Existing antibodies cannot recognise and bind to altered haemagglutinin on

Existing antibodies cannot recognise and bind to

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Existing antibodies cannot recognise and bind to altered haemagglutinin on modified viruses for degradation by immune cells; @ 1m, max 4 (d) Suggest how viruses evolved. [5] (N08 P2 Q9c) 1. Viruses are diverse in many ways, and evolved independently of one another; 2. Indicating that viruses may not have a common ancestor (a polyphyletic group); Possibilities of virus origin include: 3. Viruses are escaped cellular genes (from plasmids/transposons); 4. Intracellular symbionts that lost certain parts of their genome as they moved from cell to cell, ultimately becoming obligate intracellular parasites; 5. Viruses may have evolved with their host which explains why; 6. Viruses in the different broad types of hosts are generally so different; @ 1m * Students may refer to the following website for a summary of prevailing theories on the origin of viruses (e) Describe the differences between conjugation and transformation. [4] Conjugation Transformation 1. Transfers the F plasmid or R plasmid 1. Transfers fragments of the bacterial chromosome; 2. Donor cells are F + cells / carries the F plasmid or R plasmid; 2. Donor cells may be lysed cells that releases its DNA; 3. Recipient cells are F - cells / do not carry the F plasmid or R plasmid; 3. Recipient cells must be competent / secrete the competence factor; 4. Direct physical contact required between two cells through sex pilus; 4. No physical contact required between cells / exogenous DNA taken up directly by recipient cell; @ 1m per comparison
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