Describe how a specific gene mutation leads to cystic fibrosis.

A deletion of 3 base pairs occurs on the CFTR gene on chromosome 7, leading to a deletion of the codon coding for phenylalanine at position 508. The loss of phenylalanine disrupts the ATP binding site of the CFTR protein, which prevents binding of ATP and opening of the Cl^- channel, disrupting the diffusion of Cl^- out of the cell.

Warning signs for a pseudo-first order reaction

• Excess of reactant - since concentration of reactant does not change significantly, so can treat as a first-order reaction
• Solvent is a reactant
• Use of catalyst

How does temperature/pH affect enzyme activity?

Temperature: As temperature increases from _ºC to _ºC, rate of reaction/relative activity increases from __ to __.  (quote values!)

pH: – __, optimum pH at ___ at 100% activity. Any deviation in pH will result in decrease in the enzyme activity.

Size of organelles - from bio MCQ TYS

In order of size, largest to smallest
1. Nuclei
2. Chloroplasts
3. Mitochondria
4. Lysosomes
5. Ribosomes (0.02μm)/ER

Explain the role of telomeres.

1) Ensure genes are not lost/eroded due to end replication problem, preventing loss of vital genetic information

2) Protect and stabilise the terminal ends of chromosomes - prevent chromosomes from fusing with other chromosomes and prevent DNA repair machinery from recognising 3' overhangs as DNA breaks, preventing apoptosis.

3) Allow their own extension - attachment point for telomerase (germ cells, embryonic stem cells, cancer cells)

Golgi apparatus

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Explain the principles of RFLP.

1. Due to the polymorphic nature of DNA
2. genomic DNA from different individuals produce fragments of different lengths when digested by restriction enzymes,
3. resulting in a unique banding pattern among individuals