Download - Lytic lifecycle of a virus
Lytic Lifecycle of a Virus
AHL BiologyOption F
Let´s REVIRUS!!! (revise the virus)
• How many questions can you get right on this quiz?
11
DNAviruses
RNAviruses
ds DNA ss RNA ss RNAss DNA
RNA DNAviruses
ss RNA(Retroviruses)
ds DNA(hepadnaviruses)
Viral genomes
• genome is template for mRNA
• genome is template for DNA synthesis ("retrovirus")
• Requires reverse transcriptase to change RNA into DNA
Virulent phages only undergo a lytic cycle
Temperate phages can follow both cycles
Prophage can exist in a
dormant state for a long time
It will undergo the lytic cycle
Bacteriophage
Lytic phages – add notes to your diagram as we go through the next few slides
Clockwise: Pseudomonas aeruginosa phage; Aeromonas phage; Shigella K II phage; Listeria phage
Life Cycle of a Lytic Phage
Step 1 Adsorption: virus attaches to the cell wall surface
Step 2 Penetration: entry of the viral DNA
Phage T4 adsorption to the cell wall of E. coli
Life Cycle of a Lytic Phage
Step 3 Synthesis of early viral proteins
Step 4 Replication of viral DNA
Phage T2 attacks E. coli
Life Cycle of a Lytic Phage
Step 5 Synthesis of late viral proteins
Step 6 Assembly
Step 7 Lysis and release of mature viruses
Lysis of E. coli cell by Phage T4
Life Cycle of a Lytic Phage
Antibiotics and their mode of action
MRSA
•Methicillin-resistant Staphylococcus aureus
•Resistance to beta-lam antibiotics which include the penicillins and cephelasporins
•MRSA is especially troublesome in hospitals where patients with open wounds, invasive devices and weakened immune systems are at greater risk of infection than the general public.
Superbug gone rogue…
Questions to consider….• What is the situation with regard to MRSA?
-Is it emerging? -Highly prevalent? -Why do you think the issue has gained so much press right recently?
• Do you think that the message that recent articles about MRSA disease highly publicised in the news were talking about risks associated with sick, hospitalized patients and not the public at large came through?
• Do you think that the media has portrayed a reliable representation of the threat of MRSA?