is called the ________ code.

A)protein
B)ribosomal
C)translation
D)genetic
E)amino acid

Question 19

To remove noncoding sequences in the pre-mRNA of eukaryotes,multiple snRNPs combine with proteins to form a larger complex called the ________.

A)5' cap
B)introsome
C)ribosome
D)spliceosome
E)3' poly-A tail

Question 20

To begin transcription,RNA polymerase must bind to a segment of DNA called the ________.

A)initiation site
B)primer
C)inducer
D)promoter
E)transcription bubble

Question 21

During ________,nucleotide sequence information is changed into amino acid sequence information.

A)replication
B)sequencing
C)transcription
D)translocation
E)translation

Question 22

During translation,the nucleotides that make up the mRNA are read in groups of three.These groups are called

A)codons.
B)anticodons.
C)exons.
D)introns.
E)templates.

Question 23

The location of translation in prokaryotic cells is

A)in the nucleoid.
B)on ribosomes.
C)on the plasma membrane.
D)on mesosomes.
E)on chromosomes

Question 24

Codons that serve as "stop" signals for translation are recognized by

A)tRNA.
B)release factors.
C)anticodons.
D)translation terminators.
E)aminoacyl-tRNA synthetases

Question 25

The A,P,and E sites are progressively occupied by amino acids being assembled into a polypeptide.These sites are part of

A)DNA.
B)the large ribosomal subunit.
C)mRNA.
D)tRNA.
E)the spliceosome.

Question 26

In prokaryotes,the form of RNA polymerase that can accurately initiate synthesis of RNA is called

A)the holoenzyme.
B)the core polymerase.
C)RNA polymerase II.
D)RNA polymerase III.
E)the sigma subunit.

Question 27

Eukaryotic mRNA molecules may contain noncoding sequences that must be removed before translation.These are called

A)anticodons.
B)introns.
C)exons.
D)nucleosomes.
E)noncodons.

Question 28

Which statement about the genetic code is false?

A)There is no punctuation or spacing between codons.
B)Nucleotides are always read in groups of three.
C)Every codon codes for one amino acid.
D)Some amino acids are specified by more than one codon.
E)The genetic code is almost universal,but not quite.

Question 29

Ribosome movement along the mRNA is called

A)transcription.
B)initiation.
C)replication.
D)translocation.
E)activation.

Question 30

During translation in prokaryotes,formation of the initiation complex requires all of the following except

A)a small ribosomal subunit.
B)mRNA.
C)tRNA charged with N-formylmethionine.
D)RNA polymerase.
E)initiation factors.

Question 31

Ribosomes are complex aggregates of

A)RNA and DNA.
B)RNA and proteins.
C)RNA and sugars.
D)DNA and proteins.
E)nucleosomes and RNA.

Question 32

When a polypeptide is being assembled,the bond that forms between a newly added amino acid and the previous amino acid in the chain is a ________ bond.

A)hydrogen
B)hydrophobic
C)terminal
D)phosphodiester
E)peptide

Question 33

The tRNA nucleotide sequence that pairs with bases on the mRNA is called a(n)

A)intron.
B)exon.
C)codon.
D)initiation factor.
E)anticodon.

Question 34

The genetic code uses ________ nucleotide(s)to specify one amino acid.

A)one
B)two
C)three
D)four
E)64

Question 35

In eukaryotes,pre-mRNA processing may involve all of the following except

A)removal of exons from the pre-mRNA.
B)addition of a 5' cap.
C)addition of a 3' poly-A tail
D)pre-mRNA splicing by the spliceosome.

Question 36

In eukaryotes,translation takes place

A)on the plasma membrane.
B)inside the nucleus.
C)on ribosomes.
D)on the nuclear membrane.
E)on spliceosomes.

Question 37

During translation,uncharged tRNA molecules leave the ribosome from the ________ site.

A)E
B)P
C)A
D)termination
E)release

Question 38

In eukaryotic cells,transcription occurs

A)on the surface of the nuclear membrane.
B)on ribosomes.
C)on spliceosomes.
D)inside the nucleus.
E)on the surface of the plasma membrane.

Question 39

How many unique mRNA codons can be constructed from the four different RNA nucleotides?

A)four
B)12
C)16
D)61
E)64

Question 40

Specific amino acids are attached to tRNA molecules by

A)aminoacyl-tRNA synthetases.
B)hydrogen bonds.
C)anticodons.
D)deactivating enzymes.
E)initiation factors.

Question 41

Although 61 different codons code for amino acids,cells contain fewer than 61 different tRNAs.Why?

