Cells are the most basic living component of an organism. According to cell theory/doctrine (it's not a theory anymore- it's kinda universally accepted at this point), every living organism is made up of one or more cells.
Cell theory has three basic tenets (parts):
The cell is the most fundamental unit of structure in living organisms
All organisms are composed of one or more cells
Cells come from other cells through cellular division
The CSEC syllabus requires that you know the general structure of four types of cell: the general animal cell, the general plant cell, the bacterial cell and a protist, for which we will use the amoeba.
Plant and Animal Cells
Plant and animal cells share a few structures in common:
a cell membrane
cytoplasm
nucleus
mitochondria
Animal Cells
Functions of the parts of the animal cell:
Nucleus: the nucleus contains the genetic information of the cell and controls all cell functions, including cell division.
Cytoplasm: The cytoplasm is a mostly water-based substance containing dissolved substances such as proteins. It is the site of many chemical reactions and supports organelles.
Cell membrane: this is a selectively permeable membrane through which food materials diffuse in and waste materials diffuse out. It controls this movement of materials, and is composed of lipids and proteins.
Mitochondrion: the powerhouse of the cell, it contains enzymes which carry out respiration, providing the cell with energy.
Golgi Apparatus: Processes and packages proteins.
Vacuoles: membrane-bound compartments which contain waste, water food or other such substances.
Rough Endoplasmic Reticulum: Has structures called ribosomes on its surface and creates proteins before sending them to the Golgi Apparatus.
Smooth Endoplasmic Reticulum: Has no ribosomes on its surface. The smooth endoplasmic reticulum is responsible for synthesizing lipids.
Glycogen granules: granules of glycogen which work as food storage for the cell.
Plant Cells
The plant cell has four structures that are either not present in animal cells or are different:
Cell Wall: this freely permeable wall maintains the shape of the cell and protects the cell. It is made of cellulose.
Chloroplasts: These contain chlorophyll and certain enzymes, and are the sites at which photosynthesis occurs.
Amyloplasts: Also called starch grains, they serve the same function as the glycogen grains in animal cells. They store excess food.
Vacuole (large): this large membrane bound compartment contains cell sap and is far larger than it is in the animal cells. Cell sap contains a solution of sugars, mineral salts, amino acids and waste products. It stores food or cell waste, and can support the structure of the cell.
So, comparing animal and plant cells;
Animal Cells:
Have no cell wall;
Contain no chloroplasts and chlorophyll;
Vacuoles are small and are scattered throughout the cell, and their contents vary;
Have no regular or defined shape;
Store excess food as glycogen granules.
Plant Cells:
Have a cell wall made of cellulose;
Contain chloroplasts;
Contain one, large, central vacuole which contains cell sap;
Have a regular, definite shape (defined by the cell wall), usually round or rectangular;
Store excess food as starch grains.