Hiv And Splicing

Question 1

Explain the process of splicing

Answer 1

To make proteins the introns need to be removed from the pre-mRNA (using a spliceosome), leaving only the exons. These exons can be re-joined (spliced) in a variety of combinations so that 1 gene can code for more than one mRNA and therefore translation will produce many different proteins. This is called post transcription modification.

Question 2

Explain how hiv enters and infects the cell

Answer 2

1. The gp120 glycoproteins on the HIV envelope binds to the CD4 receptor on t-helper cells.
2. Viral envelope fuses with the T-helper cell membrane allowing the viral RNA and proteins (enzymes reverse transcriptase and integrase) to enter.
3. Viral reverse transcriptase copies viral RNA into viral DNA.
4. Viral integrase inserts virus DNA into T-helper cell DNA.
5. Viral DNA is converted to viral mRNA through transcription as part of the T-helper cell processes.
6. Viral mRNA moves to cytoplasm to find a ribosome for translation to make viral proteins.
7. Some viral proteins are made on ribosomes free in the cytoplasm and others on ribosomes on rER. The gp120 glycoprotein is modified in the T-helper cell’s Golgi apparatus (carbohydrate added).
8. Viral proteins move to T-helper cell membrane. New HIV bud out of T-helper cell, destroying the cell.