Cell and Molecular Biology Exam 3

Using radiolabeled amino acids, Palade and colleagues were able to define the pathway taken by secreted proteins. Which of the following represents that pathway?

a. Rough ER → smooth ER → Golgi → secretory vesicles → cell exterior

b. Rough ER → smooth ER → Golgi → endosomes → cell exterior

c. Rough ER → Golgi → lysosomes → cell exterior

d. Rough ER → Golgi → secretory vesicles → cell exterior

d. Rough ER → Golgi → secretory vesicles → cell exterior

A signal sequence in the polypeptide chain targets all but _______ proteins to the rough ER surface.

a. secreted

b. plasma membrane

c. mitochondrial

d. lysosomal

C. Mitochondrial

Ribosomes that are free in the cytosol and those that are bound to the ER membrane have

a. different types of large and small subunits.

b. the same types of large and small subunits.

c. different types of large subunits but the same small subunits.

d. different types of small subunits but the same large subunits.

b. the same types of large and small subunits

When compared to polypeptides synthesized in vitro on free ribosomes, the polypeptides synthesized from the same mRNA on microsome-bound ribosomes often are

a. the same size.

b. larger.

c. smaller.

d. more hydrophobic.

c. smaller

As they emerge from the ribosome, signal sequences are recognized and bound by a(n)

a. tRNA.

b. signal peptidase.

c. signal recognition particle (SRP).

d. SRP receptor.

C. Signal Recognition particle (SRP)

Which of the following provides evidence for the signal hypothesis for the targeting of a secretory protein to the rough ER?

a. The protein is larger when synthesized in vitro on free polysomes.

b. The secretory protein ends up in the cytosol when a short sequence is deleted by genetic engineering.

c. A normally cytosolic protein is secreted when a specific sequence is added to it by genetic engineering.

d. All of the above

D. All of the above

If the secretory protein is isolated from secretory vesicles and injected into the cytosol, it will

a. be taken up into the rough ER and follow the secretory pathway.

b. remain in the cytosol until it is degraded.

c. be secreted through channels in the plasma membrane.

d. be taken up into secretory vesicles and secreted.

b. remain in the cytosol until it is degraded.

Protein folding in the ER is assisted by a chaperone called

a. BiP.

b. PiP.

c. Hsp60.

d. Hsp90.

a. BIP

Disulfide bonds within or between proteins form easily in which of the following?

a. The ER but not the cytosol

b. Neither the cytosol nor the ER

c. The cytosol but not the ER

d. Both the cytosol and the ER

a. The ER but not the cytosol

GPI-anchored proteins are synthesized

a. on free ribosomes and attached to the GPI group on the outside of the ER.

b. as transmembrane proteins, cleaved, and attached to the GPI group on the cytosolic surface of the ER.

c. as transmembrane proteins, cleaved, and attached to the GPI group on the lumenal surface of the ER.

d. on free ribosomes and attached to the GPI group on the cytosolic surface of the ER.

c. as transmembrane proteins, cleaved, and attached to the GPI group on the lumenal surface of the ER.

The unfolded protein response involves

a. general inhibition of protein synthesis.

b. increased synthesis of chaperones.

c. increased activity of proteosomes.

d. All of the above

d. All of the above

Most cellular lipids are synthesized in

a. fat droplets.

b. mitochondria.

c. the endoplasmic reticulum.

d. the Golgi apparatus.

c. the endoplasmic reticulum

Newly synthesized membrane lipids are found in both halves of a membrane bilayer because they are

a. synthesized on one surface and flipped to the other surface by proteins called flippases.

b. removed and transported to these locations by lipid transport proteins.

c. synthesized on one surface and flipped spontaneously to the other surface.

d. synthesized on both surfaces.

a. synthesized on one surface and flipped to the other surface by proteins called flippases.

The sequence Lys-Asp-Glu-Leu (KDEL) serves as an ER retention signal for proteins by binding to KDEL receptors that

a. hold the proteins in the rough ER.

b. hold the proteins in the smooth ER.

c. hold the proteins in both the smooth ER and rough ER and prevent their transport to the Golgi apparatus.

d. transport the proteins from the Golgi apparatus back to the ER.

d. transport the proteins from the Golgi apparatus back to the ER.

