Viral Structure and Replication

Viruses

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Viral Structure

Viral Reproduction

Viral Structure

Viruses have Very Simple Structures.

A Single viral particle is called a VIrion.

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Viral Structure

A virion is made up of genetic material surrounded by a protein coat called a capsid.

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Viral Structure

In some viruses, the capsid is surrounded by a lipid envelope.

This envelope allows the virus to enter cells easier.

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Surface protein spikes allow the virus to attach to a cell.

Replication

Viral Reproduction

Viruses can only reproduce after they have infected a host cell.

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Viruses only infect one type of cell.

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Viral Reproduction

Viruses that infect Bacteria are called Bacteriophages.

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Viral Reproduction

Viruses that infect Eukaryotic Cells may enter the cell through endocytosis or by fusing with the cell membrane.

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Viral Reproduction

There are 2 basic pathways that viruses use to reproduce. Both pathways lead to the cell making more viruses, but one path will take longer to reach viral replication.

Lysogenic Cycle

Lytic Cycle

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Lytic Cycle

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Attachment

Release / Lyse

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Insertion

Assembly

Biosynthesis / Replication

Lytic Cycle

Infection occurs when the virus enters a host cell. The Cell Dies when virsues burst from the cell. Virus then spreas to other cells. Host knows that they are sick within hours or days of initial infection. Ex: InFluenza

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Lysogenic Cycle

INfection occurs when the virus enters a host cell. The viral DNA becomes embedded within the cell DNA, and it duplicates whenever the cell divides. Host knows that they are sick weeks, months, or years after infection. (Can reoccur) Ex: HIV

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Lysogenic Cycle

the viral DNA can remain dormant in the cells for a long time and then suddenly switch to the Lytic cycle.

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