Culture Club Flashcards
What size is a virus?
10-100nm
What genome do viruses have?
DNA or RNA
- ss or ds
- linear or circular
How metabolically active are viruses?
Metabolically inert
What detects PAMPs?
Toll-like receptors
What is tropism?
The idea that specific cells, tissues and hosts can support the growth of particular microbes
What does HIV normally infect?
Macrophages, but not neurons (cellular tropism)
What does the influenza virus infect?
lung tissue but not brain tissue (tissue tropism)
How do viruses exit a host cell?
They can bud from the surface
Why will some viruses immortalise their host cell?
To use it for their benefit
What do some viruses come pre-packaged with?
With enzymes required for their replication, which are virus specific (targets for anti-viral drugs)
What is the range for virus host cells>
Can be very specific or broad (multiple cell types/different host species)
What does the virus do in the host cell?
Replicate
What is the function of a capsule on a bacterium?
- surrounds the cells
- prevents phagocytosis
What is the function of a cell wall on a bacterium?
Prevents the cell from bursting
(antibiotic target)
(not always present)
What is the function of the plasma membrane on a bacterium?
Site of ATP synthesis
not always present
What ribosomes are present on a bacterium?
70s
target for antibiotics
What is a plasmid?
Mobile DNA
can carry antibiotic resistant genes
What is the function of flagella on a bacterium?
Required for motility
not always present
What is the function of pili on a bacterium?
-facilitate DNA transfer between cells
-helps cells move and adhere to surfaces
(not always present)
Is the nucleoid always present in a bacterium?
Yes
DNA and RNA polymerases are antibiotic targets
What are the 3 groups of bacteria?
- gram positive
- gram negative
- atypicals/acid fast
How are bacteria divided?
Based on the structure of their cell wall
How are atypicals/acid fast visualised?
Using acid based stains
What is present in the membrane of gram negative?
- Lipopolysaccharide
- outer membrane
- peptidoglycan (thin)
- inner (plasma) membrane
What is present in the membrane of gram positive?
- (lipo)teichoic acid
- peptidoglycan (thick)
- inner (plasma) membrane
What is significant about finding out whether a bacterium is gram negative or positive?
Certain antibiotics can selectively target Gram negative/positive (narrow spectrum antibiotics). Some can target both (broad spectrum)
Why can broad spectrum antibiotics be useful?
- if the patient has an unknown infection
- multiple bacteria infecting at once
In which bacteria is it easier for water to leave?
Gram negative
Which bacteria finds it easier to live on the skin?
Gram positive e.g. streptococcus, staphylococcus
skin is generally dry, and water finds it difficult to leave gram positive
Why do gram negative find it difficult to live on the skin?
they will dry out - water finds it easier to leave
What is LPS?
Lipopolysaccharide = endotoxin
What effect does LPS have on the host?
- induces a strong inflammatory response (can lead to sepsis)
- can induce clotting
- is pyrogenic (leads to fever)
What colour does Gram positive stain?
Purple
What colour does Gram negative stain?
Pink
