Deck 15: How Genes Work

Question 1

The proteome is all the proteins produced by an organism.The genome is the totality of all genes of an organism.If the proteome is much larger than the genome,which of the following statements would be accurate?

A)This finding lends support to the one gene-one enzyme hypothesis.
B)The number of monomeric subunits found in proteins is fewer than the number of monomeric subunits found in genes.
C)At least in some cases,a single gene must code for more than one protein.
D)Noncoding DNA is important in determining the proteome.

Answer 1

C

Question 2

Which of the following observations may have resulted in the hypothesis that a codon is made up of three bases?

A)A codon of 2 bases in length,from 4 different bases,would code for a maximum of 16 different amino acids;therefore,2 are too few.
B)A codon of 3 bases in length,from 4 different bases,would code for a maximum of 12 different amino acids;therefore 3 are too few.
C)A codon of 4 bases in length,from 4 different bases,could code for a maximum of 24 different amino acids;therefore,4 is likely.
D)A codon of 3 bases in length,from 4 different bases,would code for a maximum of 64 different amino acids;therefore,3 is possible.

Answer 2

D

Question 3

In the process of transcription,

A)DNA is replicated.
B)RNA is synthesized.
C)proteins are synthesized.
D)mRNA attaches to ribosomes.

Answer 3

B

Question 4

What is a codon?

A)the base sequence of the tRNA that brings the correct amino acid to the ribosome where protein synthesis will take place
B)the amino acetyl tRNA synthase that ensures that the correct amino acid is added to the right tRNA
C)the three-base sequence of mRNA that specifies the addition of a specific amino acid
D)the complementarity of DNA and RNA

Question 5

Knockout mice have been genetically altered to knock out specific genes.How are these mice most often used in research?

A)to study DNA replication in the defective genes (those that have been altered)
B)to determine the role of proteins coded for by those genes that are knocked out
C)to examine defects in DNA structure in those regions that have been altered
D)to study the effect of radiation on DNA

Question 6

Which molecule carries the message from the DNA in the nucleus to the cytoplasm where the code is translated?

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

Question 7

Which of the following is NOT synthesized from a DNA template?

A)messenger RNA
B)amino acids
C)tRNA
D)ribosomal RNA

Question 8

Figure 15.3
Above is a metabolic pathway for the synthesis of an amino acid (E), without which an organism could not live. Enzymes are represented by numbers, and substrates by letters. Use this figure for the next two questions.
According to the figure above,if enzyme 3 was nonfunctional in an organism,which of the following outcomes would you predict?

A)The cell would die because of a lack of the essential amino acid.
B)Another enzyme would be able to catalyze the reaction and the pathway would proceed.
C)Substrate C would accumulate,and there would be no substrate D formed.
D)Lack of enzyme 3 would result in a cessation (halt)of the entire metabolic pathway.

Question 9

How might a single base substitution in the sequence of a gene affect the amino acid sequence of a protein encoded by the gene,and why?

A)Only a single amino acid could change,because the reading frame is unaffected.
B)The amino acid sequence would be substantially altered,because the reading frame would change with a single base substitution.
C)All amino acids following the substitution would be affected,because the reading frame would be shifted.
D)It is not possible for a single base substitution to affect protein structure,because each codon is three bases long.

Question 10

Beadle discovered that metabolic pathways are studied most effectively using which of the following techniques?

A)gene amplification
B)adding additional intermediates of the metabolic pathway
C)adding energy in the form of ATP
D)creating single gene mutations resulting in nonfunctional enzymes specific to a metabolic pathway

Question 11

Figure 15.5
Refer to Figure 15.4.Homocystinuria is a genetic disorder that results from a defect in one of the enzymes of the metabolic pathway shown.The gene for which enzyme/molecule is most likely defective?

A)methylenetetrahydrofolate reductase
B)methionine synthase
C)tetrahydrofolate reductase
D)cystathione beta synthase

Question 12

In the Morse code,a series of dots and dashes code for letters of the alphabet.How is this analogous to the genetic code?

