Bio/Biochem Flashcards
Compare and contrast osteoclasts and osteoblasts
Osteoclasts increase bone resorption (secretion of parathyroid hormone to inc. blood Ca2+ levels) while osteoblasts increase bone formation (secretion of calcitonin).
Therefore, increased osteoclast activity compared to osteoblast activity leaves cavities on the bone surface and results in weaker bone structure.
What is the difference between a coenzyme, prosthetic group, and an allosteric effector?
Prosthetic groups are usually tightly bound to an enzyme via a covalent bond and are necessary for the enzyme’s function.
Coenzymes are organic molecules that are required by an enzyme to function but not usually covalently bound, instead they are “loosely” bound.
Allosteric effectors are molecules that bind to an enzyme at a site other than the enzyme’s active site and regulate its function. Enzymes can and do function without allosteric modulators, they just function differently under that regulation. For this reason allosteric regulators cannot be prosthetic groups.
Give a brief summary of meiosis
During prophase, the chromatin condenses, the spindle forms, and the nuclear envelope disappears.
During metaphase, the chromosomes align at the equatorial plate.
During anaphase, the sister chromatids separate and the centromeres divide.
During telophase, the nuclear membranes form, the chromosomes spread apart, and the spindle breaks down.
What physiological process prevents cross-species fertilization among hominids?
The mechanism that prevents cross-species fertilization is species specific receptors expressed on the outside of the egg, which are bound by species-specific ligands expressed on the outside of the sperm.
What are some major functions of calcium?
Calcium combines with phosphate and hydroxide in hydroxyapatite, the major component of the extracellular bone matrix, so it aids in bone formation.
It is also required for blood clotting and muscle contraction (plays a role in both smooth and skeletal muscle).
Finally, calcium is necessary for the release of neurotransmitter bundles at the synapse, so it plays a role in nerve signal transmission.
How do protein-based vaccines stimulate an immune response?
Vaccines that are protein-based work because the antigens they contain resemble the antigens of the invading pathogen.
For example, viral vaccines usually contain viral capsid proteins, and bacterial vaccines contain surface proteins. This allows the host immune system to initiate a primary immune response and prepare for a secondary immune response without an actual pathogen infection.
What are micelles?
Micelles are spheres of amphipathic molecules, usually lipids, with hydrophilic heads on the surface of the sphere and hydrophobic tails pointed into the center of the sphere. Because of this, a protein that can integrate into a micelle must also be amphipathic, featuring both polar and non-polar regions.
Integral membrane proteins are both hydrophobic and hydrophilic and therefore are likely to be incorporated into micelles.
Are proteases common regulatory enzymes? WHy or why not?
No, proteases are not common regulatory enzymes because the action of a protease is not reversible, so the inhibition would be permanent.
When repairing a double stranded break in human DNA, what nucleotide polymer is used as the homologous template?
When homologous recombination is used to repair a double-stranded break, the template used is the sister chromatid.
During this process, the recombination machinery seeks out DNA that compliments the overhangs on each side of the break, and the sister chromatid will have that exact sequence. The sister chromatid is not likely to be damaged in the same region that the broken DNA on the other chromatid, so incorporating DNA from the sister chromatid is an efficient method.
