Biology Chapter 7

Front 1

Cellular membranes are fluid mosaics of _________ and _________.

Back 1

Cellular membranes are fluid mosaics of lipids and proteins.

Front 2

The ______ of a phospholipid is polar but the _______ is nonpolar, making it a(n) __________ molecule.

Back 2

The head of a phospholipid is polar but the tail is nonpolar, making it an amphipathic molecule.

Front 3

In the fluid mosaic model, the membrane is a mosaic of _________ molecules bobbing in a fluid bilayer of _______________.

Back 3

In the fluid mosaic model, the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.

Front 4

At relatively (high/low) temperatures, cholesterol molecules in plasma membranes restrict phospholipid movement, increasing the rigidity of the membrane.

Back 4

At relatively high temperatures, cholesterol molecules in plasma membranes restrict phospholipid movement, increasing the reigidity of the membrane.

Front 5

A membrane remains fluid to a lower temperature if it is rich in phospholipids with (saturated/unsaturated) hydrocarbon tails.

Back 5

A membrane remains fluid to a lower temperature is it is rich in phospholipids with unsaturated hydrocarbon tails.

Front 6

Cholesterol (raises/lowers) the temperature required for a membrane to solidify.

Back 6

Cholesterol lowers the temperature requires for a membrane to solidify.

Front 7

Integral Proteins

Back 7

proteins which penetrate the hydrophobic interior of the lipid bilayer

Front 8

Peripheral Proteins

Back 8

proteins loosely bound to surface of lipid bilayer, often to exposed parts of integral proteins

Front 9

List six functions of membrane proteins.

Back 9

1. Transport

2. Enzymatic activity

3. Signal Transduction

4. Cell-Cell Recognition

5. Intercellular Joining

6. Attachment to cytoskeleton and ECM

Front 10

___________ are carbohydrates that bond to lipids while __________ are carbohydrates that bond to proteins.

Back 10

Glycolipids are carbohydrates that bond to lipids while glycoproteins are carbohydrates that bond to proteins.

Front 11

(Polar/Nonpolar) molecules are (hydrophilic/hydrophobic) and therefore can easily cross the bilayer without the help of membrane proteins.

Back 11

Nonpolar molecules are hydrophobic and therefore can easily cross the bilayer without the help of membrane proteins.

Front 12

__________ transport is diffusion of a substance across a membrane with no energy investment.

Back 12

Passive transport is diffusion of a substance across a membrane with no energy investment.

Front 13

Channel proteins have a (hydrophobic/hydrophilic) channel through which certain molecules or ions can travel to get into the cell. One example is the transport of water molecules through ____________.

Back 13

Channel proteins have a hydrophilic channel through which certain molecules or ions can travel to get into the cell. One example is the transport of water molecules through aquaporins.

Front 14

____________ proteins hold onto molecules and change shape in order to transport them through the membrane.

Back 14

Carrier proteins hold onto molecules and change shape in order to transport them through the membrane.

Front 15

Concentration Gradient

Back 15

the region along which the density of a chemical substance changes

Front 16

Any substance will diffuse (down/up) its concentration gradient.

Back 16

Any substance will diffuse down its concentration gradient.

Front 17

Osmosis

Back 17

the diffusion of free water across a selectively permeable membrane

Front 18

Tonicity

Back 18

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

Front 19

In a (hypertonic/hypotonic) solution, a cell will lose water to its surroundings and become ________ if an animal cell or _________ if a plant cell.

Back 19

In a hypertonic solution, a cell will lose water to the surrounding solution and become shriveled if an animal cell or plasmolyzed if a plant cell.

Front 20

In a (hypertonic/hypotonic) solution, a cell will gain water from its surroundings and become ______ if an animal cell or __________ if a plant cell.

Back 20

In a hypotonic solution, a cell will gain water from its surroundings and become lysed if an animal cell or turgid if a plant cell.

Front 21

Osmoregulation

Back 21

the control of solute concentrations and water balance

Front 22

In an isotonic solution, plant cells become __________.

