More molecular biochem

Question 1

Xeroderma pigmentosum defect

Answer 1

nucleotide excision repair. pts cn’t repari pyrimadine dimers that form d/t UV light exposure

Question 2

Hereditary nonpolyposis colorectal cancer defect

Answer 2

mismatch repair defect.

Question 3

ataxia telangiactasia defect

Answer 3

ATM gene defect. mutation results in poor non-homologous end joing after double stranded breaks

Question 4

mRNA processing in the nucleus

Answer 4

capping of 5’ end, polyadenylation of 3’ end, splicing of introns

Question 5

alpha amanitin

Answer 5

found in death cap mushrooms. inhibits RNA pol II (makes mRNA). causes severe haptotoxicity if ingested.
recall that RNA pol I makes rRna, and RNA pol III makes tRNA

Question 6

mRNA quality control

Answer 6

occurs at cytoplasmic P bodies.

they contain exonucleases, decapping enzymes, and microRNAS.

Question 7

Significance of autoantibodies to splicesomal snRNPs (small nuclear ribonuclear proteins) and autoantibodies to U1RNPs

Answer 7

Anti-smith antibodies are highly specific for lupus (splicesomal snRNPs), antibodies against U1RNPs are specific for mixed connective tissue disease

Question 8

tRNA structure

Answer 8

looks like a T. amino acid is charged on the ACC end (3’). T arm carries the tymine, T-pseudouridine, cytosine sequence for binding to tRNA-ribosome. D arm carries the sequence for recognition by the aminoacyl-tRNA synthetase (dihydrouracil residues)

Question 9

Important energy molecules used in protein synthesis

Answer 9

ATP required for charging a tRNA (activation)
GTP required for initiation of protein synthesis (initiation factors assemble the 40S subunit with the initiator tRNA. they are released when the mRNA and the ribosomal 60S subunit assemble with the complex). GTP is also used for translocation

Question 10

Rough ER: function, specialized types

Answer 10

make proteins for secretion. Also does N-linked oligosaccharide addition. in neurons, the RER is called a Nissl body. Nissl bodies synthesize neurotransmitters.

Question 11

Smooth ER function

Answer 11

makes steroid synthesis and detoxification of drugs and poisons.

Question 12

Function of Golgi

Answer 12

modified N-oligosaccharides on asparagine. Adds O oligosacchraides on serine and threonine. Adds mannose-6-P for trafficking of proteins to lysosomes

Question 13

I cell disease

Answer 13

defect in addition of mannose-6-P for trafficking of proteins to lysosomes. causes excretion of lysosomal proteins. symptoms: coarse facial features, clouded corneas, restricted joint movement.

Question 14

COPI vs COPII

Answer 14

trafficking proteins. COPI is retrograde. within the Golgi and golgi to ER.
COPII: anterograde. Golgi-Goli anterograde; ER to Golgi

Question 15

What is digested in the peroxisome?

Answer 15

very-long-chain fatty acids, branched chain fatty acids, amino acids

Question 16

What disease is associated with defective proteosomes?

Answer 16

Parkinsons