Ch 3, 2 plasma membrane structure

Question 1

plasma membrane

Answer 1

composed of bimolecular layer of lipids and proteins in a constantly changing fluid mosaic

• separates intercellular fluid from extracellular
• also plays a big role in cellular activity

Question 2

Two components of plasma membrane

Answer 2

lipids; phospholipid bilayer, cholesterol, glycolipids

proteins; integral and peripheral

Question 3

phospholipids

Answer 3

75%, the lipid bilayer
phosphate heads-polar, hydrophilic
fatty acid tails-non polar, hydrophobic

Question 4

glycolipids

Answer 4

5%
lipids with attached polar sugar groups
on the outer surface of membrane

Question 5

cholesterol

Answer 5

20%
stabilizes membrane, regulates fluidity of membrane
decreases phospholipid mobility

Question 6

lipid rafts

Answer 6

20% of the outer membrane surface
contains phospholipids, sphingolipids and cholesterol
may function as stable platforms for cell-signalling molecules

Question 7

integral proteins

Answer 7

firmly inserted into the membrane (most are transmembrane)
transport protein (channels and carriers), enzymes or receptors

Question 8

peripheral proteins

Answer 8

loosely attached to integral proteins either on the inside or outside the membrane
enzymes, motor proteins, cell to cell links, provide support on intracellular surface

Question 9

glycoproteins

Answer 9

proteins with sugar groups attached
function in cell identification and form part of the glycocalyx (sugar coating)

Question 10

transport proteins

Answer 10

movement of materials in or out of the cell (passive or active)

Question 11

receptor protein

Answer 11

signal transduction-sites for chemical messengers to bind on eg. hormones

Question 12

attachment proteins

Answer 12

attach to the cytoskeleton and extracellular matrix, maintains the cell shape

Question 13

enzymatic proteins

Answer 13

act as organic catalysts

Question 14

intercellular joining proteins

Answer 14

anchor cells to one another

Question 15

cell-cell recognition proteins

Answer 15

identify cells, self or foreign
eg WBCs can tell whether to attack or not
glycoproteins act as id tags

Question 16

glycocalyx

Answer 16

the sugar coating on cells, made up of glycolipids and glycoproteins

Question 17

microvilli

Answer 17

outfoldings of the apical cell membrane

increases the surface area

Question 18

tight junction

Answer 18

prevent fluids and most molecules from moving between cells

link cells together between integral proteins-impermeable

Question 19

desmosome

Answer 19

like rivets or spot welds that anchor cells together
resists tension, prevents cells from being separated
acts as the Velcro

Question 20

gap junction

Answer 20

transmembrane proteins form pores that allow small molecules to pass from cell to cell
permits quick spread of ions between cells