Cell Biology and Signalling

Question 1

What are bacterial cell walls made from?

Answer 1

Peptidoglycan

Question 2

Which has an antagonistic action to adenylate cyclase?

Answer 2

Phosphodiesterase

Question 3

α helices and β sheets are formed by which type of bonding?

Answer 3

Hydrogen

Question 4

What is KM a measure of?

Answer 4

Enzyme performance

Question 5

Where does ATP respiration occur in:

a) prokaryotes
b) eukaryotes

Answer 5

a) Cell membrane

b) Mitochondria

Question 6

What 3 filaments is the cytoskeleton made up of?

Answer 6

Actin
Microtubules
Intermediate filaments

Question 7

3 functions of S.E.R?

Answer 7

N-linked glycosylation
Detoxification of xenobiotics
Biosynthesis of membrane lipids + steroids

Question 8

2 functions of R.E.R?

Answer 8

Proteins for secretion/insertion go to cell membrane Proteins folded - cys-cys bridge formed

Question 9

3 functions of Golgi apparatus?

Answer 9

Glycosylation of O-linked carbs + lipids
Synthesise lysosomes
Synthesise + package material to be secreted, direct proteins to correct compartments

Question 10

4 functions of peroxisomes?

Answer 10

Detoxification of toxins, alcohols. FAs
Phospholipid synthesis
Oxidation of VLCFA
Enzymes which generate and degrade H2O2

Question 11

What causes Zellweger syndrome?

Answer 11

Inherited absence of peroxisomes due to defects in targeting

Question 12

What causes adrenoleukodystrophy (ALD)?

Answer 12

Affects protein that imports VLCFA into peroxisomes

Question 13

What is autophagy?

Answer 13

Organelle turnover/replacement

Question 14

Myoclonic epilepsy with Ragged Red Fibre (MERRF Syndrome)?

Answer 14

Mutation of mitichondrial gene for tRNA -lys

Question 15

Hutchinson-Gilford Progeria?

Answer 15

Mutation in lamin-A prt of nuclear envelope
Distorted shape of nucleus (blebbed)
Production of unique progerin protein

Question 16

Tay-Sachs disease?

Answer 16

Mutation of lysosomal hexosaminidase- A enzyme

Causes accumulation of ganglioside that is neurotoxis

Question 17

What are operons (in bact)?

Answer 17

Functining unit of DNA containing cluster of genes under control of a single promoter

Question 18

What are the 6 types of enzymes and their functions?

Answer 18

Oxidoreductases - catalyse transfer of H + electrons
Transferases - catalyse transfer of functional groupss between molecules
Lyases - cleavage of C-C, C-O, C-N, addition to/formation of double bonds
Hydrolases - cleavage of bonds by addition of H2O
Isomerases - transfer of functional groups within same molecule
Ligases - catalyse formation of new covalent bonds using ATP, repair DNA breakage

Question 19

Soluble vs Membrane Protein?

Answer 19

Soluble - present in cytosol, hydrophobic core and hydrophilic surface
Membrane - embedded within membrane, hydrophobic surface

Question 20

What type of enzyme is chymotrypsin and what does it affect?

Answer 20

Hysrolase
Cleaves peptide bond on carboxyl side of tryptophan, tyrosine, phenylalanine + large hydrophobic residues e.g. Methionine

Question 21

What makes up chymotrypsin catalytic triade?

Answer 21

Serine
Histidine
Arginine

Question 22

3 assumptions about Michaelis-Menton plot?

Answer 22

[S]»[E]
[ES] x change with time (steady-state0 - made at same rate as broken down
Initial velocities used, [product] small, bakc reaction of P to S ignored

Question 23

What is Michaelis-Menton equation?

Answer 23

V0 = Vmax[S]/Km + [S]