Compulsory question 1

Question 1

what is kochs postulates

Answer 1

criteria established to define relationship between microbe and a disease

Question 2

what are the 4 of kochs postulates

Answer 2

1. association: the pathogen must be present in every case of the disease
2. isolation: the pathogen must be isolated from the diseased host and grown in pure culture
3. causation: the the cultured pathogen must cause the disease when introduced into a healthy host
4. reisolation: the same pathogen must be reisolated from the experimentally infected host

Question 3

what is gram staining

Answer 3

gram staining is a differential technique used to classify bacteria into two groups

Question 4

define and explain the two types of gram staining

Answer 4

1. gram positive: bacteria retain the crystal violet stain and appear purple under the microscope due to their thick peptidoclycan layer

2.gram negative : bacteria do not retain crystal violet stain instead the retain counterstain (safranin) and appear pink under the microscope due to their thinner peptidoglycan layer and outer membrane

Question 5

flagella

Answer 5

flagella are long whip like appendages used for movement in many bacteria, they rotate like a propeller to propel the bacterium through liquid environments.

Question 6

write the stages of viral replication

Answer 6

viral replication involves several stages

1.attachment:the virus binds to a host
2.penetration:the virus or its genetic material enters the host cell
3.replication:viral nucleic acids and proteins are synthesized using hosts machinery
4.assembly:new viral particles are assembled
5.release:new virions exit the host cell, often causing cell lysis

Question 7

Archae

Answer 7

are a domain of single celled microorganisms distinct from bacteria and eukaryotes. They are known for surviving in extreme conditions, e.g. hot springs, salty lakes. They lack a nucleus (prokaryotic) and have unique membrane lipid The types of archae include methanogenes, thermophiles and halophiles

Question 8

common classifications of fungi

Answer 8

classified into several groups based on their reproductive structures and life cycles

1.ascomycota:produce spores in sac like structure called asci (e.g. yeast and mould)
2.basidiomycota: produce spores on club-shaped structures called basidia (e.g. mushrooms)
3.zygomycota:form zygospores during sexual reproduction(e.g.bread mould)
4.chyridiomycota:mostly aquatic fungi with flagellated spores (e.g. chytrids)
5.deuteromycota:fungi with no known sexual reproduction stage based on asexual reproduction

Question 9

an infection caused by gram positive bacteria

Answer 9

Streptoccocus pyogenes is a gram positive bacterium causing
>strep throat: pharyngitis caused by s.pyogenes
>impetigo:a stain infection characterised by red sores

Question 10

Three domains of life

Answer 10

bacteria: single celled organisms with simple cell structure, lacking a nucleus (prokaryotic)
archae: single celled organisms similar to bacteria with distinct molecular and biochemical features
eukraya: organisms with complex cells containing a nucleus including, plants, animals, fungi and protists

Question 11

what do microbial risk groups do ? and lsi the 4 groups

Answer 11

they classify microorganisms based on their risk to humans
risk group 1:low risk, unlikely to cause disease in healthy individuals (e.g. non pathogenic e.coli)
risk group 2: moderate risk, can cause disease but is easily treatable (e.g. salmonella)
risk group 3: high risk, can cause serious disease with no treatment available (e.g. mycobacterium tuberculosis)
risk group 4: extreme risk, can cause severe disease often with no treatment available (e.g. ebola virus)

Question 12

short notes on endotoxins

Answer 12

endotoxins are lipopolysaccharides in the outer membrane of gram negative bacteria. released when bacteria die, they can cause fever, inflammation and septic shock. they are not secreted but are part of the bacterial cell structure

Question 13

difference between bacterial exotoxins and endotoxins

Answer 13

exotoxins are potent proteins that are secreted by bacteria, causing diseases such a tetanus botulism and are heat sensitive. endotoxins are lipopolysaccharides found in the outer membrane of gram negative bacteria, released when bacteria die, causing symptoms such as fever and inflammation. exotoxins are more toxic and immunogenic whereas endotoxins are less toxic and heat stable.

Question 14

disease caused by gram NEGATIVE bacteria

Answer 14

infection caused by gram negative bacteria is salmonella, causing symptoms such as diarrea fever and abdominal cramps.
name=salmonellaosis
disease=salmonella

Question 15

importance of fungi

Answer 15

fungi play a crucial role in decomposing organic matter, recycling nutrients in ecosystems and are essential for producing antibiotics and other pharmaceuticals.

Question 16

mannitol salt agar

Answer 16

is a selective and differential medium used to isolate and differentiate staphylococcus species based on their ability to ferment mannitol. they contain high salt concentrations and turn yellow in the presence of mannitol fermentation, indicating potential pathogenic strains such as staphylococcus aureus.

Question 17

bacterial endospores

Answer 17

bacterial endospores are highly resistant, dormant forms of bacteria that can survive extreme environmental conditions like heat and dessication . they are produced by a certain type of bacteria like bacillus and clostridium to ensure survival in these extreme conditions