A)Because the 5' base on the tRNA anticodon has some flexibility (wobble); thus,some tRNA anticodons can pair with more than one mRNA codon.
B)Although 61 different codons code for amino acids,any given cell contains fewer than 61.
C)Because the 5' base on the mRNA codon has some flexibility (wobble); thus,some mRNA codons can pair with more than one tRNA anticodon.
D)Because each amino acid is coded for by just one codon.

Question 42

During translation,translocation refers to

A)releasing a tRNA molecule from the ribosome.
B)joining an amino acid to a tRNA molecule.
C)joining an amino acid to the next amino acid in the chain.
D)joining a tRNA molecule to the ribosome.
E)moving the ribosome along the mRNA molecule.

Question 43

In eukaryotes,the 3' poly-A tail is attached to

A)poly-A polymerase.
B)mRNA.
C)tRNA.
D)the ribosome.
E)the template strand of DNA.

Question 44

What is the first step during transcription initiation in prokaryotes?

A)the transcription bubble is formed
B)RNA polymerase binds to the promoter
C)the DNA double helix is unwound
D)RNA polymerase synthesizes a short primer
E)transcription factors bind to the TATA box sequence

Question 45

If the sequence of bases in the template strand of a DNA molecule is 3' ATCGCTCC 5',what is the sequence of bases in the RNA that is transcribed from this molecule?

A)3' UAGCGAGG 5'
B)3' TAGCGAGG 5'
C)5' UAGCGAGG 3'
D)5' TAGCGAGG 3'
E)5' AUCGCUCC 3'

Question 46

Transcription in prokaryotes is carried out by ________,which unwind(s)and transcribe(s)the gene.

A)RNA synthetase
B)RNA polymerase II
C)RNA polymerase III
D)transcription factors
E)RNA polymerase

Question 47

In eukaryotes,each type of RNA polymerase recognizes a different

A)start codon
B)stop codon
C)promoter
D)release factor
E)transcription factor

Question 48

The Central Dogma of biology can be stated as

A)proteins→ RNA→ DNA.
B)RNA→ DNA→ proteins.
C)DNA→ proteins→ RNA.
D)DNA→ RNA→ proteins.

Question 49

Eukaryotic pre-mRNA molecules are modified

A)in the cytoplasm.
B)at the ribosome.
C)inside the nucleus.
D)as they pass through the nuclear membrane.
E)at the transcription bubble.

Question 50

Which molecule combines with proteins to form both the large and small ribosomal subunits?

A)DNA
B)RNA polymerase
C)miRNA
D)rRNA
E)tRNA

Question 51

The template strand of a DNA segment that codes for mRNA has the sequence: ATGCGT.Which tRNA anticodons would pair with the mRNA that is coded for by this sequence?

A)AUG CGU.
B)ATG CGT.
C)UAC GCA.
D)UAG CGU.

Question 52

During protein synthesis in eukaryotes,what happens during RNA splicing?

A)The product of translation,called the primary transcript,is cut and some pieces are joined back together to form the mature mRNA.
B)The product of transcription,called the primary transcript,is cut and some pieces are joined back together to form the mature tRNA.
C)The product of transcription,called the secondary transcript,is cut and some pieces are joined back together to form the mature mRNA.
D)The product of transcription,called the primary transcript,is cut and some pieces are joined back together to form the mature mRNA.
E)The product of transcription,called the primary transcript,is cut and all pieces are joined back together to form the mature mRNA.

Question 53

What would happen if snRNPs did not recognize the branch point within an intron?

A)A lariat would not form.
B)snRNPs would not base-pair with the 5' end of the intron.
C)A 3' poly A tail would not be added to the transcript.
D)A 5' cap would not be added to the transcript.

Question 54

Eukaryotic and prokaryotic organisms differ in how they process genetic information.Which statements best explain one of these differences?

A)In prokaryotes,translation of the mRNA begins before transcription is complete.In eukaryotes,transcription and modification of the mRNA is completed before translation begins.
B)In prokaryotes,genes are transcribed directly into polypeptides.In eukaryotes,genes are transcribed into RNA which is used to assemble polypeptides.
C)In prokaryotes,translation occurs before genes are transcribed into mRNA.In eukaryotes,genes are transcribed into mRNA which is then translated into polypeptides.
D)In prokaryotes,introns are removed before genes are transcribed into mRNA.In eukaryotes,introns are removed after genes are transcribed into mRNA.

Question 55

Initiation of transcription differs from initiation of DNA replication in several ways.One difference is that initiation of transcription does not require

A)a promoter.
B)enzymes.
C)a primer.
D)a DNA template strand.

Question 56

Why are there fewer tRNA anticodons than the 61 needed to match each mRNA codon that codes for an amino acid?

