Inheritance of disease L5 Flashcards
when are chromosomes best scene
metaphase
female=
XX
male=
XY
down’s syndrome=
extra 21
germ cells are
haploid
in meiosis what is the overall change
cell go from diploid to haploid
have many divisions in meiosis
2
how many cells produced in meiosis
4 haploid cells
what happens in meiosis 1
pairs of homologous chromosomes form tetrads
members of each homologous pair separate –> 2 haploid cells
what happens in meiosis 2
2 cells divide like in mitosis and form 4 genetically different haploid cells
what can happens in meiosis 1 to create genetic diversity
recombination
what is recombination
crossing over of chromatid arms within the tetrad to produce a new combination of genes
somatic gene mutation
only effect that individual
germline mutation
in all cells including germ cells can be inherited and passed on
types of mutation (4)
missense
nonsense
frameshift
repeat expansion
missense mutation=
change in one DNA base pair
nonsense mutation=
a change in one DNA base pair causes a stop signal to be produced
e.g of frameshift mutations
deletion mutation
insertion mutation
insertion mutation=
changes the number of DNA pieces by adding a piece
deletion
removes a piece of DNA
genetic polymorphism=
2 or more varients of an allele
what is a single nucleotide polymorphism
change in 1 base
restriction fragment length polymorphism
restriction enzymes recognise a specific DNA sequence to cut
short tandem repeats also called
microsatelites
what are short tandem repeats mainly made out of
introns
what can polymorphism be used for
genetic markers, genetic fingerprinting
