Cell Structure | AQA GCSE Biology Revision Notes 2016

What are the two distinct types of cells in biology?

Eukaryotic and prokaryotic cells.

What is a defining feature of eukaryotic cells?

Their genetic material (DNA) is enclosed within a nucleus.

What size range do eukaryotic cells typically fall within?

10 to 100 µm.

What is a defining feature of prokaryotic cells?

Their genetic material is not enclosed within a nucleus and is found as a single loop of DNA in the cytoplasm.

What are plasmids?

Additional smaller, circular pieces of DNA that may be present in prokaryotic cells.

What surrounds the cell membranes of all prokaryotic cells?

A cell wall, usually made from peptidoglycan.

What is the typical size of prokaryotic cells?

Approximately 1 µm.

How do scientists measure the size of cells?

In micrometers (µm).

How many micrometers are in one millimeter?

1000 µm in 1 mm.

What is the process called that allows cells to specialize?

Differentiation.

What is the function of nerve cells (neurones)?

Conduction of electrical impulses.

What special feature do muscle cells have that aids in contraction?

Many mitochondria to release energy for contraction.

What is the primary function of sperm cells?

Transfer of genetic material to an egg cell for fertilization.

What is the function of root hair cells?

Absorption of water and mineral ions from soil.

What feature of root hair cells increases absorption efficiency?

The root hair is an extension of the cytoplasm that increases surface area.