Microbiology

Question 1

How big is the average bacteria?

Answer 1

1 micrometer

Question 2

What are the 5 core components of bacteria?

Answer 2

Cytoplasmic membrane 
Cytoplasmic matrix 
Ribosomes
Genome
Cell wall

Question 3

Where in the body would you find strict anaerobes?

Answer 3

The gut

Question 4

Sometimes blank is used to see whether immune cells can phagocytose?

Answer 4

Yeast

Question 5

If streptococcus divides in one plane, in what arrangement would it be found?

Answer 5

Chains

Question 6

Would you expect to find many gram negative rod bacteria on the skin?

Answer 6

No

Question 7

What is the effect of the bile salts added to MacConkey agar?

Answer 7

Bile salts reduce the ability of many bacteria to grow.

Question 8

On MacConkey agar, what colour is former if the bacteria are lactose fermenters, compared to non fermenters?

Answer 8

Colonisation by lactose fermenters results in a deep pink compared to non fermenters which cause yellow colouration.

Question 9

Name 4 environmental origins of skin/soft tissue pathogens?

Answer 9

Soil, surfaces, water, animals.

Question 10

What colour do gram positive bacteria stain?

Answer 10

Purple

Question 11

What colour do gram negative bacteria stain?

Answer 11

Pink

Question 12

Which type of bacteria has more peptidoglycan in its cell wall?

Answer 12

Gram positive

Question 13

Which type of bacteria has LPS in its cell wall?

Answer 13

Gram negative

Question 14

What has the only genome that could be RNA or DNA?

Answer 14

A virus

Question 15

What is a single celled parasite called?

Answer 15

Protozoa

Question 16

What is a parasite with tissue differentiation called?

Answer 16

Metazoa

Question 17

What component of all cells is highly conserved and used to differentiate the three domains?

Answer 17

16S ribosome subunit.

Question 18

How big is the average animal cell?

Answer 18

Approximately 10 micrometers

Question 19

Why are almost all bacterial genes dominant?

Answer 19

They have one circular chromosome. Only one allele per gene.

Question 20

What component of animal cells is thought to be an endosymbiont?

Answer 20

Mitochondria

Question 21

What are two main functions of bacterial cytoplasmic membrane?

Answer 21

• allows selective interaction with environment (entry of nutrients and elimination of waste)
• location of metabolic processes such as respiration.

Question 22

Is the cytoplasmic matrix of bacteria relatively hypotonic or hypertonic?

Answer 22

Hypertonic - contains more dissolved material than animals.

Question 23

Does the bacterial nucleoid make replication quicker or slower than animals?

Answer 23

Quicker- whilst mRNA is being transcribed, it is also being translated and then destroyed and recycled.

Question 24

Is plasmid replication dependent or independent of chromosome?

Answer 24

Independent

Question 25

Name two factors that antibiotics can interfere with?

Answer 25

Tight supercoiling of chromosome, | Peptidoglycan- which is found only in bacterial cells.

Question 26

What is a component that can only be found in gram positive walls (that isn't peptidoglycan)?

Answer 26

Teichoic acids (polymers of glycerol or ribitol)

Question 27

What happens if you swallow cholera toxin and why?

Answer 27

Short lived cholera - you don't have the bacteria to continue making the toxin so it doesn't last.

Question 28

What are 3 features of acid fast bacteria? And name an example of one.

Answer 28

Thick, waxy walls. Consist of peptidoglycan base layer. Conferred resistance to drying (which contributes to slow uptake of nutrients and therefore slow growth). Mycobacterium tuberculosis.

Question 29

Is a gram positive cell wall relatively porous?

Answer 29

Yes

Question 30

Is a gram negative cell wall relatively porous or impervious?

Answer 30

Impervious

Question 31

What is the function of fimbriae (pili)?

Answer 31

Adhesion, gene transfer.

Question 32

What features of bacteria allows them to survive a) short term and b) long term.

Answer 32

Capsules; endospores.

Question 33

What are flagella composed of?

Answer 33

Flagellin protein (H antigen)

Question 34

What are thin, long, hollow, helical filaments that bacteria use for locomotion?

Answer 34

Flagella

Question 35

What is needed to diagnose a bad case of cholera?

Answer 35

Rice water stools with motile bacteria present in wet preparation.

Question 36

Where in he body are bacteria loose in the lumen, and where are they attached to epithelia?

Answer 36

Bacteria in lumen of large bowel are mostly unattached from epithelia whereas pathogens in the throat use fimbriae to avoid the swallowing mechanism.

Question 37

How does transfer of plasmids occur in bacteria?

Answer 37

Using sex pili

Question 38

On which kind of bacteria are pili usually found?

Answer 38

On most gram negative and some gram positive bacteria.

Question 39

What can colonise the small intestine - which is usually mostly free of bacteria? And how do they do it?

Answer 39

Enterotoxigenic coli, adhere using adhesive pili (CS1 and CS3)

Question 40

What are bacterial capsules usually made of?

Answer 40

Polysaccharide extending from cell surface.

Question 41

What effect do capsules have on the appearance of colonies?

Answer 41

Makes them look larger and shiny.

Question 42

What are three functions of a bacterial capsule?

Answer 42

Protects against dehydration. | Contributes to virulence. Often protects against phagocytosis.

Question 43

When would bacterial sporulation normally occur?

Answer 43

When growth ceases due to a lack of nutrients and/or water.

Question 44

Name 6 features of endospores.

Answer 44

Do not replicate. Impermeable to most stains. Resistant to: Heat, UV, desiccation, and many chemicals.

Question 45

Which gram positive rods require a special spore stain in order to see them?

Answer 45

Clostridium and bacillus

Question 46

Describe the lag phase of the bacterial growth curve.

Answer 46

Bacteria adapt to media and start growing- getting longer and bigger.

Question 47

Describe the stationary phase of the bacterial growth curve.

Answer 47

As resources become more sparse, growth plateaus. Both growth and death occur simultaneously.

Question 48

What happens on the last phase of a bacterial growth curve?

Answer 48

The volume of bacteria decreases as byproducts produced make the media unfavourable.

Question 49

What is metabolism called if oxygen is the final electron acceptor?

Answer 49

Aerobic respiration

Question 50

What is metabolism called if an inorganic compound is the final electron acceptor?

Answer 50

Anaerobic respiration.

Question 51

What is metabolism called if an organic compound is the final electron acceptor?

Answer 51

Fermentation.

Question 52

Name a facultative anaerobes and describe what that means.

Answer 52

E. coli, once O2 has been used up, it can switch to anaerobic respiration.

Question 53

What is the name of an organism that grows best in low concentrations of O2?

Answer 53

Microaerophile

Question 54

What makes the holes in Swiss cheese?

Answer 54

Propionic acid produced by bacteria.