Membranes

Question 1

Define Cholesterol

Answer 1

regulates fluidity and restricts movement

Question 2

Define Phospholipid bilayer

Answer 2

allows passage of lipid soluble substances e.g. O2 and CO2 and prevents passage
of water soluble substances

Question 3

Define Channel Protein

Answer 3

allows small charged, molecules through membrane
have a pore or passage, through centre of the protein which allow the diffusion of
ions or any substances which are polar, water soluble or not lipid soluble

Question 4

Define Carrier protein

Answer 4

• transport large molecules across the membrane
• attach to on one side of the membrane and changes shape when the molecule
  binds and then release the molecule on other side of the membrane

Question 5

Define Glycolipids

Answer 5

antigens for cell recognition

Question 6

What effect does temperature have with the permeablity of a membrane

Answer 6

• cell surface / plasma membrane damaged
• membrane structure disrupted ;
• phospholipid bilayer becomes more fluid
• membrane proteins e.g. carrier molecules are denatured and unable to function ;
• membrane becomes more permeable e.g. pigment released / moves out by diffusion

Question 7

Define Diffusion

Answer 7

Movement from an area of high concentration to an area of low concentration, down
a concentration gradient

Question 8

Define Active Transport

Answer 8

carrier proteins only
against concentration gradient
uses, energy / ATP

Question 9

Define Facilitated diffusion

Answer 9

(carrier proteins and channel proteins)
* down concentration gradient
* no, energy / ATP, required (passive)

Question 10

Define Bulk Transport

Answer 10

the movement of large amounts of molecules across a membrane

Question 11

Define Membrane Bound Receptors

Answer 11

• sites where hormones and drugs can bind
• Receptor has specific shape and is complementary to shape of hormone/drug
• Binding to a receptor triggers a response

Question 12

What is the process of Endocytosis

Answer 12

• membrane folds in and engulfs
• fuses with itself and pinches off to form a vesicle
• vesicle moves through cytoplasm
• requires energy; ATP(NOT active transport)
• triggered by binding of molecule (to receptor site);
• uptake of solid and liquid (not name alone);

Question 13

What is the process of Exocytosis

Answer 13

• vesicle fuses with cell surface membrane releasing, contents e,g proteins which are therefore secreted outside of the cell,
• Uses energy in the form of ATP.