Bio 148 exam 2

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Mastering Biology Questions

B

How does the simple primary and secondary structure of DNA hold the information needed to code for the many features of multicellular organisms?

A. The width of the double helix changes at each gene due to differences in hydrogen bonds.
B. The base sequence of DNA carries all the information needed to code for proteins.
C. The amino acids that make up the DNA molecule contain the information needed to make cellular proteins.
D. The hydrogen bonding among backbone constituents carries coded information.

ligase

Short segments of newly synthesized DNA are joined into a continuous strand by _____.

E

After DNA replication is completed, _____.

A. there are four double helices
B. each new DNA double helix consists of two new strands
C. one DNA double helix consists of two old strands and one DNA double helix consists of two new strands
D. each of the four DNA strands consists of some old strand parts and some new strand parts
E. each new DNA double helix consists of one old DNA strand and one new DNA strand

replication forks and replication bubbles

The action of helicase creates _____.

C

Why is the new DNA strand complementary to the 5' to 3' strands assembled in short segments?

A. it is more efficient than assembling complete new strands
B. DNA polymerase can assemble DNA only in the 3' to 5' direction
C.DNA polymerase can assemble DNA only in the 5' to 3' direction
D. the replication forks block the formation of longer strands
E. only short DNA sequences can extend off the RNA primers

template

An old DNA strand is used as a _____ for the assembly of a new DNA strand.

DNA polymerase

What catalyzes DNA synthesis?

C

Which of the following statements about DNA synthesis is true?

A. Nucleotides are added in a random fashion to single-stranded DNA.
B. DNA polymerase adds dNTP monomers in the 3' to 5' direction.
C. Primers are short sequences that allow the initiation of DNA synthesis.
D. As DNA polymerase moves along the template strand, each new nucleotide provides a 5' hydroxyl group for the next reaction to occur.

Phosphate groups

Which part of a deoxynucleoside triphosphate (dNTP) molecule provides the energy for DNA synthesis?

primase

Which of the following enzymes creates a primer for DNA polymerase?

C

Which of the following statements about Okazaki fragments in E. coli is true?

A.They are sealed together by the action of helicase.
B.They are synthesized in the 3' to 5' direction.
C.They are formed on the lagging strand of DNA.
D.They are usually 50 to 500 bases long.

Topoisomerase

Which of the following enzymes is important for relieving the tension in a helix as it unwinds during DNA synthesis?

True

True or false? Single-stranded DNA molecules are said to be antiparallel when they are lined up next to each other but oriented in opposite directions.

C

What would be the consequence(s) for DNA synthesis if DNA ligase were defective?

A. Both leading and lagging strand synthesis would be incomplete.
B. Leading strand synthesis would be incomplete; lagging strand synthesis would be unaffected.
C. Lagging strand synthesis would be incomplete; leading strand synthesis would be unaffected.
D. Both leading and lagging strand synthesis would be unaffected.

C

What would be the consequence(s) for DNA synthesis if primase were defective?

A. Lagging strand synthesis would be incomplete; leading strand synthesis would be unaffected.
B. Leading strand synthesis would be incomplete; lagging strand synthesis would be unaffected.
C. Both leading and lagging strand synthesis would be incomplete.
D. Both leading and lagging strand synthesis would be unaffected.

A

Which statement is correct concerning DNA synthesis catalyzed by DNA polymerase?

A. The new DNA strand is synthesized in the 5'→3' direction; the template strand is read in the 3'→5' direction.
B. The new DNA strand is synthesized in the 5'→3' direction; the template strand is read in the 5'→3' direction.
C. The new DNA strand is synthesized in the 3'→5' direction; the template strand is read in the 3'→5' direction.
D. The new DNA strand is synthesized in the 3'→5' direction; the template strand is read in the 5'→3' direction.

deoxyribonucleoside triphosphates (dNTPs)

DNA polymerases use _____ as their substrate.

prevent twisting of DNA in front of the replication fork

Toposiomerase works to _____.

short RNA sequences

The primers used for DNA synthesis are _____.

on the lagging strand

Okazaki fragments are found _____.

ends of linear chromosomes

What is a telomere?

B

Why does telomerase need to have a built-in template for DNA synthesis?

A. All of lagging strand synthesis requires genetic information that is not present in the parent DNA molecule.
B. Telomerase is involved in adding DNA to the end of the lagging strand.
C. All of leading strand synthesis requires genetic information that is not present in the parent DNA molecule.
D. Telomerase is involved in adding DNA to the end of the leading strand.

D

Nucleotide excision repair _____.

A. recognizes and removes mismatched bases
B. corrects errors in nucleotide excision
C. repairs single-strand breaks in DNA
D. recognizes and repairs thymine dimers in DNA

C

After DNA replication is completed, _____.

A. there are four double helices
B. each of the four DNA strands consists of some old strand parts and some new strand parts
C. each new DNA double helix consists of one old DNA strand and one new DNA strand
D. each new DNA double helix consists of two new strands
E. one DNA double helix consists of two old strands and one DNA double helix consists of two new strands

helicase

The first step in the replication of DNA is catalyzed by _____.

