chapter-3-cellular-level.pdf - lOMoARcPSD|1516709 Chapter 3 Cellular Level Human Anatomy and Physiology(Athabasca University StuDocu is not sponsored or

chapter-3-cellular-level.pdf - lOMoARcPSD|1516709 Chapter 3...

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StuDocu is not sponsored or endorsed by any college or university Chapter 3 Cellular Level Human Anatomy and Physiology (Athabasca University) Downloaded by Yury Elena Ezhov ([email protected]) lOMoARcPSD|1516709
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Chapter 3: The Cellular Level of Organizaion Cells Living structural and funcional units enclosed by a membrane. Cell Division All cells arise from cell division; one cell divides into two idenical cells. Cell Biology (cytology) Study of cellular structure and funcion. 3.1 Parts of a Cell 1. Plasma Membrane Flexible outer surface separaing the external and internal environments. Selecive barrier that regulates low of materials for normal cellular aciviies. Plays a role in communicaion between cells. 2. Cytoplasm Area between the membrane and nucleus i. Cytosol (intracellular luid): contains water, dissolved solutes, and paricles. ii. Organelles: characterisic shapes and funcions. 3. Nucleus Contains the DNA Chromosomes : a single molecule of DNA, contains thousands of genes . Genes: controls the aspect of cellular structure and funcion. Downloaded by Yury Elena Ezhov ([email protected]) lOMoARcPSD|1516709
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3.2 The Plasma Membrane Plasma Membrane Funcions: Sturdy lipid (amphipathic) barrier that surrounds the cytoplasm of the cell. Allows passage of several lipid-soluble molecules, but prevents polar substances to come in or out. o Ion Channels (integral proteins) are pores or holes that lets speciic ions, such as K + , low through. They are selecive . o Carriers selecively move polar substances or ions across the membrane. Proteins in the layer can act as signal receptors or links the plasma membranes to intra/extracellular proteins. o Receptors (integral proteins) recognizes and binds to speciic molecules. Speciic molecules that bind to the receptor is called a Ligand. o Enzymes catalyze chemical reacions in and outside the cell. o Linkers connect proteins of plasma membrane to other cells. S o Idenity Markers (glycoprotein and glycolipids) enable a cell to recognize other similar cells during issue formaion, and recognize and respond to dangerous foreign cells. Plasma Membrane Structure: The Lipid Bilayer two back-to-back layers of 3 types of lipid molecules. 1. Phospholipids (75%): Phosphate (polar, hydrophilic) head, and faty acid (non-polar, hydrophobic) tail. They orientate themselves with the head outward – cytosol and extracellular luid – and tails point inward, hydrophobic membrane interior. 2. Cholesterol (20%): hydroxyl head (polar) forms hydrogen bonds with the phosphate of phospholipids. Sif, steroid rings (non-polar tails) it with the faty acids of the membrane. 3. Glycolipids (5%): carbohydrate (polar) head faces the extracellular luid (outside of cell), while the faty acid (non-polar) tails are in the membrane layer.
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