Transcription/Translation:

Question 1

Complementation Test

Answer 1

Breed animals with 2 different homozygous recessive mutations that produce the same phenotype. If they “complement” each other and the offspring is normal, they are in 2 different genes. If the offspring are sick, mutations are in the same gene.

Question 2

LacZ operon

Answer 2

• LacZ metabolizes lactose.
• LacI binds and deactivates LacZ until lactose is present, when a metabolite of lactose binds to LacI and disables it, enabeling transcription of LacZ, LacY, LacA

Question 3

Promoter sites on DNA

Answer 3

• TTGACA at -35 from start site
• TATATT box (-10)

Question 4

In bacterial tarnscription, _____ induce binding of RNA polymerase to promoter. DNA is transcribed until _____.

In eukaryotic transcription, _______ bind at ___ to recruite ______ enzyme. ______ is phosphorylated, _____ fall off, and transcription begins.

Answer 4

Sigma factors induce binding of RNA polymerase to promoter; they fall off after transcription initiation.

transcribed until terminator (stop) codon is reached.

In eukaryotic transcription, TFs (including TFIID) bind at TATA and other upstream sites to recruit RNA polymerase II enzyme. RNA polymerase II is phosphorylated, TFs fall off, and transcription begins.

Question 5

RNA processing

Answer 5

• 5’ cap (modified guanine)
• 3’ poly-A tail
• introns spliced out (exons expressed)

Question 6

• heterochromatin:
• euchromatin:

Answer 6

• heterochromatin: inactive, encased by methylated histone proteins (methylation of DNA at CpG islands turns off the gene
• euchromatin: active bc of modifications (acetylation = active)
  *

Question 7

RNA interferance

Answer 7

mammalian RNA contains 3’ UTR. When these are bound by microRNA fragments, bound RNA is destroyed.

Question 8

amount of protein translated from RNA is determined by

Answer 8

mRNA transcripts present

Question 9

amount of protein translated corresponds to

Answer 9

mRNA transcripts

Question 10

start codon

Answer 10

AUG (methionine)

Question 11

Ribosome components

Answer 11

• 2 subunits (small, large) with A site, P site (peptide bond) , E site (ejection)

Question 12

AA is added to the tRNA opposite the anticodon by _____ enzyme

Answer 12

aminoacyl tRNA synthetase with ATP.

Question 13

Steps of translation

Answer 13

1. small ribosome subunit with Initiation Factors and tRNA with Met bind mRNA
2. tRNAs with matching anticodons and AA bind the A site
3. Peptide bond is formed (N–>C) between Met and the next AA
4. large subunit shifts, ejecting tRNA for Met and shifting next AA to P, and preparing for next tRNA to enter A site.
5. Ribosome collapses when stop codon is bound.

Question 14

Spinal Muscular Atrophy

Answer 14

• SMN protein in motor neuron synapses is made twice (SMN1 and SMN2
• SMN1 most utilized
• SMN2 typically degraded because of exon 7 nucleotide difference–> alterantive splicin –> unstable protein.
• 10% of SMN2 is still produced/stable
• In Spinal Muscular Arophy (SMA, SMN1 is degraded because of an exon 7 or other mutation. pt must rely on SMN2

1. Treatment: generate full length SMN2

Question 15

methylated uracil is:

Answer 15

thymine