ireland3e_lecture_ch04

ireland3e_lecture_ch04 - 8/18/2011 Chapter 4 Cells:...

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8/18/2011 1 Chapter 4 Cells: Organization and Communication Cells Cells are the building blocks of life, they are highly organized and dynamic the human body contains trillions of cells cells differ in both shape and size The study of cells is called cytology
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8/18/2011 2 Cell Theory All cells have similar characteristics Current cell theory holds: all living things are composed of cells all cells arise from preexisting cells through cell division cells contain hereditary material, which they pass to daughter cells during cell division the chemical composition of all cells is quite similar the metabolic processes associated with life occur within cells Parts of a Cell The cell is a highly organized structure that has three basic parts a barrier called the plasma membrane (in animals) or cell wall (in plants and bacteria) a fluid called cytosol, which supports multiple types of organelles, each with a function vital to the life of the cell a nucleus
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8/18/2011 3 Prokaryotic Cells Millions of years ago, cells adapted to their environments Early life forms were prokaryotic, adapting to the extreme environments of early Earth Prokaryotic cells have no internal membrane-bound compartments, usually having only genetic material as organelles Today, they survive as bacteria and archaebacteria they have no nucleus their genetic material floats in their cytoplasm, anchored at one spot to the cell wall Eukaryotic Cells Eukaryotic cells have a nucleus and organelles plant, animal, and fungal cells are eukaryotic they are believed to have evolved from prokaryotic ancestors which took in smaller, energy-producing prokaryotic cells
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8/18/2011 4 Plant Cells Plant cells have organelles not found in animal cells the central vacuole maintains cell pressure (turgor) chloroplasts produce energy through photosynthesis Many believe that chloroplasts originated as bacteria that were “adopted” by the plant cell The Cell Membrane The cell membrane separates the cell from the extracellular fluid It is composed of two layers of phospholipids, interspersed with proteins, fats, and sugars phospholipids are arranged in a double layer, or bilayer, with the hydrophilic, water-loving heads oriented toward the aqueous environment both inside and outside the cell the hydrophobic, water-fearing, non-polar, lipid portion of the molecules is sandwiched in the center proteins and lipids associated with the cell membrane have sugars attached to their external surface and are called glycoproteins and glycolipids
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8/18/2011 5 The Cell Membrane The Glycocalyx The glycoproteins and glycolipids form a layer called the glycocalyx both blood type and tissue type are defined by the specific structures on the glycocalyx each person's white blood cells carry a group of identifying proteins called the human leukocyte antigens (HLAs) that serve as markers indicating that our cells belong to us HLA is used to match tissues before organ transplants HLA is inherited, close tissue matches often occur within immediate family
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This note was uploaded on 12/26/2011 for the course BSC 2023 taught by Professor Staff during the Fall '08 term at FIU.

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ireland3e_lecture_ch04 - 8/18/2011 Chapter 4 Cells:...

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