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Week # 8 Lecture pp 15-128 Lecture Presentations for Integrated Biology and Skills for Success in Science Banks, Montoya, Johns, & Eveslage

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Cells and Their Membranes By the end of the lecture today, students will be able to: State the cell theory Define cell biology Describe the different classes of cells in the human body Describe the functions of the plasma membrane Describe the components of the plasma membrane and explain the role of each component, including lipids and proteins Differentiate between microvilli, cilia and flagellum

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Modern Cell Theory All organisms are composed of cells and cell products Cell is the simplest structural and functional unit of life cells are alive An organisms structure and functions are due to the activities of its cells Cells come only from preexisting cells, not from nonliving matter therefore, all life traces its ancestry to the same original cells Cells of all species have many fundamental similarities in their chemical composition and metabolic mechanisms Cell biology study of cells (i.e., their morphology, physiological properties, organelles, interactions with the environment, life cycles, division and death)

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http://www.youtube.com/watch?v=4OpBylwH9D U

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Cell Shapes about 200 types of cells in the human body Squamous - thin and flat with nucleus creating bulge Polygonal - irregularly angular shapes with 4 or more sides Stellate starlike shape Cuboidal squarish and about as tall as they are wide Columnar - taller than wide Spheroid to Ovoid round to oval Discoid - disc-shaped Fusiform - thick in middle, tapered toward the ends Fibrous threadlike shape Note: some of these shapes are cell appearance in tissue sections, but not their 3 dimensional shape

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Cell Shapes Squamous Polygonal CuboidalColumnar Spheroid DiscoidFusiform (spindle-shaped) Stellate Fibrous

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Two Classes of cells in the Human Body Sex cells, also known as germ cells or reproductive cells, are either sperm cells of males or oocyte cells of females. Somatic cells are the cells that make up everything else in the body.

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Cell Size Human cell size most from 10 - 15 micrometers (m) in diameter egg cells (very large)100 m diameter barely visible to the naked eye nerve cell at 1 meter long longest human cell too slender to be seen with naked eye Limitations on cell size cell growth increases volume more than surface area surface area of a cell is proportional to the square of its diameter volume of a cell is proportional to the cube of its diameter nutrient absorption and waste removal utilize surface area if cell becomes too large, may rupture like overfilled water balloon http://projects.cbe.ab.ca/ict/udlsci/udlscience/biology/cells/saVol/notes /saVol.htm http://projects.cbe.ab.ca/ict/udlsci/udlscience/biology/cells/saVol/notes /saVol.htm

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Major Constituents of Cell plasma (cell) membrane surrounds cell made of proteins and lipids composition and function can vary from one region of the cell to another cytoplasm organelles cytoskeleton cytosol (intracellular fluid - ICF) extracellular fluid ECF fluid outside of cell Apical cell surface Microfilaments Secretory vesicle undergoing exocytosis Golgi vesicles Golgi complex Lateral cell surface Intermediate filament Lysosome Rough endoplasmic reticulum Smooth endoplasmic reticulum Microtubule Plasma membranes Basement membrane Basal cell surface Free ribosomes Mitochondrion Nucleolus Nuclear envelope Nucleus Intercellular space Centrosome Centrioles Secretory vesicle Desmosome Fat droplet Hemidesmosome Terminal web Microvillus

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Plasma Membrane unit membrane forms the border of the cell and many of its organelles -appears as a pair of dark parallel lines around cell (viewed with the electron microscope) plasma membrane unit membrane at cell surface -defines cell boundaries -governs interactions with other cells -controls passage of materials in and out of cell -intracellular face side that faces cytoplasm -extracellular face side that faces outward (a) Nuclear envelope Nucleus Plasma membrane of upper cell Plasma membrane of lower cell Intercellular space 100 nm..

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Membrane Lipids 98% of molecules in plasma membrane are lipids Phospholipids 75% of membrane lipids are phospholipids amphiphilic molecules arranged in a bilayer hydrophilic phosphate heads face water on each side of membrane hydrophobic tails directed toward the center, avoiding water drift laterally from place to place movement keeps membrane fluid

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Plasma Membrane Oily film of lipids with diverse proteins embedded Extracellular face of membrane Intracellular face of membrane (b) Peripheral protein Extracellular fluid Glycolipid Glycoprotein Carbohydrate chains Transmembrane protein Peripheral protein Channel Intracellular fluid Cholesterol Proteins of cytoskeleton Phospholipid bilayer

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Membrane Protein Functions receptors, second-messenger systems, enzymes, ion channels, carriers, cell-identity markers, cell-adhesion molecules Chemical messenger Breakdown products Ions CAM of another cell (a) Receptor A receptor that binds to chemical messengers such as hormones sent by other cells (b) Enzyme An enzyme that breaks down a chemical messenger and terminates its effect (c) Ion Channel A channel protein that is constantly open and allows ions to pass into and out of the cell (d) Gated ion channel A gated channel that opens and closes to allow ions through only at certain times (e) Cell-identity marker A glycoprotein acting as a cell- identity marker distinguishing the bodys own cells from foreign cells (f) Cell-adhesion molecule (CAM) A cell-adhesion molecule (CAM) that binds one cell to another.

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http://www.youtube.com/watch?v=y31DlJ6uGgE

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Extensions of membrane (1-2 m) serves to increase cells surface area best developed in cells specialized in absorption gives 15 40 times more absorptive surface area on some cells they are very dense and appear as a fringe brush border milking action of actin actin filaments shorten microvilli pushing absorbed contents down into cell Microvilli

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Actin microfilaments are found in center of each microvilli. (a) 1.0mm (b) 0.1 Glycocalyx Actin microfilaments Microvillus.. mm

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Cilia Hairlike processes 7-10 m long single, nonmotile primary cilium found on nearly every cell antenna for monitoring nearby conditions sensory in inner ear, retina, nasal cavity, and kidney Motile cilia respiratory tract, uterine tubes, ventricles of the brain, efferent ductules of testes beat in waves sweep substances across surface in same direction power strokes followed by recovery strokes (a) Mucus Saline layer Epithelial cells 1234567 Power strokeRecovery stroke (b).

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Structure of Cilia Cilia (a) 10 m..

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http://www.youtube.com/watch?v=dXVG- DwOtKU Flagella tail of the sperm - only functional flagellum whiplike structure with axoneme identical to cilium much longer than cilium stiffened by coarse fibers that supports the tail movement is more undulating, snakelike no power stroke or recovery stroke as in cilia

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Exit Quiz 1). Name the three fundamental parts of the cell theory and identify who introduced each of these parts to the scientific community. 2). Why are the majority of cells observed to be so small? 3). What are the major components to a cell? What are the primary functions of each of these components? 4). What are the seven major functions of proteins in a cell membrane? 5). What are the fundamental differences between cilia and flagella?