chapter 4- transport across membranes

Question 1

phospholipids

Answer 1

-hydrophillic heads
-hydrophobic tails
-allow lipid soluble substances tp enter and leave

Question 2

function of proteins

Answer 2

-act as a channel transporting water-soluble substances across the membrane
-help cells adhere together

Question 3

function of cholesterol

Answer 3

-prevent leakage of water and dissolved ions from the cell
-reduce lateral movement of other molecules

Question 4

function of glycolipids

Answer 4

-acts as recognition sites
-helps maintain membrane stability

Question 5

function of glycoproteins

Answer 5

-act as recognition sites
-allows cells to recognize one another

Question 6

diffusion

Answer 6

the movement of molecules from a region of high concentration to a region of low concentration

Question 7

facilitated diffusion

Answer 7

movement of molecules down a concentration gradient with the use of protein channels and carrier proteins

Question 8

protein channels

Answer 8

allow specific water soluble ions to pass through
-channels are selective, each opening in the presence of a specific ion

Question 9

carrier proteins

Answer 9

when a molecule such as glucose which is specific to the protein present, it binds with the protein
-this causes a shape change and is released to the inside of the molecule

Question 10

osmosis

Answer 10

the passage of water from a region of high water potential to a region of low water potential through a partially permeable membrane

Question 11

active transport

Answer 11

the moment of molecules from a region of lower concentration to a region of higher concentration using ATP

Question 12

sodium potassium pump

Answer 12

sodium ions are actively removed from the cell while potassium ions are actively taken in from the surroundings

Question 13

increasing rate of movement across a membrane

Answer 13

-microvilli
-increase number of proton channels and carrier proteins

Question 14

absorption of glucose in the ilium

Answer 14

• sodium ions are actively transported out of epithelial cells by the sodium potassium pump into the blood
  -sodium ions diffuse into epithelial cells down a conc gradient by carrier protein
  -sodium brings with it either AAs or glucose molecules
  -the glucose/AAs pass into blood plasma by facilitated diffusion using another type of carrier protein