Mutations

Question 1

Mutation Type 1: Point Mutations

Answer 1

• May be caused by errors in DNA replication
• Includes; base pair substitution, deletion and insertion

Question 2

Base Pair Substitution

Answer 2

• Where one or more base pairs is replaced by another base pair
• Overall effect depends on gene in question
• Example: A-T is replaced by G-C

Question 3

Base Pair Deletion

Answer 3

• Where 1 or more base pairs is omitted
• Changes the reading of the code from that point on
• Frameshift mutation
• Big effects usually

Question 4

Base Pair Insertion

Answer 4

• Where 1 or more base pairs is added
• Changes the reading of the code from that point on
• Frameshift mutation
• Big effects usually

Question 5

Mutation Type 3: Changes in Chromosome Number
(Atypical numbers)

Answer 5

• Can be caused by non-disjunction
  an individual has more or fewer chromosomes
  
  • Members of a homologous pair may not separate properly during meiosis I
  • Sister chromatids fail to separate during meiosis II
  • In mitosis of early embryo, error is passed on to many body cells
• Includes: Aneuploidy and Polyploidy

Question 6

Aneuploidy

Answer 6

• One more or less chromosome
• Offspring has an abnormal chromosome number
• Includes: Trisomy and Monosomy

Question 7

Trisomy

Answer 7

• Where the cell has 1 extra chromosome
• ie. Down’s syndrome in humans

Question 8

Monosomy

Answer 8

• Where the cell has 1 less chromosome
• One less from a homologous pair

Question 9

Polyploidy

Answer 9

• One of more entire SETS of chromosomes
• Where the organism has more than 2 complete sets of chromosomes
• Does not happen in humans
• Rare in animals but relatively common in plants

Question 10

What are mutations caused by?

Answer 10

Mutagens, or substances that damage DNA by changing the genetic code

Question 11

What are the 3 major types of mutagens to exist?

Answer 11

1. Physical Mutagens
2. Chemical Mutagens
3. Biological Mutagens

Question 12

Physical Mutagens

Answer 12

• There’s physically strike the DNA and damage it
• Ex. Radiations (UV light)

Question 13

Chemical Mutagens

Answer 13

• These chemically damage/alter DNA
• Ex. Nicotine, Mercury

Question 14

Biological Mutagens

Answer 14

• Microscopic virus or bacteria that damage DNA
• Ex. HPV

Question 15

Carcinogens

Answer 15

• Mutagens that are known to cause cancer
• Way mutagens can be further classified

Question 16

Teratogen

Answer 16

• Mutagens that are known to cause birth defects (during fetal development)
• Way mutagens can be further classified

Question 17

Mutagen effects for multi-celled organisms that are already developed

Answer 17

Mutations tend to cause tumours in damaged tissue, which can then progress to cancerous tumours

Question 18

Mutagen effects for multi-celled organisms that are undeveloped

Answer 18

• Mutations may affect embryos/fetuses, which can eventually cause birth defects that will then show up in the offspring after birth
• They could also be good/positive mutations