Chapter 3: Cells 1Chapter 3: Cells - Basic unit of organization in the bodyo Erythrocytes, Fibroblasts, epithelial cells, skeletal muscle cells, fat cells, etc- “typical cell”o 2 basic compartments o Compartmentalized: different reactions happen in different parts Organelles in cytoplasm of cello Mitochondria: contains 2 membranes Main function: power house of cell and apoptosis- Apoptosis: programmed cell death (prevents cancer) Reaction: glucose + oxygenCO2+H2O+Energy (ADP)- Energy= ADPATP Defectsaffect muscle and nervous system  Contains its own DNAo Ribosomes: consist of RNA and protein; small in size (small dots in cytoplasm) Large and small subunit Function: synthesize proteins from the RNA template o Endoplasmic Reticulum: Smoot and Rough (ribosomes attached)- Series of membranes  Smooth: detoxification, phospholipid synthesis Rough: ribosomes attached- Proteins in: ER, Golgi, Lysosomes, Secretedo Golgi Body: series of membrane sacs Function: modify proteinsadds carbohydrate groups, cuts proteins; “Packages proteins”o Lysosomes: contains hydrolytic enzymes Destroys stuff (DNA, RNA, Proteins, Carbs) Compartmentalized cell= importantprotectionPlasma membraneNucleoplasmNucleus cytoplasmChapter 3: Cells 2- Flow of Informationo Synthesized Proteins: RERGolgisecreted (exocytosis) o Transport occurs in vesicles (membrane sacs)o Cells that secrete a lot have a lot of RER and Golgi bodieso Can bring substances into the cellfuse with lysosomes and destroyed- Cytoskeleton: filaments in the cytoplasm o Microfilaments: (smallest) comprised of individual actin molecules Functions: maintain shape, involved in cell movement  Has ability to polymerize and depolymerize- Changes lengthhelps movement- Polymerize: get longer- Depolymerize: shortens o Intermediate Filaments: Larger than microfilaments  Keratin: found in skin, very strong, provides structure in our skin Neurofilaments: in neurons o Microtubules: comprised of tubulin Can polymerize and depolymerize  Has hollow center Function: maintains shape, involved in movement - Motor Moleculeso Moves vesicles they walk on filaments and carry the vesicle Truck= molecules; Highway= filamentso Cause filaments to slide back and forth - Ciliao Small hair like structureso Made of microtubules o Found in respiratory tractmoves mucus - Flagellao Found in spermo Cause sperm to move - Nucleuso Site of RNA synthesis, RNA processing, DNA replicationo DNA is in nucleus  Nuclear Envelope: double layered membrane; has pores Nuclear Pores: selective gates used to pass things in and out of the nucleus  Nucleolus: site of ribosome formationlysosomesChapter 3: Cells 3 Chromatin: DNA (-) and Protein- DNA wraps around nucleosomesgets tighter and tighterchromatido Nucleosome: histone (+) proteins bind to DNA- Plasma Membrane: critical point in the cell Hydrophobic: water fearing- Non-polar (ie. Lipids) Hydrophilic: water loving- Polar (charged)o Phospholipids: backbone of membrane Responsible for permeabilities  Hydrophobic corebare- Only non-polar molecules pass through- Charged particles can’t pass througho Cholesterol: stabilizes plasma membrane  Found in hydrophobic regiono Proteins:  Integral membrane proteins: inserted into the bilayer - Transmembrane protein: reaches from one side of the membrane to the other Peripheral membrane protein: NOT interacting with hydrophobic region- Sits on outside of the membrane  Glycoprotein: protein attached to a carbohydrate Glycolipid: cholesterol attached to a carbohydrate  Helps polar molecules get through the membrane- Transport: transmembrane protein provides a hydrophilic channel across the membrane that’s selective for a particular solute- Receptors for Signal Transduction: membrane protein exposed to the outside of the cell has a binding site with a specific shape that fits the shape of a chemical messenger- Attachment to the cytoskeleton and extracellular matrix (ECM): elements of the cytoskeleton and the extracellular matrix are anchored to membrane proteins, which help maintain cell shape and fix the location of certain membrane proteins- Enzymatic activity: protein built into the membrane may be an enzyme with its active site exposed to substances in the adjacent solution- Intercellular joining: membrane proteins of adjacent cells may be hooked together in intercellular junctions.Chapter 3: Cells 4o Held together by proteins- Cell-Cell Recognition: some glycoproteins serve as ID tags that are specifically recognized by other cellso Specializations Microvilli: finger like projections - Increase surface area/ amount of membrane- Found in small intestinesmore surface area allows it to absorb more Junctions- Tight junctions: membranes fuse together o Prevent substances from passing around the cells(they must be absorbed)o Ie. small intestines- Desmosomes: very strongo Cells held together by filaments keep things togethero Plaque o Ie. Small intestines, skin, epithelial cells- Gap Junctions: provide a passageway between cellso Cytoplasm of two cells are linked together by tunnels allows communicationo Ie. Smooth muscle cells o Transport: How molecules get in and out of the cell Differentially permeable Passive Transport: no energy needed- Simple Diffusiono Molecules move randomly (no direction)o Smaller molecules diffuse fastero Higher temperature= faster diffusiono Net movement is down the concentration gradiento Non-polar molecules only! (O. CO2, steroid hormones, fats etc.)-Osmosis: diffusion of a solvent (H2O) through a semi-permeable membraneChapter 3: Cells 5o Consequences: tonicity – refers to solutions - Facilitated Diffusiono For molecules too large to fit through membraneo Larger, polar molecules Sugars, amino acidso Needs proteins to help it cross membrane Channel proteins Carrier proteins o Very specifico Easily regulated Active Transport: needs energy (ATP must be cleaved)- Move up concentration gradient - Ions, amino acids, sugarso Ex. Na+ and K+ pump for muscle contraction - Vascular Transport (bulk transport)o Exocytosis: process of secretion  Movement from celloutside  Ie. Mucus, neurotransmitters, hormoneso Endocytosis: outsideinside Phagocytosis: large particles (ie. Bacteria)- Cells that do