Control Of Gene Expression Flashcards
How do transcription factors work
Bind to start codon of DNA
RNA polymerase then binds to the transcription factor
What are totipotent cells
Cells which can develop into any cell type
What are transcription factors
Molecules which stimulate transcription of a gene
What plant cells aren’t totipotent and why
Xylem cells
They don’t have nucleus
Explain why all cells possess the same gene yet can’t produce the same proteins
The gene that codes for the certain protein isn’t expressed
Points to use in case arguing for the use of embryos in stem cell research
Potential to treat human diseases as can develop into a wide range of different human tissues
Also can be used to regrow tissues that have been damaged eg skin damage burn graphs
Points to use in case arguing against the use of embryos for stem cell research
Don’t know long term effects
May lead to cloning
Aren’t only source of stem cells eg can use bone marrow
Ethical arguments eg is 14 day old embryo life or not
Why is it better to use own stem cells
Less likely to be rejected than donor cells are
Describe how transcriptional factors are used
Bind to specific site of DNA in nucleus
Stimulates the DNA region to begin transcription
mRNA is produced, genetic code it carries is translated to a polypeptide
When gene not expressed, binding site is blocked by inhibitor molecule
Inhibitor molecule prevents TF from binding so prevents transcription and polypeptide synthesis
Describe how oestrogen affect gene transcription
Oestrogen diffuses into cytoplasm Binds to site on receptor Site complementary to oestrogen Site changes shape Receptor molecule changes shape Inhibitor is released from DNA binding site Allows TF to enter nucleus and combine with DNA Allows transcription of gene
What is siRNA
Small interfering RNA
Small double stranded sections of RNA
How does siRNA affect gene expression
Breaks down RNA before genetic code is translated to polypeptide
How does siRNA work
Enzyme cuts RNA into sections of siRNA
One of the 2 siRNA strands combines with an enzyme
Enzyme guided to mRNA by siRNA as their complementary bases pair up
Enzyme cuts mRNA into smaller sections
mRNA can’t be translated to polypeptide
Gene can’t be expressed
How can siRNA be used in science and medicine
Block genes that cause some diseases
Used to inferior role of genes in biological pathways eg block gene then observe effect to see its role
What are stem cells
Cells which can become any cell
