Lecture 1&2 The Bacterial Cell Flashcards
Describe the shape of a Cocci Bacteria
Grape-like
Spherical
E.g Streptococci
Define Opsonisation
The process in which the immune system tags pathogens with opsonins for elimination by phagocytes
What is the sugar coated capsule’s role around a bacterium?
The capsule protects the cell wall of the bacterium. The immune system no longer recognises the bacterium which helps them proliferate more
What is the role of fimbriae/pili?
Helps attach to surfaces. I.e sex pili bring cells into close contact in order for genetic exchange of plasmids (exchanging RNA)
What is the role of the bacterial flagella?
Helps move towards the nutrients and away from danger
What is chemotaxis?
The motion of cells towards nutrients and away from toxic conditions. The flagella helps propel the movement.
What is the name of the bond between the two hydrophilic heads?
Ester bond
What’s the difference between gram-positive and gram-negative bacteria?
Gram-positive bacteria only have peptidoglycan cell walls and are more susceptible to antibiotics than gram-negative. Gram-negative have thinner peptidoglycan (glyco-protein) surrounded by an outer layer of lipoprotein and lipopolysaccharide.
What colour does gram-positive bacteria stain and why?
The cell walls stain purple as the peptidoglycan retains the crystal violet dye.
What colour does gram-negative bacteria stain and why?
They have less peptidoglycan, the cell wall doesn’t retain the crystal violet dye and stains red due to the background stain.
Where do you find Lipid A?
Lipid A is the monomer head of the lipopolysaccharide
What symptoms is Lipid A responsible for?
1) Black spots on the skin
2) Can cause a cytokine storm
3) Causes blood to clot
4) Can cause amputations due to the surrounding cells dying from a lack of oxygen
What is the difference between gram-positive and gram-negative peptidoglycan?
Gram-positive peptidoglycan contains pentaglycine cross-links
Gram-negative peptidoglycan contains direct cross-links
Define Virulent
The ability for a pathogen to cause damage to a host
How many base pairs do viruses have?
200 bp
What is the cytoplasmic bridge used for?
The transfer of a single-stranded copy of the plasmid from one cell to another. Pilli are used to help the transfer.
Describe the lysogenic cycle
1) Phage DNA enters cell
2) Phage DNA integrates and becomes prophage
3) Integrated prophage replicates within the cell
4) Prophage may separate and cell enters lytic cycle
Describe the lytic cycle
1) Phage binds to the cell
2) Phage DNA enters host cell
3) Host DNA is digested
4) New phage DNA forms
5) Host transcribes and translates phage DNA, when the assembly is complete the encoded enzyme causes lysis.
6) New phages are released
Name the toxin produced by Corynebacterium diphtheria
Diphtheria toxin
Name the toxin produced by Clostridium boltulinum
Botulin
Name the toxin produced by Vibrio cholerae
Choleratoxin
Name the toxin produced by Clostridium tetani
Neurotoxin
Name the toxin produced by E.coli
Enterotoxin
Name the toxin produced by Staphylococcus aureus
Coagulase enterotoxin
