Cell Biology Basics

Study Notes

Cytosol: involved in metabolism, protein synthesis, and cell signaling
Cytoskeleton: maintains cell shape, enables cell movement, and facilitates transport
Nucleus: holds genome, synthesizes DNA and RNA
Mitochondria: generates ATP through oxidative phosphorylation, stores calcium
Smooth ER: synthesizes lipids, stores calcium
Ribosomes: translates mRNA into proteins
Rough ER: translates mRNA into membrane proteins for secretion
Lysosome: facilitates intracellular degradation
Endosome: mediates cellular uptake of cholesterol, removal of receptors from the plasma membrane, uptake of small molecules and water into the cell
Golgi Apparatus: modifies, sorts, and packages proteins and lipids for delivery within the cell or secretion
Proteosome: degrades intracellular proteins
Peroxisome: detoxifies substances

5 nm-thick lipid bilayer composed of lipids, cholesterol, proteins, and carbohydrates
Lipids include phospholipids and phosphoglycerides
Polar ends form the surface (hydrophilic) and non-polar ends face inward (hydrophobic)
Composition varies according to cell type
Lipid bilayer helps with cell signaling
Cholesterol stabilizes the membrane at normal body temperature, involved in cell building and repair

50% of the membrane is composed of membrane proteins (integral, lipid-anchored, or peripheral)
Integral proteins: embedded in the lipid bilayer, span the bilayer (transmembrane proteins), act as receptors inside the cell
Lipid-anchored proteins: covalently bonded to lipid molecules
Peripheral proteins: associated with the lipid bilayer, often bound to integral or lipid-anchored proteins
Outer membrane proteins undergo glycosylation (attachment of a carbohydrate to a protein)

Diffusion: particles move from high to low concentration areas
Osmosis: water moves from high to low concentration areas
Transport: movement of molecules or substances, can go against the concentration gradient (requires energy)
Active transport: uses ATP, example: Sodium/ Potassium pump