Theme 2D Mutations Flashcards

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1
Q

What are mutations

A

Changes to nucleic acid sequence (DNA and RNA)

Primary force in evolution where natural selection favours beneficial mutations

More likely to be harmful than beneficial

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2
Q

What happens if the gene sequence is altered?

A

It can change the amino acid sequence of the polypeptide which result in variation of phenotype

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3
Q

If the gene sequence is altered, what can be the effect on the phenotype?

A

It can be harmlesss/neutral, harmful/deleterious, or beneficial/advantageous

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4
Q

What are germline mutations?

A

Mutations that originally occurred in gametes and are therefore heritable

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5
Q

Give an example of a germline mutation

A

A gender influence trait, so a dominant trait that is dependent on gender

example a man’s ring finger is bigger than his index finger

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6
Q

What are somatic mutations? What cells do they occur in

A

These mutations happen in all other cell types, other than gametes meaning, they are not heritable

Occurs in progenitor cells (cells that turn into other cells), and all other daughter cells will express the mutation

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7
Q

What are somatic mutations expressed as?

A

Sectors, so the size of mutation depends on the time of mutation

If the mutation occurs earlier, there’s more sectors of mutation and vise versa

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8
Q

Example of a somatic mutation

A

Cancer tumours

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9
Q

What are small scale mutations?
What are the types of small scale mutations?

A

Changes to one or a few base pairs
Base substitution
Insertion
Deletion
transitions
Tranvsersions

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10
Q

What is a base substitution mutation

A

A single nucleotide change as a result of a point mutation
Example C changes to T

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11
Q

What is an insertion mutation?

A

One or more base pairs, added to the sequence during DNA replication, which results in a frameshift mutation

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12
Q

What is a deletion mutation?

A

One or more base pairs, skipped during DNA replication, which result in a frameshift mutation

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13
Q

What is a transition mutation?

A

Purine to purine (a to g)
or pyrimidine to pyrimidine changes (c to t)

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14
Q

What is a transversion mutation?

A

Purine to pyrimidine (G to C)
Or pyrimidine to purine changes (C to A)

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15
Q

What is the effect of point mutations on the amino acid sequence of polypeptides?

A

You can get missense mutations, nonsense, mutation, silent mutations, or frameshift mutations

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16
Q

What is a missense mutation?

A

Non-synonymous
codon change cause a change in the amino acid

17
Q

What is a nonsense mutation?

A

A premature stop
The sense codon changes to a stop codon, resulting in a shorter polypeptide

18
Q

What is a silent mutation

A

Synonymous
Change in codon does not change the amino acid
Because of degeneracy of the genetic code

19
Q

What is a frameshift mutation?

A

Insertion or deletion of a small number of base pair that alters the open reading frame

20
Q

What is an example of a missense mutation

A

Sickle cell anemia

the beta haemoglobin gene has a sixth amino acid that changes from Glutamic acid to Valine.

This causes deficiency in oxygen exchange, clogs the arteries, and give circulatory problems.

21
Q

What are large scale, chromosomal mutations?

A

Deletion
Duplication/amplification
Translocation
Inversion

22
Q

What is a deletion?

A

Loss of many genes

23
Q

What is duplication/amplification

A

Increasing genes, so duplicating the region of the chromosome

24
Q

What is translocation

A

Switching genetic parts from nonhomologous chromosomes
So one chromosome has FGH the other has N, now the first chromosome has N and the other one has FGH

25
Q

What is inversion?

A

Reversing the orientation of a segment of the chromosome
So if it was EFG, that part is now GFE

26
Q

What is a spontaneous mutation?

A

A naturally occurring mutation, which is mainly caused by replication errors and spontaneous lesions

27
Q

What are spontaneous lesions

A

Depurinaton (losing a purine)
Deamination (CH or NH2 is removed so C changes to U)

28
Q

What are induced mutations. What are the different types

A

Natural or artificial agents or mutagents that causes mutations at higher rate than spontaneous mutation

Mutagens
Base analogs
Chemicals
Damage to bases

29
Q

What do mutagens do

A

Induce mutations by replacing a base, or altering a base so that it mispairs or damages another base where it can’t pair with any base

30
Q

What do base analogs do

A

Mimic bases and incorporates itself into DNA, which causes mispairing during DNA replication

31
Q

What do chemicals do during induced mutations

A

Alter the base structure and causes misparing

Ex. Alakylating agents that warp dna

32
Q

What cause damage to bases during induced mutations

A

UV light thymine dimers (bulky thymines)
Aflatoxin
B-apurinic sites (a and g disappear

33
Q

What is an allele

A

One of different forms of a gene (sequence variation) which can cause different phenotypes

34
Q

What are wildtype alleles

A

Normal form of a gene found in nature, or the standard laboratory strain of the organism

These allele are the frame of reference

35
Q

What are loss of function alleles

A

Mutations that reduces/eliminate, gene function or expression

36
Q

What are gain of function alleles?

A

Mutations that enhance gene function/expression or increase relative to wild type

Gene expressed greatly but in wrong places