Lecture 27 Flashcards
What is PCR? What is it used for? (don’t include process)
- polymerase chain reaction
- used to copy specific regions of DNA
What is the process of PCR?
- identify target sequence, make appropriate small primers
- primers bond to each strand
- add lots of primer, DNA pol, nucleotides, H2O, salt
- heat up to melt/break apart DNA
- lower temp, primers added
- increase temp, DNA pol adds nucleotides, goes until falls off or reaches end
- repeat 30 times, results in billions of copies of target sequence
What is gel electrophoresis used for? What do the results mean?
Separates PCR products by size.
Smaller DNA strands travel further in gel
2 bands = heterozygous
1 band = homozygous
How does the pre-implantation genetic diagnosis of IVF embryos work?
- one cell removed (ok as not specialized)
- PCR used to get more of the genome and see if present
- can also see if carrier
What are the main issues with pre-implantation genetic diagnosis of IVF embryos using PCR?
- only for IVF
- lots of risks, expensive
What is Amniocentesis?
Genetic screening from amniontic fluid
What is cell-free DNA used in PCR? Where is it found?
- DNA from child in mother’s plasma
- from dying placental cells
- makes up 10% of mother’s plasma
- found as mother had Y chromosome in plasma
What is chorionic
villus sampling?
Genetic screening from placenta
Why might it be better to use cell-free DNA for PCR for the pre-implantation genetic diagnosis of IVF embryos?
Less invasive and less risks.
Why can fetal cell-free DNA be isolated?
Is shorter compared to maternal cell-free DNA
Why are 3 parent babies flawed?
- some mitochondrial DNA transferred
- that % can increase over time
- leads to 1 in 5 having mitochondrial disease
If a mother has a genetic disease in her mitochondrial DNA, what % of her children will have the same condition?
100%