Vesicles enter the Golgi apparatus by fusing with _______ and they exit _______.

a. the cis (convex) face; the trans (concave) face

b. the trans (concave) face; the cis (convex) face

c. both the cis (convex) and the trans (concave) faces; the sides of cisternae

d. the sides of the cisternae; the cis (convex) face

a. the cis (convex) face; the trans (concave) face

Which of the following proteins do not pass through the Golgi apparatus?

a. Lysosomal enzymes

b. Cell surface proteins

c. Ribosomal proteins

d. Proteins secreted by exocytosis

c. Ribosomal proteins

N-linked oligosaccharides are added in the _______ and modified in the _______.

a. ER; Golgi

b. cis Golgi; medial Golgi

c. medial Golgi; trans Golgi

a. ER; Golgi

Lysosomal proteins are marked by the addition of a phosphate to a _______ group.

a. glucose

b. serine

c. GDP

d. mannose

D. Mannose

The enzyme that modifies the mannose group on lysosomal proteins recognizes and binds to a(n)

a. signal patch.

b. signal sequence.

c. α helix.

d. KDEL sequence.

a. Signal patch

Which of the following classes of lipids is synthesized in the Golgi apparatus?

a. Phospholipids

b. Glycolipids

c. Cholesterol

d. Ceramide

b. Glycolipids

Plasma membrane proteins of intestinal epithelial cells requires separate targeting to

a. one continuous plasma membrane domain.

b. two plasma membrane domains: the apical and basolateral.

c. three plasma membrane domains: the apical, lateral, and basal.

d. four plasma membrane domains: one apical, two lateral, and a basal.

b. two plasma membrane domains: the apical and basolateral.

In plant cells, vesicles transport proteins from the Golgi apparatus to

a. lysosomes.

b. vacuoles.

c. chloroplasts.

d. mitochondria.

b.vacuoles

Brain tissue is useful for studies of vesicular transport because

a. many brain diseases involve mutant vesicular transport.

b. synaptic vesicles are abundant in the brain and can be isolated in large quantities for biochemical analysis.

c. the mechanisms of vesicle transport and fusion are unique to neurons.

d. All of the above

b. synaptic vesicles are abundant in the brain and can be isolated in large quantities for biochemical analysis.

Vesicles that carry proteins from the rough ER to the Golgi apparatus bud off as _______ vesicles.

a. uncoated

b. clathrin-coated

c. COPI-coated

d. COPII-coated

d. COPII-coated

Lysosomal proteins are initially incorporated into _______ vesicles.

a. uncoated

b. clathrin-coated

c. COPI-coated

d. COPII-coated

b. clathrin-coated

Clathrin coats are bound to specific receptors by a protein called

a. adaptor protein.

b. ARF.

c. COPI.

d. NSF.

a. adaptor protein.

ARF function on vesicles is regulated by

a. phosphorylation of serine residues.

b. phosphorylation of mannose residues.

c. binding of GTP.

d. binding of ATP.

c. Binding of GTP

Rothman and colleagues proposed that the specificity of a vesicle fusing with its target membrane lies in the interaction of pairs of proteins called v-(vesicle) and t-(target)

a. SNAPs.

b. SNAREs.

c. NSFs.

d. COPs.

b. SNAREs

In vesicle fusion with a target membrane, ATP hydrolysis is required to

a. separate the bound target and vesicle SNAREs.

b. bind SNAREs to Rabs.

c. bind NSF to SNAP.

d. bind target and vesicle SNAREs.

a. separate the bound target and vesicle SNAREs.

The protein complexes in which exocytosis occurs are called

a. exocysts.

b. exocytocysts.

c. secretosites.

d. secretion sites.

a. exocysts

Lysosomes digest

a. proteins.

b. nucleic acid.

c. carbohydrates.

d. All of the above

d. All of the above

The pH inside lysosomes is about

a. 7.0.

b. 6.0.

c. 5.0.

d. 4.0.

c.5.0

. Gaucher disease is a failure of lysosomes in macrophages to hydrolyze

a. proteins.

b. glycolipids.

c. DNA.

d. polysaccharides.

b. glycolipids

Transport vesicles carrying acid hydrolases fuse with

a. lysosomes.

b. endocytic vesicles.

c. early endosomes.

d. late endosomes.

d. late endosomes

Which of the following is not a contiguous membrane domain?

a. Rough ER

b. Secretory granules

c. Smooth ER

d. ER exit sites (ERES)

b. Secretory granules

. In the "pulse-chase" experiment, Palade and colleagues studied the pathway taken by newly secreted proteins in pancreatic acinar cells by labeling them with radioactive amino acids and then determining their progressive location within the cells. Which of the following represents the correct order in which the proteins were identified?