A)There is complementarity in the genetic code (A is complementary to T,and C is complementary to
B)The bases that make up DNA are associated by hydrogen bonds.
C)The machinery involved in DNA synthesis is analogous to the telegraph equipment used in sending Morse code.
D)The bases of DNA code for the more complex amino acid sequence of the various proteins found in cells.
G))

Question 13

Figure 15.2
Refer to Figure 15.2.In the branched metabolic pathway,if enzyme 3 is defective,you might expect to see an increase in the amount of which intermediate/product?

A)E
B)F
C)D
D)A

Question 14

Which of the following contradicts the "one-gene,one-enzyme hypothesis"?

A)A mutation in a single gene can result in a defective protein.
B)Alkaptonuria results when individuals lack a single enzyme involved in the catalysis of homogentisic acid.
C)Sickle-cell anemia results in defective hemoglobin.
D)A single antibody gene can code for different related proteins,depending on the splicing that takes place post-transcriptionally.

Question 15

Codons,the three base sequences that code for specific amino acids,are part of

A)protein.
B)mRNA.
C)tRNA.
D)rRNA.

Question 16

Figure 15.4
Given the DNA template shown above,which of the following bases would you find in a complementary RNA strand?

A)A-A-A-A-A
B)U-U-U-U-U
C)T-T-T-T-T
D)G-C-G-C-G

Question 17

Homogentisic acid would accumulate under which of the following conditions?

A)a deficiency of p-hydroxyphenolypyruvate
B)defective enzyme 1
C)defective enzyme 2
D)a deficiency of 4-maleylacetoacetic acid

Question 18

Figure 15.2
Refer to Figure 15.2.A branched metabolic pathway synthesizes two related amino acids (D and

A)Supplement intermediate B.
B)Supplement intermediate C.
C)Add enzyme 2 to the medium.
D)Supplement with intermediate E.
F))If there is a genetic defect,resulting in a nonfunctional enzyme (3),how could you ensure that adequate amounts of the amino acid F are synthesized?

Question 19

Figure 15.3
Above is a metabolic pathway for the synthesis of an amino acid (E), without which an organism could not live. Enzymes are represented by numbers, and substrates by letters. Use this figure for the next two questions.
Refer to the figure above.If an organism is given E in their diet,they survive.However,if the same organism is given only substrate A,B,C,or D in their diet,they die.Which of the enzymes is most likely defective?

A)Enzyme 1
B)Enzyme 2
C)Enzyme 3
D)Enzyme 4

Question 20

What molecule serves as a link between the information-containing macromolecule,DNA,and protein synthesis?

A)rRNA
B)tRNA
C)mRNA
D)snRNA

Question 21

The HIV virus that causes AIDS is a retrovirus.What is a retrovirus?

A)a DNA virus that uses DNA as a template in the process of translation
B)an RNA virus that makes proteins directly from RNA
C)an RNA virus that has reverse transcriptase,enabling it to make DNA from RNA
D)a DNA virus that is acellular and is able to reproduce outside a living cell

Question 22

The term "point" in point mutation is in reference to which of the following?

A)It affects an organism once during its lifespan.
B)If affects only one nucleotide.
C)It affects only one type of chromosome
D)It affects only one protein in the body.

Question 23

For a hypothetical gene,how do the terms dominance and recessive relate to gene expression and how genes work?

A)The allele with the dominant phenotype inhibits transcription of the allele for the recessive phenotype.
B)Both alleles get expressed,but the product of the allele with the dominant phenotype masks the phenotype of the recessive allele.
C)A dominant phenotype results in the expression of the most beneficial genes resulting in increased chances of survival of the organism.

Question 24

The original DNA has the base sequence AGCGTTACCGT;a mutation in the DNA strand results in the base sequence AGGCGTTACCGT.What does this tell you about the mutation?

A)It was caused by radiation poisoning.
B)It may result in a single amino acid change in the protein being coded for by this base sequence.
C)There is no mutation.
D)It is a frameshift mutation.

Question 25

What feature makes organisms less vulnerable to small mutations in DNA replication that are not corrected?

A)alternative splicing
B)redundancy in the genetic code
C)differential gene expression
D)pleiotropy

Question 26

The statement,DNA → RNA → Proteins,

A)has become known as the central dogma.
B)depicts the regulation of gene expression.
C)is reversible in most living organisms.
D)describes a series of catalytic reactions.

