19 - Genetics Of Living Systems

Question 1

Define a mutation

Answer 1

A change in the sequences of bases in DNA

Question 2

What causes the change in sequence in a mutation?

Answer 2

Deletion, substitution or insertion

Question 3

What is it called if only one nucleotide is affected by a mutation?

Answer 3

A point mutation

Question 4

The substitution of a single nucleotide causes what to occur?

Answer 4

Changes the codon, so a new a.a. is coded, changing the 1Y of the protein

Question 5

How can substitution not actually affect the protein?

Answer 5

Due to degenerate nature of code, the new codon may still code for the same a.a.

Question 6

What does the insertion or deletion of a nucleotide(s) cause!

Answer 6

Frameshift mutation

Question 7

What is the reading frame of a sequence of bases?

Answer 7

The triplet code that transcribes consecutively in non-overlapping groups of 3

Question 8

How many bases equals an amino acid?

Answer 8

3 bases

Question 9

What does the addition or deletion of nucleoside do!

Answer 9

Shifts the reading frame of the sequence of bases, changing every successive codon from the point of mutation

Question 10

In what circumstance would the reading frame not be changed in addition or deletion?

Answer 10

If the multiples of 3 correspond to fill codons

Question 11

What does it mean if a mutation has no effect?

Answer 11

The phenotype isn’t changed and normal functioning proteins are synthesised

Question 12

What does it mean if a mutation is damaging?

Answer 12

The phenotype of an organism is affected in a negative way which can interfere with essential processes

Question 13

What does it mean if a mutation is beneficial?

Answer 13

The mutation provides a useful characteristic to improve survival

Question 14

What is a mutagen?

Answer 14

A chemical, physical, or biological agent which causes mutations

Question 15

How are mutations described?

Answer 15

As spontaneous

Question 16

What does the mutation of an absence of a base lead to?

Answer 16

The insertion of an incorrect base through complementary base pairing during DNA replication

Question 17

What are free radicals?

Answer 17

Oxidising agents

Question 18

What can free radicals do to nucleotides?

Answer 18

Affect their structure and disrupt base pairing

Question 19

Why are antioxidants known as anti carcinogenic?

Answer 19

Due to their ability to negate the effects of free radicals

Question 20

What are silent mutations?

Answer 20

They have no effect on the phenotype of an organism

Question 21

What are nonsense mutations?

Answer 21

These reused in a codon becoming a STOP codon instead of an amino acod

Question 22

What are missense mutations?

Answer 22

This results in the incorrect amino acid in the 1Y

Question 23

Beneficial Mutations

Where is the ability to digest lactose most commonly found?

Answer 23

In European populations who are more likely to farm cattle

Question 24

Beneficial Mutations

The majority of mammals become lactose intolerant after they what?

Answer 24

Cease to suckle

Question 25

Where do gene mutations occur?

Answer 25

In single genes or sections of DNA

Question 26

Where do chromosome mutations affect?

Answer 26

The whole chromosome or number of chromosomes in a cell

Question 27

What normally causes chromosome mutations?

Answer 27

Caused by mutagens normally in meiosis

Question 28

Chromosome mutations

How does deletion change chromosome structure?

Answer 28

Section of chromosomes breaks off and is lost

Question 29

Chromosome mutations

How does duplication affect?

Answer 29

Sections get duplicated on a chromosome

Question 30

Chromosome mutations

How does translocation affect chromosome structure?

Answer 30

A section of one chromosome breaks off and joins another non-homologous chromosome

Question 31

Chromosome mutations

How does inversion affect the chromosome structure?

Answer 31

A section breaks off, is reversed, and joins back onto the chromosome