13.7 Gene expression Flashcards
Universal definition
The same 3 bases code for the same amino acid in all organisms
Non overlapping definition
Each base is read once in a triplet
Degenerate definition
More than one codon codes for the same amino acid
Consequence of DNA mutation
May alter the 1 structure of the polypeptide, changing the secondary structure of the hydrogen bonds, affecting the alpha helices and beta pleated sheets
May alter the tertiary structure, changing the position of the hydrogen and ionic bonds and disulphide bridges
Making the protein non functional by altering the binding site
Mutagenic agents
- High ionising radiation
- Biological agents
- DNA reactive chemicals
What do mutagenic agents do?
Increase the rate of spontaneous mutations
Totipotent cells
Zygote and early embryo
Pluripotent cells
Embryonic and fetal stem cells
Multipotent cells
Adult stem cells
Unipotent
Used in the formation of single type of cells ie. cardiomyocytes
How can stem cells be used in medical research?
- Producing new tissue for skin grafts
- Research into producing new organs for transplant
- Research into how cells become specialised
- Research into cancer and other diseases
- The use of stem cells to cure diseases such as parkinsons
Ethical concerns about stem cells
- Some people think its not right to use stem cells as embryos have human status
- Some people believe embryos have no moral rights whatsoever
- Animals must be used in experiments with stem cells before they can be used on humans
- The patient donor has to consent for their cells to be used
Promotor region definition
One or more base sequences found upstream of a gene that control the expression of that gene
Transcription factors definition
Proteins which when activated bind to the target promotor region of a gene stimulating RNA polymerase to begin transcription of the target gene
Describe the activation of transcription via oestrogen
- Oestrogen diffuses through the phospholipid cell membrane
- Diffuses through the nuclear envelope
- Binds to the oestrogen receptor in the nucleoplasm
- Changes the tertiary structure which releases the transcription factor
- Transcription factor binds to the DNA at the promotor region
- This stimulates RNA polymerase to transcribe the gene
- This increases transcription so mature mRNA is produced
