Genetic diversity due to mutation (9) Flashcards
What is meant by mutation?
alteration to DNA sequence
What are 2 reasons why mutation may not lead to a change in the amino acid sequence?
- genetic code is degenerate so mutation may end up coding for same amino acid as original triplet
- mutation may occur in intron
What is a mutagenic agent?
factor that increases rate of gene mutation
What is meant by chromosome non-disjunction?
when chromosomes fail to separate correctly in meiosis, resulting in gametes with 1 more or 1 less chromosome than normal
What is meant by a quiet mutation?
when mutation causes no change to amino acid sequence
What does it mean if a mutation is harmful and significant?
entire amino acid sequence will be different due to mutation causing a frameshift
What is meant by a polyploidy chromosome mutation?
where an individual has 3 or more sets of chromosomes instead of 2
What type of mutation causes an individual to have 3 or more sets of chromosomes instead of 2?
polyploidy chromosome mutation
What is meant by meiosis?
a form of cell division that produces 4 genetically different haploid cells known as gametes
What is a haploid cell?
cell with half the number of chromosomes found in the parent cell
What is meant by mitosis?
a form of cell division that produces 2 genetically identical cells with same number of chromosomes as parent cells
Draw a diagram showing the 3 stages of meiosis.
Look at diagram in notes.
What are the 3 steps of the first meiosis stage?
1) homologous chromosomes pair to form bivalents
2) crossing over occurs at chiasmata
3) cell divides into 2 and homologous chromosome separate randomly with each cell containing either the maternal or paternal copy of a chromosome
What is crossing over?
exchanging of sections of genetic material
What are the 2 steps that occur in the second stage of meisosis?
1) independent segregation of sister chromatids
2) each cell divides again, producing 4 haploid cells
