Membranes and Metabolism

When studying with a friend for a test, what key points about osmosis would you make sure you tell them?

- Osmosis refers to the movement of water along a concentration gradient - In osmosis, water moves to equalize solute concentrations on either side of the membrane - The movement of water across a membrane can affect the turgor pressure of some cells

During one cycle, the sodium-potassium pump binds and moves

3 Na+ and 2 K+.

Consider the biochemical pathway below, where A, B, and C are substrates and products and E1 and E2 are the enzymes that catalyze the reactions. If Enzyme 1 (E1) is inactive, which of the following compounds will accumulate? A--E1-> B --E2-> C

A only

Membranes used to form vesicles coming into and leaving the cell have the potential to change the size of a cell, yet under normal circumstances the cell's membrane doesn't change it's volume very much. What two processes involving the membrane would need to be balanced over time?

Endocytosis and exocytosis

Facilitated Diffusion or Active Transport: molecules move down their concentration gradient

FD

A cellular protein is involved in the cotransport of glucose and sodium ions into the cell. If sodium is blocked from moving through this transporter, what would be the most likely outcome?

Glucose would be unable to move without the movement of sodium into the cell, down its concentration gradient.

A B-cell uses its surface antibodies as receptors to attach to specific antigens before they are taken in. By what mechanism does a B cell engulf an antigen?

Receptor-mediator endocytosis

What happens to sucrase when it binds to sucrose?

Sucrase goes through a conformational change.

T/F: Whenever a molecule is oxidized, another molecule must be reduced.

True

Red blood cells put in a hypotonic solution will

be destroyed by hemolysis.

Simple diffusion is defined as the movement of

molecules from areas of higher concentration to areas of lower concentration.

Exocytosis is a process by which cells

release substances from the cell via vesicles.

Red blood cells put in a hypertonic solution will

shrivel and become crenated.

In feedback inhibition, the inhibitor of the biochemical pathway is often

the final product of the biochemical pathway.

Cotransport captures its energy from

the movement of one of the transported substances down its concentration gradient.

Sucrase uses ____ to cleave sucrose into two monosaccharides.

water

Osmosis is best defined as the movement of

water molecules across a membrane from an area of high water concentration to an area of lower concentration.

In the process of diffusion, when sugar is mixed with water, equilibrium would be reached when what happens?

when the dissolved sugar molecules are evenly distributed throughout the solution.

Molecules are synthesized in _____ reactions.

anabolic

Facilitated Diffusion or Active Transport: molecules move against their concentration gradient

AT

Facilitated Diffusion or Active Transport: requires energy

AT

Facilitated Diffusion or Active Transport: carriers are specific for the structures of individual molecules

Both

Facilitated Diffusion or Active Transport: molecules move through a protein carrier in the membrane

Both

What do the processes of active transport and facilitated diffusion have in common?

Both use transport proteins to move material across the membranes.

What is the source of energy used to power the sodium-potassium pump?

Breakdown of ATP

How often can a sucrase molecule be used to hydrolyze sucrose?

Many times

Consider the biochemical pathway used to synthesize the amino acid proline. A large increase in the level of proline will most likely lead to

a decrease in proline production.

Molecules are broken down in ______ reactions.

catabolic

Anabolic reactions _____ NADH and ATP.

consume

If the cytoplasm of a cell is a 1% salt solution, a 10% salt solution will be _____ to it, a 1% solution will be _____to it, and a 0.1% solution will be _____ to it.

hypertonic isotonic hypotonic

Sea water is approximately 3% salt. Sea water is hypertonic to tissues of freshwater fish. Their tissues contain

less than 3% salt.

Cells obtain energy by ________ food molecules such as glucose.

oxidizing

Catabolic reactions _____ NADH and ATP.

produce

The sodium-potassium pump functions to move

sodium ions out of the cell and potassium ions into the cell.

Which of the following binds most tightly to the active site of an enzyme?

substrate

Facilitated diffusion is used to transport

sugars and amino acids.