mutation and gene expression Flashcards
(14 cards)
Explain how the structure of DNA is related to its functions
- Double stranded so stable
- Large molecule so can store lots of information
- Coiled so compact
- Sequence of bases coding for a specific amino acids coding for a specific protein
- Double stranded so replication can occur semi – conservatively
- Weak hydrogen bonds for strand separation
How can a protein with one amino acid missing lead to a disease?
- Changes tertiary structure of protein
- Non – functional protein
Give 2 characteristics of stem cells
- Undifferentiated
- Will keep dividing/replace themselves
How can the insertion of DNA into a host cell cause cancer?
- Affects tumour suppressor gene
- Inactivates gene
- Rapid cell division
Oestrogen is a hormone that affects transcription. It forms a complex with a receptor in the cytoplasm of target cells. Explain how an activated oestrogen receptor affects target cells
- binds to promotor site
- Stimulates RNA polymerase
Describe what is meant by a malignant tumour
- Mass of unspecialised cells
- Uncontrolled cell division
- Spread to other parts of the body by metastasis
give one reason death rate from tumours increases with age
cancer takes time to develop
Explain why skin colour is a factor in death rate caused by a skin cancer
- Dark skin prevents burning
- Less cancer risk
In a trial of new drug for treating cancer, the control group of patients weren’t given a placebo, suggest why
- Unethical to fail to treat cancer
A disease is caused by a faulty receptor protein on cell surface membrane of cells, suggest why the immune system can destroy these cells
- Faulty protein recognised as foreign protein
- T cells bind to foreign protein
- T cells stimulate clonal selection of B cells
- Release of antibodies against faulty protein
Explain how methylation of tumour suppressor genes can lead to cancer
- Tumour suppressor gene not transcribed
- Protein that prevents cell division not produced
- No control of mitosis
Explain how a single base substitution causes a change in the structure of a polypeptide
- Change is base sequence of amino acids
- Change in hydrogen/ionic bonds
- Alters tertiary structure
Describe how alterations to TSG can lead to development of tumours
- Increased methylation of TSG
- Mutations in TSG
- TSG not transcribed/expresses
- Results in uncontrollable cell division
Testosterone is a hormone in a group called androgens, testosterone binds to a specific androgen receptor, suggest and explain why testosterone binds to a specific AR. An AR is a protein
- Has a tertiary structure
- Complementary
