cell structure and organisation
cells- the basic units of life, functioning as the building blocks for all living organisms. They carry out essential processes
the living material in a cell is called protoplasm. the protoplasm contains of the cell surface membrane, cytoplasm and nucleus.
parts of animal and plant cells and their functions
Cell surface membrane: made of lipids, proteins and carbohydrates. the cell surface membrane is a partially permeable membrane. it controls the movements of the substances ( e.g. oxygen, carbon dioxide, water salt, glucose, proteins ) into and out of the cell.
cell wall: made of cellulose, fully permeable to all substances, serves as a protective barrier against injury, gives plant cells a regular shape, prevents plants cell from bursting when too much water enters them.
Cytoplasm: contains cytosol, organelles are found in the cytoplasm. an organelle is a part of a cell which has specialised functions.
Nucleus: controls all cellular activities in the cell. it is essential for cell division, it contains chromatin.
vacuoles: an animal cells contains many small vacuoles. vacuoles in an animal cells contain a fluid and they store small of substances in it. plant cells contain one large vacuole. the large vacuole in the plant cells contain a fluid called cell sap. sugars, water and other substances are stored in the plant cell vacuole.
chloroplasts: present in some plant cells. a chloroplast is an oval-shaped organelle which contains the green pigment ( chlorophyll ) it is the site for photosynthesis which is a process by which plants make food using light energy from the sun.
mitochrondria: a mitochrondrion is an oval or sausage-shaped organelle which generates energy for the cell through cellular respiration.
ribosomes: ribosomes are tiny round structures that are the sites where proteins are made.