a. Secretory vesicles → Golgi apparatus → rough ER → nucleus

b. Golgi apparatus → rough ER → nucleus → secretory vesicles

c. Rough ER → Golgi apparatus → secretory vesicles

d. Rough ER → secretory vesicles → Golgi apparatus

c. Rough ER → Golgi apparatus → secretory vesicles

Which of the following is not a destination for vesicles leaving the Golgi apparatus?

a. The plasma membrane

b. The exterior of the cell

c. Lysosomes

d. Mitochondria

d. Mitochondria

The ribosomes of the rough endoplasmic reticulum are targeted to the cytoplasmic side of the membrane via

a. a signal sequence within the 28S ribosomal RNA.

b. a sequence within the protein being synthesized.

c. the S6 ribosomal protein.

d. the cap sequence at the 5′ end of the mRNA being translated.

b. a sequence within the protein being synthesized

Which of the following statements about transmembrane proteins is true?

a. The signal sequences are always cleaved off.

b. They are always inserted with the amino terminus on the lumenal side and the carboxyl terminus in the cytosol.

c. They cross the membrane only once.

d. They usually have one or more α helices spanning the membrane bilayer.

d. They usually have one or more α helices spanning the membrane bilayer.

The lumen of the ER is equivalent topologically to the

a. cytoplasm.

b. cytoplasmic face of the plasma membrane.

c. extracellular space.

d. nucleoplasm.

c. extracellular space

Proteins that span the membrane multiple times have multiple _______ that alternate with multiple transmembrane stop-transfer sequences.

a. glycosylation sites

b. internal signal sequences

c. phosphorylation sites

d. sulfation sites

b. internal signal sequences

The major site at which membrane lipids are synthesized is the

a. cytosolic side of the ER membrane.

b. cytosol.

c. lumenal side of the ER membrane.

d. cytosolic side of the Golgi membrane.

a. cytosolic side of the ER membrane.

The sequence Lys-Asp-Glu-Leu (KDEL) serves to retain proteins in the ER by

a. preventing their packaging into vesicles destined for the Golgi.

b. binding to receptors within the membranes of the ERGIC and Golgi, which retain them or return them to the ER.

c. binding the SRP receptor in the ER membrane.

d. associating with the lipids in the ER membrane.

b. binding to receptors within the membranes of the ERGIC and Golgi, which retain them or return them to the ER.

. Which of the following lipids is/are synthesized in the Golgi apparatus?

a. Phospholipids

b. Cholesterol

c. Ceramide

d. Glycolipids

d. Glycolipids

Clathrin-coated vesicles are involved in

a. the retrieval of ER resident proteins from the cis Golgi or the ER-Golgi intermediate compartment.

b. the uptake of extracellular molecules by endocytosis and the transport of molecules from the trans-Golgi network to the lysosomes.

c. transport from the ER to the Golgi.

d. the recycling of Golgi resident proteins during cisternal maturation.

b. the uptake of extracellular molecules by endocytosis and the transport of molecules from the trans-Golgi network to the lysosomes.

Which of the following would you expect to find at high concentrations in lysosomes?

a. Proteins destined for secretion

b. Glycosylation enzymes

c. Degradative enzymes

d. Recycling endosomes

c. Degradative enzymes

The process by which cells degrade their own components by enclosing them in a cytosolic membrane is

a. autophagy.

b. ER-mediated endocytosis.

c. phagocytosis.

d. pinocytosis.

a. autophagy

Proteins attached to the outer half of the plasma membrane bilayer are usually attached by a

a. farnesyl tail.

b. glycosylphosphatidylinositol (GPI) anchor.

c. prenyl tail.

d. geranyl tail.

b. glycosylphosphatidylinositol (GPI) anchor.

Which of the following types of vesicles does not bud directly from the trans-Golgi network?

a. Those transporting plasma membrane receptors

b. Those that form regulated secretory vesicles

c. Those carrying lysosomal enzymes

d. Lysosomes

d. Lysosomes

Which of the following polysaccharides is (are) synthesized in the Golgi apparatus?

a. Pectin

b. Cellulose

c. Amylose

d. Glycogen

a. Pectin

Yeasts are advantageous for studying secretory pathways because

a. they secrete more proteins per cell than animal cells do.

b. Golgi apparatuses are easily isolated in yeasts.

c. they are amenable to genetic analysis.

d. they have only one simple pathway for secreted proteins.

c. they are amenable to genetic analysis.