Question 27

The central dogma has been challenged on several levels (e.g.,the discovery of RNA viruses,which use their RNA to directly synthesize proteins,and the discovery of reverse transcriptase,which makes DNA from RNA).Which of the following is another example of an exception to the central dogma?

A)DNA from viruses can insert themselves into host cell chromosomes.
B)Chaperone molecules guide the folding of protein molecules.
C)Gene mutations result in altered amino acid sequences of proteins.
D)Prions are infectious protein molecules capable of altering the folding of normal proteins.

Question 28

What does it mean when we say the genetic code is redundant?

A)A single codon can specify the addition of more than one amino acid.
B)The genetic code is different for different domains of organisms.
C)The genetic code is universal (the same for all organisms).
D)More than one codon can specify the addition of the same amino acid.

Question 29

When is a single base substitution mutation least likely to be deleterious?

A)when the single base change results in a stop codon
B)when the single base change results in a codon that specifies the same amino acid as the original codon
C)when the base change results in an amino acid substitution that alters the tertiary structure of the protein
D)when the base change results in an amino acid substitution at the active site of an enzyme

Question 30

Figure 15.6 Use the figure to answer the following question(s).

Refer to Figure 15.5.If you had an mRNA for which the codons were read beginning from the start codon,which amino acids would be added (in order)? UCUGAUGGGCUUU…

A)serine,aspartic acid,glycine,leucine
B)methionine,glycine,phenylalanine
C)methionine,valine,glycine,phenylalanine
D)threonine,methionine,glycine

Question 31

Genotype is to ________ as phenotype is to ________.

A)DNA base sequence;amino acid sequence
B)heredity;DNA base sequence
C)gene regulation;translation
D)transcription;amino acid sequence

Question 32

According to the central dogma,what molecule should go in the blank? DNA → ________ → Proteins

A)complementary DNA
B)transport molecules
C)mRNA
D)chaperone molecules

Question 33

Which of the following findings violated the central dogma?

A)the discovery of RNA viruses that synthesize DNA using reverse transcriptase
B)he discovery that the Archaea and Bacteria are more distantly related than Achaea and Eukarya
C)the discovery of ribozymes
D)the discovery of DNA as the unit of genetic inheritance

Question 34

Figure 15.6 Use the figure to answer the following question(s).

All three domains (Bacteria,Archaea,and Eukarya)follow the same genetic code.Which of the following statements would most likely be accurate given that information?

A)The genetic code evolved three times.
B)The genetic code evolved before DNA replaced RNA as the unit of genetic information.
C)There were no mutations following the evolution of the genetic code.
D)The genetic code evolved before the different domains diverged.

Question 35

The synthesis of RNA through complementary base pairing is known as

A)semiconservative replication.
B)dispersive polymerization.
C)transcription.
D)translation.

Question 36

Once researchers identified DNA as the unit of inheritance,they asked how information was transferred from the DNA in the nucleus to the site of protein synthesis in the cytoplasm.What is the mechanism of information transfer?

A)DNA from a single gene is replicated and transferred to the cytoplasm,where it serves as a template for protein synthesis.
B)Messenger RNA is transcribed from a single gene and transfers information from the DNA in the nucleus to the cytoplasm,where protein synthesis takes place.
C)Proteins transfer information from the nucleus to the ribosome,where protein synthesis takes place.
D)Lipids are soluble in the nuclear membrane and serve to transfer information from the DNA to the cytoplasm,where protein synthesis takes place.

Question 37

There are three stop codons (nonsense codons);all remaining codons specify addition of an amino acid (sense codons).How many sense codons are there?

A)20
B)45
C)61
D)72

Question 38

Figure 15.6 Use the figure to answer the following question(s).

Refer to Figure 15.5.Transfer RNA contains the anticodon XXX (three-base sequence that is complementary to the mRNA codon).tRNA with which anticodon would transport phenylalanine to the ribosome?

A)UUU
B)AAA
C)TTT
D)CCC

Question 39

Figure 15.6 Use the figure to answer the following question(s).

Refer to Figure 15.5.If the codon CAC was present in the ribosome A site,which amino acid would be added?

A)phenylalanine
B)methionine
C)aspartic acid
D)histidine