BIOC 305 Final Exam Questions and
Answers
Deoxyribonucleotide biosynthesis - ANSWER-synthesized by ribonucleotides using
ribonucleotide reductase
Ribonucleotide reductase - ANSWER-- Enzyme reduces 2' C of nucleodiphosphates
(substrates = ADP, CDP, GDP, UDP)
- 3 types: all employ a free tyrosyl radical for catalysis
- Class I most common form in humans
- alpha and beta subunits
- alpha = contains the active site and 2 allosteric sites
- beta = contains a tyrosine residue and a pair of metal ions bridged by oxygen atom
Thymidine synthesis (thymidylate synthase) - ANSWER-de-novo
- methylation of deoxyuridate (dUMP) by thymidyate synthase
Folic acid deficiency - ANSWER-decreased thymidylate synthesis causes uracil to
be incorporated into DNA
- repair mechanisms remove uracil by creating strand breaks that affect the structure
and function of DNA - cancer, heart disease, neurological impairment
catabolism of nucleotides - ANSWER-1) dephosphorylating
2) Deglycosylation to yield purine/pyrimidine
3) catabolism/elimination
Gout (xanthine oxidase) - ANSWER-- sodium urate crystals in joints
- genetic under-excretion of urate or over-consumption of fructose
- avoid eating purine-rich food - sea-food, liver or avoid fructose. Xanthine oxidase --
> converts purines to uric acid
- treated with xanthine oxidase inhibitor - allopurinol
Transcription bubble - ANSWER-Melting of DNA --> addition of NT forms hybrid
strand --> RNA strand separates from DNA --> DNA reanneals to close bubble
- only one DNA strand copied --> RNA has same sequence as coding strand = non-
template strand = sense strand
Pre-initiation - ANSWER-in bacteria, RNA polymerase + core promoter (plus sigma
factor)
Core promoter = TATA box (bound to TATA binding protein, other proteins and
multiple TFs bind)
Initiation - ANSWER-in prokaryotes, binding of RNA polymerase to a sigma factor
completes the initiation complex
Answers
Deoxyribonucleotide biosynthesis - ANSWER-synthesized by ribonucleotides using
ribonucleotide reductase
Ribonucleotide reductase - ANSWER-- Enzyme reduces 2' C of nucleodiphosphates
(substrates = ADP, CDP, GDP, UDP)
- 3 types: all employ a free tyrosyl radical for catalysis
- Class I most common form in humans
- alpha and beta subunits
- alpha = contains the active site and 2 allosteric sites
- beta = contains a tyrosine residue and a pair of metal ions bridged by oxygen atom
Thymidine synthesis (thymidylate synthase) - ANSWER-de-novo
- methylation of deoxyuridate (dUMP) by thymidyate synthase
Folic acid deficiency - ANSWER-decreased thymidylate synthesis causes uracil to
be incorporated into DNA
- repair mechanisms remove uracil by creating strand breaks that affect the structure
and function of DNA - cancer, heart disease, neurological impairment
catabolism of nucleotides - ANSWER-1) dephosphorylating
2) Deglycosylation to yield purine/pyrimidine
3) catabolism/elimination
Gout (xanthine oxidase) - ANSWER-- sodium urate crystals in joints
- genetic under-excretion of urate or over-consumption of fructose
- avoid eating purine-rich food - sea-food, liver or avoid fructose. Xanthine oxidase --
> converts purines to uric acid
- treated with xanthine oxidase inhibitor - allopurinol
Transcription bubble - ANSWER-Melting of DNA --> addition of NT forms hybrid
strand --> RNA strand separates from DNA --> DNA reanneals to close bubble
- only one DNA strand copied --> RNA has same sequence as coding strand = non-
template strand = sense strand
Pre-initiation - ANSWER-in bacteria, RNA polymerase + core promoter (plus sigma
factor)
Core promoter = TATA box (bound to TATA binding protein, other proteins and
multiple TFs bind)
Initiation - ANSWER-in prokaryotes, binding of RNA polymerase to a sigma factor
completes the initiation complex
