Vnhs Ch 7 Biology

Front 1

plasma membrane

Back 1

the outer layer of the cell

Front 2

selective permeability

Back 2

it allows some substances to cross it more easily than others

Front 3

amphipathic molecule

Back 3

has both hydrophobic and hydrophilic regions

Front 4

fluid mosaic model

Back 4

the membrane is a fluid structure with a "mosaic" of various proteins embedded in or attached to a double layer (bilayer) of phospholipids

Front 5

how is the membrane held together?

Back 5

through weak hydrophobic interactions which make it fluid

Front 6

When the temperature decreases, the fluidity of the membrane ....

Back 6

the membrane is liquid until the phospholipids are closely packed enough to form a solid

Front 7

unsaturated hydrocarbon tails make the temperature at which the phospholipid bilayer stays liquid ...

Back 7

lower

Front 8

steroid and membrane temperature

Back 8

it usually makes the membrane more solid at relatively warm temperatures

Front 9

Integral proteins

Back 9

penetrated the hydrophobic core of the lipid bilayer. They are transmembrane proteins which span the whole bilayer

Front 10

What do the hydrophobic regions of the integral proteins consist of?

Back 10

one or more nonpolar amino acids, usually coiled into alpha helixes

Front 11

Peripheral proteins

Back 11

are not embedded in the lipid layer at all,they are appendages loosely bound to the surface of the membrane

Front 12

What are the six major functions performed by proteins of the plasma membrane?

Back 12

Transport, Enzymatic activity, Signal Transduction, Cell-cell recognition, Intercellular joining, Attachment to the cytoskeleton and extracellular matrix(ECM)

Front 13

How are the proteins held in place on the cytoplasmic side of the plasma membrane?exterior side?

Back 13

by attachment to the cytoskeleton, are attached to fibers of the extracellular matrix

Front 14

Why is cell-cell recognition important to cells?

Back 14

sorting cells into tissues and organs, identifying foreign cells, etc

Front 15

carbohydrates on the membrane

Back 15

usually short branched chains of fewer that 15 sugar units

Front 16

glycolipids

Back 16

carbohydrate covalently bonded to a lipid on the membrane

Front 17

glycoproteins

Back 17

most carbohydrates are covalently bonded to proteins

Front 18

How do the inside and outside faces of the lipid bilayer differ?

Back 18

they have differ in specific lipid composition, each protein has directional orientation in the membrane

Front 19

For which kind of molecule is the membrane really hard to go through?

Back 19

hydrophilic molecules which find it hard to permeate through the hydrophobic core, so they need assistance to get through the plasma membrane

Front 20

What is one way for a hydrophilic molecule to get through the plasma membrane?

Back 20

transport proteins

Front 21

transport proteins

Back 21

some are called channel proteins as they serve as a tunnel for polar of ionic molecules to pass through

Front 22

aquaporins

Back 22

the passage of water molecules through the membrane in certain cells

Front 23

carrier proteins

Back 23

hold onto their passengers and change shape in a way that shuttles them across the membrane

Front 24

diffusion

Back 24

the tendency for molecules of any substance to spread out evenly into the available space

Front 25

concentration gradient

Back 25

a substance will diffuse from where it is more to where it is less

Front 26

diffusion: with or against concentration gradient?

Back 26

with concentration gradient

Front 27

What does diffusion eventually establish?

Back 27

An equilibrium, so it may be directional to establish an equilibrium

Front 28

passive transport

Back 28

diffusion is passive transport as the cell does not expend energy

Front 29

osmosis

Back 29

the diffusion of water through a selectively permeable membrane

Front 30

tonicity

Back 30

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

Front 31

isotonic, apply to cell environment.

Back 31

the water and the solute concentrations are equal, so there will be equal movement across the membrane, and no net movement

Front 32

hypertonic, apply to cell environment

Back 32

the solute concentration is higher outside, which cause the water to travel outside of the cell and the cell will shrivel up and die

Front 33

hypotonic, apply to cell environment

Back 33

the solute concentration is lower outside and higher inside so the water will flow inside and the cell will probably swell and lyse

Front 34

osmoregulation

Back 34

the control of water balance, this is needed when organisms without a rigid cell wall live in a hypertonic or hypotonic environment

Front 35

turgid

Back 35

very firm, plant cells, when water enters the cell, the elastic wall will only stretch until it exerts back pressure on the cell and opposes further water uptake

Front 36

flaccid

Back 36

very limp, if a plant's cells and their surrounding are isotonic then there will be no net movement of water across the membrane which causes the cell to become very limp

Front 37

facilitated diffusion

Back 37

many polar molecules and ions diffuse passively with the help of transport proteins

Front 38

ion channels, gated channels

Back 38

there is a stimulus that causes the channels to open or close, the stimulus can be electrical or chemical

Front 39

active transport

Back 39

transport in which the cell expends energy

Front 40

sodium-potassium pump

Back 40

exchanges sodium for potassium across the plasma membrane of animal cells

Front 41

membrane potential

Back 41

ranges from about -50 to -200 millivolts (mV)

Front 42

charge of cytoplasm

Back 42

negative

Front 43

electrochemical gradient

Back 43

the combination of forces acting on an ion

Front 44

ions diffuse down their _______.

Back 44

electrochemical gradient

Front 45

electrogenic pump

Back 45

a transport protein that generates voltage across a membrane

Front 46

proton pump

Back 46

the main electrogenic pump of plants, fungi, and bacteria

Front 47

cotransport

Back 47

a substance that has been pumped across the membrane by diffusion

Front 48

exocytosis

Back 48

a cells secretes macromolecules by the fusion of vesicles with the plasma membrane

Front 49

endocytosis

Back 49

the cell takes in macromolecules and particular matter by forming new vesicles from the plasma membrane

Front 50

ligands

Back 50

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

Front 51

phagocytosis

Back 51

a cell engulfs a particle by wrapping pseudopodia around it and packaging it in the vacuole

Front 52

pinocytosis

Back 52

the cell "gulps" droplets of extra-cellular fluid into tiny vesicles

Front 53

receptor-mediated endocytosis

Back 53

the cells acquire bulk quantities of specific substances, even though those substances may not be very concentrated in areas of the extracellular fluid