Binary fission and viral replication

Binary fission – step 1

The circular DNA molecule replicates once

Binary fission – step 2

The plasmids replicate (can be multiple times)

Binary fission – step 3

The cell membrane grows between the two DNA molecules and pinches inwards, dividing the cytoplasm

Binary fission – step 4

A new cell wall forms, producing two daughter cells

Binary fission – what does each daughter cell receive?

One copy of the circular DNA and a variable number of plasmid copies

Why can't viruses undergo cell division?

They are acellular and non-living

Viral replication – step 1: attachment

Viral attachment proteins bind to complementary receptors on the host cell surface

Viral replication – step 2: injection

The virus injects its nucleic acid (DNA or RNA) into the host cell

Viral replication – step 3: synthesis

The host's ribosomes and enzymes are hijacked to replicate viral nucleic acid and make viral proteins (capsids)

Viral replication – step 4: assembly and release

New viral particles are assembled and released, often by lysis