Introduction To Microbes

Question 1

What are the 4 microorganism causing human disease? List them in size order (small to large)

Answer 1

Virus
Bacteria
Fungi
Parasites

Question 2

What method is used to view bacteria?

Answer 2

Oil immersion microscopy

Question 3

What are prions?

Answer 3

Proteins (v small) capable of generating copies of themselves

Question 4

Name types of microorganisms that need a host cell to survive? (4)

Answer 4

Viruses, mycoplasma, chlamydiae, rickettsiae

Question 5

Why are mitochondria technically a bacteria?

Answer 5

Because they are derived form bacteria

Question 6

What is the lipid bilayer on the outside of a virus called?

Answer 6

The envelope

Question 7

What does the protein coat on a virus do?

Answer 7

Protects the genetic material

Question 8

What type of genetic code does a virus have?

Answer 8

Either DNA or RNA

But not both

Question 9

What are the spikes on the outside of a virus for?

Answer 9

For attaching to specific cell surfaces

Helps binding to host cells

Question 10

What are the 3 types of DNA virus classification?

Answer 10

Single-stranded, non enveloped
Double stranded, non enveloped
Double stranded, enveloped

Question 11

How might enveloped viruses be disprupted?

Answer 11

With chemicals ie alcohol

Question 12

What is tissue tropism?

Answer 12

the cells and tissues of a host which support growth of a particular viruses.
Some viruses have a broad tissue tropism and can infect many types of cells and tissues.
Other viruses may infect primarily a single tissue

Question 13

What type of genetic code is found within bacteria?

Answer 13

DNA

Question 14

How is antimicrobial resistance transmitted between bacteria?

Answer 14

Conjugation

Question 15

What is a Bacterium’s capsule made of?

Answer 15

Polysaccharides

Question 16

What is the function of bacteria’s capsules?

Answer 16

Protect against immunological attack

NB:it is possible to find different strains of capsules for the same organisms. Equally so you can find non-capsulated strains of the same bacteria

Question 17

What is a bacterium’s ‘tail’ called?

Answer 17

Bacterial flagellum

Question 18

What are the 3 layers of a bacterium surrounding the organism?

Answer 18

Plasma membrane (innermost)
Cell wall
Capsule

Question 19

What are the projections found on bacteria called?

Answer 19

Pili

Question 20

What are the 3 bacterial shapes?

Answer 20

Coccus (cocci pl.)-circle
Bacillus (bacilli pl.)-rods (rectangles)
Spirillus- long lines in a wave/spiral

Question 21

How are bacilli bacteria often found?

Answer 21

As singular isolated cells

Question 22

What are the 2 types of cocci bacteria arrangements?

Answer 22

Clusters and chains

Question 23

What is a gram stain?

Answer 23

Gram staining is a common technique used to differentiate two large groups of bacteria based on their different cell wall constituents

Question 24

What are the possible results from a gram stain and how are they identified?

Answer 24

Gram positive (stains purple)
Gram negative (stains red)

Question 25

What does a gram positive result mean for the structure of a bacterium?

Answer 25

The cell wall contains a peptidoglycan layer (external to the plasma membrane and next to periplasmic space)

Question 26

What does a gram negative stain mean for the structure of the bacterium?

Answer 26

It means there is still a peptidoglycan layer but it is much smaller and there is an outer membrane as well

Question 27

What types of organisms cannot be identified using a gram stain and why?

Answer 27

Those lacking a cell wall such as mycoplasma

Question 28

How is a gram stain performed?

Answer 28

- add positive charge crystal violet ( bind to negative cell components- wall proteins) - add iodine= crystal violet complex if formed. Crystalises dye in cell wall (stops it from being washed out) (ALL bacterial cells are stained purple) - add methanol/acetone- removes crystal violet unless cell wall is very thick- thicker wall = less likely methanol/acetone will remove purple crystals gram-positive organisms retain the stain (stay purple) whereas gram-negative species lose the stain, becoming colourless. -Add red (safranin) stains to colour the clear, gram-negative, bacteria pink or red

Question 29

What are the two classifications of bacteria according to their oxygen tolerance?

Answer 29

Aerobes | Anaerobes

Question 30

What are aerobes?

Answer 30

Bacteria that can survive in the presence of oxygen

Question 31

What are obligate aerobes?

Answer 31

Bacteria that require oxygen for survival, they absolutely rely on it!

Question 32

What are anaerobes?

Answer 32

Bacteria that can survive in the absence of oxygen

Question 33

What is an obligate anaerobe?

Answer 33

Bacteria that requires oxygen free environments to survive, oxygen is 'poisonous'

Question 34

In what situation can an obligate anaerobe tolerate oxygen?

Answer 34

If they're able to form spores

Question 35

What is a spore?

Answer 35

A dormant form of bacterial life | a rounded resistant form adopted by a bacterial cell in adverse conditions

Question 36

What are the two types of parasites? What are the difference?

Answer 36

Protozoa (unicellular) and helminths (worms, multicellular)

Question 37

Give an example of a protozoa parasite

Answer 37

Sarcodina

Question 38

Give an example of a helminth parasite

Answer 38

Threadworm

Question 39

Give an example of a yeast fungus

Answer 39

Torula

Question 40

Give an example of a mould fungus

Answer 40

Acremonium

Question 41

Give an example of a bacterium

Answer 41

E.Coli

Question 42

Give an example of a virus

Answer 42

HIV

Question 43

What are the two classifications of fungi? What is the difference between them?

Answer 43

Yeast (unicellular) | Molds (multicellular)

Question 44

Why is it difficult to treat fungi?

Answer 44

Because they are eukaryotes and it is difficult to target just the fungal cells and not our own

Question 45

What is hyphae?

Answer 45

a long, branching filamentous structure of a fungus, collectively called a mycelium

Question 46

What type of fungi have hyphae?

Answer 46

Molds

Question 47

What is bacterial pathogenesis?

Answer 47

process by which bacteria infect and cause disease in a host

Question 48

What is a virulence factor?

Answer 48

Molecules produced by bacteria/fungi/viruses/protozoa that add to their effectiveness and enable them to: - colonise a host - achieve immunoevasion - achieve immunosuppression - enter and exit cells - obtain nutrition from the host

Question 49

Name some virulence factors used by bacteria (4)

Answer 49

- host entry (capsule) - adherence to host cells (pili) - invasiveness (enzyme) - iron sequestration (siderophores)

Question 50

What two types of toxins are used in bacterial pathogenesis?

Answer 50

Exotoxins and endotoxins

Question 51

What are exotoxins? Give an example

Answer 51

toxin released by a living bacterial cell into its surroundings (deliberately released by bacteria) Diphtheria toxin

Question 52

What is the human papilloma virus associated with? (2)

Answer 52

Warts and cervical cancer

Question 53

What are helicobacter pylori associated with?

Answer 53

Stomach ulcers

Question 54

What must a virus have in order to count as a virus?

Answer 54

A capsid/coat of proteins

Question 55

What are endotoxins? Give an example

Answer 55

Given out during cell death (lipopolysaccharides)