B cell biology

Question 1

what is the function of channel proteins?

Answer 1

channel proteins have hydrophilic pores which allow movement of hydrophilic molecules like charged ions and polar molecules.

Question 2

what is the function of carrier proteins?

Answer 2

carrier proteins have specific binding sites which bind to specific solutes and transport them across the cell membrane down their concentration gradient or against their concentration gradient using ATP

Question 3

what is the function of receptor proteins?

Answer 3

they have sites of attachments for signal molecules to bind which allow for cell signalling

Question 4

why is the function of glycoproteins/glycolipids?

Answer 4

cell-cell adhesion, cell-cell recognition, also act as receptor sites for signal molecules to bind allowing for cell signalling

Question 5

what is the function of cholesterol?

Answer 5

helps to regulate fluidity and prevents leakage of small polar molecules

Question 6

how does temperature affect membrane fluidity?

Answer 6

At low temp, molecules have low KE and thus membrane is less fluid. At high temp, molecules have high KE, thus they vibrate faster and membrane is more fluid. Phospholipids may more far apart frequently, creating gaps in the membrane, increasing its permeability.

Question 7

how does liquid composition affect membrane fluidity?

Answer 7

Unsaturated fatty acid chains have kinks at sites of double bonds which prevents fatty acid chains from packing closely together, causing it to be more fluid.

Question 8

structure and function of RER?

Answer 8

consist of 3D network of interconnecting flattened membrane-bound sacs called cisternae + lined with thin single membrane -> exerts quality control on protein folding + transport vesicles bud off RER to GA + chemical modification of proteins like glycosylation involving the addition of a short carbohydrate chain which is covalently bonded to protein

Question 9

structure and function of SER?

Answer 9

consists of a 3D network of interconnecting membrane-bound tubules called cisternae + lined by single membrane -> enzymes in the SER facilitate detoxification of poisons and drugs + enzymes in the SER are important to the synthesis of lipids

Question 10

structure and function of GA?

Answer 10

consists of one or several stacks of flattened, curved membrane-bound sacs called cisternae, bounded by single membrane

phosphorylation involving the addition of phosphate groups to proteins + proteins made in RER temporarily stored and then packaged into secretory vesicles

Question 11

what is process of protein secretion?

Answer 11

1. Radio active amino acids and teleseller through the cell surface membrane by facilitated diffusion or active transport. Polypeptide synthesised by a ribosome attached to the ER using radio active AA. 2. The polypeptide enters the lumen of RER and folds into its 3D conformation to form protein. 3. Transport vesicle containing protein buds off from RER and fuses with the cis face of GA. 4. The protein is chemically modified and concentrated in the GA. 5. Secretory vesicles buds off from trans face of GA, moves along cytoskeleton towards the cell surface membrane. 6. Membrane of secretory vesicle fuses with CSM, releasing protein into the pancreatic duct by exocytosis.

Question 12

structure and function of mitochondria?

Answer 12

cylindrical or rod-shaped, bounded by double membrane, extensively folded cristae increases SA for proteins/enzymes to be embedded

site of cellular respiration during which glucose is metabolised resulting in the synthesis of ATP. ATP is the energy source for the cellular processes

Question 13

structure and function of chloroplast?

Answer 13

cylindrical, bounded by double membrane

site of photosynthesis: light energy is trapped by the pigments and used to synthesise organic compounds.

Question 14

similarities between the mitochondrion and chloroplast?

Answer 14

double membrane, contain circular DNA, divide by binary fission, contain 70S ribosome

Question 15

structure and function of centrioles?

Answer 15

exist as a pair of rod-like structures, positioned at right angles to each other, NINE sets of triplet microtubules arranged in a RING

during cell division, centrioles replicate and will migrate to opp poles of the cell and are involved in organising the microtubules into spindle fibres, which align the chromosomes during metaphase and pull the chromosomes apart during anaphase