Cell Bio Final Review Nick and quiz

Under the same conditions that lead cultured normal cells to exhibit decreased growth rates, which of the following does NOT happen with malignant cells?

Their growth rates decrease.

HSC70 and LAMP-2a tag proteins including alpha-syn for degredation in parkiinson's disease patients, alpha-syn is upregulated forming lewy bodies, which essentially cause apoptosis. The western blots below exhibit HSC70 and LAMP-2a in the presenece of varyong overexpressed micro-RNA. Which of the following is true based on the data

These 7 micro-RNA should be targeted for down regulation to treat PD patients

About 25% of breast cancers are composed of cells that overexpress the HER2 gene. What property does the overexpression of this gene confer upon the tumor cells?

These cells are especially sensitive to growth factor stimulation.

Why are G-protein coupled receptors often known as 7-TM receptors?

They have 7 transmembrane alpha-helices.

Protein kinases transfer the terminal phosphate from ATP onto a protein

True

The growth factor RGF stimulates proliferation of cultured rat cells. The receptor that binds RGF is a receptor tyrosine kinase called RGFR. Which of the following types of alteration would be most likely to prevent receptor dimerization?

A mutation that prevents RGFR from binding to RGF

No matter how the signal initiated by the binding of an extracellular ligand is, what is the outcome of that signal?

A protein at the top of an intracellular signaling pathway is activated.

Which of the following is NOT a characteristic of the pathways activated by second messengers?

Each protein in the pathway typically acts by altering the conformation of the previous (upstream) protein in the series, an event that activates or inhibits the protein

Once the kinase domain of receptor protein-tyrosine kinase has been activated, what does the activated receptor protein-tyrosine kinase do?

Each receptor subunit phosphorylates its partner on tyrosine residues found in regions adjacent to the kinase domain.

Dissolved gasses such nitric oxide (NO) can act as signal molecules, but because they cannot interact with proteins they must act by affecting membrane lipids.

False

Extracellular signaling molecules that are hydrophobic must bind to cell-surface receptor so as to signal a target cell to change behavior.

False

MAP Kinase is important for phosphorylating MAP Kinase Kinase

False

Why can cancer cells proliferate in the absence of serum

The cell cycle of cancer cells does not depend on signal transmitted from serum growth factor receptors located at there surface

You are interested in cell-size regulation and discover that signaling through GCPR called ERC1 is important in controlling cell size in embryonic rat cells. The G-protein downstream of ERC1 activates adenyl cyclase, which activates pKa. You discover that cells that lack ERC1 are 15% smaller than normal cells, which cells that express a mutant, constitutively activated version of pKa 15% larger than normal cells. which treatment will lead to smaller embryonic rat cells?

addition of a drug that causes cAMP-phosphodiesterase to be hyperactive.

How do cells in the body of a multicellular organism usually communicate with each other?

extracellular messenger molecules

What enzyme below does diacylglycerol (DAG) recruit and activate?

protein kinase C

Mutant forms of tumor-suppressor genes act _____; both copies of the gene must be _______ before their protective function is lost.

recessively, mutated or deleted

What part of the cell cycle does the pRB protein help to regulate?

the G1 - S transition

What is the oncogene that is most often mutated in human tumors and what does it encode?

the RAS gene, a GTP-binding protein that serves as an on-off switch for a key cell signaling pathway that controls cell proliferation

In cells exposed to stressful stimuli, like X-rays or damaging chemicals, what response does the MAP kinase cascade coordinate?

withdrawal from the cell cycle

What happens to a cell that is carrying damaged DNA if both of its TP53 alleles become inactivated? 1) It lacks the genetic integrity required for controlled growth. 2) It lacks the genetic integrity required for uncontrolled growth. 3) It fails to be destroyed.

