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The Structure of Cells

By GoKnights16 Nov 03, 2013 480 Words
3A The Structure of Cells

Monday, September 30, 2013

• Cytology
○ Cyto = cell
○ Logos = study of
• Background
○ 1665 Robert Hook's Micrographia
§ Was studying cork cells
○ 1833 R. Brown
§ Discovered nucleus
○ 1838 M. Schleiden
§ Said that all plants consist of cells
○ 1839 T. Schwann
§ All animals consist of cells
○ 1855 Virchow
§ Cells come only from preexisting cells
• The Cell Theory
○ Cells are the structural units of all living things
○ Cells are the functional units of living things
○ Cells come from preexisting cells
• Processes of the cell
○ Absorption
○ Digestion
○ Synthesis
○ Respiration
○ Movement
○ Irritability
○ Excretion
○ Egestion
○ Secretion
○ Homeostasis
○ Reproduction
• Cellular Organization
○ Unicellular
§ Consists of only one cell
§ Examples include
□ Bacteria
□ Protozoans
□ Some algae
□ Some fungi
○ multicellular
§ Organisms made of many cells
§ Colonial
□ A group of similar cells living together that could exist separately
□ Examples include
® Algae
® Fungi
§ Multicellular levels
□ Tissues
® Groups of similar cells
□ Organs
® Groups of tissues
□ Systems
® Groups of organs
• Structures of the Cell
§ Boundaries
§ Cytoplasm
§ Nucleus
○ Organelles
§ A structure inside the cell that performs a specific function
• Types of cells
○ Prokaryotic
§ Lack of true nucleus
§ Have only non-membrane-bound organelles
○ Eukaryotic
§ ''True nucleus''
§ Have membrane-bound and non-membrane-bound organelles
• Cell boundaries
○ Cell membrane
§ Outermost boundary
§ Surrounds every cell
§ Composed of lipids and proteins
□ Lipid bilayer (phospholipids)
□ Hydrophilic and hydrophobic ends
§ Fluid mosaic model
□ Cell membrane flows like a liquid
○ Cell wall
§ Primarily composed of cellulose
§ Examples include
□ Plants
□ Algae
□ Fungi
□ Many protozoans
□ Bacteria
○ Capsule or sheath
§ Many unicellular and colonial organisms
§ Extra protection
○ Cytoplasm
□ All of the materiel within the cell membrane except the nucleus
□ Cytoplasmic organelles
§ Mitochondria
□ Powerhouse of the cell
□ Center of cellular respiration
□ Cristae
® Folds of the inner membrane
® Contain enzymes for cellular respiration
§ Ribosomes
□ Non-membrane-bound organelles functioning as "protein factories"
§ Endoplasmic Reticulum
□ Often called "ER"
□ Folds of membranes running throughout the cytoplasm
□ Rough and smooth
□ Channel and synthesis
§ Golgi Apparatus
□ Composed of flat, curved membrane-covered sacs
□ Synthesis and secretion
§ Lysosomes
□ Contain enzymes for digestion
□ Destroy old or useless cell structures
§ Cytoskeleton
□ The system of fibers within the cell that provides structure for the cell
□ Microtubules
□ Centrosome
□ Microfilaments
§ Flagella and Cilia
□ Flagellum
® Long whip-like structure
® Motility
□ Cilia
® Short, hair-like structures
® Motility
§ Plastids
□ Found in the cells of plants and algae but not in animal cells
□ Leucoplasts
® "leuco" - clear
® Storehouse for plant products
□ Chromoplasts
® "chromo" - color
® Contain pigments
□ Chloroplast
® Important in photosynthesis
® Thylakoids
◊ Flattened sacs inside the chloroplast
◊ Organized into stacks called grana (granum, sing.)
□ Vacuoles
® Membrane bound sacks for storage
® Vesicle - a small vacuole
Vauole Function
centralMaintain turgor pressure in plant cells
ContractileRemoves extra water from unicellular organisms

§ Nucleus
□ Control center
□ Nuclear envelope
□ Chromatin material
□ Nucleolus
® Concentrated RNA
® Ribosome synthesis

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