Deck 16: How Genes Work

Question 1

Figure 16.2

-Refer to Figure 16.2. A branched metabolic pathway synthesizes two related amino acids D and 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?

A) Add enzyme 2 to the medium.
B) Supplement intermediate C.
C) Supplement intermediate B.
D) Supplement with intermediate E.

Answer 1

Supplement with intermediate E.

Question 2

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

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

Answer 2

C

Question 3

Figure 16.1
$\begin{array}{|l|l|l|l|l|}\hline \text { Mutant Strain } & \text { Medium with: } & \text { Medium with: } & \text { Medium with: } & \text { Medium with: } \\& \text { No ornithine } & \text { Ornithine } & \text { No ornithine } & \text { No ornithine } \\& \text { No citrulline } & \text { No citrulline } & \text { Citrulline } & \text { No citrulline } \\& \text { No arginine } & \text { No arginine } & \text { No Arginine } & \text { Arginine } \\\hline \text { argl } & \text { no growth } & \text { GROWTH } & \text { GROWTH } & \text { GROWTH } \\\hline \text { arg2 } & \text { no growth } & \text { no growth } & \text { GROWTH } & \text { GROWTH } \\\hline \text { arg3 } & \text { no growth } & \text { no growth } & \text { no growth } & \text { GROWTH } \\\hline\end{array}$

-According to the table and Figure 16.1, which enzyme is defective in the strain with the arg2 mutation?

A) the enzyme that converts ornithine to citrulline
B) the enzyme that converts the precursor to ornithine
C) the enzyme that converts the precursor to citrulline
D) the enzyme that converts citrulline to arginine

Answer 3

the enzyme that converts ornithine to citrulline

Question 4

In the process of transcription,

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

Question 5

Refer to Figure 16.2. In the branched metabolic pathway, if enzyme 1 is defective, you might expect to see an increase in the amount of which intermediate/product?

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

Question 6

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

Question 7

Figure 16.4
Codons, the three base sequences that code for specific amino acids, are part of

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

Question 8

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

Question 9

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.

Question 10

What is a codon?

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

Question 11

Figure 16.3
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.
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 G).
B) The machinery involved in DNA synthesis is analogous to the telegraph equipment used in sending Morse code.
C) The bases of DNA code for the more complex amino acid sequence of the various proteins found in cells.
D) The bases that make up DNA are associated by hydrogen bonds.

Question 12

Figure 16.3
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 13

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

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

Question 14

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

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

Question 15

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

Question 16

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

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

Question 17

Figure 16.4
Given the DNA template shown above, which of the following bases would you find in a complementary RNA strand?

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

Question 18

Figure 16.4
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

A) 3' UCA 5'.
B) 3' UGS 5'.
C) 3' ACU 5'.
D) 5' TCA 3'.
E) either UCA or TCA, depending on wobble in the first base.

Question 19

Figure 16.3
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) Substrate C would accumulate, and there would be no substrate D formed.
C) Lack of enzyme 3 would result in a cessation halt) of the entire metabolic pathway.
D) Another enzyme would be able to catalyze the reaction and the pathway would proceed.

Question 20

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

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

Question 21

A mutation that results in premature termination of translation

A) is a reading frame mutation.
B) is a missense mutation.
C) usually has no effect on the function of the protein.
D) is a silent mutation.
E) is a nonsense mutation.

Question 22

Use the figure to answer the following questions).
Figure 16.5
Refer to Figure 16.5. A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence Phe- Leu- Ile- Val would be

A) 3' AAA- GAA- TAA- CAA 5'.
B) 5' TTG- CTA- CAG- TAG 3'.
C) 3' AAC- GAC- GUC- AUA 5'.
D) 3' AAA- AAT- ATA- ACA 5'.
E) 5' AUG- CTG- CAG- TAT 3'.

Question 23

Use the figure to answer the following questions).
Figure 16.5
Refer to Figure 16.5. If the codon CAC was present in the ribosome A site, which amino acid would be added?

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

Question 24

Genotype is to as phenotype is to .

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

Question 25

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

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

Question 26

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 27

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) Lipids are soluble in the nuclear membrane and serve to transfer information from the DNA to the cytoplasm, where protein synthesis takes place.
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) DNA from a single gene is replicated and transferred to the cytoplasm, where it serves as a template for protein synthesis.

Question 28

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

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

Question 29

Which of the following findings violated the central dogma?

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

Question 30

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

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

Question 31

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

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

Question 32

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

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

Question 33

The synthesis of RNA through complementary base pairing is known as

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

Question 34

The statement, DNA -RNA -Proteins,

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

Question 35

According to the central dogma, what molecule should go in the blank? DNA - _ - Proteins

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

Question 36

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

Question 37

Use the figure to answer the following questions).
Figure 16.5
Refer to Figure 16.5. If you had an mRNA for which the codons were read beginning from the start codon, which acids would be added in order)?
5' UCUGAUGGGCUUU… 3'

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

Question 38

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) It is a frameshift mutation.
D) There is no mutation.

Question 39

Use the figure to answer the following questions).
Figure 16.5
Refer to Figure 16.5. 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) CCC
B) TTT
C) UUU
D) AAA