Eukaryotic Cell Structure 7.3

Human Cell

Nucleus Nuclear Envelope- double membrane that surrounds the nucleus nuclear pores - regulates what enters and leaves the nucleus Chromatin- long strands of DNA that form chromosomes (grainy-looking in a cell) Nucleolus- spherical structures inside the nucleus, functions in making ribosomes

Nucleus

Plasma Membrane Found in all cells Flexible boundary: –Outer boundary in animal cells Function: - regulates what enters and leaves the cell

Cell Boundaries Cell Wall: -Found in bacteria, some protists, fungi and plants Functions: -forms a rigid, strong boundary -when present, it is outside the cell membrane

Cell Wall Cell Wall In plants, the cell wall is composed of cellulose

Cytoplasm Jelly-like substance found between the plasma membrane and the nucleus 1. Suspends the cell organelles (membrane-bound structures) 2. Area where cell metabolism occurs

Organelles: Assembly, transport and store materials 1.Ribosomes -spherical structures where proteins are synthesized -free-floating groups or attached to ER

2. Endoplasmic reticulum (ER) -folded system of membranes a.folds increases the exposed surface area b. forms sheet-like and tube-like areas c. functions to make and transport materials

Rough ER (RER) Smooth ER (SER) Rough ER (ER that has ribosomes attached) -’sheet-like’ area -proteins made here are secreted out of the cell or incorporated into cell membranes Smooth ER (no attached ribosomes) -’tube-like’ area -site of lipid and carbohydrate production -toxins and drugs broken down here Endoplasmic Reticulum (ER)

3. Golgi Apparatus -series of stacked, flattened sacs -functions to process and package proteins, lipids and carbohydrates -some are stored in the cell and others are secreted out of the cell

4. Vacuole (membrane sac) -functions to store food and waste *contractile vacuole – pumps out excess cell water from unicellular animals 5. Plastids – (plants only) -store pigments and starchs 6. Lysosome- sac of digestive enzymes -break down old organelles and foreign bodies

Energy Transformers Energy Transformers 1. Mitochondria-“power house of the cell” -site of Cellular Respiration -Foods are converted into useable energy using oxygen -double membranes -Inner membrane is folded to increase surface area -has own DNA and ribosomes

2. Chloroplast (plants only) -contains Chlorophyll -traps light energy then transforms CO 2 and H 2 O into sugar. -double membranes -inner membrane forms stacks called grana -fluid-filled space between the grana is called the stroma -has own DNA and ribosomes

Cytoskeleton- support structure within the cytoplasm or “ skeleton of the cell” 1.Microtubules -thin hollow cylinders -give rigid support -can transport material (on the outside)

2. Microfilaments –thin, solid helical fibers -Contractile (contract to change cell shape)

3. Cilia - short, hair-like projections for: -movement in free-swimming cells -capture food in free-swimming animal cells -moving materials across the surface of fixed cells (mucus in the lungs) - composed of series of microtubules

4. Flagella- long, whip-like structure -for locomotion -composed of microtubules arranged in the same pattern as in cilia

Centriole -cell component that produces microtubules that are used inside animal cells -centrioles are not visible in plant cells