Exam 3: Cellular Structure, Proteins, and Metabolic Pathways

You are observing the rate of an enzymatic reaction.You continue to add substrate in higher and higher concentrations,but eventually you see the rate of reaction plateau,no further increases in the rate of the reaction could be observed.Which of the following are plausible explanations for your observation (select all that apply)?

NAD⁺ is a byproduct of cellular respiration that diffuses out of the cell and is eliminated from the body in urine.

Which is a series of reactions by which fatty acid catabolism occurs?

During oxidative phosphorylation,hydrogen atoms are passed serially from a coenzyme down a chain of molecules called cytochromes.

In the lab you are re-creating the metabolic pathway that produces the hormone testosterone.Unfortunately,you've run out of the enzyme that catalyzes the third reaction.It's no problem,though,because you can substitute any of the other enzymes as all enzymes in a metabolic pathway are interchangeable.

Which is NOT true about a binding site on a protein?

Neurons have extremely long cytoplasmic extensions.Their chemical signals are produced in one portion of the cell,but released from a distant location.How are the chemicals transported?

Which of the following is not true of the cytoskeleton?

Removal of the amino group from an amino acid is necessary before the amino acid can be metabolized for energy.

What is the term for the segments of primary RNA that are cleaved and discarded by spliceosomes?

Tom tries a new diet that involves no food intake.Instead of eating,he takes plenty of multivitamin pills.This is OK because vitamins are a significant source of energy.

Many popular diet trends involve severe reductions in dietary carbohydrates so that the body must utilize fats and lipids as energy sources.Under these conditions,a greater than usual rate of protein deamination occurs.Which of the following could be expected?

In the absence of oxygen,cells can derive energy to form ATP from the metabolism of fatty acids.

The major lipids in cellular membranes are phospholipids.

Macrophages are motile cells that crawl within tissues of the cells.Hepatocytes are stationary cells that are anchored in place within the tissue.  Compared to hepatocytes,macrophages would likely have more of which cytoskeletal filament?

What is the function of a catalyst in a chemical reaction?

Which best describes functions of the smooth (agranular) endoplasmic reticulum?

Allosteric modulation of a protein involves noncovalent binding of a ligand to a regulatory binding site.

One function of integral membrane proteins in the plasma membrane of cells is to form channels to allow passage of nonpolar solutes into the cell.

Tamoxifen is a breast-cancer drug that binds to the estrogen receptor.When in the body,tamoxifen binds to the estrogen receptor for much longer than the patient's own estrogen.Tamoxifen stays bound for so long that it prevents the binding of circulating estrogen to its receptor.Tamoxifen must have a higher ________ for the estrogen receptor than estrogen.