Weekly Homework 12

If any of these examples of DNA damage are not repaired before ________________, the information content of DNA is changed ________________

1. DNA replication 2. permanently

The Process of Base Excision Repair

1. One strand of the DNA contains a deaminated base, such as uracil 2. A uracil-specific DNA glycosylase recognizes and removes the uracil, leaving and apurinic (AP) site 3. AP endonuclease nicks the DNA backbone at the AP site 4. DNA exonuclease removes nucleotides near the nick, leaving a gap 5. DNA polymerase synthesizes new DNA to fill the gap 6. DNA ligase seals the nick in the backbone

Naturally occurring radiation, such as _____________, can beak the sugar phosphate backbone and lead to __________ of DNA bases

1. cosmic rays and X-rays 2. deletion

The information stored in DNA can change by natural process that ______________ DNA

1. damage

______________ is the removal; of an amino group. Deamination of C to form U followed by DNA replication may result in a ___________ transition

1. deamination 2. C-G to T-A

_____________ occurs when an A or G base is hydrolyzed behind a site with no bases. DNA polymerase will introduce a _______________ opposite the apurinic site

1. deprination 2. random base

Ultraviolet light, which produces ____________, and oxidation also damage DNA

1. thymine dimers

Substitutions

Base analogs Hodroxylating agents Alkylating agents Deaminating agents

Additions

Interlacing agents

Chromosomal rearrangements

X-rays

Deletions

X-rays Interlaccing agents