AQA A Level Biology - Topic 8A:
Mutations and Gene Expression Exam
Q’s and A’s
What are mutations? - -Any change to the base nucleotide sequence of DNA.
- How can mutations be caused? - -Errors during DNA replication and
mutagens.
- what are mutagenic agent - -they increase the rate at which mutations
occur
- what are the 6 types of muttion - -- addition
substitution
duplication
deletion
inversion
translocation
- What is a substitution mutation? - -One or more bases are swapped for
another.
eg. ATGCCT becomes ATTCCT
- What is a deletion mutation? - -One or more bases are removed.
eg. ATGCCT becomes ATCCT
- What is a addition mutation? - -One or more bases are added.
eg. ATGCCT becomes ATGACCT
- What is a duplication mutation? - -When one or more bases are repeated
- What is a translocation mutation? - -A sequence of bases is moved from
one location in the genome to another. This could be movement within the
same chromosome or movement to a different chromosome.
- Why would a mutation affect the function/production of a protein? - -The
order of DNA bases determines the sequence of amino acids in a
polypeptide. If a mutation occurs, the sequence of amino acids in the
polypeptide that it codes for could be changed.
Polypeptides make up proteins, so if there is a change in the AA sequence, it
may change the final 3D shape of the protein causing it to not function
properly.
, - What are genetic disorders? - -An inherited disorder cause by abnormal
genes or chromosomes eg. cystic fibrosis.
- What are hereditary mutations and how do they occur? - -Occur if a
gamete containing a mutation for a type of cancer or genetic disorder is
fertilised, causing the mutation to be present in the fetus.
Mutations passed on to the offspring.
- What does the degenerate code mean? - -Some amino acids are coded for
by more than one DNA triplet.
- Why do not all mutations affect the order of amino acids? - -Because of
the degenerate nature of the genetic code. Not all types of mutation will
always result in a change to the amino acid sequence.
- What is it called when a mutation doesn't cause a change in the amino
acid sequence? - -Silent mutation.
- What is cystic fibrosis? - -A genetic disorder of the cell membranes,
resulting in the body producing a lot of thick, sticky mucus in air passages
and the pancreas.
- What is a frameshift mutation? - -A mutation that results in a misreading
of all following nucleotides.
Additions, duplications and deletions will almost always change the amino
acid sequence of a polypeptide because these mutations cause a change in
the number of bases in the DNA code.
- What are mutagenic agents? - -Outside factors that increase the rate of
mutations.
- What are examples of mutagenic agents? - -UV radiation, ionising
radiation, some chemicals and some viruses.
- what is the ame of the chemicalmutagenic agent whhich acts as a base - -
base analogs
- What are 3 ways mutagenic agents can increase mutation rate? - -1.
Acting as a base - chemicals known as base analogs can substitute for a
base during DNA replication (changing base sequence of new DNA).
2. Altering bases - some chemicals can delete or alter bases.
3. Changing structure of DNA - some types of radiation can change the
structure of DNA, which causes problems during DNA replication.
- What are acquired mutations? - -Mutations that occur in individual cells
after fertilisation.
Mutations and Gene Expression Exam
Q’s and A’s
What are mutations? - -Any change to the base nucleotide sequence of DNA.
- How can mutations be caused? - -Errors during DNA replication and
mutagens.
- what are mutagenic agent - -they increase the rate at which mutations
occur
- what are the 6 types of muttion - -- addition
substitution
duplication
deletion
inversion
translocation
- What is a substitution mutation? - -One or more bases are swapped for
another.
eg. ATGCCT becomes ATTCCT
- What is a deletion mutation? - -One or more bases are removed.
eg. ATGCCT becomes ATCCT
- What is a addition mutation? - -One or more bases are added.
eg. ATGCCT becomes ATGACCT
- What is a duplication mutation? - -When one or more bases are repeated
- What is a translocation mutation? - -A sequence of bases is moved from
one location in the genome to another. This could be movement within the
same chromosome or movement to a different chromosome.
- Why would a mutation affect the function/production of a protein? - -The
order of DNA bases determines the sequence of amino acids in a
polypeptide. If a mutation occurs, the sequence of amino acids in the
polypeptide that it codes for could be changed.
Polypeptides make up proteins, so if there is a change in the AA sequence, it
may change the final 3D shape of the protein causing it to not function
properly.
, - What are genetic disorders? - -An inherited disorder cause by abnormal
genes or chromosomes eg. cystic fibrosis.
- What are hereditary mutations and how do they occur? - -Occur if a
gamete containing a mutation for a type of cancer or genetic disorder is
fertilised, causing the mutation to be present in the fetus.
Mutations passed on to the offspring.
- What does the degenerate code mean? - -Some amino acids are coded for
by more than one DNA triplet.
- Why do not all mutations affect the order of amino acids? - -Because of
the degenerate nature of the genetic code. Not all types of mutation will
always result in a change to the amino acid sequence.
- What is it called when a mutation doesn't cause a change in the amino
acid sequence? - -Silent mutation.
- What is cystic fibrosis? - -A genetic disorder of the cell membranes,
resulting in the body producing a lot of thick, sticky mucus in air passages
and the pancreas.
- What is a frameshift mutation? - -A mutation that results in a misreading
of all following nucleotides.
Additions, duplications and deletions will almost always change the amino
acid sequence of a polypeptide because these mutations cause a change in
the number of bases in the DNA code.
- What are mutagenic agents? - -Outside factors that increase the rate of
mutations.
- What are examples of mutagenic agents? - -UV radiation, ionising
radiation, some chemicals and some viruses.
- what is the ame of the chemicalmutagenic agent whhich acts as a base - -
base analogs
- What are 3 ways mutagenic agents can increase mutation rate? - -1.
Acting as a base - chemicals known as base analogs can substitute for a
base during DNA replication (changing base sequence of new DNA).
2. Altering bases - some chemicals can delete or alter bases.
3. Changing structure of DNA - some types of radiation can change the
structure of DNA, which causes problems during DNA replication.
- What are acquired mutations? - -Mutations that occur in individual cells
after fertilisation.
