Chapter 35: DNA Repair and Recombination

Question 1

DNA is the only cellular macromolecule that can _____ - mutations can have a very high cost

Answer 1

Be repaired

Question 2

A _____ is a physical or chemical agent that changes the genetic material

Answer 2

Mutagen

Question 3

How can we test if a chemical is a mutagen? Two ways:

Answer 3

1. ) Use a bacteria strain that cannot grow on histidine
2. ) Add a mutagen and plate the bacteria, and if this bacteria grows on histidine, this means that a mutation has occurred allowing this bacteria to grow on histidine. (Ames’ Test)

Question 4

What are 5 types of mutagens that can cause DNA damage?

Answer 4

1. ) Cellular metabolism
2. ) UV Light exposure
3. ) Ionizing radiation
4. ) Chemical exposure
5. ) Replication errors

Question 5

What repairs DNA?

Answer 5

• DNA polII does a great job, but not good enough

- Introduces errors in about 1 in 10^7 nucleotides added, which it does not correct

Question 6

Most DNA mistakes and damage are corrected. %?

Answer 6

99% -leaving just a few - only 1 in 109 errors are left

Question 7

DNA repair systems follow the same mechanistic outline:

Answer 7

• Recognize the inappropriate base(s).
• Remove the inappropriate base(s).
• Fill in the resulting gap with DNA polymerase I and DNA ligase.