Biology Cellular Organelles

Organelles = Cell Parts Cell membrane: –Structure: phospholipid bilayer cholesterol floating proteins (channel proteins, receptor proteins) –Function: controls what enters and exits the cell.

Cellular Organelles (con’t) Endoplasmic reticulum (ER): –Structure: series of tubes –Function: transport of molecules within the cell. –Smooth ER –Rough ER: imbedded with ribosomes.

Cellular Organelles (con’t) Ribosomes: –Structure: pieces of protein & RNA. –Function: put amino acids together in the correct order to make proteins. –Some are embedded in ER; others are free-floating in the cell.

(Although they are often drawn greatly simplified, ribosomes are, in reality, very complex structures. ) (picture: DNA, James Watson, 2003)

Cellular Organelles (con’t) Golgi apparatus: –Structure: stacks of membranes –Function: modifies & packages (puts a membrane around) proteins as they leave the ER.

Cellular Organelles (con’t) Mitochondria: –Structure: highly folded tiny structures of enzymes and other proteins. –Function: break down lipids & carbohydrates to release energy from them. (powerhouses of the cell).

Cellular Organelles (con’t) Lysosomes: –Structure: bags of “digestive” enzymes –Function: break down worn-out cell parts inside the cell.

Cellular Organelles (con’t) Cilia & Flagella –Structure: identical: thin, whiplike structures Flagella look like tails –Function: movement

Cellular Organelles (con’t) Microfilaments & microtubules: –Structure: tiny, thin protein tubes. –Function: serve as the structure that “holds up” a cell (cellular skeleton).

Cellular Organelles (con’t) Nucleus: –Structure: round structure. –Function: site of DNA storage within a cell.