Bacterial Structure & Classification Flashcards
What are the three domains of life?
Bacteria
Archaea
Eukaryotes
State the name of one E.coli strain which is non hazardous to humans
E. coli K12
State the name a E.coli strain which can cause food poisoning or haemolytic uraemia
E. coli O157:H7
Give the name of one bacterial causative agent for Meningitis
Neisseria meningitidis
Give the name of one bacterial causative agent for Gonorrhoeae
Neisseria gonorrhoeae
How is genetic material in bacteria arranged?
It consists of circular and double stranded DNA, floating freely in cytoplasm and is not membrane bound. Known as a nucleoid
What are bacterial pili / fimbriae used for?
Cell adhesion
Give the name of one bacterial causative agent for Listeriosis
Listeria monocytogenes
Give the name of one bacterial causative agent for Peptic ulcers / Chronic gastritis
Helicobacter pylori
How do Gram+ and Gram- bacteria react differently to the Gram stain?
- Stain with crystal violet (purple)
- Wash with alcohol
- In Gram+, stain is retained due to biochemistry of cell wall
- In Gram-, stain is washed out and can be stained with Counterstain fuchsin (pink)
If a bacteria is stained dark purple, what does this mean?
Gram positive
If a bacteria is stained pink, what does this mean?
Gram negative
Describe the Gram negative cell wall
They have a cytoplasmic cell membrane, followed by a thin Peptidoglycan cell wall (within the Periplasm) and an outer LPS membrane
How is the Lipopolysaccharide tail of Gram negative bacteria recognised by Immune cells?
By TLR4
How is the Peptidoglycan recognised by Immune cells?
By TLR2
Describe the Gram positive cell wall
They have a cytoplasmic membrane, followed by a thick Peptidoglycan cell wall plus Teichoic acids
A bacteria is not successfully stained with crystal violet or fuchsin, what can be deduced and what stains can be used?
May not be Gram positive or negative, could be acid-fast -> Proceed to stain with Ziehl Neelson stain (will stain red if acid fast)
Give an example of a bacteria which does NOT have a cell wall
Chlamydia sp.
Mycoplasma sp.
Give an example of an acid fast bacteria
Mycobacterium tuberculosis
Give an example of a bacterial causative agent which causes Lyme disease
Borrelia burgdorferi
What is a “coccus”?
Any bacteria which has a spherical or round shape
Outline the different arrangements of Cocci (6)
- Coccus
- Diplococcus (two)
- Staphylococcus (grape-like)
- Streptococcus (chain-like)
- Sarcina (cuboidal-like)
- Tetrad (square)
What is a “bacilli”
Any bacteria which has a rod shape
Outline the different arrangements of Bacilli (5)
- Bacilli
- Coccobacilli (round bacilli)
- Diplobacilli (two)
- Streptobacilli (chain-like)
- Pallisades (side on bacilli)
