Lecture 2 Cell COVID (3) PDF

Cellular Level of Organization Cell Basic structural and functional unit of life Smallest unit that performs all life functions Comes from division of preexisting cells Maintains homeostasis Types of Cells Somatic cells (soma = body): all body cells except sex cells Sex cells (...

Cellular Level of Organization Cell Basic structural and functional unit of life Smallest unit that performs all life functions Comes from division of preexisting cells Maintains homeostasis Types of Cells Somatic cells (soma = body): all body cells except sex cells Sex cells (germ; reproductive cells) male sperms female oocytes (eggs) Structure of The Cell Cell Structure Cytoplas m Nucleus Cell membrane Cell Structure Cytoplas m Nucleus Cell membrane Cell Membrane Integral EXTRACELLULAR FLUID glycoproteins Phospholipid Integral protein Glycolipids bilayer with channel of glycocalyx Hydrophobic tails Cell membrane Cholesterol Peripheral Hydrophillic proteins heads Gated Cytoskeleton channel = 2 nm (Microfilaments) CYTOPLASM General Functions of Cell Membrane Physical isolation (barrier) Sensitivity to the environment extracellular fluid composition chemical signals Regulates exchange with the environment Ions, nutrients, waste and cellular products Structural support cell – cell cell - tissue Structure of the Cell Membrane Membrane Lipids (42%) Phospholipid bilayer ̶hydrophilic heads:  toward environment, both sides ̶hydrophobic tails:  inside membrane Cholesterol Other lipids Membrane Proteins (55%) Integral proteins ̶within the membrane Peripheral proteins ̶inner or outer surface of the membrane Functional Types of Membrane Proteins (a) (b) Cell-Cell Enzymes Transporte Recognition Anchors Receptors Junctions rs (a) Channels (b) Carriers Membrane Carbohydrates (3%) Glycocalyx Part of complex molecules: e.g., glycolipids, glycoproteins & proteoglycans Glycocalyx (sugar coat): carbohydrate part extends outside cell membrane function:  anchoring and protection  lubrication and locomotion  specificity in binding (receptors)  recognition (immune response) Which of the following portions of the cell membrane is hydrophobic? A. Carrier proteins B. Heads of the phospholipid bilayer C. Glycocalyx D. Tails of the phospholipid bilayer E. Receptors Which of the following portions of the cell membrane is hydrophobic? A. Carrier proteins B. Heads of the phospholipid bilayer C. Glycocalyx D. Tails of the phospholipid bilayer E. Receptors Cell Structure Cytoplas m Nucleus Cell membrane Cytoplasm All materials inside the cell and outside the nucleus: cytosol (intracellular fluid):  dissolved materials (nutrients, ions, proteins, and waste products) organelles:  structures with specific functions Intracellular vs Extracellular Fluid Intracellular Extracellular Fluid Fluid (Cytosol) Sodium Ions   Potassium   Ions Proteins   CHO, Fat &   Reserve AA Types of Organelles Nonmembranous organelles no membrane direct contact with the cytosol Membranous organelles covered with plasma membrane isolated from the cytosol Cell Organelles Nonmembranou Membranous s Organelles Organelles Cytoskeleton Endoplasmic reticulum Microvilli Golgi apparatus Centrioles Lysosomes Cilia Peroxisomes Ribosomes Mitochondria Proteasomes Cell Organelles Nonmembranou Membranous s Organelles Organelles Cytoskeleton Endoplasmic reticulum Microvilli Golgi apparatus Centrioles Lysosomes Cilia Peroxisomes Ribosomes Mitochondria Proteasomes Nonmembranous Organelles Cytoskeleton Microvillus Backbone of the cell Microfilaments Gives the cytoplasm strength & flexibility Components: Plasma membrane microfilamnets Terminal web intermediate filaments Mitochondrion thick filaments (only in muscle cells) Intermediate filaments microtubules Endoplasmic reticulum Microtubule Secretory vesicle Microfilaments Thin (