Genetics: principles, variants, mutations & cancer Flashcards
how many chromosomes do we have(normally)
46 XX/XY
22Ch, 2 copies of each + 2 sex chromosomes
briefly describe mitosis
diploid parent, 2 diploid daughters
briefly describe meiosis and crossing over
diploid parent, 4 haploid daughters
Crossing over - 2 chromosomes of a homologous pair exchange equal segments with each other
what is the central dogma
DNA=> premature mRNA=(spliced)> mature mRNA =(translation+ post translational modification)> protein
what is the central dogma affected by
transcription rate, splicing + polypeptide processing, and mRNA half-life
what is a variant and what is a mutation
variant = any change in DNA sequence mutation = any heritable change
what is a polymorphism
= a variation in the human genome with population frequency >1%, or any variant that doesn’t cause disease in its own right(may predispose)
what are mutations that occur during mutations called and in what cells do they occur
they occur in every cell and they are called somatic mutations(i.e. non-inherited)
describe mosaicism
different cells have different genetic constitutions, due to somatic mutations
(everyone is a somatic mosaic)
what is germ line and post-zygotic mosaicism
germ line = occurs in gamete before fertilisation (one parent mosaic)
post-zygotic = child mosaic
what role do somatic mutations play in cancer
they enable certain characteristics; uncontrollable growth, ability to invade + metatstasise
how is cancer a genetic condition
it is driven by mutations, usually acquired over time and heterogeneous( multiple mutations)
can be driver + passenger mutations, as well as germ line + somatic mutations involved
describe role of oncogenes in cancer
they are the gas pedal, ‘turned on’ in cancer, largely dominant and found in ,for example, growth factors
describe the role of tumour suppressors in cancer
they are the breaks, ‘turned off’ in cancer, largely recessive and found in, for example, DNA repair genes
