Topic 6 - Microbiology and Pathogens

Question 1

What is the purpose of culturing microorganisms?

Answer 1

To provide microorganisms with the nutrients, level of oxygen, pH, and temperature they need to grow in large numbers for observation and measurement.

Question 2

What is aseptic technique in microbiology?

Answer 2

A method to prevent the growth of unwanted organisms by only introducing desired bacteria into sterile conditions.

Question 3

List the steps involved in the aseptic culture technique.

Answer 3

• Decide on the microorganisms to culture and obtain the culture
• Provide appropriate nutrients in sterile nutrient medium (broth or agar)
• Inoculate the culture using sterile techniques

Question 4

What is the lag phase in microbial growth?

Answer 4

The phase where microorganisms are adapting to their environment and the reproduction rate increases slowly.

Question 5

What occurs during the log phase of microbial growth?

Answer 5

Microorganisms grow at their maximum rate as long as there are sufficient nutrients.

Question 6

Describe the stationary phase in microbial growth.

Answer 6

The death rate equals the reproduction rate due to the buildup of waste products and lack of nutrients.

Question 7

What happens during the death phase of microbial growth?

Answer 7

Deaths exceed new cell population as conditions continue to deteriorate.

Question 8

What is a haemocytometer used for?

Answer 8

To count bacterial cells in a liquid sample.

Question 9

How does turbidimetry measure microbial growth?

Answer 9

It measures the cloudiness of a culture, which is linked to cell count through absorbance.

Question 10

What is dilution plating?

Answer 10

A method where serial dilutions are made to isolate and count individual colonies from a culture.

Question 11

Define endotoxins.

Answer 11

Lipopolysaccharides in the outer membrane of Gram-negative bacteria that can have local effects upon release.

Question 12

What are exotoxins?

Answer 12

Soluble proteins produced and released by bacteria that spread throughout the body in blood and body fluids.

Question 13

What is tuberculosis and how is it caused?

Answer 13

A bacterial disease caused by Mycobacterium tuberculosis that infects phagocytes in the lungs.

Question 14

What are bactericidal antibiotics?

Answer 14

Antibiotics that kill bacteria by destroying their cell wall.

Question 15

What is the function of bacteriostatic antibiotics?

Answer 15

To inhibit the growth and reproduction of bacteria by stopping protein synthesis and nucleic acid production.

Question 16

True or False: Antibiotic resistance occurs when bacteria acquire a selective advantage.

Answer 16

True

Question 17

List some methods hospitals use to control antibiotic-resistant infections.

Answer 17

• Screening new patients
• Isolating infected patients
• Completing antibiotic courses
• Strict hygiene practices

Question 18

What is the transmission method for influenza?

Answer 18

Droplet infection, direct contact with virus-filled mucus, direct contact with animal waste, and infected surfaces.

Question 19

How does the stem rust fungus infect plants?

Answer 19

Spores germinate in water on plants, producing hyphae that enter through the stomata and absorb nutrients.

Question 20

What are the pathogenic effects of Plasmodium spp. (Malaria)?

Answer 20

Causes paroxysm, sweating, shaking, muscle pains, headaches, liver damage, and anemia.

Question 21

What are some challenges in controlling endemic diseases?

Answer 21

• Diseases are often widespread
• Difficult to remove all sources of infection
• Expensive treatment

Question 22

List some physical barriers to infection.

Answer 22

• Skin
• Stomach acid
• Gut and skin flora

Question 23

What is the role of inflammation in the immune response?

Answer 23

Histamines released by white blood cells cause vasodilation, increasing blood flow and allowing antibodies and white blood cells to reach the infected area.

Question 24

What is phagocytosis?

Answer 24

A process where white blood cells engulf pathogens and destroy them using lysosomal enzymes.

Question 25

What is the specific immune response?

Answer 25

An antigen-specific response relying on lymphocytes to produce responses specific to one type of pathogen.

Question 26

Fill in the blank: B cells mature in the _______.

Answer 26

[bone marrow]

Question 27

Fill in the blank: T cells move to the _______.

Answer 27

[thymus]

Question 28

What process kills bacterial cells by damaging their cell wall?

Answer 28

Lysis ## Footnote Lysis is the breaking down of the cell wall of bacteria, leading to cell death.

Question 29

What is phagocytosis?

Answer 29

A process in which white blood cells engulf pathogens and destroy them by fusing a pathogen enclosed in a phagocytic vesicle with a lysosome ## Footnote This process is crucial for the immune response against infections.

Question 30

What type of immune response is specific to one type of pathogen only?

Answer 30

Specific immune response ## Footnote This response relies on lymphocytes produced in the bone marrow.

Question 31

Where do B cells mature?

Answer 31

In the bone marrow ## Footnote B cells are involved in the humoral immune response.

Question 32

Where do T cells mature?

Answer 32

In the thymus gland ## Footnote T cells are involved in the cell-mediated immune response.

Question 33

What is the first step in the cell-mediated response?

Answer 33

Pathogen invades a host cell ## Footnote This initiates the immune response by activating the host cell.

Question 34

What do host cells display on their Major Histocompatibility Complexes to become antigen-presenting cells?

Answer 34

Antigens ## Footnote This display is crucial for T cell activation.

Question 35

What do T Killer cells do after being stimulated by cytokines?

Answer 35

They divide by mitosis ## Footnote This results in the formation of active T Killer cells and T Killer Memory cells.

Question 36

What effect do active T Killer cells have on infected cells?

Answer 36

They cause pores to form in the cell membrane ## Footnote This leads to the death of the infected cell.

Question 37

What is the role of macrophages in the humoral response?

Answer 37

They act as antigen-presenting cells (APCs) ## Footnote Macrophages engulf bacteria and present antigens to T Helper cells.

Question 38

What do B cells do after binding to antigens?

Answer 38

They act as APCs and present antigens on MHCs ## Footnote This is crucial for T Helper cell activation.

Question 39

What do B effector cells differentiate into?

Answer 39

Plasma cells ## Footnote Plasma cells are responsible for synthesizing antibodies.

Question 40

What are the effects of antibodies?

Answer 40

They include: * Agglutination * Lysis * Opsonization * Precipitation/Neutralization ## Footnote These effects enhance the immune response against pathogens.

Question 41

What is the function of T Suppressor cells?

Answer 41

They stop the immune response ## Footnote This regulation is essential to prevent overreaction of the immune system.

Question 42

What is the difference between active and passive immunity?

Answer 42

Active immunity results from the production of antibodies by the immune system, while passive immunity results from the introduction of antibodies from another person or animal ## Footnote This distinction is important in understanding how immunity is acquired.

Question 43

What is natural active immunity?

Answer 43

Immunity arising from exposure to an antigen or disease ## Footnote This occurs when the body encounters a pathogen naturally.

Question 44

What is artificial active immunity?

Answer 44

Immunity acquired through vaccinations ## Footnote Vaccination stimulates the immune system to produce antibodies.

Question 45

What is herd immunity?

Answer 45

It occurs when enough people are vaccinated to make transmission of a disease very unlikely ## Footnote Typically requires 80-90% vaccination coverage.

Question 46

What is the process of immunization?

Answer 46

It protects people from infection using passive or active artificial immunity ## Footnote Vaccination is a method of achieving immunization.

Question 47

How does the secondary immune response differ from the primary response?

Answer 47

It has less lag time, is more rapid, and produces more antibodies and T Killer cells ## Footnote This is due to the presence of Memory T and B lymphocytes from the primary infection.