Question

18. Explain why plasmids that are used for cloning have antibiotic resistance genes.

19. Will the peptide VEGY absorb UV light? Explain your answer.

20. Where are the amino acid R groups for a peptide that is an α helix?

21. Draw the structure of the following peptide: WICK

22. Put the full name (correct spelling) of one amino acid in each blank: Which two amino acids are found in ß turns? ______________________and _________________
Which amino acid forms a covalent bond that is not a peptide bond?________________________
Which amino acids are not found in keratin____________________and ____________________
Give an example of two amino acids that could form an ionic bond between each other:
__________________ and __________________
What amino acid has a pKa of 6? _________________________

Answer 1

18. Cloning is nothing but the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually.

The whole point of an artificial plasmid is to insert it into bacteria to change their gene expression. For example, you have a plasmid that has a gene for making insulin. You inject it into a culture of bacteria and let them take it up.

After a few hours, you will get some bacteria producing insulin for you, but most of the bacteria in your culture haven’t taken up the plasmid, so they’re not doing anything useful. If anything, they’re competing with your insulin-producing bacteria for nutrients. Then you are supposed to kill them with antibiotics.

Well, it works. But along with the useless bacteria, the useful bacteria that will also be killed by the antibiotics.

But if you include an antibiotic resistance gene in the plasmid, then any bacteria that take up the plasmid will produce insulin and survive when you kill off the useless ones, so that you’re only left with insulin-producing bacteria.