Public health microbiology

Question 1

Chlamydia and mycobacterium do not contain peptidoglycan, True or false?

Answer 1

True - this means that antibiotics that target the cell wall are useless in treating infections caused by these bacteria

Question 2

What is peptidoglycan composed of?

Answer 2

Carbohydrate (NAG and NAM)

Peptide chains

Question 3

Only bacteria contain NAG. True or false?

Answer 3

False - only bacteria contain NAM

Question 4

Are all human amino acids L or D form? And what is the significance of this?

Answer 4

All amino acids are L form - this means the D-amino acids in bacteria can be targeted

Question 5

Is Meso-DAP found in humans?

Answer 5

No it is only present in bacteria

Question 6

Is cross link of amino acid chains only associated with NAG or NAM?

Answer 6

NAM (and not necessarily all NAM residues)

Question 7

Is the level of cross-linking the same in all species?

Answer 7

No cross-linking is species dependent - it varies from organism to organism

Question 8

What is lost when there is cross-linking between two chains?

Answer 8

2 D-ala therefore chain becomes a tetrapeptide

Question 9

What does the interbridge join together?

Answer 9

it joins meso-DAP to D-ala on a previously synthesised chain

Question 10

What is the cell membrane composed of?

Answer 10

Phospholipids
Proteins
Fatty acids

Question 11

What is the function of the cell membrane?

Answer 11

Permeability barrier - regulates entry and exit

Metabolically active e.g. energy production (ATP Synthesis)

Question 12

What is the mesosome for?

Answer 12

DNA of organism is attached to this structure

Question 13

DNA is packaged in a nucleus in a bacterial cell. True or false?

Answer 13

False

Question 14

How many chromosomes does bacteria have?

Answer 14

One genetic type (may have more than one copy)

Question 15

Plasmids provide a competitive survival advantages for bacteria. True or false?

Answer 15

True

Question 16

Do bacteria have the same or different DNA to humans?

Answer 16

Same - however, the enzymes that are involved in the packaging of DNA into supercoils are a good target for antibiotics as if you stop supercoiling, DNA bursts

Question 17

Ribosomes in prokaryotes and eukaryotes are the same shape and size. True or false?

Answer 17

False - same shape, different size

Question 18

Capsules and slime are different things.True or false?

Answer 18

False - the only difference is morphology

Question 19

What is the difference between capsule and slime?

Answer 19

Capsules take on the shape of the organism. They are associated with the surface of the cell. Slimes are distant.

Question 20

What is the function of EPS?

Answer 20

Protection - reduce penetration of molecules into cell

Avoid desiccation

Question 21

What are flagella composed of?

Answer 21

Flagellin subunits

Question 22

Where are fimbriae found?

Answer 22

All around the cell surface

Question 23

What are the functions of fimbriae?

Answer 23

Attachment and clumping

Question 24

What are fimbriae composed of?

Answer 24

Proteins

Question 25

What are the functions of pili?

Answer 25

genetic exchange | adhesion

Question 26

What are pili composed of?

Answer 26

Proteins

Question 27

What colour do gram positive cells stain?

Answer 27

Purple

Question 28

What colour do gram negative cells stain?

Answer 28

Red

Question 29

What is the role of teichoic acids and in which gram bacteria are the found?

Answer 29

They hold the peptidoglycan together and are found in gram positive bacteria

Question 30

The outer membrane is found in gram ______ bacteria only

Answer 30

negative

Question 31

Is the peptidoglycan layer thicker in gram positive or gram negative bacteria?

Answer 31

Gram positive

Question 32

What is the role of lipoteichoic acids in gram positive bacteria?

Answer 32

They anchor the peptidoglycan to the cytoplasm to stop it from being washed away

Question 33

What is the role of lipoproteins in gram negative bacteria?

Answer 33

hold the outer membrane to peptidoglycan

Question 34

Are lipopolysaccharides found in gram positive or gram negative bacteria?

Answer 34

Gram negative

Question 35

What are the three components of liposaccharides?

Answer 35

lipid A Core O-antigen

Question 36

Lipid A is pyrogenic. True or false?

Answer 36

True

Question 37

What is the O antigen in LPS made of?

Answer 37

Trisaccharide repeating units - vary depending on the organism

Question 38

What is the difference between smooth LPS and rough LPS?

Answer 38

Smooth LPS - has a fully elongated chain | Rough LPS - one trisaccharide and no repeat units