Griscelli syndrome, a disease caused by mutations in the gene encoding Rab27a, is characterized by an abnormal

a. transport of melanosomes.

b. export of vesicles in T lymphocytes.

b. export of neurotransmitters.

d. Both a and b

d. Both a and b

Which of the following statements about mannose-6-phosphate receptors that bind and take up lysosomal hydrolases into lysosomal transport vesicles is true?

a. They are transported to lysosomes, where they hold the lysosomal hydrolases.

b. They are transported to lysosomes, where they are degraded.

c. They release the lysosomal hydrolases in the late endosomes and are recycled in vesicles back to the Golgi.

d. They are degraded in late endosomes, allowing the release of the lysosomal hydrolases.

c. They release the lysosomal hydrolases in the late endosomes and are recycled in vesicles back to the Golgi.

In cell fractionation experiments in which subcellular organelles are separated on the basis of their density, the smooth endoplasmic reticulum is _______ the rough endoplasmic reticulum.

a. denser than

b. lighter than

c. the same density as

d. the same density as lipid droplets and much denser than

c. lighter than

For many yeast proteins, posttranslational translocation of proteins targeting the ER is

a. a process affecting many newly synthesized proteins.

b. much less common than in mammalian cells.

c. rare.

d. impossible, because all translocation into the ER is driven by the process of protein synthesis.

a. a process affecting many newly synthesized proteins.

Proteins are translocated into the ER lumen

a. by flippases.

b. through an aqueous channel created by the Sec61 protein.

c. by being pushed by translation through the lipid bilayer of the ER membrane.

d. by being pulled by BiP across the lipid bilayer of the ER membrane.

b. through an aqueous channel created by the Sec61 protein.

In some proteins the only transmembrane sequence is located C-terminally in the protein. These proteins are recognized by

a. the SRP.

b. the Sec61 translocon.

c. TRC40 (GET3).

d. the GET1-GET2 complex embedded in the ER membrane.

c. TRC40

N-linked glycosylation at an Asn-X-Ser/Thr consensus sequence adds _______ sugar(s) in a single step to the protein.

a. 1

b. 14

c. 30

d. 100

b.14

Calreticulin assists in folding glycoproteins that contain one _______ residue.

a. glucose

b. mannose

c. N-acetylglucosamine

d. sialic acid

a. Glucose

Cargo proteins are transported through the Golgi apparatus

a. by forward (anterograde) moving vesicles.

b. by backward (retrograde) moving vesicles.

c. by cisternal maturation in which the cisternae themselves are the carriers for cargo transport through the Golgi apparatus.

d. by a process(es) that remain controversial and may include elements of both vesicular transport and cisternal maturation.

d. by a process(es) that remain controversial and may include elements of both vesicular transport and cisternal maturation.

The trans-Golgi network is

a. the intermediate compartment between the ER and the Golgi.

b. the part of the Golgi where fusion of vesicles from the ER occurs.

c. the exit part of the Golgi where sorting of proteins to the lysosomes, plasma membrane, and cell exterior occurs.

d. the network of vesicles that transport resident Golgi proteins between cisternae.

c. the exit part of the Golgi where sorting of proteins to the lysosomes, plasma membrane, and cell exterior occurs.

Which of the following is not involved in the specific targeting of proteins to lysosomes?

a. N-linked glycosylation in the ER

b. Mannose phosphorylation

c. The mannose-6-phosphate receptor

d. Signal patches

a. N-linked glycosylation in the ER

The major model of vesicle fusion holds that actual fusion of a vesicle with its target membrane is driven by the interaction of pairs of proteins called vesicle and target

a. SNAREs.

b. SNAPs.

c. COPs.

d. tethers.

a. SNAREs

Most eukaryotic plasma membrane proteins are synthesized on

a. free ribosomes and inserted after translation into the plasma membrane.

b. rough ER ribosomes and carried to the plasma membrane by vesicles that pinch off from the Golgi apparatus.

c. rough ER ribosomes and carried to the plasma membrane by vesicles that pinch off from the rough ER.

d. ribosomes associated with the plasma membrane and inserted into the membrane cotranslationally.

b. rough ER ribosomes and carried to the plasma membrane by vesicles that pinch off from the Golgi apparatus.

