Cells and Cell Structure

Cell

The lowest structural level, specialised to carry out specific functions.

Tissue

Made up of cells with similar specialisations that group together to carry out common functions.

Organ

Made up of two or more tissues, working together for a common function.

System

The highest level of organisation, made up of a group of organs working together for a common purpose.

Cell theory

The concept that cells are the basic structural and functional unit of all living things.

Cell membrane

Double layered membrane made up of phospholipids and proteins, controlling movement of substances into and out of the cell.

Cytoplasm

Thick fluid consisting of cytosol and organelles, allowing chemical reactions to occur and providing shape to the cell.

Cytosol

The portion of the cytoplasm that consists of 75-90% water and is the site for metabolic reactions.

Nucleus

Spherical/ovoid structure that stores genetic material, mostly in the form of DNA.

Nucleolus

Small structure within the nucleus that produces ribosomes and contains genetic material, mostly RNA.

Lysosomes

Small spherical structures in the cytoplasm that contain enzymes to break down materials and worn out organelles.

Endoplasmic Reticulum

A series of parallel membranes providing surfaces for chemical reactions and transporting materials; can be rough or smooth.

Ribosomes

Small spheres that join amino acids to form proteins, either free in the cytoplasm or attached to the endoplasmic reticulum.

Vesicles

Small membrane-bound sacs that transport materials in, out, and within the cell.

Golgi Body

Stacked, flattened membranes that modify and package proteins for secretion.

Centrioles

Pairs of cylinders located near the nucleus, involved in cell reproduction.

Mitochondria

Double membraned elongated structures that release energy for the cell through cellular respiration.

Cytoskeleton

A framework of protein fibres that gives the cell its shape and assists in cell movement.