Bio Diagrams

CELLS Organelle Appearance / Functions Common Parts Nucleus Controls cell activities such as cell growth and the repair of worn-out parts Essential for cell division (cells without the nucleus, e.g. red blood cells of mammals, are unable to divide) Nucleolus Plays a part in the making of proteins in the cell Nucleoplasm Smaller round denser protoplasm within the nucleus, surrounded by nuclear envelope Chromatin Mass of long thread-like structures found within the nucleus Made up of proteins and deoxyribonucleic acid

DNA stores hereditary information and carries instructions that a cell needs for carrying out its activities Chromatin thread condenses into chromosomes when the cell is actively dividing Appear as thick rod-shaped structures under the light microscope Nuclear Envelope Separates the contents of the nucleus from the rest of the cytoplasm Plasma Membrane Surrounds the cytoplasm of the cell Made up of lipids and proteins Controls the substances entering or leaving the cell by allowing only small substances to pass through but not the large ones Mitochondrion Performs aerobic respiration in which glucose is oxidised to release energy Sausage-shaped and double membrane appearance Cytoplasm Where most cell activities occur Contains special membrane-bound structures called organelles Plant-Specific Organelles Vacuole Fluid-filled space enclosed by a membrane, storing substances within the cell Large, Central (Plants) Contain water and food substances Exists temporarily

Small, Many (Animals) Contains a liquid called cell sap which contains dissolved substances such as sugars, mineral salts and amino acids Enclosed by a partially permeable membrane called the tonoplast Cell Wall Made of cellulose and fully permeable Protects the cells from injuries and gives the plant cell a fixed shape Chloroplast Contain chlorophyll which absorbs light energy to carry out photosynthesis Embedded Organelles Smooth Endoplasmic Reticulum Does not have ribosomes attached to its membrane and is more tubular than RER Synthesises substances such as fats and steroids Converts harmful substances into harmless substances, a process known as detoxification Rough Endoplasmic Reticulum Appears rough when viewed under the electron microscope because small particles called ribosomes are attached to its outer surface Its surface is continuous with the nuclear envelope Golgi Apparatus Consists of flattened spaces surrounded by a membrane Packages the substances in vesicles for secretion out of the cell Stores, packages and chemically modifies substances made by the endoplasmic reticulum Ribosome Small round structures needed to synthesise proteins in the cell Attached Attached to the RER

Ribosome Make proteins that are usually transported out of the cell Free Ribosome Lie freely in the cytoplasm M