Chapters 13, 15 BCM

How does energy affect the functioning of the Na+-K+ ATPase?

-ATP provides energy for this pump to function. -The pump maintains the proper cellular concentration of Na+ and K+. -Without ATP, the pump would not be able to function.

What clues provide evidence of the mechanism of channel inactivation?

-Inactivation can be restored by the addition of part of a missing peptide. -Proteolysis of the cytoplasmic side leads to permanent open channel. -Mutations in amino acid sequence leads to differences in inactivation kinetics.

What are CORRECT statements about the binding sites of membrane pumps? Select all that apply.

-The external site is open while the internal site is closed. -The internal site is open while the external site is closed.

Name the consequences of Na+-K+ pump inhibition.

-The intracellular level of Na+ ions increases. -Ca2+ extrusion slows down. -An increase in the Ca2+ intracellular level leads to an increase in the ability of cardiac muscle to contract.

The ΔG of reactions depends on:

-nature of the reactants. -nature of the products.

Select all that apply. Membrane potential is:

-the sum of concentrations and electric terms. -electrochemical potential.

Metabolic processes are regulated by:

-transcriptional regulation of the amount of enzyme. -allosteric control of enzyme activity. -accessibility of substrates by compartmentalization. -covalent modification of enzymes.

What is the differences between active and passive transport?

Active transport requires an external energy source.

How does SERCA regulate muscle activity?

An increase in Ca2+ ions causes muscle constriction, and a decrease in Ca2+ ions causes muscle relaxation.

Scurvy, a disease characterized by skin lesions and blood-vessel fragility, is caused by the deficiency of vitamin:

C

What is the ultimate product of oxidation in aerobic organisms?

CO2

What vitamin regulates calcium and phosphate metabolism?

D

The electron carrier _______ is derived from the vitamin riboflavin.

FAD

The reduced form of flavin adenine dinucleotide is:

FADH2.

How is NADPH different from NADH? Choose the statement that is correct for NADPH.

Its adenosine moiety is esterified with phosphate.

What are the main features of simple diffusion?

Molecules pass through a membrane from areas of higher to lower concentration. Only lipophilic molecules can easily pass through the membrane.

What substance serves as the electron donor for most reductive biosynthetic pathways?

NADPH

An acetylcholine receptor is permeable for:

Na+ and K+.

What channels does tetrodotoxin isolated from the puffer fish bind to?

Na+ channels

Why can Na+ NOT pass through a potassium channel?

The Na+ ion radius is smaller than the K+ ion radius.

Why does acetyl CoA have a high acetyl-group-transfer potential?

The transfer of the acetyl group is exergonic.

A thermodynamically unfavorable reaction is driven by:

a thermodynamically favorable reaction to which it is coupled.

The product of the second stage of catabolism is:

acetyl CoA.

What molecules are responsible for sending nerve impulses?

acetylcholine

What type of reactions requires energy?

anabolic

What channels do not transport ions at all?

aquaporins

Ion channels:

can be selective and exist in open and closed states

Reaction pathways that exclusively transform fuels into cellular energy are:

catabolic

What compound serves as an acyl carrier in metabolism?

coenzyme A

The phosphoryl-transfer potential of ATP is lower than that of:

creatine phosphate.

What processes underlie the nerve impulse?

depolarization of the membrane from -60 to -40mV, an increase in Na+ permeability, intracellular accumulation of Na+ ions

What process takes place right after the nerve impulse arrives at the end of the axon?

export of acetylcholine vesicles into the synaptic cleft

What is the primary role of catabolism?

generation of ATP

What amino acid determines ion selectivity of the Ca2+ channel?

glutamate

What metabolic reaction type involves a cleavage of bonds by the addition of water?

hydrolyzation

When an uncharged molecule moves against the concentration grade, the process is:

in need of energy resources.

What reactions rearrange particular atoms within a molecule while conserving the empirical formula?

isomerization

The reaction of rearrangement of atoms to form isomers is:

isomerization.

What channel opens in response to binding of a particular molecule?

ligand-gated

What enzymes catalyze reactions where carbon bonds are cleaved by means other than hydrolysis or oxidation?

lyases

Fuels are degraded and large molecules are constructed step by step in a series of linked reactions. What type of reaction corresponds to this statement?

metabolic pathway

Where does fatty acid oxidation occur?

mitochondria

What is the ultimate electron acceptor in aerobic organisms?

oxygen

Which cellular process(es) require energy?

performance of mechanical work and active transport

What molecule structures allow for permeability of biological membranes?

pumps, carriers, and channels

What does ATP contain?

ribose

What group forms the reactive site of coenzyme A?

sulfhydryl

The total free-energy change for a chemically related series of reactions equals the:

sum of the free-energy changes of individual steps.

What accepts a hydrogen ion and two electrons in the oxidation of a substrate?

the nicotinamide ring of NAD+

What bond attaches an acetyl group to coenzyme A?

thioester bond

Carrier proteins:

transport ions or molecules across the membrane without hydrolysis of ATP.

What organic molecules are the sources of coenzymes in some higher animals?

vitamins

What channel opens in response to membrane depolarization?

voltage-gated