DNA mistakes and repair

Question 1

Types of mutations

Answer 1

Substitutions, Insertions, Deletions

Question 2

Mismatch Repair System

Answer 2

enzymes correct errors in base pairing following replication; use specific enzymes to remove and replace incorrectly paired nucleotides

Question 3

Nuclease

Answer 3

Enzyme that cuts DNA or RNA, either removing one or a few bases or hydrolyzing the DNA or RNA completely into its component nucleotides

Question 4

Nucleotide excision repair

Answer 4

repair system that removes and then correctly replaces damaged segment of DNA using undamaged strand as a guide

Question 5

steps of nucleotide excision repair

Answer 5

1. enzymes detect and repair damaged DNA
2. nuclease enzymes cuts DNA strand at two points; removes damaged section
3. Repair synthesis by a DNA polymerase to fill in missing nucleotides; use undamaged strain as template
4. DNA ligase seals free end of new DNA to old DNA ; completes strand

Question 6

Significance of altered DNA nucleotides

Answer 6

Impacts protein structure, changes can be permanent (passed on to generations), source of genetic variations in populations

Question 7

Telomeres

Answer 7

tendemly repetitive DNA at the end of a eukaryotic chromosomes DNA molecule; telomeres protect an organism’s genes from being eroded by successive rounds of replication

Question 8

Telomerase

Answer 8

catalyzing the lengthening of telomeres in eukaryotic germ cells; restores original length and compensates for shortening create by replication