Cell Membrane

Question 1

Cell Membrane (Phospholipid Bilayer) Components

Answer 1

Fats: phospholipids, cholesterol, glycolipids (smaller amount) Protein: Enzymes, signal transductors and transporters, Carbohydrates: attached to lipids and proteins

Question 1

Phospholipid Bilayer Creation

Answer 1

Self forming biomolecular sheet. Hydrophobic hydrocarbon tails hydrophobic reactions repel tail away from water. Phosphate hydrophilic head is held in H bond with water. Bi-layer is self-sealing

Question 2

Types of proteins in cell membrane (integral)

Answer 2

Alpha-Helix (receptors), Helical Bundle (enzymes, receptors), Beta-Barrel Channel proteins

Question 3

Peripheral Proteins

Answer 3

Enzymes attach to cell receptors. Don’t enter hydrophobic part of bilayer but can push into peripheral regions. Attaches to integral proteins

Question 4

Cell Membrane Carbohydrates

Answer 4

Glycoproteins, glycolipids, proteoglycans. Forms glycolax layer outside of membrane

Question 5

Glycocalyx Functions

Answer 5

Barrier for cell from surroundings, holds cell shape against external forces, mediator for cell - cell interactions + involved in disease development

Question 6

Cell Membrane Functions

Answer 6

Barrier, Holds molecules inside/outside cell, maintains cell internal environment pH and receptors, structural support

Question 7

Fluid Mosaic Model

Answer 7

Membranes are 2D solutions of oriented globular proteins and lipids. Sea of lipids

Question 8

Types of movement across cellular membrane

Answer 8

Passive diffusion, facilitated diffusion and active transport

Question 9

Passive Diffusion

Answer 9

Unaided transport of solute molecules down concentration gradient. Until equilibrium is reached on both sides of membrane

Question 10

Facilitated Diffusion

Answer 10

Diffusion mediated by integral proteins. Moves down concentration gradient, no energy required

Question 11

3 Types of integrated protein ports

Answer 11

Uniport, Symport, Antiport

Question 12

Non-specific transporter

Answer 12

1 continuous channel through protein

Question 13

Specific Transporter

Answer 13

Binding sight of specific shape. Chanels 1 specific protein

Question 14

Active Transport

Answer 14

Uses energy, goes against concentration gradient. 2 Types

Question 15

Primary Active Transport (eg Na and K chanel) Outline

Answer 15

ATP molecule attaches to protein, 3 Na molecules bind to their active sites, ATP molecule splits (ADP and Phosphate), Phosphorylation of protein, confirmational changes occur, Na ions released to extracellular fluid + 2 K ions bind to binding sites, ATPase is dephosphorylised, reverts back to previous formation, K+ ions released

Question 16

Secondary Active Transport

Answer 16

Symport moves specific substance across concentration gradient. Movement of 1st pulls 2nd substance along with it (energy only spent on 1)

Question 17

Endocytosis Def.

Answer 17

Bringing molecules into cell

Question 18

Exocytosis Def.

Answer 18

Bringing molecules out of cell