AQA Biology A Level - Prokaryotic Cells and Viruses

What is an example of a prokaryotic cell?

Bacteria

Cytoplasm

Has no membrane bound organelles. It has ribosomes - but are smaller than that in a eukaryotic cell

Flagellum

Long, hair-like structure that rotates to make the prokaryotic cell more. Not all prokaryotes have a flagellum, some have more than one

Do prokaryotic cells have a nucleus?

No

What happens to the DNA in a prokaryotic cell?

It floats free in the cytoplasm. It is circular DNA, present as one long coiled-up strand

What is DNA not attached too?

Histone proteins

What are plasmids?

Small loops of DNA, that aren't part of the DNA molecule

What do plasmids contain?

Contain genes for things like antibiotic resistance, and can be passed between prokaryotes

Cell Wall

Supports the cell and prevents it from changing shape

What makes up the cell wall?

A polymer called murein

What is a murein?

Glycoprotein

What do viruses contain?

Contain a core of genetic material

What surrounds the virus?

A protein coat called the capsid

What stick out from the virus?

Attachment proteins

How do prokaryotic cells replicate?

Binary Fission

What happens during binary fission?

The cell replicates its genetic material, before physically splitting into two daughter cells

What are the four stages of binary fission?

The circular DNA and plasmids replicate

The cell gets bigger and the DNA loops move to opposite 'poles' of the cell

The cytoplasm begins to divide

The cytoplasm divides and two daughter cells are produced

What do viruses use to replicate themselves?

Host cells

How do viruses use attachment proteins?

To bind to complementary receptor proteins on the surface of host cells