Chapter 7: Membrane Structure and Function Part 1 and 2

Glycosylated proteins and lipids within the plasma membrane are important for

cell recognition and protection.

pinocytosis

cellular drinking

phagocytosis

cellular eating

aquaporins

channel proteins that facilitate the passage of water

passive transport

does not require any input of energy

membrane carbohydrates covalently bond to lipids:

glycolipids

membrane proteins:

glycoproteins

Which of the following is NOT a component of plasma membranes?

glycosylated nucleic acids

fluidity

individual molecules remain in close association

. Phospholipids and ________ are the major components of cell membranes.

proteins

membranes also contain

proteins and carbohydrates

fluid mosaic model

proteins are not randomly distributed in the membrane

can membrane fluidity be altered?

yes, as temp cools, membranes switch from fluid to solid state

hydrophilic

water loving

Active transport is different from simple diffusion in that active transport

All answer choice are correct.

What process best characterizes calcium movement from the cytosol (low calcium concentration) into the ER (high calcium concentration)?

Calcium movement involves active transport

Which molecule passes through a lipid bilayer most readily?

Carbon Dioxide

Carrier molecules in the plasma membrane are required for

Facilitated diffusion and Active transport

Animal cells are permeable to water and urea but NOT to sucrose. The inside of a cell contains 1 M sucrose and 1 M urea and the outside 1 M sucrose and 2 M urea. The solution inside with respect to outside the cell is

Hypotonic.

Which of the following is NOT true of the plasma membrane?

It is composed of an extracellular and intracellular layer of phospholipids.

Tay - Sachs disease is a neurological disorder in which a defective enzyme prohibits the breakdown of phospholipids call gangliosides. Where do you gangliosides accumulate?

Membranes

Which of the following is NOT true of passive diffusion?

Passive diffusion requires the presence of a transmembrane protein.

What is the major lipid found in membranes?

Phospholipids

Water diffuses through certain organs such as the kidneys and bladder much faster than would occur by passive diffusion through a lipid bilayer alone. What accounts for this more rapid rate of water transport in these organs?

Presence of aquaporin channels for facilitated diffusion of water.

Which of the following is TRUE of phospholipids that flip-flop across the lipid bilayer?

The process requires energy and the flippase enzyme.

Which of the following statements is TRUE of membrane phospholipids?

They freely move laterally within the membrane.

ligand

a molecule that binds specifically to a receptor site of another molecule

tonicity

ability of surrounding solution cause a cell to gain or lose water

transport proteins

allow passages of hydrophilic substances across the membrane

selective permeability

allowing some substance to cross it more easily than others

peripheral proteins

are bound to the surface of that membrane

carrier proteins

bind to molecules and change shape to shuttle them across the membrane

phospholipids

can move within the bilayer

Following a meal glucose must move from the gut lumen where there is a high glucose concentration into the intestinal cell where there is a relatively low level of glucose. This movement is called

facilitated diffusion.

The plasma membrane...

is composed of an extracellular and intracellular layer of phospholipids.

osmosis

is the diffusion of water across a selective permeability

Passive diffusion

is the process by which molecules move from an area of high concentration to an area of low concentration

diffusion

is the tendency for molecules to spread out evenly into the available space

Acetylcholine binds this membrane protein, which subsequently opens to allow sodium to enter the cell. Acetylcholine exerts its effect on what type of transport protein?

ligand-gated channel

Which of the following is NOT a function of cellular membranes?

maintenance of cell shape

amphipathic

molecules containing hydrophobic and hydrophilic regions

transmembrane proteins

one or more region that are physically embedded in hydrophobic region

integral proteins

penetrate hydrophobic core(transmembrane proteins)

Which of the following is the major lipid found in membranes?

phospholipids

active transport

requires energy

. Sodium concentrations are higher outside and glucose concentrations are higher inside the cell. Using the same membrane protein for Na+ and glucose transport, what is it called when a Na+ electrochemical gradient is used to drive glucose transport into the cell against its concentration gradient?

secondary active transport

Animal cells with a higher concentration of ions than the surrounding medium tend to

shrink

hypertonic

solute concentration greater inside the cell, but cell looses water

hypotonic

solute concentration less inside the cell, but cell gains water

isotonic

solute concentration same inside cell

factors effecting fluidity:

temperatures and steroid cholesterol

Placing celery sticks in fresh water will make them more turgid and harder. This is because

the celery is hypertonic to fresh water.

endocytosis

the cell takes in macromolecules by forming vesicles from the membrane

concentration gradient

the region along which the density of a chemical substance increase or decreases

The following affect membrane fluidity EXCEPT

the relative amounts of phospholipids containing saturated or unsaturated fatty acyl tails.

facilitated diffusion

transport proteins speed the passive movement of molecules across the plasma membrane

exocytosis

transport vesicles migrate to the membrane, release content out of cell

major functions of membrane proteins

transport, enzyme activity, signal transduction, cell recognition, intercellular joining, ECM

why is selective permeability important?

waste products exit, essential molecules enter

hydrophobic

water fearing