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Transcript
Human Biology CELL STRUCTURE & FUNCTION Instructor Terry Wiseth CELL MEMBRANE Cell membrane made up of: 1) Phospholipids 2) Sterols 3) Proteins 4) Glycoproteins 2 PHOSPHOLIPIDS cell membrane - semi-permeable lipid bilayer two layers of Phospholipids STEROLS common sterols of cell membranes Cholesterol (animal cells) prevent packing of lipid cells in the cell membrane 4 PROTEINS Proteins are embedded into the cell membrane These proteins serve a variety of cell membrane functions 5 GLYCOPROTEINS proteins are embedded in the bilayer glycoproteins - sugar-protein combinations sugars extend out to the extracellular fluid 6 CELL MEMBRANE FLUID MOSAIC MODEL membrane bilayer shows fluid behavior molecules of the bilayer are in constant motion 8 FLUID MOSAIC MODEL membrane is composite of molecules allowing a “mosaic description” cell survival depends on fluidity characteristics of the cell membrane 9 FLUID MOSAIC MODEL extracellular fluid temperature decreases cause a stiffening of the cell membrane disrupts membrane protein function 10 CELL THEORY Smallest entity that retains the characteristics of life 1) Complex organization 2) Metabolic activity 3) Reproduction 11 CELL SIZE Most cannot be seen without the aid of a microscope Larger cells ”Yolk” of bird eggs Fish eggs “caviar” 12 CELL SIZE Human eyes able to see about 100 microns 13 LIGHT MICROSCOPE The light microscope has a limit of resolution of about 200 nm (0.2 microns) 14 TEM The Transmission Electron Microscope (TEM) has a limit of resolution of about 2 nm 15 SEM The Scanning Electron Microscope (SEM) also has a limit of 2 nm Sperm & Egg Bronchiole cilia WBC engulf bacteria 16 GENERALIZATIONS OF CELL THEORY Cells vary in size, shape and activities All cells have: 1) Plasma membrane 2) DNA region 3) Cytoplasm 4) Organelles 17 PLASMA MEMBRANE Outer membrane maintains the integrity of the cell Membrane does not however isolate the cell 18 PLASMA MEMBRANE Cell membrane “Lipid bilayer” Boundary that bars free passage of water soluble substances in and out of the cell 19 NUCLEUS DNA is localized in the cell nucleus 20 CYTOPLASM Everything enclosed by the plasma membrane except the DNA semi-fluid 21 CYTOPLASMIC STREAMING Cytoplasm is not stagnant but rather is constantly moving (streaming) 22 ORGANELLES Organelles--internal sacs which have a specific metabolic function Essential in keeping chemical reactions in the cytoplasm separate from each other 23 CELL MACHINERY 24 CELL MACHINERY 25 NUCLEUS Nucleus sequesters DNA 1) Separates DNA from chemical reactions in cytoplasm 2) Nuclear membranes control access between nuclear material and cytoplasm 26 NUCLEUS Nuclear envelope has pores to allow passage of messenger units of nucleic acid 27 NUCLEUS 28 NUCLEOLUS 1) Assembly of RNA and ribosomes 2) Storage of RNA and ribosomes 29 DNA Instructions for building proteins (enzymes) are contained in DNA Instructions of heredity are distributed in several DNA molecules of various lengths Humans = 46 DNA molecules 30 DNA DNA is threadlike prior to cell division the DNA molecules duplicate 31 CHROMOSOMES DNA folds and twists into condensed structures called chromosomes 32 CYTOMEMBRANE SYSTEM Series of organelles through which lipids and proteins, produced on cytoplasmic ribosomes, pass through in becoming packaged for export 33 CYTOMEMBRANE SYSTEM 1) Endoplasmic reticulum (ER) 2) Golgi bodies 3) Vesicles 4) Lysosomes 34 ENDOPLASMIC RETICULUM 1) Rough endoplasmic reticulum Ribbon like structure with ribosomes attached Arranged as flat, stacked sacs 35 ENDOPLASMIC RETICULUM 36 RIBOSOMES Ribosomes are small spherical shaped structures Serve as the “working table” for assembling proteins 37 RIBOSOMES 38 ENDOPLASMIC RETICULUM 2) Smooth endoplasmic reticulum Lacks ribosomes 39 SMOOTH ENDOPLASMIC RETICULUM Appears like a system of pipes 1) Lipid synthesis Ex: endocrine glands produce steroid hormones 2) Inactivate harmful by-products of metabolism and drugs Ex: liver cells 40 GOLGI BODIES Resemble stacks of pancakes 41 GOLGI BODIES Flattened sacs in which lipids and protein molecules are modified 42 GOLGI BODIES Modifications allow for sorting and packaging for transport 43 GOLGI MODIFICATIONS 44 GOLGI MODIFICATIONS 45 VESICLES Sacs which transport or store enzymes, lipids and proteins 1) Peroxisomes 2) Lysosomes (microbodies) 46 VESICLES 1) Peroxisomes Contain enzymes to break down fatty acids and amino acids 47 VESICLES 2) Lysosomes Vesicles of intracellular digestion Contain enzymes which can break down any polysaccharide, protein, nucleic acid and some lipids 48 LYSOSOMES Important in proper function of white blood cells (immunity) 49 LYSOSOMES 50 CYTOMEMBRANE SYSTEM Raw materials (amino acids and lipids) are dissolved in the cytoplasm 51 CYTOMEMBRANE SYSTEM Under the instructions of the DNA molecule polypeptide chains of proteins are assembled from the dissolved raw materials 52 CYTOMEMBRANE SYSTEM 53 MITOCHONDRIA Contains a series of inner membranes folded repeatedly (cristae) Increases the total surface area available for reactions 54 MITOCHONDRIA Use oxygen to assist in liberating energy stored in sugars (aerobic respiration) 55 MITOCHONDRIA Energy is used to form ATP molecules which is used for protein synthesis and transport ATP-molecule is able to store and transport energy for short periods of time 56 MITOCHONDRIA Most numerous in high energy demanding cells Ex: muscles, liver 57 MITOCHONDRIA 58 CYTOSKELETON Interconnected system of bundled fibers, threads and lattices 59 CYTOSKELETON Extend from the cell membranes, organelles and nucleus 60 CYTOSKELETON Supply internal organization, shape, ability to move, reinforce the cell membrane and hold proteins in place 61 CELL SURFACE SPECIALIZATIONS Gap Junctions channels of exchange in animal cells ex: liver, heart 62 CELL SURFACE SPECIALIZATIONS Junction Proteins hold cells together in forming tissues 63 END Cell