3.4 Topic 4 - 3.4.3 Genetic diversity can arise as a result of mutation or during meiosis Flashcards
mutation definition
a change to the quantity or the base sequence of DNA of an organism.
when can mutations occur?
they occur during the formation of gametes.
gene mutation defintion
any change to one or more nucleotide bases, or a change in the sequence of the bases.
when can gene mutations occur?
they can arise spontaneously during DNA replication and include base substitution and base detection.
what is the type of gene mutation in which a nucleotide in a DNA molecule is replaced by another nucleotide that has a different base?
substitution mutation.
what is the type of gene mutation in which a nucleotide is lost from the normal DNA sequence?
deletion mutation.
what is a chromosome mutation?
changes in the structure or number of whole chromosomes.
how can chromosome mutations arise?
spontaneously.
when do changes in whole sets of chromosomes occur?
when organisms have three or more sets of chromosomes rather than the usual two. This condition is called polyploidy and occurs mostly in plants.
what does non-disjunction mean?
when individual homologous pairs of chromosomes fail to separate during meiosis, this can lead to changes in the number of individual chromosomes and results in a gamete having either one more or one fewer chromosome.
what is an example of a non-disjunction in humans?
down’s syndrome, this is where individuals have an additional chromosome 21.
what are the two ways cells divide?
by mitosis or meiosis.
what does mitosis produce?
two daughter cells with the same number of chromosome as the parent cell and as each other.
what does meiosis produce?
four daughter cells, each with half the number of chromosomes as the parent cell.
do gametes have a diploid or haploid number of chromosomes?
diploid.
