Cells – The Basic Units of Life

Basic Regions of the Cell Cytoplasm -the cell substance between the cell membrane and the nucleus, containing the organelles, cytoskeleton, and various particles.

Nucleus - a part of the cell containing DNA and RNA and responsible for growth and reproduction The control center of the cell.

Cell Membrane - The semipermeable membrane that encloses the cytoplasm of a cell. Also called the plasma membrane.

Cell Organelles

Organelles found in Both Animal and Plant Cells

The Plasma Membrane (or Cell Membrane) The semipermeable membrane that encloses the cytoplasm of a cell. Made up of fatty molecules arranged in a double layer It is selectively permeable – meaning it lets only SOME substances in or out. It controls what enters and leaves the cell. It has receptor proteins which detect signals from outside the cell

The Nucleus Contains all genetic information for the cell in the form of DNA Inside nucleus -instructions contained in the DNA are copied into RNA. Then the RNA leaves the nucleus and brings instructions to the rest of cell for producing proteins

Another view of the nucleus

The Nuclear Membrane Surrounds the nucleus Composed of two layers Has openings (pores) for “traffic” in and out of the nucleus. It is attached to the endoplasmic reticulum.

Mitochondria (singular “mitochondrion”) Called the “Power Plants” of the cell They convert organic materials into energy (they make a substance called ATP). Carry out cellular respiration. Sugar + oxygen  carbon dioxide + water + energy(ATP) They control the level of water and other materials in the cell. A cell can have hundreds or thousands of mitochondria, which can occupy up to 25% of the cell's cytoplasm.

Cellular Respiration Mitochondrion Sugar + Oxygen  Carbon Dioxide +Water + Energy(ATP) Takes place in the mitochondria of cells of both animals and plants.

Ribosomes Their function is to assemble proteins (from amino acids) Look like little “dots”. Some on the surface of endoplasmic reticulum and some “free” in the cytoplasm Each cell contains thousands.

Endoplasmic Reticulum Connected to the nuclear membrane. A network of tubes. The cell’s transport system The “rough type” has ribosomes on its surface. The “smooth type” lacks ribosomes. Help transport proteins to different parts of the cell.

Golgi Apparatus Protein packaging plant. Packages molecules into small sacs called vesicles.These are sent to other parts of the cell.

Vacuole Sacs with a membrane. Used for storage, digestion and waste removal. Contain water solutions. Usually one large central vacuole in plant cells and more than one smaller vacuole in animal cells.

Lysosomes lysosome animation Digestive “plant” for proteins, fats and carbohydrates. They fuse with a food vacuole, digest it and carry the wastes to the cell membrane for disposal. Help keep the cell “clean” by destroying used up organelles.

Organelles found in Animal Cells Only

Centrioles                                There is one pair in each cell. Each centriole is made up of a ring of nine microtubules. During cell division, or mitosis, the centrioles produce spindle fibers which help to pull chromosomes apart. Centrioles are found only in animal cells.

Organelles found in Plant Cells Only

Chloroplasts Found in all higher plant cells. They contain chlorophyll, which makes them green. They capture light energy from the sun to carry out photosynthesis in the cell. carbon dioxide + water + energy sugar + oxygen CO2 + H2O + energy C6H12O6 + O2 chlorophyll chlorophyll

The Cell Wall Protects the cell Makes the cell rigid (found only in plants) Lets water and nutrients pass through (porous) Thicker than cell membranes Made up of cellulose and other materials

The Differences Between Animal and Plant Cells Animal Cells Plant Cells Contain centrioles Don’t contain centrioles Don’t contain chlorplasts Contain chloroplasts Do not have a Cell Wall Have a Cell Wall Have more than one small vacuole Usually have one large central vacuole Usually smaller than plant cells Usually larger than animal cells

Summary of Cell Organelles Function Mitochondria Energy center or "powerhouse" of the cell. Turns food into useable energy (ATP) Ribosomes Make protein Golgi Apparatus Processes, packages and secretes proteins Lysosome Contains digestive enzymes, breaks things down Endoplasmic Reticulum Transport, "intracellular highway" Vacuole Stores water or other substances Chloroplast Uses sunlight to create food, photosynthesis (only found in plant cells) Cell Wall Provides additional support (plant and bacteria cells) Cell membrane Gives form to cell and controls materials going into and out of cell Nucleus Direct cell activity and forms ribosomes Centrioles Organize spindle fibers and assist mitosis Plastids (like chloroplasts) Pigment-forming structures providing color.

Some other structures found in Cells

Cilia (singular cilium) Thin, tail-like projections coming from the outer surface of the cell. One type is used for propulsion. Another type used for sensing. Found in protozoa (propulsion) Found in cells lining our trachea (sweep mucus) and ovum (move ovum from ovary to uterus) cilia cilia animations

Flagella (singular flagellum) A “whip-like” organelle used to move about. Used by many unicellular organisms mainly. (eg. bacteria) flagella animations