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Lecture 2: replication cycle
• Cells provide: ribosomes, nucleotides & aa, ATP (energy), membranes.
• Consequences of virus replication on the cells: – Diverts cell metabolism– Fill up the cells– Escape (lysis for example)– Apoptosis induction
Lecture 2: virus structure
• Some viruses affect the behaviour of their host to improve transmission
• A lot of viruses do not cause disease
Lecture 2: virus structure
• Techniques used to detect and measure viruses:– Electron microscopy– Hemagglutination– Plaque assay– Foci formation
• Replication cycle
Finding the pfu/ml
• If a dilution (1/10000) is made and 1 ml of this dilution is plated: we get 50 plaques.
• How do we solve this:
• 50 plaques in 1 ml of the dilution= 50 pfu/ml in that dilution.
• 50 pfu/ml * 10000 = 500 000 pfu/ml in the original solution.
Lecture 3: virus structure
• One step growth curve
• Baltimore classification
• Basics of virus particles
• Icosahedral and helical symmetry
Lecture 4: ssRNA phages
• Gene regulation dependent mostly on RNA secondary structure
• Replication Vs translation problem
• Replication
• Transcription of maturation gene
Lecture 5: ssDNA phage (X174)
• Displays extensive overlapping in genes. How do we regulate transcription?
• Concept of frames in transcription
• Entry
• Replication through rolling circle
• Formation of the capsid
Different frame
• ACG ATG GGG CCC TAT GCT
• -1 AC GAT GGG GCC CTA TGC
• -2 CGA TGG GGC CCT ATG CT
• +1 TGG GGC CCT ATG CT
• +2 GGG GCC CTA TGC
T7 phage
• Entry and DNA winching by RNA pols from the host and the virus.
• How it regulates transcription of its genes
• How the T7 RNA pol functions
• Problems with replication of linear dsDNA
• pET vectors for protein expression
Lambda phage
• Genome organisation
• Understanding gene regulation is crucial
• How do we repress the lytic cycle?
• How do we decide between lysis or lysogeny
• Integration into the bacterial genome and its regulation
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