Gene Expression Flashcards
What do oncogenes do?
Transform cell into a cancer cell
What is cancer ?
Disease caused by uncontrolled cell growth and division
Name the causes of mutations
Chemical - alcohol , benzene
Ionising - alpha, beta, UV, X ray
Spontaneous errors in DNA replication
What are totipotent stem cells
Able to differentiate into any type of cell found in body. Found in embryo at early stage called blastocyst
What are pluripotent stem cells?
Form any type of cell in body except embryonic cells
What are multipotent cells?
Can differentiate into other cell types but are more limited
What are unipotent stem cells?
Can only differentiate into one type of cell
What are induced pluripotent stem cells?
Stem cells created from uni potent stem cells
How does oestrogen alter transcription ?
Oestrogen diffuses into cell and binds to receptor on transcription factor
Alters shape of DNA binding site on transcription factor and makes it able to bind to DNA
Transcription molecule enters nucleus via pore and bind to DNA where it stimulates transcription of gene
How does siRNA turn off a gene ?
Binds to complementary sequence of mRNA
What is a phenotype?
A visible characteristic due to expression of alleles
In fruit flies, the genes for body colour and wing length are linked. Explain what this
means.
They are on the same chromosome
Explain how the methylation of tumour suppressor genes can lead to cancer
Methylation prevents transcription of gene;
Protein not produced that prevents cell division/
causes cell death/apoptosis;
No control of mitosis
Suggest how methylation of DNA can prevent expression of a gene
Prevent binding of transcription factor; 2. Prevents RNA polymerase binding/working; 3. Prevents complementary/specific base-pairing; 4. (No transcription, so) no (pre)mRNA made; 5. No/less translation (of mRNA);
A reccessive allele with harmful effects is more likely to reach a higher frequency in a population than a harmful dominant allele. Why?
Can be carried without showing effects
Organism more likely to reproduce
THerefore recessive alleles more likely to be passed on
