BIO201 - Homework 5

Larger size, greater mobility, and functional specialization of cells/tissue

Advantage of multicellularity?

Tight Junctions

Cell adhesion molecules are important components of:

By the time it reaches the target cell, the ligand concentration is likely to be very low.

DISADVANTAGE of endocrine signaling?

Diffusible, produced when the "first messenger" binds to its receptor, and activates enzymes

True of a second messenger in signal transduction

Endocrine

"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?

Facilitated Diffusion

Ca++ flowing down its concentration gradient through a Ca++ channel is an example of:

K+/Cl- symporter; indirect active transport

Chloride ion (Cl-) concentrations must be maintained much higher outside of cells than inside of cells. How this gradient is maintained is complex, but a key transporter co-transports Cl- along with K+ ions. The name of this transport protein could be ____ and its mode of transport would be ____.

Phosphatases

Which of the following enzymes catalyzes dephosphorylation of proteins?

More difficult to absorb nutrients

Which of the following is a disadvantage of being a multicellular organism specifically as opposed to unicellular?

An odorant that binds to a G protein-coupled receptor

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

They are held together by tight junctions.

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?

None of the above

Archeological evidence suggests that Neanderthals may have been aware of the medicinal properties of plants over 60,000 years ago. Imagine you are a modern-day ethnobotanist and have identified a compound from fossilized tree pollen that binds to the alpha subunit of the most common G-proteins. To test how the compound affects the activity of Gα, you treat liver cells with the compound and then epinephrine. You observe that the cells fail to produce glucose. Which of the following could be how the compound acts?

Na+/Cl- antiporter

Chloride ion (Cl-) concentrations are approximately 10x higher outside of cells than inside. Imagine you discovered a novel protein that is required in liver cells for transporting Cl- out of the cell up its concentration gradient, and further found that this protein only functions if the Na+/K+ ATPase is active. This suggests that the Cl- transport protein is a:

A kinesin disorder

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?

Cyclic AMP

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

Epinephrine signaling is more likely to have a short-term, reversible effect.

One of the main differences between growth factor signaling (receptor tyrosine kinase receptors) and epinephrine signaling (G-protein coupled receptors) is that:

False

T/F The concentration of Ca++ inside the cell is higher than it is outside.

True

T/F The concentration of Na+ outside the cell is higher than it is inside

Smooth ER

Where in the cell would you expect to see a Ca++ ATPase?

Both ECM and tight junctions

Which adaptation specific to becoming multicellular compensates for the destabilizing effect of increased size?