Mutations

Question 1

What is a mutation?

Mutations

Answer 1

Permanent alteration of DNA base sequence, chnaging base of genome or org/viru/extrachromosomal DNA

Question 2

What is a mutagen?

Answer 2

Agent or substance bring about permanent change to physical compositon of gene

Question 3

What is the result of an altered gene?

4 points

Answer 3

transcribed mRNA will carry an altered message
-polypeptide contains different amino acid sequence, structure
- different resultant protein
-function is lost or changed

Question 4

General effects of mutations

3 marks

Answer 4

Harmful: death of org
Neutral: no effect of mutations
Beneficial: competitive advantage

Question 5

Explain Chemical mutations using the following characteristics: Mimic, remove, add

Answer 5

• Mimic correct nucbases fail to base pair in DNA replication
• Remove part of nucl causeing improper pairing
• Add hydrocarbon groups to nucl cause incorrect base pairing

Question 6

Radiation process and its effects

Answer 6

High energy radiation from radiactive material/ x-rays absorbed by atoms in water molecules in DNA
- trabsferred energy flies away from atoms
- dangerous free and radioactive radical attacksand alters DNA

Question 7

Types of Gene mutations

3

Answer 7

Point
Frameshift
Substitution

Question 8

Point Mutattion

Explain point mutation

Answer 8

Cell’s genetic material is added, deleted orchanged
Either no effect or alteration

Question 9

Point

Types of substitution

3

Answer 9

Nonsense
Missense
Silent

Question 10

Substitution

Substitution

Answer 10

-One or more base subbed for another
-particular point changed

Question 11

Substitution

Nonsense mutation

3

Answer 11

substitution of nucleotide leading to formation of stop codon
Stop codon found end of mRNA sequence, if mutated correct protein wont be produced

Question 12

Substitution

Missense

2

Answer 12

Nucl subbed and diff codon formed, NOT a stop codon
Produces diff amino acid

Question 13

Substitution - Missense

Conservative vs non conservative

2

Answer 13

C: aa formed via mutation similar properties to one supposed to be formed
NC: ac diff properties that affect structure & function

Question 14

Substitution

Silent

2

Answer 14

Nucl subbed but same amac is produced
Multiple codons code for same amac

Question 15

Frameshift mutation

Answer 15

insertion or deletion invloving base pairs not multiple of three
Disrupts triplet reading frame
Abnormal protein products

Question 16

effects of frameshift (1 vs 3)

Answer 16

One nucl deleted: all codonshave disrupted reading = many incorrect amac in protein
3 nucl insert/delete: no shift in codon reading

Question 17

Effects of frameshift

Answer 17

• cause large scale changes to polypeptide length & chem composition
• premature translation of mRNA & extended polypeptide
• cystic fibrosis and cancer forms
• protective effects: resistance to HIV

Question 18

Deletion:

Answer 18

Loss of one sequence of bases
amac is changed making a diff protein