Immuno - Microbial Infection

Question 1

What are viruses?

Answer 1

Not cells in their own right - obligate parasites

Question 2

What do viruses contain as their genetic material?

Answer 2

DNA or RNA

Question 3

How do viruses replicate?

Answer 3

Using cells nuclear replication machinery

Question 4

What type of specificity do viruses exhibit?

Answer 4

Show some host cell specificity however they infect almost all other forms of life.

Question 5

How do viruses divide from one another?

Answer 5

Budding from host cells, sometimes allowing the virus to have an outer membrane.
Or cytolysis where a host cell ruptures, therefore releasing virus into the environment.

Question 6

What are the routes of viral infection?

Answer 6

Faecal oral
Blood borne
Air borne
Insect vectors

Question 7

What is an example of a virus, its genetic material and its ability to replicate and divide?

Answer 7

HIV is an enveloped virus that contains RNA and there reverse transcriptase. HIV allows the host cell to survive after budding.

Question 8

What are bacteria?

Answer 8

Prokaryotes

Question 9

What do bacteria lack in terms of cell structure?

Answer 9

No organelles or internal membranes

Question 10

What bacteria have internal membranes?

Answer 10

Photosynthetic bacteria (not pathogenic)

Question 11

Are prokaryotes haploid or diploid?

Answer 11

Haploid

Question 12

What does the haploid number of chromosomes in a bacteria mean in terms of effect?

Answer 12

Mutated genes in bacteria will always have an effect.

Question 13

What makes up the cell wall of bacteria?

Answer 13

Peptidogylcan

Question 14

How do bacteria divide?

Answer 14

Binary fission - very rapidly cells can reach rapid numbers due to exponential division

Question 15

What is the role of the pilli?

Answer 15

Important for cell adhesion

Question 16

What is the role of capsule?

Answer 16

Prevent cells desiccation and hinder phagocytosis

Question 17

What is the role of the flagella?

Answer 17

Aid in motility of the cell

Question 18

How is the shigella bacteria transmitted and were does it affect?

Answer 18

Faecal oral route - affects the GI tract.

Question 19

Why does the shigella bacteria have no flagella?

Answer 19

Cells has developed a mechanism so that it can nucleate host cell actin filaments at the tail of the bacteria. This then allows the bacteria to be propelled around the cytoplasm and thus infect other cells

Question 20

How do pathogens evolve so quickly?

Answer 20

Viruses have no way of correcting mistakes made in DNA replication unlike the polymerases of human cells. This makes viruses much more prone to expressing mutations. Also, bacteria divide at a much faster rate via binary fission and they are haploid, meaning that the rate of expressed mutation occurs a lot more quickly.

Question 21

What are fungi?

Answer 21

Single celled eukaryotes

Question 22

What are the 3 groups of fungi?

Answer 22

Cutaneous
Mucosal
Systemic

Question 23

How do we classify fungi?

Answer 23

Based on where they infect/ cause mycoses which is the term for ideas caused by fungi.

Question 24

What can fungi occur as?

Answer 24

Yeasts, filaments or both.

Question 25

What is the difference between yeasts and filaments?

Answer 25

Yeasts can bud or divide, filaments (hyphae) have cross walls or septa

Question 26

What is an example of a fungi?

Answer 26

Candida Albicans

Question 27

What are protozoa?

Answer 27

Single celled eukaryotes

Question 28

What does protozoa include?

Answer 28

Intestinal, blood and tissue parasites

Question 29

How do protozoa replicate?

Answer 29

Either via binary fission or through the formation of trophozoites

Question 30

What is the life cycle of a protozoa?

Answer 30

Complex life cycle involving 2 or more host cells

Question 31

What is the method of infection for protozoa?

Answer 31

Usually through an insect or invertebrate vector.

Question 32

What is Genus plasmodium?

Answer 32

Causes malaria

Question 33

How is malaria transferred?

Answer 33

Mosquito vector

Question 34

How does malaria replicate?

Answer 34

Forms mosquito belt and generates trophozoites within the cell which then utilise tissue and blood parasites.

Question 35

What is Leishmania species?

Answer 35

Causes leishmaniasis

Question 36

How is leishmaniasis transferred?

Answer 36

Sandfly vector

Question 37

How is leishmaniasis replicated?

Answer 37

Trophozoites inside cell and utilises blood or tissue parasites

Question 38

What are Helminths?

Answer 38

Multicellular metazoa with eukaryotes

Question 39

What are metazoa?

Answer 39

Organism that contains differentiated cells and tissues

Question 40

Are helminths microscopic?

Answer 40

No - they are often visible to the naked eye.

Question 41

What is the life cycle of helminths?

Answer 41

Life cycle occurs outside of the host cell therefore they do not require a vector intermediate.

Question 42

What are the 3 main types of helminth?

Answer 42

Roundworms (Ascaris) Flatworms (Schistosomes) Tapeworms

Question 43

How do we often treat helminth infection?

Answer 43

Chemotherapy however this is not very efficient

Question 44

What are one of the three human disease causing species of flukes?

Answer 44

Schistosomes

Question 45

What do schistosomes require?

Answer 45

A small intermediate host, such as a freshwater snail

Question 46

When do people get infected with schistosomes?

Answer 46

When they enter contaminated water.

Question 47

How does a schistosome infect someone?

Answer 47

Cercaria from freshwater snails burrow into the skin of the affected person and migrate to the liver. In the hepatic portal vein, pairs of adult worms release eggs which go back towards the faeces via the gut. However, on their way back, the eggs travel through tissues to cause inflammation as these eggs have spines on them.

Question 48

How do we treat schistosomes?

Answer 48

Antimicrobials are available however programmes to remove freshwater snails have also been effective.