Principles of Infection I

Question 1

What are micro - organisms?

Answer 1

Bacteria / Virus / Fungi which is TOO small to be seen by the naked eye.
Often exists in single celled form or a colony of cells.

Question 2

What is a phylogenetic tree?

Answer 2

Diagram which represents evolutionary relationships among organisms.

Question 3

What is a key rule about phylogenetic trees?

Answer 3

Two species are MORE RELATED if they have a MORE RECENT common ancestor.

Question 4

Name some classifications of micro - organisms.

Answer 4

Helminths = Animals 
Fungi = Fungi 
Algae = Algae
Protozoa = Protozoa
Archea = Crenarchaeota

Question 5

Definition of infection.

Answer 5

This is a transmissible / communicable form of disease which is caused by microorganisms (including viruses)

Question 6

What are the 5 stages of infection?

Answer 6

Incubation 
Prodromal 
Illness
Decline
Convalescence

Question 7

Name some types of infection.

Answer 7

Bacterial
Fungal
Viral
Parasitic

Question 8

What are the key features of a bacterial cell?

Answer 8

There is no nucleus and they have a peptidoglycan cell wall.
They also have circular DNA and a lack of membrane bound organelles.

Question 9

What type of cell are bacterial cells?

Answer 9

Eukaryotic Cells.

Question 10

How does bacterial cells replicate?

Answer 10

Binary Fission = Asexual reproduction occurs and therefore, the bacterial cell is split into 2 separate bodies.

Question 11

List some infections caused by bacterial cells.

Answer 11

Cholera
Tuberculosis
Syphilis
Bacterial Meningitis

Question 12

In terms of gram stains, name the 2 types of gram stains which can be achieved.

Answer 12

Gram Positive

Gram Negative

Question 13

What is the difference between gram negative and gram positive stains?

Answer 13

Gram Negative LOSES the purple stain whereas the gram positive KEEPS the purple stain.

Question 14

Why does the gram negative cell LOSE the purple stain?

Answer 14

It loses the purple stain because of the presence of a peptidoglycan cell wall.

Question 15

What is the structure of a gram positive cell?

Answer 15

There are thick layers of peptidoglycan walls but there is NO outer lipid membrane.
Has one inner plasma membrane and this can be penetrated EASILY by antibiotics.

Question 16

What is the structure of a gram negative cell?

Answer 16

There are thin layers of peptidoglycan walls but there is ONE outer lipid membrane which makes it harder to penetrate the cell wall.

Question 17

Which one is easier to kill with antibiotics?

Answer 17

Gram Positive is EASIER to kill because the thick peptidoglycan wall can absorb the antibiotics easily.

Question 18

What are the main shapes of bacteria?

Answer 18

Cocci = Spheres
Bacilli = Rods
Spirlla = Spirals
Vibrio = Curves

Question 19

What are the 3 main types of bacteria regarding oxygen?

Answer 19

Aerobic
Anaerobic
Facultative Anaerobes

Question 20

Explain aerobic bacteria in more detail.

Answer 20

This is bacteria which requires oxygen in order to grow.

Question 21

Explain anaerobic bacteria in more detail.

Answer 21

This is bacteria which grows in the ABSENCE of oxygen due to oxygen ‘poisoning ‘ the enzymes.

Question 22

Explain facultative bacteria in more detail.

Answer 22

This is bacteria which can change their metabolic processes depending on the presence of oxygen.
They can switch between fermentation and respiration.

Question 23

What can viruses do?

Answer 23

They can replicate by infecting a host cell. These burst and spread the infection to OTHER PARTS of the cell.

Question 24

What are the key features of viruses?

Answer 24

These are NOT living cells and the nucleic acid is surrounded by a protein coat.

Question 25

Name the stages of virus reproduction.

HINT = 6 stages

Answer 25

Attachment 
Penetration
Uncoating
Replication
Assembly
Release

Question 26

Explain the attachment stage in virus reproduction.

Answer 26

The virus must attach itself to the host cell.

Question 27

Explain the penetration stage in virus reproduction.

Answer 27

Virus enters the cell via RECEPTOR MEDIATED ENDOCYTOSIS and is known as ‘Viral Entry’.

Question 28

Explain the uncoating stage in virus reproduction.

Answer 28

This the process by which the viral capsid is REMOVED.

This results in the genomic nucleic acid being released.

Question 29

Explain the replication stage in virus reproduction.

Answer 29

This is the synthesis of the viral messenger RNA and is essentially where VIRAL PROTEIN synthesis occurs.

Question 30

Explain the assembly stage in virus reproduction.

Answer 30

This is where some modification of proteins occurs.

This particular modification is knowns as MATURATION.

Question 31

What is the name of the process of modification which occurs during the assembly stage of virus reproduction?

Answer 31

This is known as MATURATION.

Question 32

Explain the release stage in virus reproduction.

Answer 32

The viruses can be released from the HOST CELL.

The viruses are released via LYSIS.

Question 33

What is the process by which viruses are released?

Answer 33

Lysis.

Question 34

Explain the process of lysis.

Answer 34

The process which kills the cell by bursting its membrane.

Question 35

Name the infections caused by viruses.

Answer 35

HIV / Aids 
Smallpox
Common Cold
Ebola
Flu