AQA GCSE Biology Topic 1 Cell Biology

Flashcards created from AQA GCSE Biology Topic 1 Cell Biology notes.

What is an order of magnitude?

A power to the base 10 used to quantify and compare size

Why is the misconception 'A prokaryotic cell doesn't have DNA' wrong?

Despite not having a nucleus, it still has DNA (found in cytoplasm)

What is the function of the cell membrane?

Controls movement of substances in and out of cell

What is the function of the cytoplasm?

Gel-like substance where chemical reactions take place

What is the function of the nucleus?

Contains genetic material (DNA) → controls activities of cell

What is the function of the mitochondria?

Site of aerobic respiration releases energy from glucose

What is the function of ribosomes?

Site of protein synthesis

What is the function of the cell wall?

Made of cellulose → strengthens cell (algal cells have one too)

What is the function of chloroplasts?

Contain chlorophyll → to absorb light for photosynthesis to make glucose

What is the function of a permanent vacuole?

Filled with cell sap→help keep cell turgid/support plant

What are eukaryotic cells?

Cells with genetic material (DNA) enclosed in a nucleus; examples are plant and animal cells

What are prokaryotic cells?

Cells with genetic material (DNA) not enclosed in a nucleus; bacterial cells

Describe the genetic material in a prokaryotic cell

A single loop of DNA, may also have small rings of DNA called plasmids

Why is the misconception 'Bacterial cells have mitochondria' wrong?

They have no sub-cellular structures surrounded by a membrane, eg. nucleus, mitochondria, chloroplasts. They do still respire, but use other structures.

Why is the misconception 'The cell wall controls what moves in and out of the cell' wrong?

Just like any other wall, the cell wall provides strength. The cell membrane is what controls what moves in and out of a cell.

What are chromosomes?

Tightly coiled strands of DNA molecules, found in nucleus of a cell, carries a large number of genes

How are chromosomes arranged in the nucleus of a body cell?

In pairs

Why is the misconception 'All organisms have 46 chromosomes' wrong?

Different species have different numbers of chromosomes.

Why is the misconception 'Different cells in the body have different genes/chromosomes / DNA' wrong?

All cells in the body originate from a fertilised egg cell. This divides by mitosis to form all the genetically identical cells of the body.

Why is cell division by mitosis important?

Parent cell divides to produce 2 genetically identical cells for growth and development of multicellular organisms and replacing (worn out or damaged) cells to repair damaged tissues

Describe the cell cycle

Series of stages in which a cell divides (DNA is doubled then divided into 2 identical cells)

Why is the misconception 'Mitosis repairs cells' wrong?

Mitosis creates new cells to replace damaged or dead ones, therefore repairing the tissue (group of cells) but not the cells themselves.

What is a stem cell?

An undifferentiated cell which can give rise to many more cells of the same type or any body cell