Chapter 3 Compartmentation: Cells and Tissues

About This Chapter • Functional compartments of the body • Biological membranes • Intracellular compartments • Tissues of the body • Tissue remodeling • Organs

Lumens of Hollow Organs • Hollow organs – Heart – Lungs – Blood vessels – Intestines • Lumen – For some organs, not the internal environment

Functional Compartments • Extracellular fluid – Plasma – Interstitial fluid • Intracellular fluid

Cell Membrane: Function • Physical isolation • Regulation of exchange with the environment • Communication between the cell and its environment • Structural support

Cell Membrane: Composition • Proteins – Integral – Transmembrane – Lipid-anchored – Peripheral

• Lipids – Phospholipids – Sphingolipids – Cholesterol

• Carbohydrates – Glycoproteins – Glycolipids

Intracellular Compartments • Cytoplasm – Cytosol – Inclusions – Cytoskeleton – Organelles • Nucleus

Inclusions Have No Membranes • Ribosomes – Fixed – Free – Polyribosomes

Cytoplasmic Protein Fibers • Actin (microfilaments) • Intermediate filaments – Keratin – Neurofilaments • Microtubules – Centrioles, cilia, flagella

Microtubule Function • Centrosome – Assembles tubulin monomers into microtubules • Centrioles – Direct DNA movement in cell division • Cilia – Fluid movement across cells • Flagella – Cell (sperm) movement through fluid

Cytoskeleton: Function • Cell shape • Internal organization • Intracellular transport • Assembly of cells into tissues • Movement

Motor Proteins: Function • Myosins – Muscle contraction • Kinesins and dyneins – Movement of vesicles along microtubules • Dyneins – Movement of cilia and flagella

Mitochondria • Two membranes create two compartments – Mitochondrial matrix – Unique DNA – Intermembrane space – Cellular ATP production

Endoplasmic Reticulum (ER) • Rough ER – Ribosomes attached – Protein assembly and modification • Smooth ER – Synthesis of fatty acids, steroids, lipids – Modified forms in liver, kidney, muscles

Golgi Apparatus (Golgi Complex) • Stacked membranes surrounded by vesicles • Modifies protein from rough ER • Packages proteins into vesicles

Cytoplasmic Vesicles • Secretory vesicles – Released from cell • Storage vesicles • Lysosomes – Enzymes to degrade bacteria or old organelles – Acidic interior • Peroxisomes – Enzymes to degrade long-chain fatty acids and toxic foreign molecules – Generate hydrogen peroxide

Nucleus • Nuclear envelope: two membranes • Nuclear pore complex • Chromatin: DNA and associated proteins • Nucleoli – Control RNA synthesis

Primary Tissue Types • Epithelial • Connective • Muscle • Neural/nerve

Extracellular Matrix • Synthesized and secreted by cells • Proteoglycans – Glycoproteins • Insoluble protein fibers – Examples: collagen, fibronectin, laminin – Strength – Anchor cells to matrix for communication

Cell Junctions and CAMs • Cell to cell – Gap junction (communicating junction) – Tight junction (occluding junction) – Anchoring junction – Cell–cell with cadherins – Adherens junctions – Desmosomes – Cell–matrix with integrins – Hemidesmosomes – Focal adhesions

Epithelial Tissue: Structure • One or more layers of epithelial cells • Separated from underlying tissue by basal lamina or basement membrane • Two types – Sheets of cells lining body surfaces – Secretory epithelia

Epithelial Tissue: Classified • Layering – Simple or stratified • Shapes – Squamous, cuboidal, columnar • Function – Exchange, transporting, ciliated, protective, secretory

Transporting Epithelium: Characteristics • Cell shape • Membrane modification – Apical membrane: faces lumen – Basolateral membrane: faces ECM • Cell junctions • Cell organelles

Secretory Epithelium • Scattered • Grouped into glands – Exocrine: release products to external environment (most through ducts) – Serous secretions – Mucous secretions/mucus: produced by goblet cells – Endocrine: release hormones into extracellular compartments

Connective Tissues: Structure • Ground substance (matrix) – Highly variable • Cells – Fixed – Blasts, clasts, and cytes – Mobile • Matrix fibers – Collagen, elastin, fibrillin, fibronectin

