Unit 1: Human Cells - Key Area 4 - Mutations Flashcards

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1
Q

What is a mutation?

A

Mutations are changes in the DNA, either in a gene or a chromosome, that can result in no protein at all or an altered protein being synthesised. this change in DNA can result in genetic disorders.

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2
Q

Are mutations rare and random?

A

Yes

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3
Q

What are mutations the only source of?

A

Mutations are the only source of new variation in populations.

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4
Q

What can mutations be for an organism?

A

Sometimes a mutation can be useful but many mutations have a harmful and lethal effect on an organism,

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5
Q

What is a mutant?

A

An organism which has been effected by and is the result of a mutation.

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6
Q

What are the two main types of mutation?

A

Gene and chromosome mutations.

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7
Q

What do single gene mutations involve?

A

A single gene mutation involves a change in the number or sequence of bases in a gene.
or
Single gene mutations involve the alteration of a DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides.

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8
Q

What are the three types of gene mutation?

A

Substitution, Insertion and Deletion.

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9
Q

What are substitution mutations?

A

Substitution mutations are point mutations and involve ONE base being exchanged for another. THEY WILL ONLY EFFECT ONE CODON.

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10
Q

What are insertion and deletion mutations?

A

Insertion and deletion are frame-shift mutations and effect every single codon after the mutation. This involves whole sections of DNA being misread.

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11
Q

What results in frame-shift mutations?

A

Nucleotide Insertion and Deletion.

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12
Q

What are the 3 types of substitution mutation?

A

Missense, Nonsense and Splice-Site.

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13
Q

What are the 2 frame-shift mutations?

A

Insertion and Deletion.

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14
Q

What is the description of a Missense mutation?

A

A type of substitution mutation which changes the codon for an amino acid so that a different amino acid is inserted into the protein.

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15
Q

What is the effect on the protein from a Missense mutation?

A

Different amino acid is inserted into the protein meaning a different protein is produced.

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16
Q

What is an example of a condition caused by a Missense mutation?

A

Sickle cell anaemia.

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17
Q

What is the description of a Nonsense mutation?

A

A mutation which results in a codon for a specific amino acid being changed to a stop codon.

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18
Q

What is the effect on the protein from a Nonsense mutation?

A

It causes the protein to be stopped prematurely and a shorter protein being produced.

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19
Q

What is an example of a condition caused by a Nonsense mutation?

A

Duchenne muscular dystrophy.

20
Q

What is the description of a Splice-Site mutation?

A

Mutations in the area that makes the start or end of an intron, may lead to one or more introns not being removed. This will lead to the creation of a protein that does not function properly.

21
Q

What is the effect on the protein from a Splice-Site mutation?

A

The protein does not function properly.

22
Q

What is an example of a condition caused by a

Splice-Site mutation?

A

Thalassemia

23
Q

What is the description of a Insertion mutation?

A

A nucleotide is added to the strand.

24
Q

What is the effect on the protein from a Insertion mutation?

A

Every amino acid after the mutation is affected so the protein is usually non-functional.

25
Q

What is an example of a condition caused by an Insertion mutation?

A

Tay Sachs

26
Q

What is the description of a Deletion mutation?

A

A nucleotide is removed/missing from the strand.

27
Q

What is the effect on the protein from a Deletion mutation?

A

Every amino acid after the mutation is affected so the protein is usually non-functional.

28
Q

What is an example of a condition caused by an Deletion mutation?

A

Cystic fibrosis

29
Q

Why do insertion and deletion tend to have a greater effect on the protein produced than substitution mutations?

A

Every amino acid after the mutation is effected in Insertion and Deletion so the protein is usually non-functional which can be lethal, rather than just one codon being changed in substitution which has less effect.

30
Q

What are gene mutations?

A

Gene mutations are a change in the number or sequence of nucleotides/bases in a gene.

31
Q

What are chromosome mutations?

A

Chromosome mutations are a change in the number or sequence of genes in a chromosome.

32
Q

Why can the broken end of a chromosome join to another broken end?

A

The broken end of a chromosome is ‘sticky’.

33
Q

What are the 4 type of chromosome mutations?

A

Deletion, Duplication, Inversion and Translocation.

34
Q

What happens in a Deletion chromosome mutation?

A

In a deletion chromosome mutation one or more genes are removed from the chromosome, resulting in the chromosome being shorter.

35
Q

What is an example of a deletion chromosome mutation and how is this caused?

A

An example of a chromosome deletion mutation is Cri-Du-Chat.

36
Q

What happens in an Inversion mutation?

A

Part of the chromosome is flipped over/reversed/re-orientated (different order)and put back into the chromosome.

37
Q

What is an example of a condition caused by an Inversion mutation?

A

Hemophilia A

38
Q

What happens in a duplication mutation?

A

One or more genes are copied/replicated and inserted into the same part of the chromosome. (Repeated within the chromosome).

39
Q

What does a translocation mutation involve?

A

A translocation mutation involves a section of a chromosome breaking off and becoming attached to another chromosome (not its matching/homologous partner). These can be RECIPROCAL or NON - RECIPROCAL.

40
Q

What is a homologous chromosome?

A

Genes in the same area/region/location.

41
Q

What is the difference between reciprocal and non - reciprocal translocation mutations?

A

In reciprocal translocation mutations a section of chromosome breaks of two different chromosome and they switch/ swap places but don’t go to their homologous partners, whereas in non - reciprocal translocation mutations a section of chromosome breaks off one of the chromosomes and attaches to a non - homologous partner but no chromosome is received/ broken off the chromosome which received the chromosome( they are are not shared only one gives part of the chromosome away).

42
Q

What are the 2 types of translocation mutation

A

Reciprocal and non - reciprocal.

43
Q

What is an example of a condition caused by a Duplication mutation?

A

Charcot-Marie-Tooth

44
Q

Why are chromosome mutation so lethal?

A

Chromosome mutations are so lethal as they often involve such a substantial change to the chromosomes structure.

45
Q

What is an example of a condition caused by a translocational mutation and what genes are translocated?

A

Chronic Myeloid Leukaemia. It results from the translocation of genes on chromosome 9 and 22.

Familial Down’s Syndrome. This results from the translocation of chromosome 21 into 14.