Enzymes and Microbial Growth

Sodium and potassium ions need to be pumped simultaneously against their concentration gradients. Which one of the transport proteins would be most effective at this?

Antiport

A drug such as imipenem is chemically modified from penicillin, but acts specifically on the causative agent of his infection. Assuming that imipenem acts on a bacterial enzyme - what is the most plausible explanation for why this drug acts only on one causative agent?

Because the drug interacts with an enzymes active site, it must match specifically with the enzyme - leaving no 'wiggle-room'.

Why do all enzymatic reactions need activation energy?

Energy is required to disrupt a substrate's stable electron configuration

Why are enzymes important to biological systems?

Enzymes decrease the amount of activation energy required for chemical reactions to occur

What is meant by the statement "Enzymes are biological catalysts"?

Enzymes speed up the chemical reactions in living cells

How is simple diffusion different from other types of passive transport?

Simple diffusion does not require a permease

What type of transport uses two transport proteins?

Symport

Which of the active transport types employs diffusion?

Symport

Why do the beta-lactam drugs affect bacteria but NOT human cells?

The beta-lactam antibiotics act on bacterial cell walls; human cells do not have cell walls

Beta-lactam drugs are typically considered more active against Gram-positive bacteria and less so against Gram-negative bacteria, why?

The cell walls of Gram-positive bacteria have a thick peptidoglycan component

ATPases are associated with active transport proteins because...

They provide transport proteins with the energy needed to pump molecules against their concentration gradients

Efflux pumps can be used to pump antibiotics out of a cell once they enter to protect the cell. This will be done against the concentration gradient of the antibiotic. Which of the active transports would most likely be used?

Uniport

Osmosis differs from simple diffusion in that...

Water movement is driven by the concentration of solutes rather than its own concentration

Nonspecific permeases...

allow a variety of molecules to cross the cytoplasmic membrane

Lipases are enzymes involved in the ______ of ______.

catabolism; fats

Which of the following is true concerning enzymes? a. enzymes increase the activation energy required for a chemical reaction to occur b. enzymes are broad acting and can bind a wide variety of substrates c. enzymes bind substrates at their allosteric sites d. apoenzymes may need to combine with cofactors or coenzymes to become active

d. apoenzymes may need to combine with cofactors or coenzymes to become active

Enzymes speed up the rate at which chemical reactions occur within a cell because the enzyme...

lowers the activation energy of the reaction

Any molecule that serves as an electron accepter will be...

reduced