Prokaryotic Cells And Viruses

Single-celled organisms

Bacteria

Mainly of lipids and proteins Controls movement of substances into and out of the cell

Supports the cell and stops it changing shape Polymer called murein

Capsule made of secreted slime

Small loops of DNA that aren’t part of main circular DNA molecule Genes

DNA floats free in cytoplasm Circular, 1 long coiled-up strand

Long hair-like structure Rotates it make prokaryotic cell move

Extremely Less than 2 micrometers

Binary fission

Cell replicates its genetic material before physically splitting into 2 daughter cells

Circular DNA and plasmids replicate Main DNA loop only replicates once but plasmids can be replicated many times

Cell gets bigger and DNA loops move to opposite ‘poles’ of the cell

Cytoplasm begins to divide New cell walls begin to form

Cytoplasm divides and 2 daughter cells are produced Each daughter cell has 1 copy of circular DNA but can have a variable number of copies of plasmids

Acellular

Nucleic acids surrounded by protein

HIV Influenza

Invade and reproduce inside cells of other organisms

Host cells

Protein coat (capsid) with attachment proteins sticking out from it

Let virus cling onto suitable host cell

Inject DNA or RNA into host cell so hijacked cell uses its own ‘machinery’ to replicate them

Different viruses have different attachment proteins and therefore require different receptor proteins on host cells