Virus Replication

There are 6 distinguish stages of viral replication;

1. Attachment
-affinity between the virus and the host cell's plasma membrane permits this stage.

2. Penetration
-virus particles are brought inside the cell, either by endocytosis or directly pass through the cell's plasma membrane.

3. Uncoating
-removal of capsid, to expose the viral nucleic acid.

4. Biosynthesis
-synthesis of viral nucleic acid, capsid, and enzymes.

5. Maturation
-two phases, phase I is assembly which the polypeptide chains assembled into capsomeres to form procapsid
-phase II is the intake of nucleic acid into the procapsid, forming a complete virion.

6. Release
-occurs by 3 mechanisms.
-cell lysis (host cell is killed by virus-induced)
-budding (no cell killing, usually by enveloped viruses)
-cell degeneration (after cell death, the virus released. non-virus-induced)

Fungus.

Fungus is a plant that does not have any flower or leaves.

The study of fungus is called mycology.

Mykos = Mushrooms.

Mushrooms are a type of fungus.

Differences with bacteria;
- rigid cell wall, comprises of chitin, mannan.
- cytoplasmic membrane contains sterol.

Classification of fungi (plural for fungus)

Taxonomical.
a)Zygomycetes
b)Ascomycetes
c)Basidiomycetes
d)Deuteromycetes

Morphological.
a)Yeasts
b)Yeasts-like fungi
c)Moulds
d)Dimorphic

Common features (for the ease of classification)

Unicellular, multiple by budding,
it is a YEAST
e.g. Cryptococcus

Pseudohyphae
it is a YEAST-LIKE
e.g. Candida

Hyphae in groups, tangled
it is a MOULDS
e.g. Penicillium

can live inside or outside the body, causing systemic mycosis
it is a DIMORPHIC
e.g. Blastomyces

Bacteria Gram-staining.

What is Gram staining?
A type of differential staining, commonly used to differentiate bacterial species into two large groups (Gram-positive and Gram-negative) based on the physical properties of their cell walls.

Gram-positive bacteria have a thick mesh-like cell wall made of peptidoglycan (50-90% of cell wall), which stains purple while Gram-negative bacteria have a thinner layer (10% of cell wall), which stains pink.

Aerobic bacteria.

Gram-positive cocci
- Staphylococci
- Streptococci
- Pneumococci

Gram-positive bacilli
- Corynebacterium
- Bacillus
- Clostridium
- Actinomycetes (filamentous)
- Mycobacterium (stains poorly)

Gram-positive coccobacilli
- Listeria
- Erysipelothrix

Gram-negative cocci
- Neisseria
- Moraxella

Gram-negative bacilli
- all aerobic bacteria which have not been mentioned.

Gram-negative coccobacilli
- Bordetella
- Brucella

Anaerobic Bacteria.

Gram-positive cocci
- Peptococcus
- Peptostreptococcus

Gram-positive bacilli
- Eubacterium
- Lactobacillus
- Bifidobacterium
- Propionibacterium
- Actinomyces
- Mobiluncus

Gram-negative cocci
- Veillonella

Gram-negative bacilli
- Bacteroides
- Prevotella
- Porphyromonas
- Fusobacterium
- Leptotrichia


tips : there are about 30 bacteria species which are Gram-negative bacilli. so in viva voce, if you unsure about the Gram staining of an aerobic bacilli, just say Gram-negative bacilli! insyaAllah, it worth a guess :)