Genomic Evolution Flashcards
What percentage of people will suffer from a genetic based disease in their lifetime?
30%
What are 2 types of genetic disease?
Chromosomal abnormalities
Single gene disorders
What is the name given to non sex chromosomes?
Autosomes
How many pairs of chromosomes?
23
What can induce a chromosomal abnormality?
Radiation, Chemicals
Errors in replication eg Gaining or loosing a single chromosome
What is Downs/ Trisomy 21 examples of?
Trisomy- grain of chromosome to diploid chromosomes
What is monosomy?
Loss of a single chromosome
Not tolerated in mammals
When was down syndrome discovered and by who?
1966 John Downs
What is the type of partial monomy that humans can have?
Cri-Du-Chat syndrome
Severe mental retardation
Physical abnormalities
How common is Cri-Du-Chat?
1/50,000 infants
What factor in mothers is linked to downs?
Age
The older the mother the higher the chance of Downs
Name the 2 types of mutation
1) point mutation
2) insertion/ deletion mutation
Define transversion
a point mutation in DNA in which a single (two ring) purine (A or G) is changed for a (one ring) pyrimidine (T or C), or vice versa.
Name 3 types of spontaneous Insertion/deletion mutations
Replication errors
Tautomerizations
Deamination
Name 3 types of induced Insertion/deletion mutations
Radiation UV
Intercalating agents
base analogues
How common are replication errors?
And do they get repaired?
Wrong pair introduced every 10^10 base pairs
Good chance it will be repaired
Define tautomeric Shift
Interconverted forms of DNA bases
Name 2 examples of tautomeric shift
Amino group of A or C ( NH2) Imino group (NH)
Keto group of G or T ( C+O) Enol group (C-OH)
What is deamination?
Loss of amino group
What causes induced mutations
Chemical ( broken bonds and bases chemically altered) or Physical ( Radiation, X rays, UV)
What are intercalating elements?
Insert themselves between bases
Name an example of a intercalating agent?
Ethidium bromide
What are base analogues?
Incorporated into DNA
More prone to tautomeric shifts
Name an example of a base analogue
Bromouracil - T analogue
What classifies single gene defects?
X-linked if on X chromosome
Autosomal if on autosome
Cystic Fibrosis is autosomal recessive.
What causes this?
caused by a defective CFTR gene ( cystic fibrosis transmembrane conductance regulator)
CFTR encodes a Cl- ion transporter
Name an example of a autosomal dominant gene
Huntington’s disease
progressive neurological degenerative disease
Inherited breast cancer accounts for how many of all breast cancer cases?
What gene is mutated?
5%
Mutation sin BRACA 1 or BRACA 2
Name an example of a X-linked disease?
Hemophillia
What techniques are used to obtain a DNA sample from a fetus and at what weeks?
Amnicentisis - 12th week +
Chorinic Villus Sampling - 8/12th week
In vitro fertilisation how can they test the gender before it develops?
PGD
Pre-implantation genetic diagnosis
Name the 3 advantages to PGD
detects ~ 100 genetic disorders
Increases success rate of IVF
Gives a choice to the couples
How do we get DNA samples from adults?
Blood Sample
Skin biopsy
What stain is used to visual chromosome in a light microscope?
Giemsa Stain
