Cell Structure & Function http://koning.ecsu.ctstateu.edu/cell/cell.html

Cell Theory All living things are made up of cells. Cells are the smallest working units of all living things. All cells come from preexisting or other cells through cell division.

Definition of Cell A cell is the smallest unit that is capable of performing life functions.

Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell

Prokaryotic 2. Eukaryotic Two Types of Cells Prokaryotic 2. Eukaryotic Can you see what the difference between them is? http://www.biology4kids.com/files/cell_main.html

Prokaryotic DNA is not in a nucleus, it sort of floats around the cell. No organelles contain membranes. Few internal structures. No mitochondria, no chloroplasts, no nucleus One-celled organisms, Example: Bacteria, virus, amoebas http://library.thinkquest.org/C004535/prokaryotic_cells.html

Examples of Cells that Move Bacteria Cells Notice the bacteria and paramecium have cilium & flagella. Flagella is the tail-like structure and cilia are the hair-like structures. Both help the cell with locomotion or movement of the cell. http://library.thinkquest.org/C004535/prokaryotic_cells.html

Eukaryotic Cells Contain organelles surrounded by membranes Have a true nucleus Make up most living things. Plant Animal http://library.thinkquest.org/C004535/eukaryotic_cells.html

Animal and Plant Cells What’s the difference? Animal cells do not have a cell wall, but they both have a cell membrane. Plant cells have a cell wall, chloroplasts, and larger vacuoles Animal cells are found in humans, animals, insects, etc…

Cell Parts. . . are called Organelles They are very small in size They perform all the functions of the cell. Can only be observed under a microscope Have specific functions Found throughout cytoplasm of the cell.

Surrounding the Cell

Cell Membrane Flexible outer membrane of the animal cell and found under the cell wall in plants. Membrane controls movement in and out of the cell Must move oxygen, wastes, water, and nutrients in and out of the cell. http://www.biology4kids.com/files/cell_main.html

Cell Wall Most commonly found in plant cells & bacteria Found to be more tough and rigid than the cell membrane Supports & protects cells Cell wall allows nutrients and water through the holes in the wall which are called plasmodesmata. http://www.biology4kids.com/files/cell_main.html

Inside the Cell

Nucleus Directs cell activities Separated from cytoplasm by nuclear membrane Contains genetic material – DNA on chromosomes Inside the nucleolus is RNA and protein, not much DNA at all. Typically the largest organelle in the cell. When chromosomes are bundled together they are called chromatin. http://www.biology4kids.com/files/cell_main.html

Nuclear Membrane Surrounds nucleus Made of two layers Openings allow material to enter and leave nucleus Only found in cells with a nucleus. (Eukaryotic) Pre-Ap only http://library.thinkquest.org/12413/structures.html

Chromosomes Inside nucleus Made of DNA DNA contains instructions for traits & characteristics DNA is made up of 4 nitrogen bases: 1. Adenine 2.Guanine 3. Cytosine 4. Thymine Pre-Ap only http://library.thinkquest.org/12413/structures.html

Nucleolus What’s inside the nucleolus. Appears tightly bundled within the nucleus Contains DNA & RNA. RNA is used to build proteins that will carry out many functions of the cell. Pre-Ap only http://library.thinkquest.org/12413/structures.html

Cytoplasm Thick gel-like mixture that fills the cell (light blue below) Surrounded by cell membrane 80% water that is clear – fills the cell

Mitochondria Produces energy through chemical reactions – breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates Like the digestive system of the cell. http://library.thinkquest.org/12413/structures.html

Vacuoles Sac with a membrane used for storage of food, water, and waste products. Vacuoles contain water solution Vacuoles are much larger in plant cells than animal cells. A drooping plant would indicate empty vacuoles, but a full plant shows the vacuoles are full of water. http://www.biology4kids.com/files/cell_main.html

Chloroplast Usually found in plant cells, not in animal cells – photosynthesis takes place here. Contains green fluid called chlorophyll Chlorophyll uses the sun’s energy to combine Carbon Dioxide (CO2) & Water (H2O) to create sugars. The plant releases the O2 created and uses the sugar to grow. http://www.biology4kids.com/files/cell_main.html http://hyperphysics.phy-astr.gsu.edu/hbase/biology/chloroplast.html

Endoplasmic Reticulum Also called ER Looks like a maze Main function: helps make proteins and other substances Works with Ribsomes Usually found around the nucleus

Ribosomes Look like dots Main job: make proteins needed by the cell Is helped by the ER Can be found attached to the ER or floating in the cell

Golgi Apparatus Also called Golgi Bodies Flattened sacs and tubes Is like a warehouse Main job: packages and sends out proteins to other organelles or to other cells

Lysosomes Sac like structures They are like recycling centers Main job: break down old cell parts. Break down large food particles into smaller ones