Chapter 1: The Microbial World and You

Question 1

Explain the meaning of each of the following components: staphylo-coccus-aureus

Answer 1

Staphylo describes the clustered arrangements of the cells;
coccus indicates that they are shaped like spheres;
aureus, latin for golden, describes the colour of many colonies of this bacterium.

Question 2

Explain the meaning of coli in E. coli.

Answer 2

Coli, the species name, simply means that E. coli lives in the colon, or large intestine. Escherichia is named after a physician, Theodor Escherich.

Question 3

Name 3 common shapes of bacterial cells.

Answer 3

1. Bacillus (bah-SIL-lus) - rodlike
2. Coccus (KOK-kus) - spherical
3. Spiral

Question 4

Describe the composition of bacterial cell walls.

Answer 4

Bacterial cell walls consist of a carbohydrate and protein complex called peptidoglycan.
(Essentially, a polymer consisting of sugars and amino acids)

Question 5

What do algal cell walls consist of?

Answer 5

Cellulose.

Question 6

How do bacteria reproduce?

Answer 6

Binary Fission

Question 7

True or false:

1. The cell walls of archaea contain peptidoglycan.
2. Archaea cause diseases in humans.

Answer 7

1. FALSE

2. FALSE

Question 8

Explain the meaning of strepto-

Answer 8

It indicates that cells appear in chains.

Question 9

Explain the meaning of pyo (e.g. Streptococcus pyogenes)

Answer 9

It forms pus.

Question 10

Name the types of archaea that:

1. Produce methane as a waste product from respiration - in the intestines of cattle
2. Live in extremely salty environments such as the Dead Sea
3. Live in hot sulphurous water such as hot springs at Yellowstone

Answer 10

1. Methanogens
2. Extreme halophiles
3. Extreme thermophiles

Note: Halo denotes salt (halogens)

Question 11

Determine whether the following are prokaryotes or eukaryotes:

1. Bacteria
2. Archaea
3. Fungi
4. Protozoa
5. Algae

Answer 11

1. Prokaryotes
2. Prokaryotes
3. Eukaryotes
4. Eukaryotes
5. Eukaryotes

Question 12

Name the envelope surrounding the cell’s genetic material in eukaryotic cells.

Answer 12

The nuclear membrane.

Question 13

True or false:

1. Fungi can carry out photosynthesis.
2. Mushrooms are fungi.

Answer 13

1. FALSE

2. TRUE

Question 14

Describe the composition of fungal cell walls.

Answer 14

Chitin, a nitrogen containing polysaccharide.

Question 15

Name (and describe) three examples of fungi.

Answer 15

1. Yeasts, oval microorganisms larger than bacteria.
2. Moulds, which form visible masses called mycelia.
3. Slime moulds, which are ameba-like protozoa.

Question 16

What are mycelia and hyphae?

Answer 16

Mycelia are visible masses formed by moulds. Each mycleium consists of long thread-like filaments known as hyphae that branch and intertwine.

Question 17

True or false: Fungi can reproduce sexually.

Answer 17

TRUE: Fungi can reproduce both sexually and asexually.

Question 18

Name 3 means by which protozoa move.

Answer 18

1. By pseudopods - pseudopods are extensions of the cytoplasm.
2. By flagella - long moving appendages for locomotion
3. By cilia - shorter moving appendages for locomotion

Question 19

Determine whether the following types of microorganisms reproduce asexually, sexually, or both.

1. Bacteria
2. Archaea
3. Fungi
4. Protozoa
5. Algae

Answer 19

1. Asexually, generally by binary fission
2. Asexually
3. Both sexually or asexually
4. Both sexually and asexually
5. Both sexually and asexually

Question 20

True or false: Viruses consist of cells

Answer 20

FALSE: Viruses are acellular (that is, they are not cells)

Question 21

Briefly describe the structure of a virus.

Answer 21

A virus consists of a core made of either type of nucleic acid: DNA or RNA. The core is surrounded by a protein coat, which is sometimes encased by a lipid membrane known as an envelope.

