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Unformatted text preview: January, 24 th , 2012 Notes: An introduction to cells Cell is the smallest living unit in the human body Characteristics of cells o Very small (0.1mm in diameter) o Need a microscope to cell individual cells o Study of cell structure and functions is? o Robert Hook discovered cells using cork in 1665 Cell Theory Developed from Robert Hookes research o Cells are the building blocks of all plants and animals o All cells come from the division of preexisting cells. o Cells are the smallest units that perform all vital physiological functions o Each cell maintains homeostasis at the cellular level Human body contains trillions of cells. Two major types: Sex cells: (Germ Cells) o Reproductive cells o Male Sperm o Female oocyte (a cell that develops into an egg) Somatic Cells o Soma = body o All body cells except sex cells. Anatomy of a model cell: Microvilli Cilia Proteasomes Ribosomes Golgi apparatus Mitochondira powerhouse of the cell (produces 95% of ATP) (DNA comes from Mother) Endoplasmic reticulum (ER) Peroxisomes neutralizations of toxins Lysosomes January, 26 th Notes 3-1 Plasma Membrane Nucleus the control center of the cell comes from your mom and dad Extracellular Fluid (Interstitial Fluid) o A watery medium that surrounds a cell o Plasma membrane (cell membrane) separates o Cytoplasm from the extracellular fluid Cytoplasm o Cytosol = liquid o Intracellular structures collectively known as organelles Functions of the Plasma Membrane Physical Isolation Barrier Separates the inside of the cell from the outside of the cell (extracellular fluid) Regulation of Exchange-- Functions of the Plasma Membrane Sensitivity to the Environment First to respond to changes in cellular environment (composition, concentration, and pH) Chemical signals Structural support Anchors cells and tissues Membrane is thin and contains--- Membrane Lipids (42 percent of weight) o Phospholipid bilayer two layers of phospholipids Hydrophilic head toward watery environment, both sides (phosphate) Hydrophobic fatty-acid tails inside membrane (lipid portion) Lipid bilayer also contains cholesterol Barrier to ions and water soluble compounds Membrane Proteins (55% of weight) o Many functions of proteins (enzymes, structural, hormones, etc..) o Integral Proteins Within the membrane. Some span the width of membrane (trans- membrane proteins) Peripheral Proteins o Bound to inner or outer surface of the membrane Membrane Proteins o Anchoring Proteins (stabilizers) Attach to inside or outside structures Recognition Proteins (identifiers) o Label cells as normal or abnormal Enzymes o Catalyze reactions Receptor proteins o Bind and respond to ligands (ions, hormones) Carrier Proteins o Transport specific solutes through membrane Channels o Regulate water flow and solutes through membrane Membrane Carbohydrates (3% of weight) o Proteoglycans, glycoproteins and glycolipids Extend outside cell membrane...
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This document was uploaded on 02/14/2012.
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