membrane structure

Question 1

selective permeability

Answer 1

allowing some substances to cross more easily than others

Question 2

amphipathic

Answer 2

containing hydrophobic and hydrophilic regions

Question 3

fluid mosaic model

Answer 3

a mosiac of protein molecules bobbing in a fluid bilayer of phospholipid

Question 4

temperature cools

Answer 4

membrane goes from fluid state to solid state

Question 5

to work properly

Answer 5

membranes must be fluid ( at the right temperature )

Question 6

what does cholesterol do at warm temperatures

Answer 6

it reduces fluidity

Question 7

integral proteins

Answer 7

that span the membrane ex:transmembrane protein

Question 8

hydrophobic regions of integral proteins

Answer 8

consist of one or more stretches of non polar amino acids

Question 9

peripheral proteins

Answer 9

are loosely bound to the surface of the membrane

Question 10

six functions of membrane proteins

Answer 10

transport enzymatic activity signaling recognition, intercellular joining and attachment to the cytoskeleton

Question 11

membrane carbohydrates

Answer 11

with lipids are called glycolipids and with proteins they are called glycoproteins

Question 12

cross the membrane easy

Answer 12

non polar especially small (carbon dioxide water oxygen urea)

Question 13

cannot cross the membrane easily

Answer 13

polar and large (sugars and ions)

Question 14

transport proteins

Answer 14

allow passage of hydrophilic/polar substances across the membrane

Question 15

aquaporins

Answer 15

facilitate the passage of water

Question 16

channel proteins

Answer 16

have hydrophilic channels that certain molecules or ions can use as a tunnel

Question 17

diffusion

Answer 17

molecules spread out evenly in available space

Question 18

concentration gradient

Answer 18

substances diffuse from where it is more concentrated to where it is less concentrated through the bilayer

Question 19

passive transport

Answer 19

diffusion or when no energy is used from the cell

Question 20

facilitated diffusion

Answer 20

speeds transport of a solute by providing efficient passage through the membrane using transport proteins

Question 21

active transport

Answer 21

moves against the concentration gradient by using proteins and energy

Question 22

why is a lipid bilayer fluid

Answer 22

because it is held together by hydrogen bonds and so the layer can shift

Question 23

cholesterol

Answer 23

wedged in the bilayer to regulate under different conditions