All organisms are made up of one or more cells 2. Cells come from only pre-existing cells **When it comes to studying life, all living things have something in common. Cells provide the F. Cell Variation basic for studying all life. 1. Cells vary in size and shape 2. Vary in shape G. Cell organization in organisms 1. Unicellular 2. Colonial Multicultural – live together but can be independent 3. Other multicultural organisms have specialized cells organized as follows: Specialized Cells – cells that perform one or few functions very well. Examples: white blood cells, red blood cells, muscle ells.
Tissue – Groups of specialized cells that work together Organ – groups of tissues that work together Organ System – groups of organs that work together II. Parts off cell : all cell parts have functions A. Parts found in all cells cells, nerve 1 . Cell membrane – two layers of lipids with proteins embedded a. Function : regulates what enters and leaves the cell b. Selectively permeable – allows some molecules to pass through but not others c. Factory analogy = security 2. Cytoplasm – gelatin-like substance inside cells that hold all cell parts together mostly water 3.
Ribosome – very small structures made of RNA and protein a. Can be free in the cytoplasm or attached to the ERE b. Function : amino acids put together to make proteins c. Factory analogy = assembly line 4. All cells have DNA as genetic material a. The DNA in a cell contains the blueprints or instructions for all of the cell processes B. Internal cell parts made from membrane – organelles (only eukaryotic) 1. Nucleus – contains DNA a. DNA carries instructions for assembling a cell’s proteins which are responsible or running all of the cell’s reactions .
DNA is packed into bundles called chromosomes when a cell is ready to divide c. The nucleus makes ribosome for the cell d. Factory analogy = data base room or blueprint room 2. ERE – A network of winding membrane channel a. Function : transportation of materials b. 2 kinds of ERE I. Rough ERE – ERE with ribosome ii. Smooth ERE – ERE without ribosome c. Factory analogy = conveyor belt 3. Googol apparatus – flattened membrane sacs a. Function : package proteins to be shipped out of the cell b. Gland cells that secrete enzymes or hormones have many googol apparatus c. Factory analogy = shipping department 4.
Mitochondria – double membrane sacs a. Function: hold all the enzymes that are used to turn food into energy b. Almost all of the energy a cell needs are produced in these structures c. Factory Analogy = power house of the cell d. The more energy a cell needs, the more mitochondria a cell has: muscle and nerve cell have many mitochondria 5. Lissome – membrane sacs that contain digestive enzymes a. Function : break down molecules so that the building blocks can be recycled b. Cells that cannot make their own food often have lissome to help reek down food c.