Cell Structure
Cells: What we Already Know All living things are made of 1 or more cells. Single-celled organisms include Paramecium, amoeba, chlamydomonas and yeast. These can carry out all the functions of living things. Cells vary in shape.
Cells: What we Already Know Cells are small because diffusion of substances in and out becomes very difficult when they become larger. Also it is easier for a single nucleus to handle a smaller cell. Cells can be divided into 2 types: Prokaryotes – before the nucleus Eukaryotes – true nucleus
General Characteristics of Cells Cytoplasm and Nucleoplasm a jelly-like substance surrounded by a membrane. The portion of jelly outside the nucleus is called cytoplasm. The portion inside the nucleus is called nucleoplasm.
General Characteristics of Cells Size and Shape These are related to function. Some cells like white blood cells can change shape as they move about.
General Characteristics of Cells Cell Structure Suspended in the cytoplasm are various organelles. Intracellular fluid, called cytosol, consists mainly of water. In this are dissolved amino acids, sugars and other substances used to make bigger molecules. Structural proteins, enzymes and ions used to maintain a balanced biochemical environment are also present.
General Characteristics of Cells Organelles The inside of cells are divided into small compartments so different functions can go on at specific places in the cell at the same time. The compartments are called organelles, each has a different function.
Plant Cell
Animal Cell
Prokaryote Cell
Plant Cells Animal Cells Plasma Membrane Microvilli Plastids Nucleus Endoplasmic reticulum Ribosomes Golgi body Lysosomes Vacuoles Peroxisomes Mitochondria cytoskeleton Centrioles Cilia Flagella Plastids Chloroplasts Cell walls Large vacuole
Cell Membrane This separates the cell from the environment and maintains stable cell environment by controlling entry and exit of substances. It is selectively/partially permeable
Cytoplasm A jelly-like substance found between the cell membrane and the nuclear membrane. Holds the organelles in place Contains dissolved substances and is the site of many chemical reactions.
Mitochondria The site of respiration – energy production in the cell.
Golgi Apparatus This modifies proteins made by the ribosomes then packages them up and secretes them.
Endoplasmic Reticulum A transport network within the cell Smooth ER is the site for lipid synthesis (sER) Rough ER is the site for protein synthesis. (rER)
Ribosomes These can be associated with ER to form rough ER or free in the cytoplasm. The site of protein synthesis.
Nucleus This is the control centre for cell – it contains genetic material. Surrounded by a nuclear membrane. The nuclear membrane has a number of nuclear pores so substances can enter and leave the nucleus. Contains a nucleolus where RNA is made.
The Nucleus
Vacuoles These are found in plant cells Storage sac for chemicals or water.
Lysosomes These are specialized vacuoles containing enzymes
Centrioles Found only in animal cells. forms spindle fibre in cell division
Chloroplasts These are found in plant cells. The site of photosynthesis.
Cell Wall This is found in plant cells and is made of cellulose. It provides a rigid support for the cell and prevents it from expanding too much.