B

The synthesis of a new strand begins with the synthesis of a(n) _____.

A. single-strand binding protein
B. RNA primer complementary to a preexisting DNA strand
C. short pieces of DNA
D. poly(A) tail
E. Okazaki fragment

C

Recent studies have shown that xeroderma pigmentosum (an error in the nucleotide excision repair process) can result from mutations in one of seven genes. What can you infer from this finding?

A. These seven genes are the most easily damaged by ultraviolet light.
B. There are seven genes that produce the same protein.
C. There are several enzymes involved in the nucleotide excision repair process.
D. These mutations have resulted from translocation of gene segments.

the mitotic phase

During _____ both the contents of the nucleus and the cytoplasm are divided.

interphase

During _____ the cell grows and replicates both its organelles and its chromosomes.

C

What is the difference between a chromatid and a chromosome?

A. Chromosomes are always replicated, whereas chromatids are not.
B. Chromatids consist of DNA, whereas chromosomes consist of proteins.
C. A chromatid is one half of a replicated chromosome, whereas a chromosome consists of DNA wrapped around proteins in a highly organized manner.
D. A chromatid always consists of two linear DNA molecules, whereas a chromosome always consists of just one linear DNA molecule.

A

Which event does not take place before the start of mitosis?

A. The nuclear envelope disintegrates.
B. Organelles proliferate.
C. The parent cell grows.
D. DNA is replicated.

False

True or false? Mitosis takes place during M phase, which is the longest phase of the cell cycle.

sister chromatids

Which term describes two recently replicated DNA strands that are joined together just before cell division?

metaphase

During which stage of mitosis are chromosomes lined up in the center of the cell?

telophase

Which stage of mitosis is characterized by the disintegration of mitotic spindles and the formation of two new nuclear membranes?

Kinetochore

To which part of the centromere do mitotic spindle fibers attach during prometaphase?

anaphase

During which substage of mitosis do sister chromatids break apart and start moving to opposite poles of the cell?

B

Which of these correctly illustrates the pairing of DNA and RNA nucleotides?

A. GTTACG
CAATCG

B. GTTACG
CAAUGC

C. GTTACG
GTTACG

D. GTTACG
ACCGTA

E. GTTACG
UAACAU

B

The direction of synthesis of an RNA transcript is _____.

A. 1' —> 5'
B. 5' —> 3'
C. 1' —> 3'
D. 3' —> 5'
E. 2' —> 4'

B

A promoter is _____.

A. a protein that associates with bacterial RNA polymerase to allow it to bind to DNA
B. a sequence in DNA that binds RNA polymerase near the site for transcription
C. one or more eukaryotic proteins that bind to DNA near the start of a gene
D. a sequence in RNA that promotes the release of RNA polymerase from DNA

C

Which statement is correct concerning the function(s) of the 5' cap and the 3' poly(A) tail of eukaryotic mRNAs?

A. The poly(A) tail stabilizes the mRNA, but plays no direct role in its translation to protein.
B. The 5' cap serves as a recognition signal for the translational machinery but plays no role in stabilizing mRNA.
C. Both structures serve as recognition signals for the translational machinery and extend the life span of the mRNA.
D. Neither structure has any known function.

A

What enzyme catalyzes the attachment of an amino acid to tRNA?

A. aminoacyl-tRNA synthetase
B. rubisco
C. dextrinase
D. argininosuccinate lyase
E. nuclease

P

The initiator tRNA attaches at the ribosome's _____ site.

D

During splicing, _____ recognize and remove _____.

A. snRNPs that make up the spliceosome; exons
B. RNAs within the ribosome; introns
C. RNAs within the ribosome; exons
D. snRNPs that make up the spliceosome; introns

Transcription

What is the process called that converts the genetic information stored in DNA to an RNA copy?

Organelles

DNA does not store the information to synthesize which of the following?

A

Transcription begins at a promoter. What is a promoter?

A. A site in DNA that recruits the RNA Polymerase
B. Part of the RNA molecule itself
C. A site where many different proteins will bind
D. A nontranscribed sequence on the DNA
E. A site found on the RNA polymerase

A

Which of the following statements best describes the promoter of a protein-coding gene?

A. The promoter is a nontranscribed region of a gene.
B. The promoter is a site at which only RNA polymerase will bind.
C. The promoter is part of the RNA molecule itself.
D. The promoter is a site found on RNA polymerase.

C

What determines which base is to be added to an RNA strand during transcription?

A. The previous base
B. The order of the chemical groups in the backbone of the RNA molecule
C. Base pairing between the DNA template strand and the RNA nucleotides
D.Base pairing between the two DNA strands

Complementary

Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?

B

What happens to RNA polymerase II after it has completed transcription of a gene?

A. It joins with another RNA polymerase to carry out transcription.
B. It is free to bind to another promoter and begin transcription.
C. It begins transcribing the next gene on the chromosome.
D. It is degraded.

unwound DNA, mRNA, and RNA polymerase

What would one expect to find in a transcription bubble?

D

For any given gene, what ultimately determines which DNA strand serves as the template strand?