Dense Connective Tissues • Tendons – Skeletal muscles to bone • Ligaments – Bones to bones

Supporting Connective Tissues • Cartilage – Solid and flexible – Lacks blood supply – Nose, ears, knee, windpipe/trachea • Bone – Calcified – Strong and rigid

Additional Connective Tissues • Adipose connective tissue – White – Single lipid droplet – Brown – Multiple lipid droplets • Blood – Plasma matrix – Free blood cells

Muscle Tissues • Excitable • Contractile – Force and movement • Three types – Cardiac – Smooth – Skeletal

Nervous Tissues • Neurons (nerve cells) send signals – Excitable • Glial cells (neuroglia) support

Tissue Remodeling • Cell death – Necrosis – Apoptosis (programmed cell death, cell suicide) • Stem cells – Totipotent – Pluripotent – Multipotent

Organs • Groups of tissues with related function • Skin as an example of an organ

Summary • Functional compartments of the body • Biological membranes • Intracellular compartments • Tissues of the body • Tissue remodeling • Organs: skin as an example

Chapter 4 - Energy and Cellular Metabolism

About This Chapter • Energy in biological systems • Chemical reactions • Enzymes • Metabolism

Energy: Capacity to Do Work • Chemical work – Making and breaking of chemical bonds • Transport work – Moving ions, molecules, and larger particles – Useful for creating concentration gradients • Mechanical work – Moving organelles, changing cell shape, beating flagella and cilia – Contracting muscles

Energy Comes in Two Forms • Kinetic energy – Energy of motion – Work involves movement • Potential energy – Stored energy – In concentration gradients and chemical bonds – Must be converted to kinetic energy to perform work – Transformation efficiency

Thermodynamic Energy • First law of thermodynamics – Total amount of energy in the universe is constant • Second law of thermodynamics – Processes move from state of order to randomness or disorder (entropy)

Chemical Reactions • Bioenergetics is the study of energy flow through biological systems • Chemical reactions – Reactants become products – Reaction rate • Activation energy • Net free energy change of the reaction – Exergonic versus endergonic reactions – Coupled reactions – Reversible versus irreversible reactions

Enzymes: Overview • Enzymes speed up the rate of chemical reactions – Catalysts – Reactants are called substrates • Isozymes • Catalyze same reaction, but under different conditions • May be activated, inactivated, or modulated – Coenzymes → (e.g., vitamins) – Chemical modulators → temperature and pH

Metabolism • All chemical reactions that take place in an organism • Catabolism versus anabolism • Kilocalories are measures of energy released from or stored in chemical bonds • Molecules in pathways are intermediates

Cells Regulate Their Metabolic Pathways 1. Controlling enzyme concentrations 2. Producing modulators that change reaction rates 3. Using different enzymes to catalyze reversible reactions 4. Compartmentalizing enzymes within organelles 5. Maintaining optimum ratio of ATP to ADP

ATP Transfers Energy Between Reactions • High-energy phosphate bond • Aerobic metabolism – Glycolysis – Citric acid cycle – Electron transport chain • Anaerobic metabolism RNA Synthesis • RNA polymerase • Promoter • Transcription factors

Protein Sorting Directs Proteins to Their Destination • Signal sequence

Proteins Undergo Post-Translational Modification • Protein folding • Cross-linkage • Cleavage • Addition of other molecules or groups • Assembly into polymeric proteins

Summary • Energy in biological systems • Chemical reactions • Enzymes • Metabolism • ATP production

Summary • Chemical reactions – Reactants – Products – Reaction rate • Free energy • Activation energy • Exergonic versus endergonic reactions • Reversible versus irreversible reactions

Summary • Enzymes and substrates • Cofactors versus coenzymes • Classification of reactions – Oxidation-reduction – Hydrolysis-dehydration – Addition-subtraction-exchange – Ligation Summary • Metabolism – Catabolic versus anabolic reactions • Control of metabolic pathways • Aerobic versus anaerobic pathways

Summary • ATP production – Glycolysis – Citric acid cycle – Electron transport chain • Glycogen, protein, and lipid metabolism • Aerobic versus anaerobic metabolism • Gene transcription and alternative mRNA splicing • Translation and transfer and ribosomal RNA • Post-translational modifications