30. Overview of Infection and Immunity

Question 1

What are most of the top 10 best-selling drugs in the world? [EXTRA]

Answer 1

In 2018, 7 of the top 10 best-selling drugs were monoclonal antibodies.

Question 2

How many human and bacterial cells do we have in us? [EXTRA?]

Answer 2

• Human -> 10¹³
• Bacterial -> 10¹⁴

Question 3

How many bacterial genes are there in the human microbiome? How does this compare with the number of human genes? Why is this significant? [EXTRA]

Answer 3

• Around 2 million bacterial genes at any given time in a person, compared to around 22,000 human genes
• This means there is a much greater coding capacity in the microbiome than in the human
• If you factor in for differences between individuals, there are 235 million potential genes in the microbiome

Question 4

Give an example of a drug that we may look for in the human microbiome.

Answer 4

• Antiobiotics
• This is because antimicrobial agents are generated through intense competition between bacteria

Question 5

What is the importance of infectious diseases in evolution?

Answer 5

Infectious diseases tend to kill people before they reach reporoductive maturity, so they have a large effect on natural selection, thus altering the gene pool.

Question 6

Roughly what fraction of deaths globally are due to infectious diseases? [IMPORTANT]

Answer 6

Around 25% [CHECK THIS]

Question 7

Compare the percentage of global deaths caused by infectious diseases, cardiovascular diseases and cancers.

Answer 7

From most to least prevalent causes of death:

• Cardiovascular diseases
• Infectious diseases
• Cancers

Question 8

In what population and age subsets are infectious disease deaths especially common?

Answer 8

Common in children under 5 in less developed countries.

Question 9

Can all bacteria be Gram stained?

Answer 9

No. For example, Mycobacterium tuberculosis cannot be Gram stained due to the high concentration of mycolic acids in the cell membrane, which makes the bacterium impervious to the stain.

Question 10

Describe the structure of Gram positive bacteria.

Answer 10

Cell wall contains:

• Thick peptidoglycan layer -> Various proteins and teichoic acids within it
• Single membrane on the inside of the peptidocglycan layer

Question 11

Describe the structure of Gram negative bacteria.

Answer 11

Cell wall contains:

• Outer membrane -> Containing lipopolysaccharides (LPS)
• Periplasm (where the peptidoglycan is)
• Inner membrane

Question 12

In what type of bacteria are lipopolysaccharides found and how?

Answer 12

• In Gram-negative bacteria
• The lipid portion is embedded in the outer membrane, while the polysaccharide chains extend outwards

Question 13

What is the periplasm in Gram-negative bacteria?

Answer 13

• The layer between the inner and outer membranes.
• It is where a thin layer of peptidoglycan is found.

Question 14

What exactly is the cell wall in bacteria?

Answer 14

Question 15

What are the main differences between Gram-positive and Gram-negative bacteria?

Answer 15

Question 16

Why do bacteria continue to cause a problem for humans?

Answer 16

Mutation

Question 17

If not covered later, add flashcards on the complement pathway.

Answer 17

Do it.

Question 18

Draw a summary of the complement pathway.

Answer 18

Question 20

Define viruses.

Answer 20

Obligate intracellular parasites which can cause disease by inducing inflammation, causing cell death, increasing the likelihood that a tumour will develop.

Question 21

What are the 4 main categories of bacteria?

Answer 21

• Pyogenic bacteria (pus-forming)
• Enteric bacteria -> Found in the intestines of animals
• Exotoxin producers
• Facultative intracellular parasites