1 and 3

Cell signaling is also present in bacterial hydrogen peroxide induces rsp expression in Staphylococcus arureas. Rap is a transcription factor. Neutrophiles are PMN's that phagocytize and kill bacteria with water. Nue is a virulent protein. Based off the data below place the signal mechanism (chain of events) in order. (Insert graphs)

1. (III) The neutrophil phagocytizes S. aureaus as the host defense 2. (II) Water induces expression of rsp in wt S. aureus 3. (I) Rsp upregulates expression of virulence genes 4. (IV) Nue snd other proteins lyse neutrophiles

Sometimes an enzyme is activated by a receptor and brings about the cellular response by generating a second messenger. Such an enzyme is called a(n) __________.

effector

How is signaling by an activated Galpha subunit terminated?

The bound GTP is hydrolyzed to GDP.

Under the same conditions that lead cultured cultured normal cells to exhibit decreased growth rates, what happens to malignant cells

1. They continue to grow and divide 2. They pile on top of each other forming clumps 3They fail to respond to the types of signals that cause normal cells to cease growth and divide

Place the following events in the proper order. 1) Activation of one or more cellular signaling proteins. 2) Dissociation of Ga from the G protein complex. 3) Production of a second messenger, like cAMP. 4) Replacement of GDP by GTP on the Ga after interaction with an activated GPCR. 5) Conformational change in the Galpha subunit causing a decreased affinity for the Gbeta & gamma subunit. 6) Galpha-subunit with its attached GTP activates an effector like adenylyl cyclase.

4 - 5 - 2 - 6 - 3 - 1

Place the events related to the initial steps of GPCR signaling below in the correct order. 1) G protein binds to activated receptor forming a receptor-G protein complex 2) Release of GDP by the G protein 3) Change in conformation of the cytoplasmic loops of the receptor 4) Binding of GTP by the G protein 5) Increase in the affinity of the receptor for a G protein on the cytoplasmic surface of the membrane. 6) Binding of a hormone or neurotransmitter to a G-protein coupled receptor 7) Conformational shift in the alpha subunit of the G protein

6 - 3 - 5 - 1 - 7 - 2 - 4

the intercellular domain of the Notch receptor, (NICD) is cleaved. what is the role NICD in NOTCH signaling?

Allows transcription to proceed by acting as a coactivator of MAML-p300

What evidence suggests that while viruses may play a role in cancer development and increase a person risk of developing cancer, they are rarely the sole determinant responsible for the disease?

Although HPV is founded in 90% of human cervical cancer,

How can one identify oncogenes?

by introducing the DNA suspected of containing the oncogene into cultured cells and looking for altered growth properties

What is the role of the SMRT, CtBP, SIRT1 and LSD1 in Notch Signaling

Inhibits the expression of Hex, Nrarp, cMyc through steric hindrance of MAML-p300 binding RNA-pol-RBP-J

What is the reason for the withdrawal of cells from the cell cycle after exposure to stressful stimuli, like X-rays and damaging chemicals?

It gives the cell time to repair damage resulting from such adverse conditions.

What does telomerase do

It maintains telomeres at the ends of chromosomes, thus allowing cells to continue to divide

In parkinson's disease patients, alpha SYN is upregulated forming Lewy bodies in which essentially cause apoptosis in neurons. Smoking allows for rapid introductions of Nicotine into neurons. Nicotine is known to upregulate mRNA-214 in neuroins. The western blot in neurons below exhibits a-syn in the presence of vrying concentrations of miRNA-214. Which of the following support the data

Smoking nicotine can lead to a decrease chance of developing parkinson's disease.

You are studying two rodent cell lines, one malignant and one normal. You carry out an experiment in which you fuse malignant and normal cells, what happens?

Some of the hybrid cells lose malignant traits

The length of time a G protein will signal is determined by ________.

The GTPase activity of G-alpha

The following happens when a G-protein-coupled receptor activates a G protein.

The alpha subunit exchanges its bound GDP for GTP

The following happens when a G-protein-coupled receptor activates a g protein

The alpha subunit exchanges its bound GDP to GTP

The BCL-2 oncogene is the oncogene most closely linked to _________; it encodes a membrane-bound ____________.

apoptosis, protein that normally acts to inhibit apoptosis