1. Cofactors are:
- Molecule attached to haemoglobin which binds oxygen reversibly
- Molecules which control protein degradation
- Vitamins and minerals thats associate with active sites of an enzyme to increase reactivity
- Light sensitive molecules attached to a signalling protein
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2. What is the role of tRNA?
- Decodes mRNA for protein synthesis, bringing the correct amino acid to the end of the protein
- Regulated gene expression through RNA interference.
- Codes for proteins
- Component of ribosomes, catalyzing protein synthesis
3. What is the role of topoisomerase during DNA replication?
- Prevents rewinding of DNA after seperation
- Holds DNA polymerase in place to stop it falling of DNA
- Relieves twists in DNA ahead to prevent super coiling, by creating a nick ahead of the replication fork
- Unwinds DNA strands to allow access by other replication machinery
4. How does rifamycin work?
- Binds in the exit channel of the ribosome to RNA polymerase
- Prevents the transition from translation initiation to elongation
- blocks initiation of RNA chains by binding to RNA polymerase
- Blocks binding of aminoacyl-tRNA to the A-site
5. Bacterial mRNA is often polycistronic, meaning?
- Have a 5' cap
- Only one protein can be encoded from a piece of mRNA
- Several proteins can be encoded from the same mRNA
- mRNA only have one ribosome binding site