First Aid Biochem_Genetics Part I

Question 1

1 Text

Answer 1

2 Text

Question 2

Which histone # is the linker?

Answer 2

H1

Question 3

Which histone #s are the nucleosome core?

Answer 3

H2A, H2B, H3, H4

Question 4

Is euchromatin or heterochromatin more transcriptionally active?

Answer 4

Euchromatin is active; hetero is inactive

Question 5

What three amino acids are required for purine synthesis?

Answer 5

Glycine, aspartate, glutamine

Question 6

Is orotic acid a purine or pyrmidine precursor?

Answer 6

Pyrmidine

Question 7

What does a degenerate genetic code mean?

Answer 7

More than one codon codes for the same amino acid

Question 8

What is a nonsense vs a missense mutation?

Answer 8

Nonsense = STOP codon, missense = substitute one amino acid for another

Question 9

Do eukaryotes have a single or multiple origin of replication?

Answer 9

Multiple

Question 10

What does primase do?

Answer 10

Makes RNA primer on which DNA pol III can initiate replication

Question 11

What does DNA pol I do?

Answer 11

Degradees RNA primer and fills in gap with DNA

Question 12

What does DNA pol III do?

Answer 12

Adds deoxynulceotides to 3’ end; has internal proofreading actiivty. Replication!

Question 13

What type of exonuclease activity does DNA pol III have?

Answer 13

3’ to 5’; proofreads

Question 14

What does DNA ligase do?

Answer 14

Connects Okazaki fragments together

Question 15

What is nucleotide excision repair? In what disease is it defective?

Answer 15

Endonucleases remove damaged bases; ex xeroderma pigmenteosum

Question 16

What is base excision repair?

Answer 16

Specific glycosylases remove damaged bases, AP endonuclease cuts DNA at apyrimidinic site, empty sugar removed

Question 17

What is mismatch repair? In what disease is it defective?

Answer 17

Unmethylated, newly synthesized sring is recognized, mismatched nucleotides are removed, gap is resealed; HNPCC

Question 18

What is nonhomologous end joining? In what disease is it defective?

Answer 18

Double stranded DNA repair; brings 2 ends of DNA together; ataxia telangiectasias

Question 19

Is protein synthesis from C to N or N to C?

Answer 19

N to C

Question 20

In what direction is mRNA read?

Answer 20

5’ to 3’

Question 21

What type of RNA is the most abundant?

Answer 21

rRNA

Question 22

What is the start codon?

Answer 22

AUG

Question 23

What are three mRNA stop codons?

Answer 23

UGA, UAA, UAG

Question 24

Where are silencers and enhancers found on the chromosome?

Answer 24

Close, far away, or within; they can be upstream or downstream from a gene

Question 25

What are two upstream promotor sequences?

Answer 25

TATA and CAAT boxes

Question 26

What does rRNA pol I, II, and III do?

Answer 26

I = rRNA, II = mRNA, III = tRNA

Question 27

What substance can inhibit RNA pol II?

Answer 27

Alpha-amanitin

Question 28

What are there processes that occur to convert pre-mRNA to mature mRNA?

Answer 28

1. 5' 7-methylguanosine cap, 3' polyadenylation, splicing of introns

Question 29

What is the polyadenylation signal sequence?**

Answer 29

AAUAAA

Question 30

What two enzymes do not require a template to transcribe DNA?

Answer 30

Poly-A polymerase, telomerase

Question 31

What disease is associated with antibodies to spliceosomal snRNPs?

Answer 31

SLE

Question 32

Where does a repressor bind in the lac operon?

Answer 32

Operator

Question 33

What compound inhibits the repressor in the lac operon?

Answer 33

Lactose

Question 34

What compound inhibits the activator in the lac operon?

Answer 34

Glucose via decreased cAMP

Question 35

Are exons/introns the coding or noncoding sequences?

Answer 35

Exons are EXPRESSED, introns are INTERVENING

Question 36

What disease has mutations of the introns?

Answer 36

beta-thalassemias

Question 37

Is the CCA sequence on the 3' or 5' end of tRNA?

Answer 37

3'

Question 38

What does the CCA sequence do?

Answer 38

Covalently binds the amino acid

Question 39

What enzyme is responsible for tRNA charging?

Answer 39

Aminoacyl-tRNA synthetase

Question 40

What enzyme is responsible for proofreading tRNA charging?

Answer 40

Aminoacyl-tRNA synthetase

Question 41

What is the wobble effect?

Answer 41

3rd nucleotide of the codon can vary, due to degeneracy of the genetic code

Question 42

What is the energy source for protein synthesis initiation?

Answer 42

GTP

Question 43

What is the energy source for tRNA charging? tRNA translocation?

Answer 43

ATP and GTP respectively

Question 44

Which aminoacyl-tRNA does NOT bind to the A site first?

Answer 44

AUG/methionine; binds to P site first

Question 45

What antibiotic inhibits moving tRNA from the A site to the P site?

Answer 45

Macrolides (translocation!)

Question 46

What antibiotic can cause misreading of mRNA?

Answer 46

Aminoglycosides

Question 47

What is the role of ubiquitination?

Answer 47

Targets proteins for degredation in proteosome

Question 48

What are the major tumor supressors for the G1 to S phase tranistion?

Answer 48

p53 and RB

Question 49

What cells are considered quiescent (in that they can move from G0 to G1 if provoked)

Answer 49

Hepatocytes, lymphocytes

Question 50

What are labile cells?

Answer 50

Never go into G0; ex bone marrow, gut epithelium, skin, hair follicles