Plasma Membranes

Question 1

Phospholipid bilayer

Answer 1

Hydrophilic phosphate polar heads
Hydrophobic fatty tails

Question 2

Fluid mosaic model

Answer 2

Phospholipids are free to move within the later relative to each other giving flexibility and proteins embedded in bilayer vary in shape and position

Question 3

Membrane proteins

Answer 3

Intrinsic proteins
Glycoproteins
Glycolipids
Extrinsic proteins
Cholesterol

Question 4

Intrinsic proteins

Answer 4

Embedded through layers
Amino acids w hydrophobic R groups that interact w fatty acid tails
-Channel proteins
-Carrier proteins

Question 5

Channel proteins

Answer 5

hydrophilic channel that allows passive movement of polar molecules down conc gradient

Question 6

Carrier proteins

Answer 6

• role in passive and active transport can change shape

Question 7

Glycoproteins

Answer 7

Role in cell adhesion and receptors for chemical signals
Chemical bonds elicits a response from cell

Question 8

Glycolipids

Answer 8

Cell markers/ antigens can be recognised by immune system as self or not self - ATTACK!

Question 9

Extrinsic proteins

Answer 9

Present on only one side hydrophilic r groups on outer surfaces

Question 10

Cholesterol

Answer 10

Lipid that regulates fluidity of the membrane

Question 11

Factors affecting membrane structure

Answer 11

Temp -phospholipids more kinetic energy and move losing structure increase permeability and denature transport proteins
Solvents - some dissolve membranes due to them being less polar than water

Question 12

Diffusion

Answer 12

Movement of particles from high conc to low conc
Passive processs
Until reach equilibrium

Question 13

Factors affecting diffusion

Answer 13

Temp- higher the higher kinetic energy particles move at higher speeds
Conc differences - greater the difference the faster the rate
Down conc gradient

Question 14

Fascilitated diffusion

Answer 14

Diffusion across a membrane through protein channels
Selective permeability - specific to one molecule or ion
Can involve carrier proteins change shape when specific molecule binds

Question 15

Active transport

Answer 15

Movement of ions from a low to high conc by the use of energy and carrier proteins
Molecule bonds to protein
Atp binds to protein inside cell
Causes protein to change shape opening inside cell
Molecule released inside of cell and protein returns to shape

Question 16

Bulk transport

Answer 16

For large molecules such as enzymes and hormones unable to travel through proteins
Endocytosis - into cells csm invaginate forming a vesicle which punches off and moves into membrane
Exocytosis - reverse of endocytosis

Question 17

Osmosis

Answer 17

Movement of water from high wp to a low wp

Question 18

Animal cell and osmosis

Answer 18

If placed in solution water moves into cell increasing hydrostatic pressure inside cell and eventually bursts - cytolysis
If placed in low cell will become flaccid

Question 19

Plant cells and osmosis

Answer 19

If placed in solution hydrostatic pressure increases however cell wall protects cell - turgor
If lower wp cell is said to become plasmolysed- contents shrink away from cell wall