Prokaryotic cells and viruses

What are prokaryotes?

unicellular organisms that lack a nucleus

Differences between prokaryotic and eukaryotic cells

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both.

Ribosomes in prokaryotic cells

70s

cell wall of prokaryotes

made of peptidoglycan (murein)

Plasmids

Small loop of DNA in prokaryotic cells, only carry a few genes, where antibiotic resistant genes are found

Capsule

Thick, slimy layer made of protein on the outside of the cell wall and prevents bacteria from drying out (desiccating) and protects the bacteria from the host's immune system by covering the antigens

Flagella

whiplike tails found in one-celled organisms to aid in movement

What are viruses?

acellular, non-living particles, obligate parasites which are smaller than bacteria (200-300 nm)

Why are viruses classed as non-living?

Incapable of living outside a host- outside host is classed as a particle

Nucleus acids in viruses

Such as DNA/RNA as genetic material but can only multiply inside a living host cell and is enclosed within a protein coat called capsid

Attachment proteins in viruses

On lipid envelope which further surrounded virus, or if not present capsid (a protein coat), essential to allow virus to identify and attach to a host cell

Bacteriophage

A virus that infects bacteria

Life cycle of virus

Attachment proteins bind to complementary receptors on host cell surface, viral DNA or RNA is injected into host cell, host cell uses its own enzymes and ribosomes to synthesise viral proteins and nuclei's acids, new viral particles are assembled. Viruses are released by cell lysis (bursting) or budding (takes host membrane-forms viral envelope)

What does virus release do to cells?

Damages or destroys host cells, causing disease

How do prokaryotic cells divide?

binary fission

How does binary fission happen?

The main circular DNA molecule replicates, plasmids replicate,cell membrane begins to grow between the two DNA molecules, cytoplasm divides in two, new cell wall grows down the middle, cell divides