BIO 1301 EXAM 3: Chapters 9, 11, 12, 13

The movement of a hormone from the brain to its target receptors in the pancreas in an example of:

a. Autocrine signaling

b. Paracrine signaling

c. Endocrine Signaling

d. Direct intercellular signaling

e. Contact-dependent signaling

C

A high Kd means that more ligand is bound to its receptor than unbound to its receptor.

a. True

b. False

B

When a neurotransmitter released from one neuron binds to a ____ on a second neuron, that neuron depolarizes and fires.

a. Nuclear receptor

b. Enzyme-linked receptor

c. G-protein coupled receptor

d. Ligand-gated ion channel

D

When epidermal growth factor binds to its _____, the receptor phosphorylates itself, triggering a signal transduction pathway.

a. Ligand-gated ion channel receptor

b. Thermoreceptor

c. G-protein coupled receptor

d. Enzyme-linked receptor

D

When epinephrine binds to its receptor on muscle cells, its ____________ is activated, resulting in the activation of __________.

a. Ligand-gated ion channel receptor; PKA

b. G-protein coupled receptor; PKA

c. Enzyme-linked receptor; ATP

B

Which of the following is NOT an example of a secondary messenger?

a. cAMP

b. DAG

c. Ca2+ ions

d. Epinephrine

e. All are examples of secondary messengers

D

Epinephrine signaling causes glycogen to be broken down into glucose-1-Phosphate to be used in aerobic respiration.

a. True

b. False

A

What enzyme is responsible for carrying out apoptosis?

a. Caspase

b. Catalase

c. Calcium

d. Apoptase

A

When a cell secretes a growth factor that binds to receptors on its own membrane preventing it from proliferating this is an example of ____.

a. Direct intercellular signaling

b. Autocrine signaling

c. Paracrine signaling

d. Endocrine signaling

e. Contact-dependent signaling

B

When a neurotransmitter released from one neuron binds to a ______ on a second neuron, that neuron depolarizes and fires.

a. Ligand-gated ion channel

b. Nuclear receptor

c. G-protein coupled receptor

d. Enzyme-linked receptor

A

What immediate effect does activating GPCR have when binding epinephrine?

a. Phosphorylates adenyl cyclase

b. Autophosphorylates the receptor

c. Removes phosphate groups by activating phosphotase

d. Causes G-protein to bind to GTP

D

What effect does epinephrine have on liver cells?

a. Signals glucose to be metabolized into cAMP

b. Signals glycogen to break down into units of glucose-1-P

c. Signals glucose to be stored as a polymer called glycogen

d. Signals glycogen to be made at a faster rate.

B

Programmed cell death is known as ____.

a. Mitosis

b. Autophagy

c. Apoptosis

d. Cell genesis

e. Meiosis

C

In Griffith's experiment, when heat killed S bacteria was mixed with living R cells and then this mixture was injected into mice, what was observed?

a. Mice died and had living R cells inside

d. Mice didn't die and no bacteria was inside

c. Mice died and had living S cells inside

C

When Hershey and Chase labelled T2 bacteriophage with 35-S and then allowed the bacteriophage infect bacterial cells, where did they find the 35-S label after the infection took place?

a. Inside the bacterial cells

b. In the bacteriophage on the outside of the bacterial cells (never entered bacterial cells)

c. Both inside and outside the bacterial cells

B

To which atom is the nitrogenous base covalently linked to the deoxyribose sugar?

a. 5' C

b. 5' N

c. 3' C

d. 1' C

e. 3' OH

D

What feature of the structure of DNA did Chargoff's rule address?

a. The diameter of the double helix

b. The base pairing of T with A, and G with C

c. The sugar phosphate backbone

B

The major groove of the double stranded DNA is the space were proteins can associate with the bases in the DNA.

a. True

b. False

A

The mode of DNA replication that predicts that EACH DNA STRAND will be a combination of segments from the old and new DNA is:

a. Dispersive

b. Conservative

c. Semiconservative

A

Bacteria are grown in 15N (heavy) medium and then transferred to 14N (light) medium and are allowed to replicate for 2 generations. The DNA is subsequently isolated and centrifuged in a CsCl2 gradient to yield what type of band(s), as observed by Meselson and Stahl in 1958?

a. One heavy band and one half-heavy band

b. One light and one half-heavy band

c. One heavy band only

d. One half-heavy band only

B

Which of the following is responsible for separating (melting) the two DNA strands in preparation of copying the template strand?

