Session 4-bacteria, viruses and DNA/RNA envelopes

Question 1

How do you know if pathogenic microbes are causing disease? (Use Henle-Koch’s postulates(suggest or assume)-cause-effect relationship)

Answer 1

1. must be present in every case of disease and not healthy person-do this by isolating in pure culture
2. agent must not be found in cases of other disease
3. agent must be capable of reproducing disease in experimental animals

Question 2

Give 3 examples of why an individual may be more susceptible to particular infections.

Answer 2

• weakened immune system
• no access to healthcare
• lifestyle

Question 3

what 3 things influence the outcome of infection?

Answer 3

1. hosts immune system
2. affected body system
3. drugs used

Question 4

Say yes or no to the following to determine the properties of a eukaryotic cell. Does it have: cell wall, envelope, capsid, membrane bound organelles, nucleus, DNA/RNA, pili/flagella, reverse transcriptase

Answer 4

no,no,no,yes,yes,yes,no,no

Question 5

what 2 materials could the bacteria cell wall be made out of and which is on gram negative and positive?

Answer 5

peptidoglycan (+ve and -ve) or lipopolysaccharide (-ve)

Question 6

say yes or no to the following to determine whether they are present in bacteria or not: capsid (protein shell of virus), membrane bound organelles, nucleus, DNA/RNA, pili/flagella,reverse transcriptase (catalyses formation of RNA from DNA)

Answer 6

no,no,no,yes,yes,no

Question 7

say yes or no to determine whether viruses contain these structures: envelope, organelles, capsids (protein shell), DNA/RNA, pili/flagella, reverse transcriptase

Answer 7

yes,no,yes,yes,no,yes

Question 8

what determines whether a bacteria is gram positive or negative?

Answer 8

cell wall

Question 9

what colour is gram positive stained and what colour is gram negative stained?

Answer 9

• positive=blue

- negative=red

Question 10

what 3 components are used to stain the gram negative bacteria red?

Answer 10

crystal violet stain–>iodine forms complex with crystal violet—>acetone/methanol extracts complex—->red dye

Question 11

what are the acid fast stains used for?

Answer 11

detect bacterial causes of TB and leprosy (disease affecting the skin,mucous membranes,nerves and causes discolouration and lumps on skin. In severe cases, can cause disfigurement and deformities)

Question 12

define infection

Answer 12

• multiplication of pathogenic microbe

- on/in host, causing damage

Question 13

why are RNA viruses more likely to mutate?

Answer 13

less stable

Question 14

name 3 DNA enveloped viruses and their causes

Answer 14

1. Hepatitis B=inflamed liver
2. herpes=oral/genital
3. Smallpox=fever and pustule (raised spot or rounded swelling) that could leave permanent scars

Question 15

name a DNA non enveloped virus and its cause

Answer 15

HPV=warts and cervical (lower part of uterus just above vagina) cancer

Question 16

Name 3 RNA enveloped viruses and their causes

Answer 16

1. HIV=aids
2. Rubella (german measles)=rash
3. Rotavirus=diarrhoea

Question 17

Name 2 RNA non enveloped viruses and their causes

Answer 17

1. Poliomyelitis=inflamed spinal cord (myelo=spinal cord or marrow)
2. Hepatitis A=liver disease