Microorganisms

Question 1

describe bacteria

Answer 1

• prokaryotes: no true nucelus or membrane bound organelles
• the ribosomes and genetic material are free floating
• have structures like a flagella and cilia to increase motility

Question 2

what are the 3 major shapes of bacteria

Answer 2

Coccus

• spherical bacteria that can joing together and make diplococci (two bacteria joined together), streptococci (chains of spherical bacteria) or staphlyococci (clusters of spherical bacteria

Bacillus

• ros ahped that can also join forming diplobacilli, streptobacilli (chains of rod shaped) etc.

Spirillim:

• spiral shaped bacteria

Question 3

How can you tell if a bacteria is gram positive or gram negative

Answer 3

• gram staining
• apply crystal violet and iodine which forms complex that ahderes to outermost layers of bacteria
• gram positive: outmermost layer = thick peptidoglycan cell wall
• gram negative: outermost layer = thin and cmoposed of lipids
• when decolourizer like alc is applied, peptidoglycan wall is dehydrated and colour is trapped inside so gram pos show colour but not gram negative
• addition of red dye like safarin will stain gram neg a lighter colour

*** if bacteria is gram pos or neg plays big role in type of antibiotic administered

Question 4

how do bacteria reproduce

Answer 4

• asexually: 3 primary means
• transformation: acquiring DNA from the environment
• transduction: being injected with DNA from a bacteriophage
• Conjugation: direct DNA transfer vai contact between bacteria cells

Question 5

what are viruses

Answer 5

• cannot reproduce without a host and are not considered living particles
• genetic material (DNA or RNA) stores in protein capsid

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Question 6

What happens when a virus infects host cell (lytic cycle)

Answer 6

• cell entres lytic cycle
• virus penetrates the cell’s membrane injecting its own DNA -> taking contorl of cellular machinery inducing the cell to replicate viral DNA instead of its own
• eventually cell will lyse releasing the viral DNA into extracellular matrix
• viral particles infect new cells to continue lytic cycle

viruses that replicate by killing host cells are called virulent

Question 7

what happens in viral infection occurs on bacterial lawn

Answer 7

• a plaque or clearing of the lawn corresponds to area of lysed bacteria
• physical characteristics of the plaque are useful in identifying mutant phage strains that may arise

Question 8

what happens if the virus does not lyse the host cell

Answer 8

• becomes integrated into the bacterial genome in a less harmful form (provirus)
• lies dormant for one or more generations as part of lysogenic cycle
• virus does not spread as quickly so considered a latent infection
• either spontaneously or as result of environmental circumstance the provirus can emerge into a lytic cycle
• cells containing provirus are normally resistant to further infection by similar phages

Question 9

what type of cycle is HIV

Answer 9

• human immunodeficiecy virus is lysogenic cycle
• patient typically asymptomatic for moths or yeats as the virus divides within the host

Question 10

describe fungi

Answer 10

• eukaryotic
• many organelles mimic those found in human cells, BUT have cell walls
• walls made of chitin which differentiates them from plants and bacteria
• cannot produce own food and must consume other organisms for energy

*heterotrophs

Question 11

how do fungi reproduce

Answer 11

• both sexually and asexually: have both daploid and diploid phases
• asexual occurs vai fission (one organism divides into 2 daughter cells

*also common means for bacterial reproduction

• sexual occurs only w/ diploid cells which undergo meiosis to create four spores
• spores are haploid (only 1 cope of organisms genetic material, so 1 diploid can produce 4 idential progeny)
• spores are more resilient to hostile conditions than diploid cells, so occurs when environemnt not favourable for dission

Question 12

what are parasites

Answer 12

• organisms that live off of and harm a host that receives no benefit from the presence
• parasites include helminths and protozoa

Question 13

what is a helminth

Answer 13

• parasitic worms including tapeworm and roundworms
• often ingested in contaminated food ro water and live off food present in digestive tract of host

Question 14

what are protozoa

Answer 14

unicellular eukaryotes that ahve many different features depending on organism

• many causing diease

*type of parasite

Question 15

what are the 3 cycles involing microorganisms critical to function of life

Answer 15

nitrogen cycle

carbon cycle

photosynthesis

Question 16

describe the nitrogen cycle

Answer 16

• bacteria fix free atmospheric nitrogen gas itno nitrates and nitriles usable by plants to make proteins
• as these plants (and as they go up food chain) produce waste and decompose ammonia and ammonium ions are released into the environment
• bacteria then break ammonia back down into nitrate and nitrite which can replenish stores in plants or be converted to atmospheric nitrogen
• forms core nitrogen cycle: nitrogen is repeatedly used and recycled

Question 17

explain the carbon cycle

Answer 17

• microbed contribute to the transfer of carbon molecules through the carbon cycle via fermentation, catabolism and anabolism
• involved transfer of carbon and carbon containing compounds between plants animals and the atmosphere and other environmental components

Question 18

describe photosynthesis

Answer 18

• cells containing chlorophyll are capable of undergoing photosynthesis
• rxn of sunlight, CO@ and water to produce sugars serving as energy source for the cell
• organisms that produce own energy called autotrophs which are eaten by heterotrophs and serve as basis of the food chain