Plasma Membrane Proteins Pumps: transports ions, amino acids, sugars actively across membranes Channels: allow small molecules to cross the cell membrane Receptors: recognize and bind specific effector molecules initiating a response Linker : anchor the intracellular cytoskeleton to the extracellular matrix Enzyme: modify extracellular components Structural Proteins: Often link cells to one another concentrated in specific regions Endocytosis Pinocytosis: invagination of fluid and small molduce into cell. ● Formation of pit ● Surround extracellular fluid and brins inside the cell ● Not specific Phagocytosis: invagination of large substance into the cell ● Surrounds bacteria, engulf it ● Used for larger molecule Receptor mediated endocytosis ● High specificity, receptor driven ● Activate receptor with ligand Exocytosis Moves particles out of the cell Endoplasmic Reticulum (ER) RER(rough endoplasmic reticulum) ● Has polyribosomes attached to the other membrane surface for protein synthesis ● Composed of stacks of flat cisternae(cisterna) SER(smooth endoplasmic reticulum) ● Lacks polyribosomes and synthesizes steroid hormones and phospholipids ● Composed of tubular cisternae RER is continuous with SER and together thy form transport vesicles that travels to the Golgi apparatus Multiple ribosome on same mRNA creating proteins Electron Micrograph of RER Light Micrograph of cells with abundant RER Golgi Apparatus Release of trans face of the golgi ● Secretory vesicle will bud off from Trans Golgi ● Transport vesicles from RER will arrive form CIs Lysosome ● Inactive hydrolytic enzymes from RER travel through Golgi and are packaged as primary lysosomes ● Thee membrane of a lysosomes prevents leakage of enzymes into cytoplasm and self digestion ● Extracellular matter is taken up by endocytosis forming a phagosome ● The lysosome fuses with tit and releases active hydrolytic enzyme ● Indigestible matter retained in vesicle is termed a residual body ○ Cardiac muscle, neurons ● Residual bodies can form lipofuscin pigment granules within cells ● Digested material diffuse into the cytoplasm Primary lysosome: mature, but does not have gone through anything When bacteria fuses to lysosome, it becomes Secondary lysosome Will not digest golgi because pH dependent, and will not activate until right pH Electron micrographs of Lysosomes Mitochondria: Dual membrane, have intramembrane space between them Outer membrane ● Contains pores for passage of molecules to and from cytosol and intermembrane space Inner membrane ● Contains enzymes for oxidative phosphorylation, electron transport system, and ATP synthase Matrix ● Contains circular DNA,RNA and mitochondrial proteins Elementary particles-energy producing ● Increase surface area ● Finger like projection Formation of ATP in mitochondria 1. Pumps proton into intramembranous space 2. Coupled to ATP phosphorylation 3. Exchange ADP to ATP in intramembranous space Cytoplasmic inclusions:G;ycogens and lipid droplets ● Glycogen particles: carbohydrates(energy) storage(liver,muscle) ● Lipid droplets: Cholesterol storage in steroid hormone secreting cells ● Both are not enclosed in plasma membrane Brown fats ● Cytoplasmic links are filled with mitochondria nd the fat gets metabolized ○ Electron transport chain doesn't make ATP, makes heat Lipid Droplets ● Young humans for survival ○ Surface area too large compared to body size so great loss of heat Glycogen in EM can be caught in little rossett patterns 80nm in size. In lower power, glycogen may look like ribosome but are much smaller Cytoplasmic inclusions:lipofuscin ● Oxidized metabolic breakdown products Sympathetic ganglion, light micrograph H&E Q1) in microscopy, resolution is defined as The smallest distance between two items that are discernible as separate objects Nucleus ● Contains a nucleolus for formation of ribosomal RNA subunits ● Nuclear envelope has pores for communication ○ Bilayerd membrane: formed by rough ER ● Outer nuclear membrane is continuous with RER ● Lamins: filamentous proteins attached to inner nuclear membrane forms a nuclear skeletons ● Euchromatin actively transcribed DNA ○ Loosely spread out-transcription can occur ● Heterochromatin is inactive DNA ○ Highly condensed ● Average diagram 3~15μm The nuclei can have different shapes and sizes The nucleosomes and histone ● Package DNA strands Packaging of DNA: Chromatin and chromosomes Organization of the Nucleolus ● Plasma cells more RER= making proteins ○ Ribosomes needed to be replaced ● Nucleus pumping out ribosomes, chromatin being transcribed to form messenger RNA Pars fibrosa ● more grannual, transcription. RNA associate with proteins to form ribosomes Fibrillar centers with Nucleolar organizing REgions (NOR) ● Genes that code for ribosomal RNA is located ● When RNA polymerase is attached to the DNA sequences to make ribosmomal RNA, then more to pair fibrous NOR are sites of nucleolar gene transcription Nuclear envelope and nuclear pore complex ● Nucleus and cytoplasm are held together by Nuclear pores The cytoskeleton ● Intermediate filament ○ Stabilize cell ○ Dynamic, can move around ● Microtubules ○ Long holo cylinders in cell ○ Gives stability ○ Surface for motor ● Microfilaments ○ Basis for most construction ○ Mostly found in periphery of the cell ○ Projection of cell ○ Finger-like projection Microfilament ●