A. the location along the chromosome where the double-stranded DNA unwinds
B. the location of specific proteins (transcription factors) that bind to the DNA
C. which of the two strands of DNA carries the RNA primer
D. the base sequence of the gene's promoter

B,C, and E

Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus?

A. Coding sequences called exons are spliced out by ribosomes.
B. Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes.
C. A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.
D. A translation stop codon is added at the 3' end of the pre-mRNA.
E. A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.

sigma

If RNA polymerase is missing _____ then transcription initiation would not occur but elongation could.

proteins

Which polymers are composed of amino acids?

an oxygen

Which of the following is not attached to the central carbon atom in an amino acid?

Carboxyl functional group

Which part of an amino acid is always acidic?

Nucleotides

Which monomers make up RNA?

A

Which of the following statements about the formation of polypeptides from amino acids is true?

A. A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid.
B. The reaction occurs through the addition of a water molecule to the amino acids.
C. A bond can form between any carbon and nitrogen atom in the two amino acids being joined.
D. Polypeptides form by condensation or hydrolysis reactions.

true

True or false? Enzymes in the digestive tract catalyze hydrolysis reactions.

amino acids

Proteins are polymers of _____.

peptide

What type of bond joins the monomers in a protein's primary structure?

hydrogen bonds

The secondary structure of a protein results from _____.

peptide bonds

Tertiary structure is NOT directly dependent on _____.

C

What aspects of amino acid structure vary among different amino acids?

A. the presence of a central C atom
B. the long carbon-hydrogen tails of the molecule
C. the components of the R-group
D. the glycerol molecule that forms the backbone of the amino acid

D

How does the structure of an amino acid enable it to play its most important roles in cells?

A. Because both carboxyl and amino groups are present, polymerization is exergonic. In addition, the presence of a side chain makes the molecule water soluble.
B. Because each amino acid contains a variety of functional groups, they can participate in a wide variety of chemical reactions.
C. It can serve a wide variety of functions in a cell, because it contains the atoms most commonly found in organisms (C, H, N, and O).
D. The presence of carboxyl and amino groups gives it the ability to form peptide bonds, and its side chain gives it unique chemical properties.

B

Which of these does NOT contain a structural protein?

A. spider silk
B. ovalbumin
C. tendons
D. ligaments
E. muscles

immune

Defensive proteins are manufactured by the _____ system.

B

You've just sequenced a new protein found in mice and observe that sulfur-containing cysteine residues occur at regular intervals. What is the significance of this finding?

A. It will be important to include cysteine in the diet of the mice.
B. Cysteine residues are involved in disulfide bridges that help form tertiary structure.
C. Cysteine residues are required for the formation of α-helices and β-pleated sheets.
D. Cysteine causes bends, or angles, to occur in the tertiary structure of proteins.

D

Aquaporins are proteins that control the passage of water molecules across the cell membrane. The protein forms a pore, or opening, in the membrane. You isolate what you think are two different molecules of aquaporin, and determine that one of the proteins has a larger pore diameter than the second. Which of the following do you conclude?

A. You will have to sequence the proteins to compare their primary structure, because it should have no effect on pore diameter.
B. These two forms of aquaporin will have identical sequences of amino acids.
C. These molecules both can't have aquaporin because all proteins that do the same type of job (such as catalyze a reaction) have the exact same 3-D structure.
D. These two forms of aquaporin will have different sequences of amino acids.

mRNA

Which nucleic acid is translated to make a protein?

B

Which of the following processes is an example of a post-translational modification?

A. Elongation
B. Phosphorylation
C. Peptide bond formation
D. Initiation

D

Which of the following steps occurs last in the initiation phase of translation?

A. The small subunit of the ribosome binds to the 5' cap on the mRNA.
B. A peptide bond is formed between two adjacent amino acids.
C. An aminoacyl tRNA binds to the start codon.
D. The large ribosomal subunit joins the complex.

A-site

At which site do new aminoacyl tRNAs enter the ribosome during elongation?

B

What is meant by translocation?

A. The completed polypeptide is released from the ribosome.
B. The ribosome slides one codon down the mRNA.
C. The two ribosomal subunits are joined in a complex.
D.The polypeptide chain grows by one amino acid.

False

True or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated.

A

The wobble hypothesis explains the _____.

A. ability of some tRNAs to read more than one codon
B. imprecise fit between aminoacyl tRNA synthetases and their substrates
C. fact that there are three nucleotides per codon
D. redundancy of the genetic code

AGU

If the DNA code for a particular amino acid is AGT, then the anticodon on the tRNA would be _____.

D

RNA and proteins combine in cells to form structures called ribosomes. Ribosomes contain the active site for peptide bond formation. Based on their chemical structures, do you think protein or RNA molecules actually form the active site within the ribosome?

A. RNA, because proteins cannot catalyze a reaction that involves another protein
B. proteins, because only proteins can catalyze a reaction that involves another protein
C. protein, because RNA cannot catalyze reactions
D. It could be either, because both molecules have catalytic properties.

C

Consider a situation in which the enzyme is operating at optimum temperature and pH, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?

A. increase the pH.
B. Increase the temperature.
C. Increase the enzyme concentration.
D. Increase the substrate concentration.

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