Unit 1: Human Cells - Key Area 4 - Mutations

Question 1

What is a mutation?

Answer 1

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.

Question 2

Are mutations rare and random?

Answer 2

Yes

Question 3

What are mutations the only source of?

Answer 3

Mutations are the only source of new variation in populations.

Question 4

What can mutations be for an organism?

Answer 4

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

Question 5

What is a mutant?

Answer 5

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

Question 6

What are the two main types of mutation?

Answer 6

Gene and chromosome mutations.

Question 7

What do single gene mutations involve?

Answer 7

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.

Question 8

What are the three types of gene mutation?

Answer 8

Substitution, Insertion and Deletion.

Question 9

What are substitution mutations?

Answer 9

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

Question 10

What are insertion and deletion mutations?

Answer 10

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

Question 11

What results in frame-shift mutations?

Answer 11

Nucleotide Insertion and Deletion.

Question 12

What are the 3 types of substitution mutation?

Answer 12

Missense, Nonsense and Splice-Site.

Question 13

What are the 2 frame-shift mutations?

Answer 13

Insertion and Deletion.

Question 14

What is the description of a Missense mutation?

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

Sickle cell anaemia.

Question 17

What is the description of a Nonsense mutation?

Answer 17

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

Question 18

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

Answer 18

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

Question 19

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

Answer 19

Duchenne muscular dystrophy.

Question 20

What is the description of a Splice-Site mutation?

Answer 20

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.

Question 21

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

Answer 21

The protein does not function properly.

Question 22

What is an example of a condition caused by a

Splice-Site mutation?

Answer 22

Thalassemia

Question 23

What is the description of a Insertion mutation?

Answer 23

A nucleotide is added to the strand.

Question 24

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

Answer 24

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

Question 25

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

Answer 25

Tay Sachs

Question 26

What is the description of a Deletion mutation?

Answer 26

A nucleotide is removed/missing from the strand.

Question 27

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

Answer 27

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

Question 28

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

Answer 28

Cystic fibrosis

Question 29

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

Answer 29

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.

Question 30

What are gene mutations?

Answer 30

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

Question 31

What are chromosome mutations?

Answer 31

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

Question 32

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

Answer 32

The broken end of a chromosome is ‘sticky’.

Question 33

What are the 4 type of chromosome mutations?

Answer 33

Deletion, Duplication, Inversion and Translocation.

Question 34

What happens in a Deletion chromosome mutation?

Answer 34

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

Question 35

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

Answer 35

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

Question 36

What happens in an Inversion mutation?

Answer 36

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

Question 37

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

Answer 37

Hemophilia A

Question 38

What happens in a duplication mutation?

Answer 38

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

Question 39

What does a translocation mutation involve?

Answer 39

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.

Question 40

What is a homologous chromosome?

Answer 40

Genes in the same area/region/location.

Question 41

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

Answer 41

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).

Question 42

What are the 2 types of translocation mutation

Answer 42

Reciprocal and non - reciprocal.

Question 43

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

Answer 43

Charcot-Marie-Tooth

Question 44

Why are chromosome mutation so lethal?

Answer 44

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

Question 45

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

Answer 45

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.