a. DNA polymerase

b. DNA helicase

c. DNA topoisomerase

B

Which of the following statements best describes DNA polymerase?

a. It is an enzyme required to glue pieces of DNA fragments together

b. It is an enzyme required to produce a primer needed for DNA replication

c. It is an enzyme that catalyzes the addition of nucleotides to the 5' end of a growing DNA strand

d. It is an enzyme that catalyzes the addition of nucleotides to the 3' end of a growing DNA strand

D

Telomerase uses a _______________ sequence as a template for making the extended 3' end of the chromosome.

a. RNA

b. DNA

c. Protein

A

Nucleosomes are composed of:

a. Acidic proteins called Histones

b. Basic proteins called Histones

c. Positively charged lipids

d. Negatively charged carbohydrates

B

Beadle and Tatum identified mutations in genes that encoded enzymes in the pathway that synthesized _____________ as the last product in the pathway.

a. Ornithine

b. Glucose

c. Citrulline

d. Arginine

e. Homogentisic acid

D

Type S Streptococcus pneumoniae bacterium is lethal and will kill its host. If heated, the inactivated S strain dies and becomes nonlethal. Type R Streptococcus pneumoniae is a nonvirulent strain of bacteria. What would occur if one were to inject both the R strain and heat-killed S strains into a host organism such as the mouse?

a. The R strain would be transformed into the virulent S strain and not affect the host

b. The S strain would be transformed into the nonvirulent R strain and kill the host

c. The R strain would be transformed into the virulent S strain and kill the host.

d. The S strain would be transformed into the nonvirulent R strain and not affect the host

e. Neither the S nor the R strain would change

C

In order to produce a single strand of DNA, the nucleotides combine to form what type of bond?

a. Peptide

b. Phosphodiester

c. Purine

d. Hydrogen

e. Ionic

B

Bacteria are grown in 15N (heavy) medium and then transferred to 14N (light) medium and are allowed to replicate for 2 generations. The DNA is subsequently isolated and centrifuged in a CsCl2 gradient to yield what type of gradient band(s)?

a. One heavy and one half-heavy band

b. One light band

c. One light and one half-heavy band

d. One half-heavy (intermediate to heavy and light) band

e. One heavy band

C

Which of the following statements best describes DNA polymerase?

a. It is an enzyme required to produce a primer needed for DNA replication

b. It is an enzyme required to glue pieces of DNA fragments together

c. It is an enzyme that catalyzes the addition of nucleotides to the 3' end of a growing DNA strand

d. It is an enzyme that catalyzes the addition of nucleotides to the 5' end of a growing DNA strand

D

Which of the following represents the order of increasingly higher levels of organization of chromatin?

a. looped domain, 30-nm chromatin fiber, nucleosome

b. nucleosome, 30-nm chromatin fiber, looped domain

c. nucleosome, looped domain, 30-nm chromatin fiber

d. 30-nm chromatin fiber, nucleosome, looped domain

e. looped domain, nucleosome, 30-nm chromatin fiber

B

A gene always encodes a polypeptide

a. True

b. False

B

In bacteria, RNA polymerase requires a __________ to recognize and bind to the promoter

a. mRNA

b. Nucleus

c. tRNA

d. Sigma factor

D

RNA polymerase reads sequence in which direction along the DNA?

a. 3' to 5' along the template strand

b. 3' to 5' along the coding strand

c. 5' to 3' along the template strand

d. 5' to 3' along the coding strand

e. 5' to 3' along both strands of DNA

A

Which of the following is NOT a way that mRNA is processed in eukaryotes:

a. Poly A tail is added to the 3' end of the mRNA

b. The 5' end of the mRNA is capped with a modified guanosine

c. The introns are spliced out of the pre-mRNA, leaving only the exons in the mature mRNA

d. The pre-mRNA is processed in the cytoplasm

e. All of these are ways that pre-mRNAs are processed in eukaryotes

D

What defines the open reading frame?

a. The first C base in the transcript

b. An early stop codon

c. AUG - the first codon in a transcript

C

There are _____ aminoacyl-tRNA synthetases in a cell.

a. 64

b. 12

c. 20

d. 3

C

The site in the ribosome where the tRNA that is attached to the growing peptide is located is the _________ site.

a. A

b. P

c. E

d. T

B

Which of the following is NOT required for the initiation of translation?

