20.1 — gene mutations

Question 1

what are gene mutations?

Answer 1

permanent changes in the DNA sequence that make up a gene. they involve changes in one or more DNA bases within a gene.

Question 2

what are the differences between mutations in body cells and gametes?

Answer 2

body cells: disrupt normal functions, like cell division, possible causing cancer.

gametes: can be inherited by offspring, whereas body cells cannot.

Question 3

how do mutations arise?

Answer 3

naturally during DNA replication, but at a low frequency. the rate can be significantly increased by mutagens

Question 4

what is the definition of mutagens?

Answer 4

external factors that significantly increase the rate of mutations

Question 5

what are the main types of mutagens?

Answer 5

• ionising radiation (e.g. x-rays) — can break DNA start dos or alter its structure
• chemical mutagens (e.g. benzopyrene in cigarette smoke) — can modify DNA bases of interfere with DNA metabolism

Question 6

what is an example of ionising radiation?

Answer 6

x-rays

Question 7

how can x-rays act as a mutagen?

Answer 7

can break DNA strands or alter its structure

Question 8

what’s an example of chemical mutagens?

Answer 8

benzopyrene in cigarette smoke

Question 9

how can benzopyrene in cigarette smoke act as a mutagen?

Answer 9

can modify DNA bases or interfere with DNA metabolism

Question 10

what are substitution mutations?

Answer 10

when one DNA base is replaced by another within the gene’s sequence