Chapters 5 And 6

Question 1

Fluid Mosaic Model

Answer 1

Proteins in the membrane can move along the plane of the membrane, producing an ever-changing configuration.

Question 2

Cholesterol

Answer 2

Molecules are a fluidity “buffer,” keeping hydrocarbon chains fluid at low temperatures and stabilizing them at high temperatures.

Question 3

Integral membrane proteins

Answer 3

Amphiphathic proteins family bound to the membrane.

Question 4

Transmembrane proteins

Answer 4

Integral proteins that extend completely through the membrane.

Question 5

Peripheral membrane proteins

Answer 5

Located on inner or outer surface of plasma membrane, bound to exposed regions of integral proteins.

Question 6

Glycoproteins

Answer 6

Sugars are added to proteins to make glycoproteins

Question 7

Passive transport

Answer 7

The movement of substances (as by diffusion and osmosis) across a cell membrane without the expedenture of energy.

Question 8

Active transport

Answer 8

Movement of molecules against their gradient.

Question 9

Signal transduction

Answer 9

Some receptors bind with signal molecules such as hormones and transmit information into the cell.

Question 10

Intercellular junction

Answer 10

Cell adhesion proteins attach membranes of adjacent cells.

Question 11

Selectively permeable

Answer 11

Allow some, but not all, substances to pass through them. A membrane may block a particular substance at one time and actively promote passage at another time. By regulating chemical traffic across its plasma membrane, a cell controls its volume and its internal molecular composition.

Question 12

Transport proteins

Answer 12

Move ions, amino acids, sugars and other needed polar molecules through membranes.

Question 13

Carrier proteins

Answer 13

a transport protein that is specific for an ion, molecule, or group of substances. Carrier proteins “carry” the ion or molecule across the membrane by changing shape after the binding of the ion or molecule. Carrier proteins are involved in passive and active transport.

Question 14

Channel proteins

Answer 14

a type of transport protein, acts like a pore in the membrane that lets water molecules or small ions through quickly.

Question 15

Diffusion

Answer 15

The movement of molecules so that they spread out into available space (down concentration gradient.)

Question 16

Concentration gradient

Answer 16

The difference in the concentration of a substance between two areas. The bigger the difference, the steeper the concentration gradient and the faster the molecules of a substance will diffuse.

Question 17

Osmosis

Answer 17

The diffusion of water across a membrane.

Question 18

Potential energy

Answer 18

energy due to position, it is stored energy which can be used to do work. A gradient of the membrane is a form of potential energy. The stored energy of the concentration gradient is released when ions or molecules move from high to low concentration.

Question 19

Facilitated diffusion

Answer 19

the passive movement of molecules across the cell membrane via the aid of a membrane protein.

Question 20

Hypertonic

Answer 20

higher concentration of solute.

Question 21

Hypotonic

Answer 21

Lower concentration of solute.

Question 22

Isotonic

Answer 22

Equal concentration of solute.

Question 23

Sodium-potassium pump

Answer 23

helps to maintain osmotic equilibrium and membrane potential in cells. The sodium and potassium move against the concentration gradients. The Na+ K+-ATPase pump maintains the gradient of a higher concentration of sodium extracellularly and a higher level of potassium intracellularly.

Question 24

Membrane potential

Answer 24

Membrane potential is the difference in electric potential between the interior and the exterior of a biological cell.

Question 25

Electrochemical gradient

Answer 25

The electrochemical gradient is a measure of the free energy available to carry out the useful work of transporting the molecule across the membrane.

Question 26

Antiporter

Answer 26

a membrane protein that transports two molecules at the same time in the opposite direction.

Question 27

Uniporter

Answer 27

A transport mechanism that drives a single compound or ion across a membrane, not coupled with transport of any other compound or ion.

Question 28

Proton pump

Answer 28

a special kind of transporter that push hydrogen ions from areas of low concentration to areas with high concentration.

Question 29

Symporter

Answer 29

an integral membrane protein that is involved in the transport of two different molecules across the cell membrane in the same direction

Question 30

Cotransport

Answer 30

The linked, simultaneous transport one substance across a membrane, coupled with the simultaneous transport of another substance across the same membrane in the same direction.

Question 31

Exocytosis

Answer 31

The secretion of large molecules within transport vesicles.

Question 32

Endocytosis

Answer 32

Takes material in via vesicles that bud inward from the plasma membrane.

Question 33

Phagocytosis

Answer 33

Ingesting large solid particles. “Cell eating.”

Question 34

Pinocytosis

Answer 34

Taking in dissolved materials. “Cell drinking”

Question 35

Plasmodesmata

Answer 35

microscopic cytoplasmic canal that passes through plant-cell walls and allows direct communication of molecules between adjacent plant cells.

Question 36

Adhering junctions

Answer 36

cell-cell adhesion complexes that are continuously assembled and disassembled, allowing cells within a tissue to respond to forces, biochemical signals and structural changes in their microenvironment.

Question 37

Tight junctions

Answer 37

An intercellular junction between epithelial cells in which the outer layers of the cell membranes fuse, reducing the ability of larger molecules and water to pass between the cells.

Question 38

Gap junctions

Answer 38

aggregates of intercellular channels that permit direct cell–cell transfer of ions and small molecules

Question 39

Cell signaling

Answer 39

Mechanisms by which cells communicate with one another.

Question 40

Signal transmission

Answer 40

A cell releases signaling molecules (ligand). If target sells are not nearby, signal must be transported to them.

Question 41

Ligand

Answer 41

something that binds with a biological molecule to form a complex and produce some effect.

Question 42

Target cell

Answer 42

a cell that is acted on selectively by a specific agent (as a virus, drug, or hormone).

Question 43

Reception

Answer 43

Glycoprotein receptors that bind with specific signaling molecules.

Question 44

Receptor

Answer 44

A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific effect in the cell

Question 45

Signal transduction

Answer 45

The process by which a cell responds to substances outside the cell through signaling molecules found on the surface of and inside the cell.

Question 46

Response

Answer 46

A signal is converted into a response to alter some cell process.

Question 47

Neurotransmitter

Answer 47

The body’s chemical messengers. They are the molecules used by the nervous system to transmit messages between neurons, or from neurons to muscles.

Question 48

Hormone

Answer 48

chemical substances that act like messenger molecules in the body. After being made in one part of the body, they travel to other parts of the body where they help control how cells and organs do their work.

Question 49

Endocrine gland

Answer 49

An organ that makes hormones that are released directly into the blood and travel to tissues and organs all over the body. Endocrine glands help control many body functions, including growth and development, metabolism, and fertility.

Question 50

Local regulators

Answer 50

chemical signals that travel over short distances by diffusion. • Local regulators help regulate blood pressure, nervous system function, and reproduction.

Question 51

Ion channel

Answer 51

located within the membrane of all excitable cells, and of many intracellular organelles. They are often described as narrow, water-filled tunnels that allow only ions of a certain size and/or charge to pass through.

Question 52

Protein kinases

Answer 52

any of a class of enzymes that catalyze the transfer of a phosphate group from ATP to one or more amino acids in the side chain of a protein resulting in a conformational change affecting protein function.