bio hw

It would increase glycogen phosphorylase activity.

> 1; < 0

What is the second messenger in the receptor tyrosine kinase signaling pathway?

The enzyme MAPK that gets transported into the nucleus to activate gene transcription

If it were injected directly into liver cells, cAMP would have the effect of:

Activating Protein Kinase A and, therefore, glycogen breakdown

A mutation that causes a decrease in the GTPase activity of G-alpha in liver cells would have the effect of:

All of the above

As we learned in Lecture 15, protein phosphatases catalyze removal of phosphate groups from proteins. How would the activity of a protein phosphatase affect liver cell responses to epinephrine?

Decrease glucose production

After you eat, insulin is secreted by pancreatic Beta cells into the bloodstream, where it diffuses throughout the body to bind to receptors on target cells, telling them to take up glucose. This mode of signaling is referred to as:

Endocrine

Which of the following is a mechanism by which cells ensure a strong response to a small amount of ligand?

Enzyme cascades

The reaction shown above is:

Exergonic

Which of the following is an advantage of juxtacrine signaling?

It is fast.

What is the second messenger in the receptor tyrosine kinase signaling pathway?

None of the above

Which of the following is true of steroid hormones but not a signaling molecule such as a ligand for G-protein coupled receptors?

Their receptors regulate gene transcription.

A major function of the epithelium in animals is to prevent entry of pathogens and toxins from the environment. Which of the following is common to all epithelial cells?

They are held together by tight junctions.

Which of the following is true of both GPCR signaling and steroid hormone signaling?

They may result from endocrine signals.

Liver cells respond to epinephrine by breaking down glycogen. What is the second messenger in this patway?

cyclic AMP

Cell adhesion molecules are important components of:

tight junctions

Which of the following is an advantage of multicellularity?

Greater mobility/Increased mobility

ras, a small GTPase, hydrolyzes GTP slowly on its own, but its enzymatic activity is increased significantly in the presence of GTPase activating proteins (GAPs). Imagine you discovered a novel mutation that prevents GAP from binding to ras. This mutation would have the effect of:

Increasing cell proliferation

Consider the reaction: A + B <=> C + D. Under standard conditions at equiliubrium, the concentrations of the compounds are [A] = 0.1 M, [B] = 0.1 M, [C] = 1.9 M, and [D] = 1.9 M; and the pH is 7.0. Keq for the reaction is _____ and the reaction is _____. (you do not need a calculator for this!)

361; exergonic

G-protein coupled receptors have ____ transmembrane domains.

7

The Krebs cycle involves the aerobic breakdown of glucose for energy. In the first reaction of the Krebs Cycle, the enzyme Aconitase converts Citric acid to its isomer, the molecule isocitrate. The Keq' for this reaction is approximately 0.1. ∆G°' for this reaction is therefore ____ and the reaction is ____.

>0; Endergonic

Collagen, an extremely important extracellular matrix protein, is constitutively secreted by fibroblast cells, a type of connective tissue cell. If you had a patient in which collagen is synthesized normally, but fails to be secreted into the extracellular matrix, which of the following would you examine as the likely cause of this problem? (Think very carefully before answering this question!)

A kinesin disorder

If you had a patient in which the lung epithelium was leaking fluids from the bloodstream into the lumen of the lung, which of the following is the most likely cause?

A mutation in a cell adhesion molecule

Which of the following is/are likely to elicit a rapid, reversible response?

An odorant that binds to a G protein-coupled receptor

Which adaptation specific to becoming multicellular compensates for the destabilizing effect of increased size? (Think carefully about answer choices!)

Both ECM and tight junctions

Liver cells respond to epinephrine by __________.

Breaking down glycogen.

"He was awakened in the middle of the night by a low growling that sounded as if it was coming from just outside his tent. In response, the cells of his adrenal medulla began to secrete epinephrine, causing his palms to sweat, his heart to race, and his hair to stand on end." Epinephrine is involved in what type of signaling as described in this passage?

Endocrine

ATP hydrolysis is highly _____ because it involves _____.

Exergonic; separation of negatively charged phosphate groups

Which of the following is an advantage of endocrine signaling?

It affects large numbers of cells.

Dr. Hutson really likes coffee. Caffeine is a xanthine, a class of molecules that are similar to purines. One of the mechanisms by which caffeine acts is to inhibit the enzyme cAMP phosphodiesterase, which converts cAMP to plain old AMP, which is inactive. How does caffeine alter liver cell responses to epinephrine?

It would increase glucose production.

G-alpha is not only an activator of Adenylate cyclase, but it is a GTPase. How does mutation in G-alpha that decreases its GTPase activity affect liver cell responses to epinephrine?

It would increase glycogen phosphorylase activity.

Which of the following is a disadvantage of being a multicellular organism specifically as opposed to unicellular? (read and think carefully!)

More difficult to absorb nutrients

Which of the following correctly describes a second messenger?

None of the above

"During embryonic development red blood cells begin to develop in patches called blood islands. The blood cells secrete growth factors that diffuse only to nearby cells, signaling differentiation into endothelial cells. The endothelial cells eventually form the linings of the blood vessels." The growth factor described in the passage is involved in what type of signaling?

Paracrine

Imagine you walk into lab after spring break, and your TA hands you a beaker containing a solution of A, B, and C in water represented by the equilibrium shown below. If the solution has reached equilibrium, and the beaker is at pH 7.0, 25°C, and 1 atm pressure, what other information do you need to obtain in order to calculate ∆G°' for this reaction?

The concentrations of A, B, and C

What is the second messenger in the receptor tyrosine kinase signaling pathway? Selected Answer: The enzyme MAPK that gets transported into the nucleus to activate gene transcription Response Feedback: You will notice that RTK/ras signaling doesn't involve production of any new molecules, only activation of proteins including enzymes.

What is ∆G°' for the hydrolysis of ATP? Selected Answer: +7.3 kcal/mol Answer Feedback: Review lecture 16

More difficult to absorb nutrients

highly exergonic

∆G°' for the hydrolysis of ATP is considered to be:

highly exergonic