Molecular Biochemistry

Question 1

snRNP function in? Name some antibodies?

Answer 1

Splicesome

i.e. Anti-smith, anti-U1 RNP

Question 2

Anti-smith antibodies is highly specific for?

Answer 2

SLE

Question 3

Splicesomes function to splice?

Answer 3

pre-mRNA

Question 4

Three Stop Codons?

Answer 4

UAG, UGA, UAA

Question 5

DNA polymerase III vs polymerase I

Answer 5

Polymerase III- Elongates leading and lagging strand

Polymerase I-Degrades RNA primer

Question 6

Fluoroquinolones inhibit? What do these class of enzymes do?

Answer 6

Topoisomerase II and IV

Add or Remove supercoils

Question 7

Telomerase activity is increased in?

Answer 7

Cancer cells

Question 8

Frameshift vs nonsense vs missense vs silent. Rank from worst to best

Answer 8

Frameshift, non sense, missense, silent

Worst to Best

Question 9

UGA has a mutation for UAG, what is this mutation called?

Answer 9

Silent=> both produce termination sequences

Question 10

Sickle cell disease (substitution of glutamic acid with valine) is a example of?

Answer 10

missense

Question 11

Nonsense mutations result in early? Why?

Answer 11

Stop Codon

Because the C terminal would be completely removed

Question 12

Duchenne muscular dystrophy is an example of what kind of mutation?

Answer 12

Frameshift mutation

Question 13

Frameshift mutations produce?

Answer 13

Truncated, nonfunctional protein

Question 14

For a lac operon, a repressor protein exists when there is?

Answer 14

No Lactose

Question 15

How does low glucose increase CAP activity?

Answer 15

low glucose=>increased cAMP=>CAP=>transcription

Question 16

How does Nucleotide excision repair work?

Answer 16

endonuclease=>DNA polymerase =>ligase

Question 17

When does Nucleotide excision repair work? When does Base Excision Repair work?

Answer 17

G1
Repairs ONE nucleotide at a time

Base Excision
“spontaneous deamination can happen at any time”

Question 18

How does Base Excision excision repair work?

Answer 18

Spontaneous Deamination (C=>U) => Uracil Glycolyase=>AP endonuclease=>Lyase=>DNA polymerase =>ligase

Question 19

Xeroderma pigmentosum is representative of what disease? is due to? Results in?

Answer 19

Nucleotide excision repair defect

Cause: UV Result: thymine dimers

Question 20

Mismatch Repair defect leads to?

Answer 20

Microsatilite instability

Question 21

MisMatch Repair defect occurs in? How does it work? In what disease do you see it?

Answer 21

Occurs in: G2 (MisMatch has two M’s)
Finds: GATC sequence that has not been methylated (It will usually distort the DNA)
Cuts: Enzyme cuts that sequence

Disease: HNPCC

Question 22

Brings together 2 ends of DNA fragments to repair double-stranded breaks? Give 2 examples of them?

Answer 22

Nonhomologous end joining (dsDNA repair)

Ataxia telangiectasia, Fanconi’s anemia

Question 23

BRCA genes are what kind of genes?

Answer 23

DNA repair genes

Question 24

Drugs blocking DNA replication and creating Chain termination have modified? Give an example?

Answer 24

3’OH

Acyclovir

Question 25

Promotor mutation leads to? Is the promoter ever transcribed?

Answer 25

Dramatic decrease in level of gene transcription

No

Question 26

rRNA stands for? mRNA stands for? tRNA stands for? Who makes these RNAs

Answer 26

RNA polymerase I-rRNA=rampant=numerous
RNA polymerase II-mRNA=massive
RNA polymerase III-tRNA=tiny

Question 27

α-amanitin inhibits? How does it do this?

Answer 27

RNA polymerase II

How: interferes with translocation of RNA & DNA needed to empty the site for the next round of RNA synthesis

Question 28

Rifampin inhibits? How does it do this?

Answer 28

RNA polymerase in prokaryotes

How: blocking the formation (Ri-Form-pin) of the phosphodiester bond in the RNA backbone=>truncated RNA

Question 29

ß-thalassemia is a result of what abnormal process?

Answer 29

Splicing

Question 30

In Protein Synthesis, ATP is used for? GTP is used for?

Answer 30

Activation (charging)
Going places (Translocation)

Question 31

Zyomyogen=>mature protein; this process is called?

Answer 31

trimming

Question 32

Heat Shock Proteins are called?

Answer 32

Chaperone proteins

Question 33

What activity is increased in cancer cells and decreased in progeria?

Answer 33

Telomerase activity

Question 34

Transition vs Transversion?

Answer 34

Transition: purine to purine
Transversion: purine to pyrimidine (conVERTing to something different)

Question 35

Prokaryote’s mRNA start codon? What is its significance?

Answer 35

N-formylmethionine (fMet)

fMet induces neutrophil chemotaxis

Question 36

What clinical findings do you get from alpha amanitin? What is the mechanism? Treatment?

Answer 36

Stops DNA/RNA translocation=>decreases RNA synthesis=>destruction of liver cells

Tx: Silymarin: prevents toxins from entering and allows for regeneration of liver

Question 37

Actinomycin D or Called Dactinomycin inhibits? Difference between Actinomycin and Rifampin? How does it do this?

Answer 37

RNA polymerase

Actinomycin or Dactinomycin (2 words) blocks polymerase in both (2) prokaryotes and eukaryotes while Rifampin only blocks prokaryotes

How: binding DNA at the transcription initiation complex=> prevents elongation of RNA

Question 38

What is the purpose of Capping and Tailing?

Answer 38

Capping: orients mRNA on ribosome
Tailing: gives it a longer half-life

Question 39

Anti-U1 RNP is associated with?

Answer 39

Mixed Connective Tissue Disease