A)There is some flexibility in pairing between the 5' base of the codon and the 3' base of the anticodon.
B)There is some flexibility in pairing between the middle base of the codon and the middle base of the anticodon.
C)There is some flexibility in pairing between the 3' base of the codon and the 5' base of the anticodon.
D)There is some flexibility in pairing between all 3 bases of the codon and all 3 bases of the anticodon.

Question 57

During the splicing reaction,the intron-exon junctions are recognized by

A)snRNPs.
B)miRNAs.
C)SRP RNAs.
D)the lariat.
E)the branch point.

Question 58

During protein synthesis in eukaryotes,which molecule passes from the nucleus to the cytoplasm and specifies the sequence of amino acids in the new polypeptide?

A)DNA
B)RNA polymerase
C)mRNA
D)rRNA
E)tRNA

Question 59

Given the sentence "THE FAT CAT ATE THE RED RAT," which of the following would represent a frameshift mutation?

A)THE FAT RAT ATE THE RED CAT
B)THE CAT ATE THE RED RAT
C)THE FAC ATA TET HER EDR AT
D)THE FAT CAT ATE THE RED RAT

Question 60

Eukaryotes have ________ type(s)of RNA polymerase.

A)two
B)three
C)four
D)one
E)64

Question 61

How would a large chromosomal inversion affect the expression of a gene if the gene is located between the two break points but no breaks occur within the gene?

A)The inversion would probably have no effect on gene expression.
B)The gene would not be transcribed because it would be oriented in the wrong direction.
C)The gene would be transcribed in the 3' to 5' direction.
D)The gene would be transcribed normally but the mRNA would be translated in the 3' to 5' direction.

Question 62

A scientist makes three artificial mRNA strands: (x)5' AAAUUUAAAUUUAAAUUUAAAUUUAAA 3'
(y)5' UUUCCCUUUCCCUUUCCCUUUCCCUUU 3'
(z)5' AUAUAUAUAUAUAUAUAUAUAUAUAU 3'
When he analyzes the polypeptides produced,he finds that:
X produces a polypeptide that is 50% phenylalanine and 50%lysine.
Y produces a polypeptide that is 50% phenylalanine and 50% proline.
Z produces a polypeptide that is 50% isoleucine and 50% tyrosine.
Based on these results only,the best conclusion to make is that

A)AUA codes for isoleucine
B)AAA codes for phenylalanine
C)AAA codes for lysine
D)AAA codes for lysine and AUA codes for isoleucine
E)AAA codes for phenylalanine and AUA codes for isoleucine

Question 63

What is the likely consequence of a mutation that alters the branch point within an intron?

A)no effect,since introns are not expressed
B)failure to form a lariat
C)failure of snRNPs to recognize the 5' end of intron
D)no exon shuffling
E)failure of snRNAs to combine with protein and form snRNPs

Question 64

How does DNA polymerase differ from RNA polymerase?

A)Only RNA polymerase adds new nucleotides to the 3' end of a growing chain.
B)Only RNA polymerase requires a primer.
C)Only DNA polymerase uses a template DNA strand to direct synthesis of a new nucleotide strand.
D)Only DNA polymerase has a proofreading ability.

Question 65

The mutation responsible for Huntington's disease is a

A)missense mutation.
B)nonsense mutation.
C)frameshift mutation.
D)triplet repeat expansion mutation.

Question 66

You are attempting to synthesize rRNA in a test tube using DNA isolated from mouse cells.In addition to the template DNA,ribonucleotides,and the necessary transcription factors,you should also add ________ to the test tube.

A)poly-A polymerase
B)RNA polymerase III
C)RNA polymerase II
D)RNA polymerase I

Question 67

Analysis of a bacterial gene indicates that 24% of the nucleotides in the coding strand contain the base A,18% contain the base T,26% contain the base G,and 32% contain the base C.What percent of the nucleotides in the mRNA transcribed from this gene will contain the base U? (Enter your answer as a number only without the percent sign,e.g.enter 5 not 5%.)

Question 68

In prokaryotes,the RNA polymerase holoenzyme consists of

A)the core polymerase plus two alpha subunits.
B)the core polymerase plus two beta subunits.
C)the core polymerase plus two alpha subunits,two beta subunits,and a sigma subunit.
D)the core polymerase plus a sigma subunit.
E)two alpha subunits,two beta subunits,and two sigma subunits.

Question 69

You are working to characterize a novel protein in mice.Analysis shows that high levels of the primary transcript that codes for this protein are found in tissue from the brain,muscle,liver,and pancreas.However,an antibody that recognizes the C-terminal portion of the protein indicates that the protein is present in brain,muscle,and liver,but not in the pancreas.What is the most likely explanation for this result?

