Mutations Flashcards
What is a chrososme mutations
During meiosis parts of the chrosome break off and become reattached in the wrong place
What is translocation
part of the chromosome breaks off and rejoins to another completley diffrent chrososome
How can translocation be balanced
if part of 2 chrosomes swap
What is monosomy
the absence of one member of a pair of chromosomes
What is polysomy
when a cell contains 3 or more rather than 2 chrosomes of a particualr type
What is aneuploidy
When a cell contains too few or too many chromosomes
What is a non disjunction mutation
when chromosomes fail to separate during meiosis. Resulting in one gamete with 2 copies of a chromosome and a one gamete with no copies of that chromosome
How can mutations be increased
ionising radiation is know ti increase mutation rate
Certain chemicals also increase the rate of mutation (mutagens)
The rate of non disjunction increases with the age of the parents
What are mutagens
are chemicals known to increase the rate of mutation
How does polysomy occur
if there is a non disjuntion of chrosome 21 in a ovum or sperm :
- one the gametes will contain two copies of the chromosome
- After fertilisation with a normal gamete the resulting zygote will have polysomy (3 copies of the chorsomoe)
How does monosomy occur?
monosomy comes about due to unsuccessful separation of a pair of chromosomes during the process of meiosis
How do Down syndrome occur?
Non dis junction of chromosome 21 in an ovum or sperm leads to 2 copies of the chromosome.
- After fertilisation with a normal gamete the zygote will have 3 copies of the chromosome 21
What is a monosomy
non dis junction of the sex chromosome leads to various conditions this is because their a missing X chromosome (XO)
What is a non disjunction chromosome
Homologous chromosomes fail to separate during anaphase 1 or sometimes the sister chromatids fail to seperate
Gametes may end up with an extra chromosome or none at all
