Cell Bio Exam 2 Practice

Imagine that you have added the ER retention (KDEL) signal to the C-terminus of a cytoplasmic protein. If the gene was expressed in a cell, predict the final location in which your protein will localize.

Cytoplasm

Which protein is responsible for the ATP-dependent uncoating of the clathrin from the nascent vesicle?

Hsc 70

Coat proteins such as Clathrin would dissociate from the newly internalized vesicles so that ____ .

Rab proteins can associate with their proper tethering proteins

During the process of macropinocytosis, ____.

significant amount of fluid will be internalized

Animal cells contain numerous membrane proteins that are decorated with oligosaccharide. Which of the following statement is false?

When an oligosaccharide is linked to a protein through the N-Linked glycosylation, the oligosaccharide is covalently linked to the amino terminus of the protein.

1 multiple choice option

Which of the following is a member of local mediators?

Nitric Oxide

The same signal molecule can induce different outcomes from target cells only when they express different types of receptors.

False

1 multiple choice option

A cell can differently respond to different extracellular signals, but the responses occur within fairly similar time ranges, i.e., in a few minutes.

False

1 multiple choice option

A signal receptor must be localized to the plasma membrane of the signal receiving cells.

False

1 multiple choice option

The neurotransmitter acetylcholine directly binds to and activates guanylyl cyclase in the smooth muscle cell.

False

1 multiple choice option

The activation of the cdk kinase signals that a particular set of separate upstream events has been completed. Thus, cdk acts as a specific ____.

signal integrator

Cell surface receptors fall into three basic classes. Which one of the followings is not one of them?

cortisol receptor

In muscle cells, adrenaline binds to the beta-adrenergic receptor to initiate a signaling cascade that leads to the breakdown of glycogen. At what points in this pathway is the signal amplified?

Production of cAMP by AC

The ligand bound GPCR proteins activate the heterotrimeric G proteins through _____.

facilitating GDP exchange of Ga to GTP

Upon activation, which of the heaterotrimeric G proteins can function as a specific signal transmitting protein?

both G-alpha and G-beta/gamma

RGS proteins inhibit _____.

G-alpha

G-olf and Transducin are members of _____ protein.

G-alpha

Acetylchoine activates heterotrimeric G proteins and induces opening of K+ channels in the plasma membrane of heart pacemaker cells. As a consequence, the pacemaker cells will be

hyperpolarized

Which of the followings is an intracellular second messenger molecule?

Calcium

Adrenaline binds to GPCR, which increases the level of intracellular cAMP. One of the major intracellular targets of cAMP is PKA. What kind of molecule is PKA?

cAMP activated protein kinase

Acetylcholine activates PLC in smooth muscle in order to increase the level of _____?

IP3

Which of the followings opens the ligand gated calcium channel of endoplasmic reticulum?

IP3

The cytoplasmic calcium ions associate with _____ to induce cellular effects.

Calmodulin

A rod photoreceptor cell (noncolor vision in dim light) from the retina is exquisitely sensitive to light. Upon activation Rhodopsin molecules activate transudcin, which in turn activates cGMP specific phosphodiesterase (PDE). Which of the following is the consequence of the activation of transducin and cGMP PDE?

Hyperpolarization

Wnt signal transduction pathway includes multiple components. Which one of the following will facilitate the effect of Wnt ligand?

beta-catenin

Which of the statements below about intermediate filaments is false?

They show dynamic instability

2 multiple choice options

Which of the following is not a microtubule organizing structure?

Centromere

2 multiple choice options

Which of the following statements regarding dynamic instability is false?

None of the above

2 multiple choice options

Which of the following statements about microtubules is true?

GTP hydrolysis by a tubulin heterodimer discourages the growth of a microtubule.

What type of motor protein causes the flagellum to bend?

Dynein

Which of the following statements about actin is false?

ATP hydrolysis increases actin filament stability.

1 multiple choice option

Small G Protein Family members induce major cytoskeletal rearrangements. Which of the following is not one of them?