The signal sequence that targets a polypeptide to the rough ER is rich in _______ amino acids.

a. positively charged

b. negatively charged

c. hydrophilic

d. hydrophobic

d. hydrophobic

signaling by the steroid hormone estrogen is an example of _____ signaling

a. autocrine

b. endocrine

c. paracrine

d. direct cell-to-cell

b. Endocrine

Signaling by neurotransmitters is an example of _______ signaling.

a. autocrine

b. endocrine

c. paracrine

d. direct cell-to-cell

C. Paracrine

Signaling by cadherins is an example of _______ signaling.

a. autocrine

b. endocrine

c. paracrine

d. direct cell-to-cell

D. Direct cell-to-cell

Stimulation of T lymphocytes, leading to their synthesis of a growth factor resulting in T lymphocyte proliferation, is an example of _______ signaling.

a. autocrine

b. endocrine

c. paracrine

d. direct cell-to-cell

A. autocrine

Which signal molecule diffuses through the plasma membrane to ultimately bind nuclear receptors and influence transcription?

a. estrogen

b. nitric oxide

c. cadherins

d. nerve growth factor

A. Estrogen

Steroid hormones usually act via receptors that

a. are coupled to G proteins that activate adenylyl cyclase.

b. activate tyrosine kinases.

c. bind to DNA.

d. activate phospholipase C.

C. Bind to DNA

Statins, a class of drugs that are often administered to patients with high cholesterol, inhibit the biosynthesis of cholesterol. Statin drugs would not be expected to affect the biosynthetic pathway of which of the following signal molecules?

a. Thyroid hormone

b. Vitamin D3

c. Retinoic acid

d. Estrogen

C. Retinoic Acid

A glucocorticoid binding to its receptor stimulates

a. phosphorylation of a transcription factor protein that activates a gene.

b. formation of a receptor dimer that triggers an intracellular signal pathway.

c. formation of a receptor dimer that binds to and activates a gene.

d. binding of the receptor monomer to a gene.

C. Formation of a receptor dimer that binds to and activates a gene

Nitric oxide is a signal molecule that can

a. bind to surface receptors and activate second messengers.

b. bind to surface receptors and open ion channels.

c. diffuse across cell membranes and bind to receptors that regulate transcription.

d. diffuse across cell membranes and directly alter the activity of intracellular enzymes.

D. Diffuse across cell membranes and directly alter the activity of intracellular enzymes

Nitric oxide is considered a paracrine signal molecule because it

a. is slow to diffuse

b. is produced in very small quantities

c. is unstable, with a short half-life

d. binds to cell surface receptors that are very plentiful

C. Is unstable, with a short half-life

Neurotransmitters act by binding to receptors that are

a. ligand-gated ion channels.

b. located in the cytoplasm.

c. tyrosine-kinase receptors.

d. not coupled to G proteins.

A. Ligand-gated ion channels

The medical usage of nitroglycerine in heart disease is based on its

a. inhibition of adenylate cyclase and blood vessel contraction

b. conversion to NO which causes blood vessel dilation

c. activation of NO-synthase and muscle cell contraction

d. promotion of cyclooxygenase and prostaglandin synthesis

B. conversion to NO which causes blood vessel dilation

Enkephalins and endorphins bind to the same receptors in the brain as

a. nerve growth factor

b. aspirin

c. morphine

d. acetylcholine

c. morphine

In plants, cytokinins stimulate

a. cell division.

b. cell elongation.

c. cell enlargement.

d. fruit ripening.

A. cell division

In plant cells, which signaling molecule induces cell elongation?

a. Acetylcholine

b. gamma-aminobutyric acid (GABA)

c. Auxin

d. Retinoic acid

C. auxin

Which molecule stimulates fibroblasts to proliferate and thus heal a wound?

a. EGF

b. NGF

c. NO

d. PDGF

D. PDGF

Differentiation of blood cells and control of lymphocytes during the immune response is regulated by which type of signaling molecule?

a. Enkephalins

b. Fibroblast growth factor

c. Platelet derived growth factor

d. Cytokines

D. Cytokines

The G protein that activates adenylyl cyclase is a

a. monomeric G protein in the Ras family that binds GTP

b. dimeric G protein that separates into alpha and beta subunits

c. heterotrimeric G protein that separates into alpha and beta gamma subunits

d. heterotrimeric G protein that separates into alpha and beta and gamma subunits