Back 22

In an isotonic solution, plant cells become flaccid.

Front 23

Plasmolysis

Back 23

the process by which plant cells shrivel and die when placed in hypertonic solutions; plasma membrane pulls away from the cell wall in multiple places

Front 24

Facilitated Diffusion

Back 24

process by which transport proteins help certain molecules/ions that cannot passively diffuse through a membrane to cross the bilayer (throuhg channel or carrier proteins)

Front 25

Channel proteins that transport ions are called _____ ____________.

Back 25

Channel proteins that transport ions are called ion channels.

Front 26

______ channels open or close in response to a stimulus in order to facilitate passage through a membrane.

Back 26

Gated channels open or close in response to a stimulus in order to facilitate passage throuhg a membrane.

Front 27

_______ transport uses energy to move solutes against their gradients.

Back 27

Active transport uses energy to move solutes against their gradients.

Front 28

Sodium-Potassium Pump

Back 28

an active transport protein that moves two K+ ions into the cell and removes 3 NA+ ions out of the cell to maintain intercellular concentrations

Front 29

The voltage across a membrane, which ranges from about ____ to ____ mV, is called the ________ __________.

Back 29

The voltage across a membrane, which ranges from about -50 to -200 mV, is called the membrane potential.

Front 30

Because the inside of a cell is negative compared to the outside, the membrane potential favors the passive transport of (cations/anions) into the cell and of (anions/cations) out of the cell.

Back 30

Because the inside of a cell is negative compared to the outside, the membrane potential favors the passive transport of cations into the cell and of anions out of the cell.

Front 31

Two forces drive the diffusion of ions across a membrane: _________ forces from the ion's concentration gradient and _________ forces from the membrane potential. Combined, they are called the __________ ____________.

Back 31

Two forces drive the diffusion of ions across a membrane: chemical forces from the ion's concentration gradient and electrical forces from the membrane potential. Combined, they are called the electrochemical gradient.

Front 32

A transport protein that generates voltage across a membrane is called an _______ _________.

Back 32

A transport protein that generates voltage across a membrane is called an electrongenic pump.

Front 33

The main electrogenic pump of plants, fungi, and bacteria is a(n) ________ ________.

Back 33

The main electrogenic pump of plants, fungi, and bacteria is a proton pump.

Front 34

A ______________ protein can couple the "downhill" diffusion of a solute to the "uphill" transport of a second substance against its own concentration gradient.

Back 34

A cotransporter protein can couple the "downhill" diffusion of a solute to the "uphill" transport of a second substance against its own concentration gradient.

Front 35

Bulk transport across the plasma membrane occurs by __________ and _________.

Back 35

Bulk transport across the plasma membrane occurs by exocytosis and endocytosis.

Front 36

Exocytosis

Back 36

the process by which a cell excretes certain molecules (in bulk) by the fusion of vesicles with the plasma membrane

Front 37

Endocytosis

Back 37

the process by which a cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane

Front 38

The three types of endocytosis are ____________, _______________, and __________.

Back 38

The three types of endocytosis are phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Front 39

Ligand

Back 39

any molecule that binds specifically to a receptor site on another molecule; examples include LDLs

Front 40

Phagocytosis

Back 40

the process in which a cell engulfs a particle by extending pseudopodia around it and packaging it within a membranous sac called a food vacuole; the particle will be digested after the food vacuole fuses with a lysosome

"cellular eating"

Front 41

Pinocytosis

Back 41

the process in which a cell continually "gulps" droplets of extracellular fluid into tiny vesicles, formed by infoldings of the plasma membrane lined on the cytoplasmic side by coat proteins ("coated vesicle")

"cellular drinking"

Front 42

Receptor-mediated Endocytosis

Back 42

specialized type of pinocytosis that enables the cell to acquire bulk quantities of specific substances by grouping receptor proteins for those solutes on coated pits and then forming coated vesicles