8/14/17

Question 1

Phosphotidylinositol

Answer 1

Inositol sugar head group

Phosphatidylglyceride

Important for cell signaling, gets phosphorylated and recruits signaling molecules to the cell membrane

5th membrane component

Negative charge

Question 2

Lectin

Answer 2

Carb binding protein

Question 3

Lipid belayer asymmetry

Answer 3

Inner is negative

Outer has DPPC and glycolipids

Question 4

Peripheral proteins

Answer 4

Noncovalently linked to membrane proteins

Removed without detergents, like with pH

Question 5

Restrictions of lateral diffusion for membrane proteins

Answer 5

Linked to cytosolic or ECM proteins

Linked to peripheral proteins attached to another cell

Barriers of diffusion

Question 6

Cell cortex

Answer 6

Proteins that support the plasma membrane and can bind at transmembrane proteins

Spectrin for RBCs

Question 7

Proteoglycans

Answer 7

Glycoproteins with long, I branched amino-containing sugars that have a repeating pattern

Question 8

Glycocalyx

Answer 8

Outer layer of sugars on cell membrane

Question 9

Fick’s Law

Answer 9

Net solute Flux is proportional to: area of membrane, solute concentration gradient, solute permeability

Inversely: distance or thickness of membrane

Question 10

Resting membrane potential

Answer 10

Negative inside and positive outside

Question 11

Sodium-potassium ATPase

Answer 11

Primary active transport so use ATP

3 Na+ out and 2 K+ in

Question 12

Symport or co-transport

Answer 12

Secondary active transport

Both solute move in the same direction

Na+ and glucose, glucose go against gradient while Na goes down its own

(Antiport if go opposite ways)

Question 13

Osmolarity

Answer 13

Total solute conc. In solution

Account for van’t Hoff factor

300 mM for normal cells

Question 14

Tonicity

Answer 14

Concentration of NONPENETRATING solutes

Na and K are considered nonpenetrating

Question 15

Functions of vesicular transport

Answer 15

Deliver newly made molecules to destination

Communicate with extra cellular environment

Ingest extracellular particles

Question 16

Protein coats

Answer 16

Drives vesicles budding

Help pinch the vesicles off their donor membranes and sort proteins to correct to the forming vesicle

Sheds off after formation so can reach target

Question 17

Clathrin

Answer 17

Coat protein, form triskelia

Question 18

Clathrin coat process

Answer 18

Cargo binds to cargo receptor molecule, cargoreceptor has adaptin bind to it and then clathrin to the adaption, dynamin cuts off bud and then coat disassembles, cargo receptor binds to direct final location

Question 19

Docking and fusion of vesicles

Answer 19

Rab protein binds to tethering protein

v-SNARE then binds to t-SNARE to initiate fusion

Question 20

Covalent modifications in the ER

Answer 20

Formation of Cys Cys disulfide bonds and the addition of lipid membrane anchors

Also initial protein glycosylation

Question 21

Initial glycosylstion in ER

Answer 21

Oligosaccharides are connected to dolichol of the membrane

Asn adds sugars (N-linked) or Ser/Thr does (O-linked), reaction catalyzed by oligosaccharyl transferase

Question 22

Lysosome

Answer 22

Molecular degradation

Acidic cuz H+ pump, have acid hydroplanes like nucleases

Question 23

Targeting of lysosomal hydrolases

Answer 23

Hydrolases have mannose-6 phosphate groups added, move from trans Golgi in clathrin vesicles coated with mannose-6 phosphate receptors

Lysosomal membrane proteins have short signal sequence

Question 24

Lysosomal storage diseases

Answer 24

Dysfunctional hydrolases or cofactors for them

Hydrolase substrate builds up to toxic levels

Live to 15

Most severe: I-cell (inclusion cell) disease, kinase for mannose-6 phosphate is defective

Question 25

Types of endocytosis

Answer 25

Phagocytosis: large particles, rearrange actin cytoskeleton for pseudopodia

Pinocytosis:fluid and small molecules, IND or DEP on clathrin, non selective and constitutively active

Receptor-mediated endocytosis: use clathrin

Question 26

Transcytosis

Answer 26

Receptors (and possibly their bound cargo) from receptor-mediated endocytosis travel across the cell to a different membrane domain

Question 27

Uptake of LDL Cholesterol

Answer 27

Low density lipoprotein has cholesterol core and a surrounding monolayer

LDL receptor for receptor mediated endocytosis, clathrin vesicle fuse with early endosome

Receptor recycled back to cell membrane, LDL released from receptor and degraded in lysosome to release free cholesterol

Question 28

Hypercholesterolemia

Answer 28

Mutation in LDL receptor limit uptake of LDL particles

Cholesterol build up in blood and cause atherosclerosis and early cardiovascular disease