Mutations Flashcards
What is a mutation?
A change in the DNA sequence
What do mutations result from?
DNA replication errors made during cell division
Exposure to ionizing radiation
Exposure to chemicals
infection by viruses
What is a Germ line mutation?
A mutation that occurs in the egg or sperm, affect all cells in the body and can be passed on to offspring
What is a somatic mutation?
occur in a body cell and is not passed on to offspring
Why are there more errors in RNA?
RNA polymerase does not proof read like DNA polymerase
Why do errors in transcription and translation matter less than errors in genome?
The cell will be making multiple copies of RNA, unlikely to make same mistake in exactly the same place
RNAs are quickly degraded so bad copies will be quickly removed,
Not inherited or permanent
What are mitochondria?
Energy producers
Where do mitochondrial diseases usually affect?
Heart
Brain
Muscles
What problems do people with mitochondrial disease usually suffer from?
muscle weakness, problem with movement, diabetes, kidney failure, heart disease, dementia, hearing loss, vision abnormalities
What happens with mitochondrial somatic mutations?
Can not repair themselves so build up over time- raging
What must happen for someone to spontaneously get an autosomal recessive disorder?
Mutation of the same gene on both chromosomes at the same time
What mutations lead to a frameshift?
Insertions and deletions
How can errors at mitosis produce chromosomal mutations?
if chromosomes do not pair correctly at the metaphase plate may cause two copies of the chromosome in one cell and not
What does PGC mean?
Primordial Germ cells
What are the stages of Oogenesis?
PCG Oogonia Some enter prophase- primary oocytes Primordial Follicle- primary oocyte surrounded by flattened epithelial cells secondary Oocyte and polar body ovulation Egg and polar body
800,000 at birth,
due to apoptosis 40,000 at pubery
500 ovulated
What are the stages of Spermatogensis?
PGCs arrive in male gonad and remain there till puberty and form spermatozoa
100 million produced a day
Start at puberty as don’t need before
What caused most of pregnancy loss?
75% are chromosomal abnormalities e.g. structural and numerical
Is mutation rates higher in female or male gametes?
5x higher in male gametes as more divisions and continually active
Is IVF embryo aneuploidy rate an under or overestimate?
Overestimate- reason they are there as have problems, no fight for sperm
What are the outcomes if a very early embryo is exposed to radiation?
death, teratogenesis, cancer when born
What features would make a ferm line mutation inheritable?
not be lethal to gamete or impair its function would not be lethal at fertilisation, viable adult with normal capacity
In general what so recessive mutations cause?
loss of function
In general what do dominant mutations cause?
increased function
What might mutations do to drug treatment?
no effect of drug reduced effect increased effect side effects allergic reactions
What is a somatic mutation?
Error in mitosis
Can be genetical or less commonly chromosomal
what do somatic mutations cause?
Tumour
What causes somatic mutations?
Mutagens, radiation and viruses