A)The gene that codes for this protein is not transcribed in the pancreas.
B)The transcript is immediately degraded in the pancreas.
C)The transcript receives a 5' cap in the pancreas.
D)Alternative splicing in the pancreas creates a protein missing the domain that the antibody recognizes.
E)The transcript receives a 3' poly-A tail in the pancreas.

Question 70

Within the transcription bubble,the 9 most recently added nucleotides in the newly synthesized RNA strand temporarily form a helix with the template DNA strand.How might transcription be affected if helix formation did not occur?

A)Rewinding the DNA molecule would be inhibited.
B)Unwinding the DNA molecule would be inhibited.
C)The position of the 5' end of the RNA would be unstable,inhibiting elongation.
D)The position of the 3' end of the RNA would be unstable,inhibiting elongation.
E)The position of the 5' end of the RNA would be unstable,stimulating elongation.

Question 71

What is the best way to describe our current understanding of the one-gene/one-polypeptide hypothesis?

A)It continues to be an accurate description of how genes work.
B)It is oversimplified,especially in eukaryotes.
C)It has been replaced by the more accurate "one-gene/one-enzyme" hypothesis.
D)It was true for fungi like Neurospora,but not for other species.

Question 72

Cells conserve energy and resources by making active proteins only when they are needed.If a protein is not needed,which of the following methods of control would be the most energy-efficient?

A)block transcription
B)degrade the mRNA after it is made
C)prevent translation of the mRNA
D)degrade the protein after it is made

Question 73

You are excited because your lab is studying the first microorganisms retrieved from Mars! Interestingly,their genetic material consists of a single-stranded nucleic acid with six different nitrogenous bases.Like organisms from Earth,segments of the nucleic acid contain the code for making proteins.If the genetic code in these organisms was read in groups of 2 bases instead of 3,what is the maximum number of amino acids that could be coded for assuming that only one codon functioned as a stop codon? (Enter your answer as a numeral not a word,e.g.enter 17 not seventeen.)

Question 74

Two 6-base sequences are present in bacterial promoters: TATAAT (located 10 nt upstream from the start site)and TTGACA (located 35 nt upstream from the start site).What is the significance of the fact that these two base sequences are different?

A)Binding sites for both the holoenzyme and ATP are provided.
B)Both the location of the start site and the direction of transcription can be established.
C)Binding sites for both the core polymerase and holoenzyme are provided.
D)The transcription bubble can be properly formed.
E)It allows RNA polymerase to distinguish between the template strand and the coding strand of the DNA molecule.

Question 75

If the genetic code were read in groups of two bases,how many different codons would be possible? (Enter your answer as a numeral not a word,e.g.enter 5 not "five".)

Question 76

You are studying an individual with very low levels of insulin in her blood.Further analysis indicates that cells of her pancreas are producing normal levels of this protein,but it is accumulating in the cytoplasm rather than being secreted from the cells.Which hypothesis makes the most sense to explain this observation?

A)A small deletion has removed the nucleotides that code for the signal sequence at the amino terminus of the protein.
B)A missense mutation has caused premature termination during translation of this protein.
C)A chromosomal segment that includes the gene for insulin has been inverted.
D)A two-base deletion near the middle of the gene has altered the reading frame during translation of the protein.
E)A missense mutation has altered the ribosome-binding sequence at the 5' end of the mRNA.

Question 77

A gene that codes for a protein was removed from a eukaryotic cell and inserted into a prokaryotic cell.Although the gene was successfully transcribed and translated,it produced a different protein than it produced in the eukaryotic cell.What is the most likely explanation?

A)There are slight differences in the genetic code for prokaryotes and eukaryotes.
B)Unlike eukaryotes,which have three different RNA polymerases,prokaryotes have a single RNA polymerase.
C)Eukaryotic genes often contain introns while prokaryotic genes do not.
D)Eukaryotic transcripts have a 5' cap while prokaryotic transcripts do not.

Question 78

What is required for formation of the transcription initiation complex in eukaryotes?

A)binding of a transcription factor to the TATA box,followed by recruitment of additional transcription factors and recruitment of RNA polymerase II
B)binding of a transcription factor to the transcription bubble,followed by recruitment of additional transcription factors and recruitment of RNA polymerase III
C)binding of the sigma subunit to the start site followed by recruitment of RNA polymerase II
D)binding of RNA polymerase II to the TATA box,followed by recruitment of transcription factors
E)binding of the sigma subunit to promoter elements at -35 and -10,followed by recruitment of the core polymerase

Question 79

A bacterial cell has a nonsense mutation that prevents it from producing a functional sigma subunit for RNA polymerase.Inability to synthesize a functional sigma subunit would have the most direct effect on

A)transcription initiation.
B)transcription elongation.
C)transcription termination.
D)translation initiation.
E)translation termination.