a. Small subunit of the ribosome

b. mRNA

c. Initiator tRNA

d. hydrolysis of GTP

e. Elongation factors

E

What protein is involved in synthesizing messenger RNA in eukaryotes?

a. RNA polymerase III

b. RNA polymerase II

c. Sigma factor

d. Both RNA polymerase I and III

e. RNA polymerase I

B

Because more than one codon can specify the same amino acid, the genetic code is said to be

a. Wobbly

b. Degenerate

c. Repetitive

d. Redundant

e. Reverse

B

How many distinct aminoacyl-tRNA synthetases does each cell make?

a. ~60

b. ~180

c. ~20

d. ~120

e. ~1

C

Which of the following is NOT required for the initiation of translation?

a. Elongation factor

b. Small subunit of the ribosome

c. mRNA

d. Initiator tRNA

e. Hydrolysis of GTP

A

How does the ncRNA in telomerase function while extending the length of the chromosome?

a. Scaffold

b. Guide Sequence

c. Decoy

d. Blocker

B

How does ncRNA in the ribosome (ribosomal RNA) function with ribosomal protein to form the shape of the ribosome?

a. Scaffold

b. Guide Sequence

c. Ribozyme

d. Blocker of mRNA

A

How do miRNAs and siRNAS function in RNA interference in controlling the translation in the cytosol?

a. Scaffold

b. Alters protein stability

c. Ribozyme

d. Blocker of mRNA

D

How does SRP RNA function during co-translational sorting at the ER membrane?

a. Decoy

b. Alters SRP function so it can hydrolyze GTP

c. Ribozyme

d. Blocker of mRNA

B

What type of ncRNA is associated with neurological diseases?

a. miRNAs

b. tRNAs

c. rRNAs

d. SRP RNA

A

A bacteriophage (virus) infects a bacterial cell and the DNA in the viral genome is cut by Cas enzymes in order to make short DNA segments to be inserted into the CRISPR gene. Which stage of the CRISPR-Cas defense system does this describe?

a. Adaptation

b. Expression

c. Interference

A

How much of the human genome is dedicated to protein coding DNA?

a. Less than 5%

b. 20-50%

c. 100%

A

What does epinephrine do to liver cells?

a. Signals glucose to polymerized into glycogen.

b. Binds to a G-protein coupled receptor.

c. Signals glycogen to be made at a faster rate.

d. Synthesizes ATP from cAMP.

e. All choices are correct.

B

What hormone or ligand can induce apoptosis?

a. epinephrine

b. prednisolone

c. glycogen

d. adenaline

e. estrogen

B

Phosphodiesterase is an enzyme that:

a. synthesizes ATP from ADP.

b. removes the phosphate group from proteins

c. phosphates target proteins.

d. converts cAMP to AMP.

D

When histamine binds to it's G-protein coupled receptor (GPCR) what happens next?

a. The G protein loses GDP and gains GTP becoming activated.

b. The G protein loses GTP and gains GDP becoming activated.

c. The G protein loses GDP and gains GTP becoming inactivated.

d. The histamine enters the cell through the GPCR and diffuses to the nucleus where it interacts with transcription factors.

e. The G protein loses GTP and gains GDP becoming inactivated.

A

Following its initial activation, how does a G protein become inactivated?

a. The G-protein alpha subunit's GTP is hydrolyzed to GDP allowing reassociation of the G-protein alpha subunit and beta-gamma dimer.

b. The G-protein alpha subunit is digested and recycled.

c. The receptor becomes internalized.

d. It spontaneously loses activity within a few seconds.

A

The stage in cell signaling when the activated receptor has stimulated a sequence of changes inside the cell in a pathway is called:

a. Cellular response

b. Signal transduction

c. Receptor activation or reception

B

The Kd for the seratonin receptor is 3 x 10^-10M. This is considered a relatively high Kd. What does this tell you about the affinity of the receptor for its ligand?

a. There is no relationship between Kd and receptor/ligand affinity.

b. The receptor has high affinity for its ligand.

c. The receptor has low affinity for its ligand.

