Bio Exam 2

What is typically the result of receptor up-regulation?

A hormone's signal is amplified.

Phospholipids do not contain

3 fatty acid chains

A DNA molecule is made up of:

Nucleotides

An organism that is eukaryotic:

Posesses a nucleus

Which molecule is least likely to cross a cellular membrane by simple diffusion?

Potassium

What does the nucleolus, within the nucleus, synthesize?

Ribosomal RNA

Information in living organisms is transmitted by which mechanism(s)?

Genes, hormones and neurotransmitters

Why can cholesterol act as a "fluidity buffer" in cell membranes?

It is slightly amphipathic because of the presence of one hydroxyl group.13. Why can cholesterol act as a "fluidity buffer" in cell membranes?

DNA is associated with certain proteins, forming a complex called:

Chromatin

Under which of the following situations would receptor down-regulation most likely occur?

The concentration of a hormone is too high.

Which is a benefit of sexual reproduction over asexual reproduction?

The interaction of the genes from both parents brings about genetic variation.

A transmembrane protein differs from other membrane proteins because it:

completely extends through the membrane.

Which of the following describes how facilitated diffusion is powered?

Energy is required to do the work of establishing and maintaining a concentration gradient.

A receptor on the cell surface usually has several domains. What is the function of the external domain?

It is the docking site for a signaling molecule.

In a lipid bilayer, __________ fatty acid tails face each other within the bilayer and form a region that excludes water.

hydrophobic

If the concentration of solutes in a cell is less than the concentration of solutes in the surrounding fluid, then the extracellular fluid is said to be:

hypertonic

What enzyme in the ER lumen catalyze the efficient folding of proteins into proper conformations?

molecular chaperones