By specifically binding potassium ions, open potassium channels selectively transport potassium ions across cell membranes.
Group of answer choices
False
True

A mutation in the anticodon sequence 5â€²-UAU-3â€² of a tRNA results in the anticodon sequence 5â€²-UUU-3â€™. Which of the following aberrations in protein synthesis might this cause?
Group of answer choices
substitution of lysine for isoleucine
substitution of tyrosine for phenylalanine
substitution of isoleucine for lysine
substitution of phenylalanine for tyrosine

Cell crawling depends on:
Group of answer choices
hydrolysis of ADP by motor proteins.
microtubule assembly.
intermediate filaments.
actin polymerization.

Which of the following statements is NOT true?
Group of answer choices
Stage 2 of photosynthesis involves a cycle of reactions that does not directly depend on energy derived from sunlight.
Carbon fixation can be described as a process by which gaseous carbon-containing molecules are captured and incorporated into biological hydrocarbon molecules.
The electron-transport proteins, utilized in stage 1 of photosynthesis, reside in the inner membrane of the chloroplast.
The electrons passed along the chloroplast electron-transport chain are ultimately passed on to a molecule of NADP+, which becomes reduced to NADPH.
The equation â€œLight energy + CO2 + H2O â†’ sugars + O2 + heat energyâ€ summarizes photosynthesis.

For voltage-gated channels, a change in the membrane potential can have what effect on the channel?
Group of answer choices
It changes which ions can pass through the channel.
It changes the width of the channel opening.
It alters the probability that the channel will be found in its open conformation.
The channel partially opens until a voltage threshold is met; then the channel opens fully.

What event would activate a G protein?
Group of answer choices
Replacement of GDP with GTP
Phosphorylation of GDP to GTP
Phosphorylation of GTP to GDP
Hydrolysis of GTP to GDP
Hydrolysis of GDP to GTP

When an electron moves from the reaction center of photosystem I, it leaves behind a positively charged special pair which must be reduced for photosynthesis to continue. The missing electron is donated by:
Group of answer choices
CO2.
H2O.
plastocyanin.
NADPH.
O2.

Using genetic engineering techniques, you have created a protein that contains 1.) a signal for export from the nucleus and 2.) an ER retention signal. Where would this protein end up?
Group of answer choices
Cytosol
Nucleus
ER
Mitochondria
Limbo

Your friend works in a biotechnology company and has discovered a drug that blocks the ability of Ran GTPase to hydrolyze GTP. What is the most likely effect of this drug on nuclear transport?
Group of answer choices
Nuclear transport receptors would be unable to release their cargo in the nucleus.
Nuclear transport receptors would be unable to bind cargo.
Nuclear transport receptors would be unable to enter the nucleus.
Nuclear transport receptors would interact irreversibly with the nuclear pore fibrils.

When Na+ channels are opened in an animal cell, what happens to the membrane potential?
Group of answer choices
It becomes less negative inside the cell.
It disappears and the membrane potential stabilizes at 0 mV.
It rapidly reaches the resting membrane potential.
It stays the same.

How do transporters and channels select which solutes they help move across the membrane?
Group of answer choices
Transporters discriminate between solutes mainly on the basis of size and electric charge; channels bind their solutes with great specificity.
Channels allow the passage of solutes that are electrically charged; transporters facilitate the passage of molecules that are uncharged.
Both channels and transporters discriminate between solutes mainly on the basis of size and electric charge.
Channels discriminate between solutes mainly on the basis of size and electric charge; transporters bind their solutes with great specificity.

When an electron moves from the reaction center of photosystem II, it leaves behind a positively charged special pair which must be reduced for photosynthesis to continue. The missing electron is replaced by an electron removed from __________. This process results in the release of __________ into the atmosphere.
Group of answer choices
O2; H2O
H2O; O2
NADPH; O2
CO2; H2O
ferredoxin; H2O

Activated trimeric G-proteins:
Group of answer choices
phosphorylate tyrosine amino acids on specific target proteins.
must continuously hydrolyze GTP to GDP to remain active.
activate other proteins that produce secondary messenger molecules.
are released into the cytoplasm to activate gene regulatory proteins.

Which of the following statements about a protein in the lumen of the ER is true?
Group of answer choices
A protein in the lumen of the ER is synthesized by ribosomes that have been inserted into the phospholipid bilayer of the ER membrane.
Some of the proteins in the lumen of the ER can end up in the extracellular space.
Some of the proteins in the lumen of the ER can end up in the plasma membrane.
All of the other answers are correct.

For both actin and microtubule polymerization, nucleotide hydrolysis is important for:
Group of answer choices
promoting nucleation of filaments.
stabilizing the filaments once they are formed.
increasing the rate at which subunits are added to the filaments.
decreasing the binding strength between subunits on filaments.

In eukaryotes, which parts of a gene encode protein?
Group of answer choices
introns only
all introns, but only the exons that will be translated
all introns and exons
exons only

Which of the following statements is true of mitochondrial proteins that are synthesized in the cytosol?
Group of answer choices
The proteins remain folded as they are transported into the mitochondria.
The proteins must be transported across the mitochondrial membranes while being synthesized.
The proteinsâ€™ signal sequences are recognized by receptors in the outer mitochondrial membrane.
The proteins cross both the inner and outer mitochondrial membranes via vesicles.

The first three steps of glycolysis produce fructose 1,6-bisphosphate and require an energy investment of __________ that will be recouped later. The next two steps cleave fructose 1,6-bisphosphate into __________. The final 5 steps produce __________.
Group of answer choices
4 ATPs; 2 four-carbon sugars; ATP, GTP and FADH2
4 ATPs; 2 three-carbon sugars; ATP and NADH
2 ATPs; 2 three-carbon sugars; ATP, GTP and NADH
2 ATPs; 2 three-carbon sugars; ATP and NADH

In the Î± helices of a water-filled transmembrane channel, hydrophobic amino acid side chains are typically in contact with:
Group of answer choices
the lipid bilayer.
both the aqueous channel and the lipid bilayer.
neither the aqueous channel nor the lipid bilayer.
the aqueous channel.

By specifically binding potassium ions, open potassium channels sel...