Mutations

Question 1

What is a mutation?

Answer 1

Heritable alteration in gene or chromosome
and
the process that produces the alteration

Question 2

What are the types of causes of mutations?

Answer 2

Exogenous causes

Endogenous causes

Question 3

What are the types of exogenous causes of mutations?

Answer 3

Ionising radiation

Chemicals

Anti-cancer agents

Question 4

What are the types of endogenous causes of mutations?

Answer 4

DNA replication defects

Transposable elements

Question 5

How are mutations caused?

Answer 5

DNA damage

and then defective DNA repair

Question 6

What are transposable elements?

Answer 6

Sections of DNA that can move as one unit to random sites in rest of DNA

Question 7

Are transposable elements longer or shorter than genes?

Answer 7

Longer than genes

Question 8

Do transposable elements exist in the free form?

Answer 8

No

they’re always contained in DNA molecules

Question 9

Are transoposable elements more likely to move into longer genes or shorter genes?

Answer 9

More chance of them moving into longer genes

Question 10

How can transposable elements cause mutations?

Answer 10

Can transpose into genes
disrupt gene
product product is dysfunctional

Can transpose into promoter region of gene
activate gene when it shouldn’t be

Question 11

How can transposable elements have no effect?

Answer 11

If transpose into non-coding sections of DNA

or introns

Question 12

What are the types of mutations?

Answer 12

Micro

Macro

Question 13

What is the difference between micro and macro mutations?

Answer 13

Micro - few bases affeced

Macro - whole areas of chromosomes affected

Question 14

What are the types of micro mutations?

Answer 14

Substitution

Insertion

Deletion

Question 15

What are the types of macro mutations?

Answer 15

Translocation

Inversion

Duplication

Deletion

Question 16

What are the types of substitution mutations?

Answer 16

Transition/transversion

Mis-sense/nonsense/silent/non-stop

Question 17

What is a transition substitution mutation?

Answer 17

Base change to same type of base

• purine to purine
• pyrmidine to pyrimidine

Question 18

What is a transversion substitution mutation?

Answer 18

Base change to different type of base

• purine to pyrimidine
• pyrimidine to purine

Question 19

What is a mis-sense substitution mutation?

Answer 19

Causes change in amino acid in protein

Question 20

How does a mis-sense substitution mutation affect the polypeptide?

Answer 20

Changes conformation of polypeptide

Question 21

What is a non-sense substitution mutation?

Answer 21

Creates early stop codon

Question 22

How does a non-sense substitution mutation affect the polypeptide?

Answer 22

Polypeptide production stopped prematurely

polypeptide is shorter length

Question 23

What is a silent substitution mutation?

Answer 23

Same amino acid coded for

Question 24

How does a silent substitution mutation affect the polypeptide?

Answer 24

Has no effect on it

Question 25

What is a non-stop substitution mutation?

Answer 25

Stop codon now codes for an amino acid

Question 26

How does a non-stop substitution mutation affect the polypeptide?

Answer 26

Polypeptide production carries on | longer polypeptide produced

Question 27

What is an insertion mutation?

Answer 27

Addition of a few extra nucleotides into DNA strand

Question 28

What is a deletion mutation?

Answer 28

Removal of a few nucleotides from DNA strand

Question 29

What do insertons/deletions commonly lead to?

Answer 29

Frameshift

Question 30

How can insertions/deletions lead to frameshifts?

Answer 30

Insertion/deletion of 1/2/4/5/7/8 etc. bases

Question 31

What is a frameshift?

Answer 31

Downstream bases shift to right or left | gives different codons

Question 32

How do frameshifts affect the polypeptide? Why?

Answer 32

Different conformation due to different amino acid Short, longer polypeptide due to early, later stop codon

Question 33

How can insertions/deletions not lead to frameshifts?

Answer 33

Insertion/deletion of 3/6/9 etc. bases

Question 34

Why do insertions/deletions of 3/6/9 etc. bases not lead to frameshifts?

Answer 34

Add or remove codons | but rest of codons remain the same

Question 35

How does an insertion/deletion of 3/6/9 etc. bases affect the polypeptide?

Answer 35

Different conformation due to extra or missing amino acids

Question 36

What are the types of translocations?

Answer 36

Reciprocal Robertsonian

Question 37

What is an inversion?

Answer 37

Section of chromosome flipping over

Question 38

What is a duplication?

Answer 38

Section of chromosome copying itself

Question 39

What is a macro deleton?

Answer 39

Section of chromosome being lost

Question 40

How can mutations affect transcription?

Answer 40

Alter promoter activity Alter mRNA splicing

Question 41

How can mutations affect translation?

Answer 41

Alter translation initiation

Question 42

What are the consequences of mutations affecting transcription, translation?

Answer 42

Change amount of produced

Question 43

How can mutations affect promoter activity of genes?

Answer 43

Affect binding of transcription factors, RNA polymerase

Question 44

How can mutations affect mRNA splicing?

Answer 44

Alter intron-exon junction | affecting recognition by spliceosome

Question 45

How can mutations affect translation inititation?

Answer 45

Affect start codon AUG | recruitment of methionyl tRNA, ribosome