Gene mutations and cancer Flashcards
when are gene mutations likely to occur
during interphase
what can influence the frequency of gene mutations
mutagenic agents
examples of mutagenic agents
ionising radiation
UV light, x-rays
what is a carcinogen
chemicals that interfere with the structure of DNA and transcription
wjat are the 5 types of gene mutation
1.Addition
2.Deletion
3.Substitution
4.Inversion
5.Duplication
6.Translocation of bases
benign tumour
grow at a slow rate
enclosed in a membrane
don’t spread
what is it called when a tumour spreads
metastasis
what is an oncogene
mutated and permenantly activated version of a proto-onco-gene
so cell division is always stimulated
how can abnormal methylation cause cancer
methylation of a tumoir surpressor gene means the transcription factor can’t bind to it and initiate transcription
so the specific protein is not produced which initiated apoptosis
so cells can divide and mutate uncontrollably
or the opposite happens with oncogenes
what is oestrogen and how can it cause cancer
lipid-soluble hormone
can enter cells and bind to a transcription factor which changes shape so it can bind to proto-oncogenes and activate them
totipotent cells
can differentiate into any type of cell
found in embryos
pluripotent cells
can differentiate into most types of cell
found in embryos
used in research
multipotent cells
found in mature adult bone marrow
can differentiate into a few types of cell
how are induced pluripotent cells formed
formed from specialised cells
the genes that are switched off to make the cell unipotent are switched back on using transcription factors
epigenetics meaning
heritable changes in gene functionw ithout changing the DNA base sequence
how does decreased acetylation inhibit transcription
makes the histones more positive so DNA winds round them more tightly
how does siRNA inhibit translation
binds to complementary mRNA to make it double stranded
so when it leaves the cell it is recognised as abnormal and destroyed
why can the genome not be easily translated into the proteome
due to the presence of non-coding DNA
what are 3 ways to isolate DNA fragments
reverse transcriptase
gene machine
restriction endonucleases
hiw does reverse transcriptase produce DNA fragments
a cell that produces the protein of interest is selected
reverse transcriptase joins DNA nucleotides to the complementary mRNA nucleotides
to make the single-stranded cDNA
DNA polymerase makes the cDNA double-stranded
this is intron-free as it has been made ffrom mRNA
describe how a gene machine makes DNA fragments
the protein of interest is analysed to find the amino acid sequence then the mRNA sequence
the machine produces small sections of single-stranded overlapping DNA called oligonucleotides
PCR amplifies the DNA and makes it double-stranded
describe how restriction endonucleases create a DNA fragment
they cut up DNA at a specific, complementary recognition sequence
to create either a blunt end or sticky end
describe how DNA is cloned in vitro
by PCR
temperature is increased to 95 degrees C to break H bonds and make DNA single-stranded
temperature is decreased so primers can attach
temperature is increased to 72 degrees so Taq polymerase can synthesis a new DNA strand
describe how DNA is amplified in vivo
restriction endonucleases cut DNA to create sticky ends
a promotor and terminator reigon are added so RNA polymerase knows when to start/stop transcription
restriction endonucleases cut the plasmid vector
the same restriction endonucleases cut the DNA so sticky ends are complementary
DNA ligase sticks the DNA in to create recombinant DNA
