6.1 Cellular Control Flashcards
What is a gene mutation?
Change to DNA
How might they occur?
- randomly during DNA replication
- mutagenic agents such as UV light, tobacco, gamma rays etc
What is the difference between mutations in mitotic division and meiosis?
Mitotic -> cannot be passed, form cancerous tumours
Meiosis -> can be passed, in gamete formation
What is a silent point mutation?
- substitution of a base in a triplet but still coding for the same amino acid due to DEGENERACY
What is a missense point mutation?
- change to triplet causing DIFF amino acid sequence
- alteration of primary, etc, tertiary structure of protein -> might affect function
What is an example of a missense point mutation?
- sickle cell anaemia
What is a nonsense point mutation? What is an example?
- altering of a base triplet, so it becomes a stop codon
- truncated protein that will not function
- Duchenne muscular dystrophy
What is an indel mutation? What is an example?
- nucleotide bases, NOT IN MULTIPLES OF 3, get inserted or deleted
- all subsequent triplets are altered due to overlapping nature of code + FRAMESHIFT
- primary, etc, tertiary structure altered.
- some forms of thalassemia
What is the significance of an expanding triple nucleotide repeat? What is an example?
- number of repeats increases at meiosis and again from generation to generation
- Huntingtons: if CAG repeats go above a certain critical number
If glucose is absent and lactose is present, what occurs?
- induces production of lactose permease (allows it to enter) and B-galactosidase (hydrolyses to galactose and glucose)
What is lac0?
operator region
What is lacZ?
codes for B-galactosidase
What is lacY?
codes for lactose permease
What is P?
promotor region where RNA polymerase binds to begin transcription
What is I?
when expressed, LacI repressor protein is coded for which binds to operator -> prevents RNA polymerase from binding and prevents transcription