C. heterotrimeric G proteins that separates into alpha and beta gamma subunits

In an active state of a G protein, the

a. alpha subunit binds to a target protein, and the beta gamma subunit remains bound to the receptor

b. alpha and beta gamma subunits both can bind to target proteins

c. alpha beta and gamma subunits both can bind to the target proteins

d. gamma subunit can bind to a target protein, and the alpha beta subunit remains bound to the receptor

b. alpha and beta gamma subunits both can bind to target proteins

The GTP on the G protein that is linked to adenylyl cyclase is split to GDP and Pi

a. in the inactive site

b. in the process of subunit separation

c. upon activation by the receptor

d. by the active alpha subunit

D. by the active alpha subunit

Cholera toxin inhibits the ability of the alpha subunit of Gs to split GTP. If you treated cells with cholera toxin, the resulting effect would be _______ of adenylyl cyclase

a. stimulation

b. inhibition

c. molecular degradation

d. increased synthesis

A. stimulation

A mutation that causes a G-protein to lose its ability to hydrolyze bound GTP would be expected to have constitutively

a. inactive betagamma subunits

b. bound alphabetagamma subunits

c. active alpha subunits

d. inactive alpha subunits

C. active alpha subunits

The alpha subunit of the G protein that is associated with the epinephrine receptor, Gs,

a. opens Ca2+ channels.

b. closes Na+ channels.

c. activates adenylate cyclase.

d. inhibits adenylate cyclase.

C. activates adenylate cyclase

The major function of cAMP in animal cells is to activate

a. adenylyl cyclase.

b. protein kinase A.

c. protein kinase C.

d. tyrosine kinases.

B. Protein kinase A

Protein kinase A is activated by

a. phosphorylation of its catalytic subunit.

b. phosphorylation of its regulatory subunits.

c. binding of cAMP to its catalytic subunits.

d. binding of cAMP to its regulatory subunits.

D. binding of cAMP to its regulatory subunits

Binding of cAMP to the _______ subunits of protein kinase A (PKA) leads to

_______ of that protein kinase.

a. catalytic; activation

b. catalytic; inactivation

c. regulatory; inactivation

d. regulatory; activation

D. regulatory; activation

Protein kinase A regulates glycogen metabolism by phosphorylating glycogen synthase and

a. phosphorylase kinase.

b. glycogen phosphatase.

c. glycogen phosphorylase.

d. glucokinase.

A. phosphorylase kinase

Protein kinase A regulates glycogen metabolism by _______ glycogen synthase and _______ glycogen phosphorylase.

a. activating; activating

b. inactivating; inactivating

c. activating; inactivating

d. inactivating; activating

D. Inactivating; activating

The action effected by protein kinase A is terminated by

a. inactivation of initial receptor

b. inaction of the stimulatory G protein

c. degradation of cAMP

d. dephosphorylation of phosphoproteins by protein phosphatase 1

D. dephosphorylation of phosphoproteins by proteins phosphatase 1

During the odorant response in the cilia of olfactory neurons, the second messenger ______, leads to the opening of ion channels in the plasma membrane of olfactory neurons and the production of a nerve impulse.

a. Ca2+

b. cAMP

c. cGMP

d. IP3

B. cAMP

Protein X is activated by protein kinase A. A mutation in protein X that replaces the protein's only serine residue with an arginine residue would be expected to

a. increase activation of protein X

b. eliminate activation of protein X

c. have no effect on activation of protein X

d. prevent inactivation of protein X

B. eliminate activation of protein X

CREB is activated by

a. cAMP binding in the nucleus.

b. phosphorylation by protein kinase A in the nucleus.

c. cAMP binding in the cytoplasm.

d. phosphorylation by protein kinase A in the cytoplasm.

B. phosphorylation by protein kinase A in the nucleus

Which statement correctly describes how protein kinase A can activate genes?

a. Nuclear protein kinase A is activated by cAMP to phosphorylate general transcription

factors.

b. Cytosolic protein kinase A is activated by cAMP to release the catalytic subunits,

which move into the nucleus and phosphorylate CREB.

c. Cytosolic protein kinase A is activated by cAMP to release the catalytic subunits,

which move into the nucleus and phosphorylate general transcription factors.

d. Nuclear protein kinase A is activated by cAMP to phosphorylate CREB.

B. cytosolic protein kinase A is activated by cAMP to release the catalytic subunits, which move into the nucleus and phosphorylate CREB

Activated CREB protein

a. phosphorylates protein phosphatase 1, leading to its activation

b. binds to specific DNA sequences and influences transcription of genes involved in growth and development

c. binds to ribosomal subunits and influences translation of proteins important in growth and development

d. phosphorylates protein kinase A in the cytoplasm

B. binds to specific DNA sequences and influences transcription of genes involved in growth and development

The first step in growth factor pathway activation is

a. receptor dimerization.

b. receptor phosphorylation.

c. Ras activation.

d. the binding of SH2-containing proteins.

A. receptor dimerization