Genetics Flashcards
How many chromosomes does a normal cell have
46 chromosomes
23 pairs
22 autosomal pairs +XY
What are acrocentric chromosomes
They have no short arm
What are chromosomes made up of
Long arm
Short arm
Centromere
Temomeres on either end
What is a balanced mutation
All chromosomal info still present
What is an unbalance mutation
Extra/missing material after mutation
What is aneuploidy
When there is a WHOLE extra or WHOLE missing chromosome
What is Down syndrome
Trisomony of chromosome 21
An extra chromosome 21
What is a robertsonian translocation
Two acrocentric chromosomes (no short arm) going together
Edwards syndrome
Trisomy of chromosome 18
What is Turner syndrome
“turn her into a man”
Only one X chromosome
45 chromosomes
Triple X syndrome
Woman has 47 chromosomes
3 X chromosomes
What is diGeorge syndrome
Missing genes in chromosome 22
Distinct clinical features
PCR stages
heated to 100 degrees denatures DNA
cooled to 50 degrees to allow primers to bind
Heated to 72 degrees which is optimum temp for tax polymerase
What is an SNP
Single nucleotide polymorphism
What is a polymorphism
Any genetic variation that doesn’t cause disease in its own right
However may predispose to disease
What is DNA methylation
Methyl bound to DNA to prevent transcription
Can cause gene silencing
What is imprinting
Differences in gene expression depending on whether the gene was maternally or paternally inherited
Other gene is silenced by methylation
Mitochondrial inherited disease
Maternally inherited
Heteroplasmy - different daughter cells contain different proportions of mutant mitochondria - can’t know severity
What is somatic mosaicism mutation inheritance
One cell is mutated and all subsequent cells produced from this cell have mutation
Mitosis stages
IPMAT Prophase Metaphase Anaphase Telophase Interphase
Cell cycle stages
G1- growth
S - DNA replication and growth
G2- growth
M- check point then mitosis (IPMAT)
What direction does DNA polymerase work in
5’ to 3’
Introns contain genetic info true/false
False
Exons contain genetic info
Introns spliced out
What is knudson’s two hit hypothesis
Cancer as a result of two hits
1st hit = genetic predisposition
2nd hit = acquired risk factors
What ways can DNA be repaired
Cell cycle checkpoints
Mismatch repair complex
What is symptomatic testing
Testing to find cause of disease
What is pre-symptomatic testing
relative has known mutation
Testing for mutation without patient having symptoms
