Cell and Molec Exam 4

Which of the following is a long-range signaling mechanism that enables cells to signal to distant cells via hormones secreted into the blood?

Endocrine

Which of the following is a short-range signaling mechanism that enables cells to signal to adjacent cells or cells within the same tissues via secreted hormones?

paracrine

Which of the following hormones is bound by an intracellular receptor instead of a cell surface receptor?

estradiol

There are lots of different mechanisms by which cells attenuate their responses to extracellular signals. This is called desensitization or adaptation. One of these mechanisms is called receptor sequestration. what does this involve?

Endocytosis of receptors and trafficking to the endosomes

What kinds of mutations in the Ras gene could lead to hyperactivate Ras

Mutations decrease the ability of Ras to hydrolyzed GTP

Mutations that block Ras binding to Ras-GEF proteins

*B and C*

Some receptor tyrosine kinases recruit Sos (son-of-sevenless) in order to activate Ras proteins. How does Sos activate Ras

By acting as a GEF

Raf is a MAPKKK that can be activated by Ras. Imagine you are working any Cancer clinic and encounter a patient with a cancer that has the Raf-V600E mutation, which makes Raf hyperactivate even in the absence of stimulus. You treat with a Raf inhibitor but the cancer does not spread. Which of the following drugs should you try instead as part of new treatment plan?

An inhibitor of Ras

Which of the following pathways utilizes beta-catenin as a transcriptional regulator?

Wnt/beta-catnin

In which of the following pathways is in inhibitor proteins phosphorylated and degraded by the proteasomes in response to an activating signal, enabling and transcription factor to translocate to the nucleus?

NF-KappaB

Which of the following pathways is involved in lateral inhibition during the development of neural crest cells and involves a receptor that has a cytosolic domain which can act as a transcription factor when it is cleaved away from the membrane in response to an activating signal?

delta-notch

In which of the following pathways does pro-inflammatory cytokine (e.g. TNF alpha) stimulation me to the activation of the IKK complex and the nuclear translocation of a cytosolic transcription factor

NF-kappB

Frog oocytes, when exposed to progesterone mature and can then be fertilized. This process involves progesterone-stimulated activation of a kinase cascade, leading to the phosphorylation and activation of MAP-kinase. Use the diagram to help answer the question.

At the individual cell level (individual oocytes; (B)), what type of MAPK response appears to be produced when the oocytes are treated with increasing concentrations of progesterone?

+ pic

All or none

Frog oocytes, when exposed to progesterone mature and can then be fertilized. This process involves progesterone-stimulated activation of a kinase cascade, leading to the phosphorylation and activation of MAP-kinase. Use the diagram to help answer the question.

At the population level (pooled oocytes; (A)), what type of MAPK response appears to be produced when the oocytes are treated with increasing concentrations of progesterone?

Sigmodial

For signaling pathways including transcription and translation as steps, how quickly would you expect activation of these pathways to result in a change in cell behavior?

it would take minutes or hours

What would have to happen in order for an activated GPCR to stimulate expression of genes containing CRE sites in their promoters?

Their G proteins would have to be able to activate adenylyl cyciase

G proteins are activated, what happened to the G protein trimeric complex?

the alpha subunit disassociates

Which secondary messenger activate protein kinase A?

cAMP

Which secondary messengers activate protein kinases C?

Diacylglycerol

What is the name of the calcium binding complex in skeletal muscle that helps regulate Ca2+ -dependent cross-bridging of actin and myosin?

Troponin

How does the Listeria ActA protein promote actin assembly at the rear surface of the bacterium?

by activating Arp2/3 complexes to nucleate actin filaments

Which of the following actin binding proteins binds individual actin subunits and speeds the elongation of actin filaments?

profilin

When the concentration of free actin is greater than the critical concentration (Cc) for the plus ends but less than the Cc for the minus ends, what will happen to the actin filaments?

The filaments will undergo treadmilling

Which of the following compounds stabilizers actin filaments and is commonly used as a cytoskeleton stain?

Phalloidin

Which of the three major types of protein filament would you find as a meshwork of cortical filaments directly beneath the plasma membrane and also makes up the core of the microvilli?

actin filaments

Which of the three major types of protein would you find connected to desmosomes and making up the nuclear lamina?

intermediate filaments

Which of the three major types of protein filament are centrioles and axonemes composed of?

microtubles

if the concentration of stathmin proteins was increased in cells, what is likely to happen to the length of microtubules in those cells?

they would shrink

Which of the following nucleates the formation of microtubules?

Gamma-TuRC

Where in the cell would you find high concentration of gamma-tubulin?

The MTOC

How many protofilaments are there in a microtubule?

13

What is likely to happen if GDP bound by tubulin proteins at the plus end of microtubules is replaced with GTP?

Polymerization will occur at the end and the microtubule will grow longer

The rapid interconversion between microtubule growth and shrinkage is known as...

Dynamic instability

T/F: Dyneins and kinesins are highly related structurally and are encoded by genes that share a high level of sequence similarly

false

T/F: Dyneins and kinesins use GTP hydrolysis to promote conformational changes in their structure that enable them to 'walk' along microtubules.

False

Cells can use various different types of protrusions to move within tissues. which of the following involves the separation of the membrane from the actin cortex beneath, allowing the cytoplasm to flow into that space temporary early pushing the membrane outward?

biebs

When a neutrophil is migrating across a surface towards a bacterium, how is the activity of Rho Family proteins likely to be distributed across the cell?

Rac dominates at the front of the cell and Rho dominates at the back

T/F: phosphorylation of P53 increases its association with Mdm2

False

What does phosphorylation of Rb proteins stimulate the release of?

E2F transcription factors

What is propidium iodine (PI)?

A fluorescent intercalating DNA dye used for cell cycle analysis

Which of the following is not a cell cycle checkpoint?

Cytokinesis

During which stage of the cell cycle would you expect Cdk6: cyclin D complexes to be the most active?

G1

What role do APC/C Play in cell cycle regulation?

It's in E3 ubiquitin ligase and stimulate the degradation of cyclins

What holds sister chromatids together and has to be degraded before they can separate during mitosis?

Cohesion

Which of the following cell death mechanisms is likely to cause inflammation and damage to surrounding tissue?

Necrosis

T/F: the external pathway of apoptosis requires the mitochondria

False

Which proteins need to be released from within the intermembrane space of the mitochondria in order to trigger apoptosis?

Cytochrome C

In the external pathway of apoptosis, what role does caspase-8 play?

It is an inhibitor caspase

Which of the following cellular components or cleaved directly by activated executioner caspase

Nuclear Lamins, cytoskeletal proteins, cell junction proteins, and genomic DNA

How might the BH3-only protein PUMA stimulate apoptosis?

By binding anti-apoptotic Bcl2 proteins

T/F: Activated P53 proteins stimulate the expression of anti-apoptotic Bcl2 proteins

false