Dr. Howe Study Guid # 3

Front 1

Proofreading

Back 1

- Mechanism that helps keep the frequency of DNA replication errors low

Front 2

DNA polymerase

Back 2

3' to 5' exonuclease activity. Both polymerase I and III (proofreading).

Front 3

Mismatch

Back 3

-base pair are not complementary.
-DNA polymerase makes a mistake

Front 4

Mismatch repair

Back 4

identify mismatch and excise miss paired nucleotide and replace it with correct nucleotide.

Front 5

exonuclease

Back 5

DNA polymerase I- 5' to 3' activeity can remove neleotide from the 5' end of the DNA or from the RNA primer strand.
DNA polymerase III and I has 5'to 3' exonuclease proofreading activity.

Front 6

Mutation

Back 6

Any detectable and heritable change in the genetic material not caused by genetic recombination.
-change in DNA nucleotide

Front 7

When can mutations occur?

Back 7

when DNA pol makes a mistake

Front 8

What is the error rate of DNA polymerase before and after proofreading by DNA polymerase?

Back 8

1/10^5 nucleotides

Front 9

In relation to the process of replication, when do proofreading and mismatch repair occur?

Back 9

The 3' to 5' exonulease activity excises the wrong nucleotide on the new strand. Then the 5' to 3' DNA polymerase activity the resumes forward direction and inserts the correct nucleotide

Front 10

In mismatch repair, how is the newly synthesized strand distinguished from the original parent strand?

Back 10

The polymerase proofreads each neucleotide against its template as soon as it is added to the strand

Front 11

What is the DNA relication error rate after mismatch repair?

Back 11

1/10^7 nucleotide

Front 12

Methylation in Prokaryotes

Back 12

Newly made DNA gets methylated (after replication).
- The unmethylated gets identifed and the nucleotides are removed

Front 13

Methylation in Eukaryotes

Back 13

After replication the new DNA is nicked at the phosphodiester bonds.
They are identified by mismatch repair.