1. Plasma membrane : Separates cell contents from outside environment. Made up of phospholipid bilayers and proteins.
2. Cytoplasm : Liquid, jelly-like material inside cell.
3. Ribosomes : Necessary for protein synthesis.
Procaryotic versus Eucaryotic Cells Feature Procaryotic Eucaryotic Organisms Bacteria All others (animals, plants, fungi, and protozoa) Nucleus Abzsent Present DNA One chromosome Multiple chromosomes Size Small (1-10 um) Large (10 or more um) Membrane Absent Present (mitochondria, Bound golgi, chloroplasts, etc.) Organelles Division Rapid process Complex process (Binary fission) (Mitosis)
3. Receptor mediated endocytosis : Highly specific. Materials moved into cell must bind to specific receptors first.
Example: Low density lipoproteins (LDL) :
Main form of cholesterol in blood.
Globule of cholesterol surrounded by single layer of phospholipids with embedded proteins.
Liver cell receptors bind to LDL proteins and remove LDLs from blood through receptor mediated endocytosis.
Familial hypercholesterolemia : Genetic disorder in which gene for the LDL receptor is mutated. Disorder found in 1 in 500 human babies worldwide. Results in unusually high levels of blood cholesterol.
Blood Cholesterol is Taken Up by Liver Cells through Receptor Mediated Endocytosis