bacteria, fungi, virus, hgt

Question 1

What is the definition of Horizontal Gene Transfer?

Answer 1

The process by which an organism incorporates genetic material from another organism (the donor) without being the offspring of the donor organism.

Question 2

Describe 3 mechanisms of horizontal gene transfer

Answer 2

Transduction- bacteriophages (viruses that infect bacteria) move pieces of DNA from one bacterium to another
Transformation- free update of DNA from its environment
Conjugation- DNA is transferred directly cell to cell

Question 3

What are antibiotics?

Answer 3

A chemical substance produced by microorganisms that can destroy bacteria. Can be natural or synthetic and is “cidal” or “static”. Cidal kills the microorganism, static inhibits the growth of

Question 4

Describe 3 ways antibiotics work (with example)

Answer 4

-Inhibition of cell wall synthesis, eg penicillin is bacteriacidal, cell wall cannot form causing cell lysis
-Inhibition of protein synthesis, eg tetracycline is bacteriastatic, cell wall cannot perform protein synthesis therefore cannot replicate
-Inhibition of nucleic acid synthesis, eg quinolones, cell cannot perform DNA/RNA synthesis therefore cannot replicate

Question 5

Micro-organisms, when exposed to antibiotics, can develop mechanisms of resistance. Describe, with examples, 3 antibiotic resistant mechanisms.

Answer 5

1/ Drug inactivation, bacteria develop enzymes that destroy and inactivate antimicrobials. eg, beta lactomase destroys antimicrobials that contain a beta-lactum ring, like penicillin.
2/ Altered drug target, alteration of the binding site leaves the antibiotic without a binding site therefore, unable to work.
3/ Drug efflux, membrane bound proteins pump out the antibiotics from the cell.

Question 6

what is a prokaryote/bacteria?

Answer 6

single celled organism that lacks a nucleus. has DNA, plasma membrane and cell wall. cell wall is a drug target for lots of antibacterials. replicate by binary fission, can transfer DNA by horizontal gene transfer. some bacteria produce endospores (difficult to kill)

Question 7

what is a eukaryote/fungi

Answer 7

have DNA contained within a nucleus as well as a plasma membrane and cell wall. can be single or multicellular. replicate sexually or asexually and spores.
most common oral fungi is candida albicans/oral candidosis.

Question 8

bacteria + drug

Answer 8

gingivitis/ penicillin. targets cell wall. Penicillin is bactericidal, cell wall can’t form causing cell lysis

Question 9

fungi + drug

Answer 9

candida albicans/ polyenes target membrane integrity, eg nystatin

Question 10

viral + drug

Answer 10

herpes simplex/ acyclovir inhibits DNA synthesis

Question 11

bacteria cell wall?

Answer 11

made of peptidoglycan. gram positive has a thicker layer