Question 22

Explain why a virus is not considered a living cell.

Answer 22

1. All living cells have RNA and DNA, while a virus does not.
2. Living cells can reproduce as self-sufficient units, while viruses can reproduce only with the cellular machinery of other organisms. (That is, viruses are considered to be living only when they multiply within host cells, and are inert outside of living hosts.)

Question 23

What are helminths?

Answer 23

Helminths comprise two major groups of parasitic worms, flatworms and roundworms. These worms are multicellular animal parasites.

Question 24

What are aseptic techniques?

Answer 24

Aseptic techniques are procedures that prevent contamination by unwanted microorganisms.
Note: septic means that something is infected with microorganisms.

Question 25

Explain why wine and beer soured (or spoiled) when transported over long distances.

Explain how this problem was solved.

Answer 25

In the production of wine and beer, yeasts convert the sugars in these fluids into alcohol in the absence of air, in a process known as fermentation. In the presence of air, bacteria changed the alcohol into vinegar (acetic acid).

Pasteur’s solution was to heat the beer and wine just enough to kill most of the bacteria that caused the spoilage. This process is known as pasteurisation, now used to reduce spoilage and kill potentially harmful bacteria in milk and alcohol beverages.

Question 26

What does virulence mean?

Answer 26

Virulence refers to a pathogen’ (not just virus’) ability to cause disease. For example, the bacterium that causes fowl cholera loses its ability to cause disease (i.e. loses its virulence/becomes avirulent) after it being grown in the laboratory for long periods.

Question 27

Which microorganisms produce antibiotics naturally?

Answer 27

Bacteria and fungi.

Question 28

Chemotherapeutic agents prepared from chemicals in the laboratory are known as _____.

Answer 28

Synthetic drugs

Question 29

Define bacteriology.

Answer 29

Bacteriology is the study of bacteria.

Question 30

Fun Fact

Answer 30

Microbes that cause food spoilage - such as the decomposition of meats and the rancidity of fats and oils - are in the minority. The majority of microbes benefit humans, other animals and plants in many ways. For example, bacterial enzymes are used to break down cellulose so that the resultant sugars can be metabolised into ethanol by yeasts, while microbes that produce methane and ethanol can be used as alternative fuels. `

Question 31

What is microbial ecology the study of?

Answer 31

It is the study of the relationship between microorganisms and the environment. It also involves how microbial populations interact with plants and animals in various environments.

Question 32

Discuss how ADA deficiency leads to SCID.

Answer 32

ADA is an enzyme that eliminates a by-product that is toxic to lymphocytes. ADA deficiency is a cause of severe combined immunodeficiency disease (SCID), in which cells of the immune system are inactive or missing. ADA deficiency is a genetic disorder and has been treated by gene therapy.

Question 33

What is atherosclerosis?

Answer 33

Atherosclerosis is the buildup of fatty deposits on the inner walls of blood vessels. Atherosclerosis in the coronary arteries is known as coronary artery disease (CAD).
Note: CAD is also referred to as coronary heart disease (CHD).

Question 34

Discuss how LDL-receptor deficiency can increase the risk of atherosclerosis and coronary heart disease.

Answer 34

Cholesterol circulates in the blood in the particles known as low-density lipoproteins (LDLs). LDL-receptor deficiency is characterised by low-density lipoprotein receptors being defective, meaning that LDL cannot enter cells.

The LDL remains in the blood in high concentrations and leads to fatty plaque formation in blood vessels. This increases the risk of atherosclerosis and CHD.

Question 35

What do we mean by resistance in microbiology?

Answer 35

Resistance is the ability to ward off diseases.

Question 36

What is a biofilm?

Answer 36

A biofilm is a complex aggregation of microbes attached/adhered to each other and a (usually solid) surface.

Question 37

What is endocarditis?

Answer 37

It refers to inflammation of the endocardium, the inner lining of the heart.