Topic 6 - Gene mutation Flashcards
what is a mutation
a permanent change in the DNA of an organism
what are gametes
haploid sex cells produced by mitosis that fuse to form a diploid cell (zygote) in sexual reproduction
what are gene mutations
a change in one or a small number of nucleotides affecting a single gene
what is substitution
a type of gene mutation in which one base in a agene is substituted for another
what is deletion
a type of gene mutation in which a base is completely lost
what is insertion
a type of point mutation in which an extra base is added into a gene, which may be a repeat or a different base
what are chromosome mutations
changes in the position of entire genes within a chromosome
what are whole-chromosome mutations
the loss or duplication of a whole chromosome
what is the sickle cell disease
a human genetic disease affecting the protein chain making up the haemoglobin in the red blood cells
what is a mutagen
anything that increases the rate of mutation
when do mutations happen
when the gametes form, or during the division of body cells
what is the chance of mutations taking place during DNA replication
2.5 x 10^-8 per base
explain how the DNA repair system functions
specific enzymes cut out or repair part of the DNA strands that become damaged
how may mutations be an advantage
occasionally, a mutation occurs, producing a new, superior protein. This may help the organism gain a reproductive advantage, so producing more offspring than other individuals
which type of mutation is Down’s syndrome
whole-chromosome mutation
how does sickle cell disease affect the haemoglobins
the haemoglobin molecules stick together to form rigid rods that give the red blood cells a sickle shape. They do not carry oxygen very efficiently and block the smallest blood vessels
what could increase the rate of mutations
- X-rays
- ionising radiation