C

A piece of nucleic acid is composed of 19 Thymines, 19 Guanines, 12 Cytosines, and 12 Adenines. This stretch of nucleic acid is most likely:

a. Single stranded RNA

b. Single stranded DNA

c. Double stranded DNA

d. Double stranded RNA

B

In the Meselson and Stahl experiment, bacteria were grown in 15N (heavy) medium and then transferred to 14N (light) medium and was allowed to replicate for 1 generation. The DNA is subsequently isolated and centrifuged in a CsCl2 gradient to yield gradient band(s). If replication was actually conservative, rather than semi-conservative, what results would they have seen after TWO generations of replication in this experiment?

a. one heavy band and one light band

b. one heavy band and one half-heavy band

c. one light band and one half-heavy band

d. one heavy band

A

Which structure increases the stability of mRNA in eukaryotes?

a. The poly A tail

b. The AUG codon

c. The exons

d. The 5' guanosine cap

e. The introns

A

Which of the following statements about the mRNA start codon is INCORRECT?

a. The start codon defines the reading frame.

b. The start codon specifies the amino acid, methionine.

c. The start codon is usually AUG.

d. The start codon is only a few nucleotides from the ribosomal binding site.

e. The start codon is usually GGA.

E

Alternative splicing of pre-mRNA makes the proteome smaller.

a. True

b. False

B

What products of nonstructural genes are never translated?

a. messenger RNA

b. ribosomal RNA and messenger RNA

c. ribosomal RNA only

d. transfer RNA and ribosomal RNA

e. transfer RNA only

D

Which of the modifications of pre-mRNA is needed for the mRNA to exit the nucleus AND to bind to the ribosome?

a. Tagging

b. 5'-cap

c. Splicing

d. Methylation

e. Poly-A tail

B

The genetic code is called "degenerate" because:

a. all codons are associated with only one amino acid.

b. codons are made up of three bases.

c. more than one amino acid is associated with a given codon.

d. all amino acids have only one codon.

e. more than one codon is associated with a given amino acid.

E

The DNA sequence of a one strand of a gene is:

5' - CTGGAATCGCTCAT - 3'

The sequence of the corresponding mRNA is:

5' - CUGGAAUCGCUCAU - 3'

The sequence of the DNA strand shown above is that of the:

a. Coding strand

b. Template strand

A

Cysteine has two codons in the genetic code. How many aminoacyl-tRNA synthetases are required to charge tRNAs with Cysteine?

a. 2

b. 1

c. 4

d. 3

B

What type of ncRNA is associated with the formation of arterial plaques?

a. rRNA

b. RNA in telomerase

c. miRNA

d. tRNA

C

What type of ncRNA is associated with co-translational sorting at the ER membrane?

a. RNA in telomerase

b. tRNA

c. miRNA

d. SRP RNA

D

In miRNAs, the ncRNA binds to mRNA and prevents the association of the ribosome with that mRNA, and thereby, prevents translation. What is the function of ncRNA in this example?

a. Blocker

b. Ribozyme

c. Scaffold

d. Alteration of protein function

A

How does SRP RNA function during co-translational sorting at the ER membrane?

a. Blocker of mRNA

b. Ribozyme

c. Alters SRP function so it can hydrolyze GTP

d. Decoy

C

In order to lengthen a single strand of DNA, DNA polymerase makes what type of bond between two nucleotides?

a. Purine

b. Covalent

c. Ionic

d. Hydrogen

e. Peptide

B

The enzyme that attaches a repeated DNA sequence at the ends of eukaryotic chromosomes in order to prevent chromosome shortening is called _____.

a. Telomerase

b. Primase

c. Ligase

d. Topoisomerase

e. Polymerase

A

A change in the genotype and phenotype due to the assimilation or uptake of a foreign substance (like DNA) by a cell is called:

a. Transformation

b. Cell division

c. Replication

d. Translation

A

Telomerase extends the 5' end of linear chromosomes.

a. True

b. False

B

The DNA from a bacteriophage (virus) that has infected a bacterial cell and Cas enzymes are expressed and cleave the bacteriophage DNA into small pieces that become incorporated into the Crispr site in the bacterial genome. Which stage of the CRISPR-Cas defense system does this describe?

a. Adaptation

b. Interference

c. Expression

A

As a result of the infection of a bacterial cell by a bacteriophage (virus), a tracrRNA binds to a crRNA to form a complex that binds to a Cas9 protein. Which stage of the CRISPR-Cas defense system does this describe?

a. Expression

b. Interference

c. Adaptation

A

The anti-tumor drug, prednisone, is metabolized into prednisolone in the body. The anti-tumor activity (blocking cell division) of this drug is due to:

a. Prednisolone blocking apoptosis in the cells.

b. Prednisolone activating the initiator caspase enzyme in the cell.

c. Prednisolone stabilizing the cytoskeleton in the cell.

d. Prednisolone stimulating cell division.

B