u4: mutations Flashcards
(35 cards)
proto-oncogenes
- genes that control cell growth in normal cells
- become cancerous when mutated
proto-oncogenes when mutated are called…
oncogenes
what do oncogenes do
- caused uncontrolled cell division
- malignant tumours
carcinogens
things that cause cancer bc mutations
examples of carcinogens
- radiation
- cigarette smokes
- viruses (HPV)
mutagen
environmental agent that directly alters DNA inside cell
spontaneous mutation
- caused by error in DNA replication
- i.e. alkylation, oxidation, etc
induced mutation
- caused by environemntal agent
- i.e. radiation (gamma, beta, alpha)
- i.e. chemicals (CO, smoke, nitrosamines found in smoked meat nd fish)
causes of mutation types (2)
- spontanous
- induced
types of mutations
- point mutation
- frameshift mutation
point mutation
replacement of single nucleotide in base pair
frameshift mutation
- insertion/deletion of nucleotides in amnts not divisble by 3
- reading frame shifts = completely different aa sequence = manyy missense nd nonsense effects
types of point mutations + wht they do
- silent mutation: no change in aa
- missense mutation: codon change = diff aa
- nonsense mutation: codon change = premature stop codon
what is inefficient for a cell?
to transcribe and translate all genes at all times
gene regulation
genes turned on/off as needed
4 ways of gene expression in eukaryotes
- transcriptional control
- post-transcriptional control
- translational control
- post-translational control
transcriptional control
- as mRNA is synthesized
- selectrion of genes tht r transcribed + rate of transcription
- i.e. methyl group added to promoter = RNA polymerase cant bind
post-transcriptional control
- as mRNA is processed
- rate at which mRNA leaves nucleus
- i.e. masking proteins bind to mRNA to inhibit further processing/splicing
translational control
- as protein is synthesized
- how long mRNA stays in cytoplasm
- i.e. varied poly-A tail length = varied rate of translation
post-translational control
- after protein synthesis
- additoinal protein processing/feedback inhibition
- i.e. hormones alter time tht protein is functional
what molecules is gene expression a result of?
- lactose
- tryptophan
wht happens if gene expression doesnt happen to a cell
lethargic cell
whats an operon
cluster of genes tht code for a protein/commonly transcribed and regulated into mRNA
wht does operon consist of?
- structural genes
- promoter
- operator
- regulatory genes
- repressor and activator proteins
