Public health microbiology Flashcards
Chlamydia and mycobacterium do not contain peptidoglycan, True or false?
True - this means that antibiotics that target the cell wall are useless in treating infections caused by these bacteria
What is peptidoglycan composed of?
Carbohydrate (NAG and NAM)
Peptide chains
Only bacteria contain NAG. True or false?
False - only bacteria contain NAM
Are all human amino acids L or D form? And what is the significance of this?
All amino acids are L form - this means the D-amino acids in bacteria can be targeted
Is Meso-DAP found in humans?
No it is only present in bacteria
Is cross link of amino acid chains only associated with NAG or NAM?
NAM (and not necessarily all NAM residues)
Is the level of cross-linking the same in all species?
No cross-linking is species dependent - it varies from organism to organism
What is lost when there is cross-linking between two chains?
2 D-ala therefore chain becomes a tetrapeptide
What does the interbridge join together?
it joins meso-DAP to D-ala on a previously synthesised chain
What is the cell membrane composed of?
Phospholipids
Proteins
Fatty acids
What is the function of the cell membrane?
Permeability barrier - regulates entry and exit
Metabolically active e.g. energy production (ATP Synthesis)
What is the mesosome for?
DNA of organism is attached to this structure
DNA is packaged in a nucleus in a bacterial cell. True or false?
False
How many chromosomes does bacteria have?
One genetic type (may have more than one copy)
Plasmids provide a competitive survival advantages for bacteria. True or false?
True
Do bacteria have the same or different DNA to humans?
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
Ribosomes in prokaryotes and eukaryotes are the same shape and size. True or false?
False - same shape, different size
Capsules and slime are different things.True or false?
False - the only difference is morphology
What is the difference between capsule and slime?
Capsules take on the shape of the organism. They are associated with the surface of the cell. Slimes are distant.
What is the function of EPS?
Protection - reduce penetration of molecules into cell
Avoid desiccation
What are flagella composed of?
Flagellin subunits
Where are fimbriae found?
All around the cell surface
What are the functions of fimbriae?
Attachment and clumping
What are fimbriae composed of?
Proteins
What are the functions of pili?
genetic exchange
adhesion
What are pili composed of?
Proteins
What colour do gram positive cells stain?
Purple
What colour do gram negative cells stain?
Red
What is the role of teichoic acids and in which gram bacteria are the found?
They hold the peptidoglycan together and are found in gram positive bacteria
The outer membrane is found in gram ______ bacteria only
negative
Is the peptidoglycan layer thicker in gram positive or gram negative bacteria?
Gram positive
What is the role of lipoteichoic acids in gram positive bacteria?
They anchor the peptidoglycan to the cytoplasm to stop it from being washed away
What is the role of lipoproteins in gram negative bacteria?
hold the outer membrane to peptidoglycan
Are lipopolysaccharides found in gram positive or gram negative bacteria?
Gram negative
What are the three components of liposaccharides?
lipid A
Core
O-antigen
Lipid A is pyrogenic. True or false?
True
What is the O antigen in LPS made of?
Trisaccharide repeating units - vary depending on the organism
What is the difference between smooth LPS and rough LPS?
Smooth LPS - has a fully elongated chain
Rough LPS - one trisaccharide and no repeat units
