L20 - Mutagenesis

Marie Curie

• Discovered new element called radium

• She put it in her desk draw - in draw was a piece of photographic envelope so in the dark

• She left the radium in there for a while and when came but to it found that the piece of radio graphic paper had gone black as if light has touched it

• so knew that radiation came from Radium

• she had done a-lot of work on radium and then developed leukemia due to exposure of radiation and died

Radium watch dial painters

• this was job for women

• they put radium on watch dials so would glow in the dark

• this produced a- lot of radiation even to the people wearing the watch

• women making these often linked the paint brush that was used for radium and developed something called Fossae jaw

• this damaged jaw, teeth fall out and develop bone cancer

What are mutagen

• things that increase rate of mutations

Electromagnetic mutations

• X-rays → ionising radiation, produced free radicals in cells

• part of UV spectrum which causes lots of mutations

• such a small amount can have such detrimental effect

• Mulla said that there in no amount of safe radiation - Target Theory

• somewhere in cell is responding to radiation

Effects of radiation at Hiroshima and Nagasaki

• targeted by atomic bombs by USA in WW2

• Short term initial survives suffered from radiation sickness have burn marks all over body - 80,000 people died form this have vomiting, dehydration then death → so fluid loss, gut starts leaking fluid

Chernobyl

• explosion in power plant that blew up

• 50 firemen when in to stop the fire - 28 of them died of blood cancer due to the high amounts of radiation they were exposed to

• Found high rates of people developing thyroid cancer when exposed to radiation from this explosion

Other forms of radiation

• Ultraviolet

• leads to formation of thymine dimmers - thymine in DNA to join together

• typically repaired by repair enzymes but if have mutation in repair enzymes leads to Xeroderma pigmentosum

Chemical mutagens

• Radiomemetic burns

  • when exposed to mustard gas (powerful mutagen) get red blistering over skin

• then found that chemicals can actual lead to radiomemetic burns

Ames test

• Ames test - hoe efficient something is for causing mutation in bacteria

• detects mutagens

• found surprising mutagens e.g. bacon, fire retardants, natural substances e.g. black pepper were all mutagens

Age

• as age increases higher mutation rate

• Got to due with telomeres eveytime cell deivied get samller and smaller to a point where cell can no longer divide

• found that as telomers go donw with age there is a higher chance of increase in vascular dimentia

• Men have a higher mutation rate to wemen as tehy are contantly making sperm

• so nearly all cases of achondraplasia (short arms and legs) are due to new mutations that are due to father being older

• father older = increase in chances if children with schizophrenia, achondraplasia