Term
| What is different about lagging strand DNA polimerization in bac vs. mammals? |
|
Definition
- in bac, only α-subunit of DNA pol III
- in mammals, pol δ & α on lagging (pol ε for leading)
- mammalian primase forms tight complex with pol α while bacterial primase associated with helicase forming primosome |
|
|
Term
| What are the components of the DNA pol III holoenzyme (bacteria)? |
|
Definition
- pol III core (2 copies)
- β sliding clamp
- γ/τ complex clamp loader |
|
|
Term
| Components of the (bacterial) replisome? |
|
Definition
- holoenzyme
- DnaG Primase
- DnaB (helicase)
- SSB |
|
|
Term
| What 3 steps give rise to high-fidelity DNA synthesis? |
|
Definition
1) 5'-> 3' polumerization
2) 3'-> 5' exonucleolytic proofreading
3) Strand-directed mismatch repair |
|
|
Term
| Helicase function and name in mammals |
|
Definition
| opens DNA at fork; MCM Proteins |
|
|
Term
|
Definition
RNA-DNA primer synthesis for subunit of pol α-primase
- primase-pol α |
|
|
Term
| Polymerase function and types in mammals |
|
Definition
| elongates DNA; pol δ and ε |
|
|
Term
| Proofreading exonuclease function and names in mammals |
|
Definition
| 3' -> 5' nuclease; pol δ and ε |
|
|
Term
| Sliding Clamp function & name in mammals |
|
Definition
| processivity factor for pol δ and ε; PCNA |
|
|
Term
| Clamp loader (function and name in mammals) |
|
Definition
Load PCNA, polymerase switching
- RF-C |
|
|
Term
| Single STrand DNA binding protein (Funciton and name in mammals) |
|
Definition
| Protect single-stranded DNA; RP-A |
|
|
Term
| DNA Ligase I (Func and name in mammals) |
|
Definition
| Ligates DNA pieces (Lig 1) |
|
|
Term
| DNA topoisomerase (func & name in mammals) |
|
Definition
| removes DNA topological contraints (Top I & II) |
|
|
Term
| The bacterial primosome contains what two enzymes? |
|
Definition
|
|
Term
| Pol III and Pol δ are high processivity polymerases in E.coli and mammals, respectively. |
|
Definition
|
|
Term
| Name a few human polymerases? Which have proof reading activity? |
|
Definition
| Pol δ and pol ε are major replicative polymerases. Pol β, γ, and ε have proof reading capabilities. |
|
|
Term
| Which human polymerase is responsible for leading strand synthesis and which for the bulk of synthesis? |
|
Definition
| Pol ε is leading and Pol δ polymerizes bulk of DNA. |
|
|
Term
| What are the 3 steps of Okazaki Frament processing? |
|
Definition
1) removal of primer
2) synthesis of DNA across gap
3) DNA ligation |
|
|
Term
Do any eukaryotic DNA polymerases carry 5' -> 3' exonuclease activity?
What 2 exonucleases repair human DNA? |
|
Definition
| RNase H removes ribonucleotides at all locations except the 5' end. FEN1 removes the last ribonuclotide and several deoxynuleotides. |
|
|
Term
| What is the human equivalent of SSB and what the its functions? |
|
Definition
Replication Factor-A (RF-A), HSSB, etc.
- Stabilizes unwound ssDNA
- binds to ssDNA w/ocovering bases
- remove "hairpin" |
|
|
Term
| Slinding clamps. Names and function in E.coli and humans... |
|
Definition
- Protein rings that encircle DNA
- keep polymerases firmly on DNA when moving but releases once hits dsDNA.
- in E.coli - β subunit of DNA pol III
- in humans - proliferating cell nuclear antigen (PCNA)
- req for leading/lagging synth. |
|
|
Term
|
Definition
- ATPase activity involved in attaching the clamp.
- released once polymerase binds to clamp.
- called RF-C in humans |
|
|
Term
|
Definition
- DNA ligase I joins Okazaki frags.
- join segments |
|
|
Term
|
Definition
- prevents DNA tangling
- Type I - introduces single-strand breaks
- Type II - dbl strand breaks
- TopoII for daughter chromosome separation |
|
|
Term
| What is the telomerase and what are its components? Where is telomerase switched on and off? |
|
Definition
- The telomerase is a reverse transcriptase enzyme.
- it's a protein-RNA complex
- RNA component is complementary to the telomeric single strand overhand and is a template for telomeric DNA (TTAAGGG)
- The protein component is hTERT (human telomere reverse transcriptase) which provides the catalytic activity
- on in germ cells
- off in somatic cells |
|
|
