Introduction to Microbiology Study Notes

1. Define microbiology: the study of the biology of microscopic organisms 2. What are the different types of - viruses microscopic organism? - bacteria - algae - fungi - slime moulds - protozoa 3. Define acellular: not consisting of, divided into/containing cells 4. What are the 3 domains of mi- bacteria crobiology? archaea eukarya 5. Describe gram-positive cell wall structure: - thicker cell wall so provides greater protection from environmental stresses - composed of approx 20 layers of peptidoglycan + teichoic acid - no outer lipid membrane 6. Describe gram-negative cell wall structure: - multi-layered + complex - contains only a single layer of peptidoglycan + also has a periplasm - have an outer lipid membrane that protects them from their environ (used to selectively keep antibiotic drugs from entering) 7. What does penicillin do? inhibits cell wall synthesis 8. What does chloramphenicol do? inhibits protein synthesis 9. What do polymyxins do? disrupts membranes in gram-negative bacteria 10. What do fluoroquinolones do? inhibit DNA synthesis 1/7 11. Define virus - consist of segment of nucleic acid (DNA/RNA) surrounded by a protein coat 12. Define capsid protective protein coat during transmission + often target for host immune response 13. Do all viruses have an envelope? no only some 14. What is acyclovir + what is it used to treat? - antiviral medication - herpes simplex infections, chicken pox + shingles 15. What is zidovudine + what is it - antiretroviral medication used to treat? - prevents + treats HIV/AIDS 16. What microscope are viruses visible under? electron microscopes 17. What are examples of viruses? - bacteriophage - tobacco mosaic virus - adenovirus - influenza virus 18. What is the order of the phases - lag phase in bacterial growth? - log phase - stationary phase - death phase 19. Describe lag phase: increased metabolic activity of cells due to the synthesis of enzymes, proteins + DNA/ increase in cell size 20. Describe log (exponential) phase: doubling of the cell pop at regular intervals 21. Describe stationary phase: there is no net increase/decrease in cell number 2/7 22. Describe death phase: cell ability to grow (viability) decreases exponentially 23. Define generation time: the time interval required for bacterial cells/pop to double 24. What is the generation time for varies between 12 min to 24 hours bacteria? 25. Where is the genetic material of the nucleoid prokaryotes found? 26. What type of reproduction is bi- asexual reproduction nary fission? 27. Describe the steps in binary fis- - the DNA of the bacterium divides into 2 sion: replicates - the bacterial cell then elongates + splits into 2 daughter cells each with identical DNA to the parent cell 28. State pros of binary fission: - only 1 parent needed - rapid division - a lot of daughter cells produced in a limited time 29. State a con of binary fission: - lack of genetic recombination so species cannot survive the changes in their environ + whole pop is wiped out 30. How long does DNA replication 40 mins at 30 degrees take in bacteria? 31. Describe replication on bacte- - bidirectional ria: - semi-conservative 32. Define bidirectional: replicating DNA in 2 directions at the same time, from the origin of replication in the circular DNA found in most bacteria 3/7 33. What are the 2 strands in DNA - leading replication called? - lagging 34. What is a replisome? a replication complex where all the proteins in DNA replication aggregate at the replication forks 35. Describe DNA replication in E.coli - initiates at a single genomic site (oriC) where 2 replisomes are assembled - the replisomes replicate the chromosomes bi-directionally away from oriC, + after duplicating the entire genome, meet again + terminate at specific sites 36. Why does antibiotic resistance 30 mutations occur per hour in microbial occur? pop = have rapid adaptation 37. Define horizontal gene transfer: (HGT) - movement of genetic material between unicellular/+ multicellular organisms rather than vertical transmission of DNA from parent to offspring 38. What does HGT play an impor- - primary mechanism for the spread of antant role in? tibiotic resistance in bacteria 39. What are the techniques to in- - transfection troduce a foreign gene into - transduction host cells? - conjugation - transformation 40. Define competent cells: cells able to take up foreign DNA from their surrounding environ 41. Define transfection: the process of introducing nucleic acids into cells by non-viral methods to produce genetically modified cells 42. 4/7 What does transfection use to genetically modifed viruses which are no produce the genetically modi- longer pathogenic + carry the gene to be fied cells? introduced 43. Define transduction: the process whereby foreign DNA is introduced into another cell via a viral vector 44. Describe the steps in transduc- 1) bacteriophage first infects the donor tion: cells + begins the lytic cycle 2) the virus then develops its components using the host cell machinery 3) the host cell DNA is hydrolysed into small fragments by the viral enzymes 4) small pieces of bacteria DNA is now integrated into viral genome 5) when the virus infects another bacteria, the DNA is transferred into it 45. Define conjugation: - the process by which 1 bacterium transfers genetic material to another through direct contact - 1 bacteria serves as the donor + one serves as the recipient 46. Define transformation: the process of DNA uptake by the bacteria from the surrounding environ 47. Describe bacterial competence - not all bacteria are capable of taking up in transformation: DNA from the surrounding environ, so they are artifically competent - this is achieved by using chemicals + electrical pulses 48. Describe how chemicals are - cell permeability is increased using calciused in bacterial competence: um phosphate - they are then incubated with the DNA + provided with a heat shock treatment that causes the DNA to enter the cells 5/7 49. Describe how electroporation the bacterial cells are subjected to elecis used in bacterial competrical pulses to make them permeable + tence: cause DNA to enter into cells 50. How do you identify transformed cells? - the bacteria are grown on an agar medium with antibiotics - only the bacteria containing the antibiotic resistance gene will grow in the presence of antibiotics - the cells that survive + grow are transformed cells 51. What microbes form the basis - marine + freshwater of the food chain? - microorganisms 52. What kind of decomposers are primary decomposers - they recycle nutribacteria? ents back into the environ 53. What are the helpful uses of mi- - involved in food production crobes? - triggers immune response that suppresses infections - our normal microbial flora prevents potential infections 54. Define probiotics + describe their function: - a mixture of live bacteria + / yeast that lives in your body prevent pathogens from gaining access to our body - stimulate the secretion of antibodies - + prevent replication of viruses 55. Probiotics: PSV - Prevent, stimulate, virus - prevent pathogens - stimulate antibody secretion - prevent virus replication 56. Define antibiotics: a substance produced by a microorganism which at low conc kill/inhibit the growth of other microorganisms 6/7 57. Describe insect pest control + - using bacteria to control insect pop give an example: 58. Define bioremediation: - decontamination of hazardous wastes - microbes are used to clean up pollutants + toxic wastes 59. What fuels are produced by mi- ethanol, butanol, hydrogen, methane, crobes? clostridium acetobutylicium ferments carbohydrate to ethanol, butanol + acetone 60. How can microorganisms be detrimental? food spoilage adversely affects the aroma, texture /appearance + safety of food e.g. putrefaction, rotting, souring, rancidity etc. 7/7