Week 1 - Plasma Membrane & Transport

Question 1

Describe the self helmet of the plasma membrane

Answer 1

• Rearrangement

- Infold - Vesicle formation

Question 2

What are the three types of cell division?

Answer 2

Mitosis, meiosis, binary fission

Question 3

What three reasons are given to support that all organisms are derived from a single primordial cell?

Answer 3

1. Resemblance among living cells
2. Common cell components
3. Fossil evidence

Question 4

What are the three shapes of prokaryotes?

Answer 4

Spherical - coccus
Rod - bacillus, coccobacillus
Spiral - vibe, spirillum, spirochete

Question 5

What are monomorphic and pleomorphic?

Answer 5

Mono = one form 
Pleo = variable in size, shape and staining

Question 6

What are most bacteria cell walls made from?

Answer 6

Peptidoglycan, ligands for cell adherence

Question 7

Describe Gram Staining, positive and negative

Answer 7

Anthrax gram stain -
Positive - shows thick peptidoglycan cell wall - violet
Negative - shows thin peptidoglycan cell wall - red/pink

Question 8

Describe horizontal gene transfer in prokaryotes and why is has a negative impact

Answer 8

1. Pilus connects donor and recipient
2. DNA polymerase used to polymerase new F-Plasmid transferred through pilus via relaxasome transferasome
   Significant cause of increase in drug resistance

Question 9

What is a fimbriae?

Answer 9

Attachment pilus

Question 10

Describe three lipid types

Answer 10

Phospholipids
Glycolipids
Sterols

Question 11

Name the five common phospholipids

Answer 11

Phosphoglycerides 
Phosphoatdylcholine 
Phosphatidylethanolamine 
Phosphatidylserine 
Phosphatidylinositol

Question 12

Describe a glycosphingo lipid

Answer 12

Glycerol + Sphingosine base

Question 13

Describe blood group antigens

Answer 13

Glycolipids, change in sugars on the RBC dependent on enzymes
O - Fucose, Galactose x2 and N acetyl-glucosamine
A - N acetyl-galactosamine, N acetyl-glucosamine, Galactose x2, fucose
B - Galactose x3, Fucose, N acetyl-glucosamine
AB - all of A + B

Question 14

Describe phospholipid fluidity

Answer 14

• Rotation around long axis
• lateral diffusion - same monolayer
• transverse diffusion ‘flip flop’ from one monolayer to another (very rare) - energetically unfavourable

Question 15

Describe membrane fluidity with respect to cholesterol

Answer 15

Cholesterol buffers fluidity and allows membrane to be fluid over a wider temperature range
- Allows more space to be formed between phospholipids therefore encouraging more movement

Question 16

What are lipid rafts?

Answer 16

Clusters of lipids + proteins within membrane making the membrane less fluid

Question 17

What are the three classes of membrane proteins?

Answer 17

Integral - embedded - helical
Peripheral - inside/outside
Lipid anchored - surface membrane

Question 18

What is the resting membrane potential range?

Answer 18

-50mv to -90mv

Question 19

What ions are in higher conc extracellular?

Answer 19

Na+ (150) CL- (108)

Question 20

What ions are in higher conc intracellular?

Answer 20

K+ (150) Anions (65) Phosphate

Question 21

What are the four transport mechanisms?

Answer 21

Diffusion
Facilitated Diffusion
Primary active transport
Secondary active transport

Question 22

Describe Transport Proteins

Answer 22

All integral with 12 transmembrane segments

Question 23

How are carrier proteins categorised + describe

Answer 23

Uniport - single solute
Symport - 2 solutes simultaneously
Antiport - 2 solutes opposite directions

Question 24

Describe channel proteins

Answer 24

Hydrophilic transmembrane channel
ion channels
Porins
Aqua Porins

Question 25

Describe exocytosis

Answer 25

Vesicle forms inside cell containing e.g. histamine/ heparin
Fuses with membrane
membrane ruptures and releases the secretory proteins

Peptides + protein hormones
Enzymes
Neurotransmitters + water soluble hormones

Question 26

Describe mast cells

Answer 26

primary defence against antigens - inflammatory response - release vesicles against antigens via exocytosis

Question 27

Describe endocytosis

Answer 27

External materials internalised by cell - infolding of membrane

Question 28

Give the 4 types of endocytosis

Answer 28

Clathrin Mediated 100nm
Calveolae 50nm
Both receptor mediated

Pinocytosis 5um - cell drinking
Phagocytosis 0.75um - abc, macrophages and neutrophils

Question 29

Describe Arachidonic Acid

Answer 29

Precursor for many eicosanoids involved in inflammation pathways
C20 Fatty acid 3-5 double bonds

Question 30

Describe sphingolipids

Answer 30

Sphingosine + fatty acid = ceramide
Ceramide + silica acid = ganglioside
Ceramide + sugar = cerebroside
Ceramide + choline = sphingomyelin