Week 2

Question 0

Glutamate

Answer 0

Deaminated: alpha-ketoglutarate

-the amino group pool of the cell, direct link between TCA cycle and amine pool

Question 1

What are the four key amino acids?

Answer 1

Glutamate, Aspartate, Alanine & Glutamine

Question 2

Aspartate

Answer 2

Oxaloacetate - donor of nitrogen for the urea cycle, can take nitrogen from other a.a. and donate it directly to a molecule of urea and that can be excreted [it’s a TCA cycle intermediate]

Question 3

Alanine

Answer 3

Deaminated: Pyruvate - a key role in gluconeogenesis - transporter of nitrogen to the liver for the urea cycle

Question 4

Glutamine

Answer 4

Deaminated: Glutamate - transports nitrogen to liver for urea cycle - has two amino groups and is an important circulating amine pool

Question 5

What symptoms does hyperammonia cause?

Answer 5

Neurological problems- neurons are particularly sensitive to ammonia - seizures, refusal to eat/protein aversion, irritability, lethargy, ataxia, tremors, FTT

Question 6

What does CPSI do in the urea cycle?

Answer 6

It transforms carbamoyl phosphate into citrulline.

Question 7

What happens when OTC is mutated??

Answer 7

When OTC is not functioning, carbamoyl phosphate is diverted down the pyrimidine synthesis pathway and orotic acid builds up in the urine.

Question 8

What is HHH syndrome?

Answer 8

Hyperammonia, Hyperornithaemia, Homocitrullinaemia - ornithine/citrulline antiporter is defective

Question 9

What three sets of proteins play critical roles in the accurate delivery and fusion of vesicles?

Answer 9

Rabs, Rab effectors and SNAREs

1. Rab GTP first docks onto the Rab effector (teethering protein)
2. Then the v-SNARE on the vesicle binds to the t-SNARE in the membrane.
3. Then the vesicle fuses with the membrane and releases its cargo!

Question 10

Tell me about Familial Hypercholesterolemia (FH):

Answer 10

• Special defect in an endocytotic pathway - develop Xanthomas, have first myocardial infarction by age 8, deposition in coronary arteries
• This condition usually arises from mutations in the LDL receptor or in apolipoprotein B, the ligand for LDLR. These mutations don’t allow LDL to bind to LDLR and block its uptake by cells. This results in high circulating LDL levels and attendant cardiovascular disease.

Question 11

What does the position and orientation of the first Start/Stop sequence indicate?

Answer 11

It sets up the initial orientation of the membrane protein. Subsequent S/S sequences determine the number of transmembrane regions in a multipass protein

Question 12

Glycocalyx

Answer 12

Membrane proteins covalently attached to sugar groups (only on outer cell)
Glycocalyx = protection, identification, adhesion

Question 13

What is the unfolded protein response?

Answer 13

-When proteins are misfolded in the ER:
1. The increased expression of ER chaperones to facilitate refolding
2. Increased expression of genes involved in retrotranslocation and proteasomal degradation
[proteins are ubiquinated in the ER and destroyed in the proteasomes]

Question 14

What happens in the SER and RER?

Answer 14

SER - Ca++ regulation, detox reactions- cytochrome p450 & lipid synthesis
RE - Protein synthesis