AQA - Cell Biology(Cell)

Cell membrane

Surrounds the cell and controls the passage of substances into and out of the cell.

Cell wall

Found outside the cell membrane in plant and bacterial cells, provides support for the cell.

Chloroplast

Found in plant cells. Contain chlorophyll that absorbs light for photosynthesis.

Cytoplasm

Where most of the chemical reactions take place in a cell.

Domain

Name given to the groups suggested by Woese. There are three domains: Archae, Bacteria and Eukaryota.

Eukaryote

Type of cell that contains a nucleus

Mitochondria

Where aerobic respiration takes place.

Nucleus

Contains DNA and controls cell activities.

Plasmid

Small rings of DNA found in bacterial cells.

Prokaryote

Cells without a nucleus.

Ribosomes

Where protein synthesis occurs.

Vacuole

Found in plant cells. Contain a fluid called cell sap.

Cell

The basic unit of living things.

Differentiation

When cells become specialised to do a particular job.

Organ

A group of tissues working together to perform a specific function.

Organ system

Groups of organs that work together e.g. digestive system.

Specialised

Cells that have a particular job/function.

Tissue

A group of cells with a similar structure and function.

Translocation

The movement of sugars in plants.

Transpiration

The movement of water through the plant and leaves.

Epidermis (plant)

A single layer of cells that forms the outer layer.

Palisade

Tissue found in the upper layer of the leaf, packed with chloroplasts for photosynthesis.

Spongy mesophyll

Tissue found in the lower layer of the leaf, with spaces between the cells to allow gases to diffuse.

Xylem

Water travels through xylem tissue from the roots to the leaves.

Phloem

Sugars are transported through the phloem cells.

Guard cells

Cells which surround the stomata and control its opening and closing.

Stomata

Tiny pores in the epidermis of the leaf.

Electron microscope

A microscope that uses electron beams in place of light to give a higher magnification.

Light microscope

An instrument that uses visible light and lenses to magnify a specimen.

Magnification

How many times larger something appears.

Micrograph

Another word for a microscope image.

Resolving power

The ability to distinguish between two points.

Magnification of image

Magnification = size of image/size of real object

Total magnification

Magnification = magnification of eyepiece x magnification of objective lens

Adult stem cell

Stem cells found in some adult tissues. They are partly specialised and can become a range of different type of cell, but not all.

Asexual reproduction

Reproduction involving only one parent, producing genetically identical offspring.

Benign

Type of tumour that is slow growing, not cancerous and usually easy to remove.

Cancer

A condition resulting from changes in cells that leads to their uncontrolled growth, division and spread.

Carcinogen

Chemicals and other agents that cause cancer.

Chromosome

Long strands of DNA found in cells. Human body cells have 46 chromosomes.

Daughter cell

The cells that are produced in cell division.

Embryonic stem cell

Stem cells found in early embryos. They are unspecialised and can become any type of cell in the body.

Gene

A short section of DNA that contains the instructions for making a protein.

Malignant

Type of tumour that grows quickly and can spread through other tissues. These tumours can lead to the formation of secondary tumours elsewhere.

Meristem

Region of plant tissue in which stem cells are produced and so where much of the plant growth occurs.

Mitosis

Type of cell division that produces two new (identical) cells.

Mutation

A change in the DNA of a cell.

Therapeutic cloning

Producing stem cells with the same genes as the patient.

Tumour

Name given to the growths produced from extra cells.

Zygote

Another term for a fertilised egg cell.