Ran

2 multiple choice options

Which of the following conditions below would decrease the likelihood of skeletal muscle contraction?

addition of a drug that blocks Ca2+ binding to troponin

Assembly of myosin II into thick bipolar myosin II filaments in smooth muscle is known to be dependent on the Myosin II Light- chain phosphorylation by Calmodulin dependent kinase (CamK, Myosin Light Chain Kinase is one of them). What second messenger would be is responsible for Myosin II activation in smooth muscle?

Calcium

Skeletal muscle contraction is triggered by the release of Ca2+ from _______ into the cytosol.

the sarcoplasmic reticulum

Which two processes together constitute the M phase of the cell cycle?

Mitosis and cytokinesis

Different cyclin-dependent protein kinases (Cdks) trigger different stages of the cell cycle in part because:

their activities increase at different stages of the cycle.

Which of the following statements is false?

Cyclins help activate Cdks by phosphorylating them.

Which of the following statements is false?

Activated M-Cdk triggers the onset of cytokinesis

1 multiple choice option

The cell-cycle control system uses Cdk inhibitory proteins:

to arrest the cell cycle at specific checkpoints.

The shortening and thickening of chromosomes in M phase depends on:

condensins

The mitotic spindle is made of:

microtubles

Microtubules capture chromosomes by binding to:

kinetochores on the sister chromatids.

The anaphase promoting complex (APC) triggers the onset of anaphase by:

facilitating the destruction of the cohesins that holds the sister chromatids together.

The contractile ring is made of:

actin and myosin.

Which of the following statements is true?

Many cells die by apoptosis in many normal, adult, human tissues.

1 multiple choice option

Which of the following statements is false?

Bcl2 promote apoptosis

1 multiple choice option

Which of the following statements describe how growth factors stimulate animal cell enlargement?

They stimulate intracellular protein synthesis.

In connective tissues, the tensile strength of the tissue is chiefly provided by:

collagen

Fibroblasts are found in which tissues?

Connective

Fibroblasts play a role in:

orienting collagen.

A fibroblast can attach indirectly to collagen via which type of protein?

Fibronectin

Which protein in a fibroblast's plasma membrane attaches to the extracellular matrix on the outside of the cell and (through adapter molecules) to actin inside the cell?

Integrin

In the extracellular matrix of animal tissues, which of the following molecules allows the matrix to resist compression?

Proteoglycans

Which of the following is NOT true of the basal lamina?

The basal lamina lines the inside of epithelia cells at the basal membrane surface.

1 multiple choice option

Which epithelial cell junctions serve to seal neighboring cells together so that water-soluble molecules cannot easily leak between them?

Tight junctions

Cadherin proteins:

link epithelial cells together by binding to similar cadherins in adjacent epithelial cells.

In a tissue, which of the following cell types divides to create a continuous supply of differentiated cells?

Stem cells

In the intestine, Wnt proteins:

promote the proliferation of the stem cells at the base of each intestinal crypt.

Which of the following can give rise to cancer causing mutations?

All of the above

2 multiple choice options

Which of the following is NOT a key behavior of cancer cells?

They digest neighboring cells to fuel proliferation.

2 multiple choice options

In addition to stimulatory factors, some signal proteins such as ________ act negatively on their target cells, inhibiting their survival, growth, or proliferation

TGF-beta

Which of the following cell has the shortest half-life?

a cell lining the gut

p53 is known as the king of Cancer research. It is essential for cells to either stop the cell cycle or commit apoptosis upon DNA damage. How does p53 induce apoptosis?

inducing Bcl2 inhibitor PUMA

Beta-Catenin is the transcription factor that mediates Wnt signaling. What would facilitate the destabilization of beta- catenin in the absence of Wnt signal?

APC

Carcinoma is a cancer derived from _________.

Epithelial cells

Rb is a critical regulator of G1 to S transition. What inhibits Rb?

Cdk