Microbes & disease

Question 1

What viruses cause disease? Which do not?

Answer 1

DO:
Obligate parasites - viruses

DONT:
Non pathogenic/opportunistic/obligate parasites - bacteria, protozoa, fungi, worms

Question 2

What is mutualism?

Answer 2

Positive for both involved

Question 3

What is commensalism?

Answer 3

Positive for parasite, neutral for host

Question 4

What is parasitism?

Answer 4

Positive for parasite, negative for host

Question 5

Advantages of parasitism

Answer 5

Protection from outside environment
Provides nutrients
Travel without expending energy
More energy for reproduction

Question 6

How do pathogens evolve to be more effective?

Answer 6

Pathogens normally evolve to be less pathogenic over time

More pathogenic disease causes isolation so harder for the pathogens to reproduce and spread

Less pathogenic more successful as it is spread easily as people can be asymptomatic

Question 7

Bacteriophages role in the ocean

Answer 7

bacteriophages (viruses) kill and lyse between 15% and 40% of the ocean’s bacteria every single day

Question 8

How has human activity affected parasitism?

Answer 8

Human activity transporting disease around the world means there are more devastating impacts on their new hosts

Disease comes across new ‘naïve’ populations that are more susceptible to and have a higher mortality rate

Chytrid fungus – 200 amphibian species threatened

White-nose syndrome (WNS) – Bats 6 million killed

Question 9

What is the form of Ebola virus?
Shape/size/RNA/class?

Answer 9

Filamentous virus:
Shape is variable (length tubes and
number of branches). Typical size 80 nm wide and 800-1000nm long.

Membrane enveloped.

Negative sense single stranded RNA (-ssRNA)

Class 5 – needs to transcribe its minus strand to make a positive strand of RNA that will behave like messenger RNA and make viral proteins with the host

Question 10

How many proteins and genes does ebola have?

Answer 10

7 genes

8 proteins (soluble and insoluble glycoproteins)

Question 11

What does nuclear protein, transcription factors, matrix proteins and glycoprotein do in ebola?

Answer 11

Nuclear protein – helps to package RNA and nucleic acid material

Transcription factor – replicates RNA in host

Matrix proteins - make up capsid

Glycoprotein – attach to receptors of cell and allow virus to enter host cell

Has Polymerase enzyme

Question 12

Symptoms of ebola

Answer 12

Initial symptoms:
High fever
Headache
Joint and muscle aches
Sore throat
Weakness
Stomach pain
Lack of appetite

Later symptoms:
Bleeding inside the body
Bleeding from the eyes, ears, and nose
Vomiting or coughing up blood
Bloody diarrhoea
Death

Question 13

How does ebola infect body (aetiology)

Answer 13

Entry to host cell.

Trick host into replicating viral protein and nucleic acid (RNA) damaging and bursting cells

Interaction with the immune system (cytokine storm) - immune system produce reactive oxygen species or antibodies that stick to virus halting/slowing its progress

Question 14

What is non-specific immune system response? (Innate)

Answer 14

Response time - hours

Specialty - limited/fixed

Response to repeat infection - identical to primary response

Major components - physical barriers, chemicals and phagocytes

Question 15

What is specific immune system response? (adaptive)

Answer 15

Response time - days

Specifity - highly diverse improving during corse of infection

Response to repeat infection - more rapid than primary response

Major components - Lymphocytes- T cells, B-cells and antibodies.

Question 16

What is the cytokine storm?

Answer 16

Inhibition of key cells in the immune system allows the virus to replicate unchecked.

Cytokine signal too strongly resulting in massive immune response which attacks virus and healthy cells around it

Blood vessels take the brunt of it, becoming leaky.

The kidney can’t regulate fluid balance. The spleen can’t produce clotting factors.

The liver, lungs and kidneys leek fluid and shut down