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the Cell Introduction to
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Cell History Robert Hooke – 1665 Anton van Leeuwenhoek - 1673
Observed slices of cork Coined word “cell” Anton van Leeuwenhoek First to observe living cells (algae) “animalcules” Schleiden – plants Schwann – animals Virchow – cell reproduction
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Cell Theory All living things are made of one or more cells
Cells are the basic units of structure and function in organisms All cells arise from existing cells
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Why are cells important?
Gas Exchange Eat Make energy (ATP) Build molecules proteins, carbohydrates, fats, nucleic acids Remove wastes Maintain homeostasis Reproduce
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Cell Size Can’t be seen with the naked eye
Human body = ~100 trillion cells Cell Size Activity
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Why so small?! A small cell has a greater ratio of surface area to volume The microscopic size of most cells ensures a sufficient surface area Across which nutrients and wastes can move to service the cell volume 30 m 10 m Surface area of one large cube 5,400 m2 Total surface area of 27 small cubes 16,200 m2
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Intro Video
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Cell Types Prokaryotic – single celled organisms that lack a nucleus
Eukaryotic – cells with a nucleus and internal compartments
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micron = micrometer = 1/1,000,000 meter
diameter of human hair = ~20 microns
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Common Features Cytoskeleton
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Prokaryotic cells Simple, single-celled organisms All have cell walls
Many have flagella or pili Some have capsules Ex. Bacteria Prokar yotic flagella Ribosomes Capsule Cell wall Plasma membrane DNA Pili
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Eukaryotic cells Nucleus
Organelles – differentiated structures within the cell Complex, multi- cellular organisms
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Cell Membrane Functions: Structure:
Selectively permeable – regulates what goes in and out of cell Protection Controls the internal environment Provides shape Structure: Phospholipid bilayer Transport proteins
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Cell Membrane (cont.) Fatty acid tails Phosphate head
Hydrophobic – water fearing Phosphate head Hydrophilic – water loving
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Fluid Mosaic Model
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Transport Passive Transport: particles pass across the cell membrane freely Active Transport: particles cross the cell membrane with the use of energy k
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Diffusion Concentration: the amount of a particular substance in a given volume. Substances naturally move from a higher concentration to an area of lower concentration Equilibrium: is reached when a space is filled evenly
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Osmosis When water is diffused across the cell membrane
It is important for a cell to maintain water balance as their environment changes
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Solution Types Hypotonic – less molecules outside cell
Isotonic – equal molecules on both sides of the membrane Hypertonic – more molecules outside cell
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Lower concentration of solute Higher concentration of solute
Equal concentration of solute H2O Solute molecule Selectively permeable membrane Water molecule Solute molecule with cluster of water molecules Net flow of water
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Plant cell Animal cell Isotonic solution Hypotonic solution
Hypertonic solution H2O H2O H2O H2O Animal cell H2O H2O H2O H2O Plant cell
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Cytoplasm The area between the nucleus and plasma membrane
Holds organelles Cytosol – fluid between the organelles
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Ribosomes Protein synthesis
read instructions to build proteins from DNA Found in all organisms!
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Eukaryotic Cell Parts
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Review Ribosomes Cytoplasm Cell Membrane
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Nucleus Function: Directs activities of the cell
Protects genetic information (DNA) Controls the cell's growth and reproduction. Parts: Nuclear Envelope Nucleolus Chromatin Nuclear Pores
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Compartmentalize Organelle - differentiated structures within the cell
Advantage: Allows the cell to accomplish more metabolic processes Incompatible activities can happen at the same time
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Endoplasmic Reticulum
“network within the cell” 2 parts Rough Endoplasmic Reticulum (RER) Embedded with ribosomes Synthesizes and modifies proteins
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Endoplasmic Reticulum cont.
Smooth Endoplasmic Reticulum (SER) Embedded with enzymes Synthesizes lipids Processes toxins and drugs in liver cells Stores and releases calcium ions in muscle cells
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Vesicles Used for transportation within the cell
Buds off of ER and Golgi Body
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Golgi Apparatus Modifies, packages, and ships cell products that come from the ER or ribosomes
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Lysosomes & Peroxisomes
Contains digestive enzymes to break down nutrients, bacteria, and wastes Not present in most plant cells Peroxisomes Breakdown Hydroxide (H202) by-product
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Rough ER Transport vesicle (containing inactive hydrolytic enzymes) 1 Golgi apparatus Plasma membrane Lysosome engulfing damaged organelle 5 Lysosomes 2 3 Engulfment of particle “Food” Food vacuole Digestion 4
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Mitochondria Location for cellular respiration
Converts the chemical energy of foods into ATP Double membrane layer
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Cytoskeleton The cell’s internal skeleton helps organize its structure and activities A network of protein fibers Actin subunit Microfilament 7 nm Fibrous subunits 10 nm Intermediate filament Microtubule 25 nm Tubulin subunit
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Centrioles Main function is to produce and organize the cytoskeleton during cell reproduction
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Animal Cell Plant Cell
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Cell Wall rigid boundary made largely of cellulose for support and environmental resistance Central vacuole Not in animal cells Chloroplast Cell wall
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Central Vacuole Main function: Store water
Contains enzymes – equivalent to animal lysosomes Holds pigments for flower color Chloroplast Central vacuole Nucleus Colorized TEM 8,700
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Chloroplast Converts light energy into chemical energy
Only in plants and some protists Chlorophyll = green pigment
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Central vacuole Not in animal cells Chloroplast Cell wall
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Nucleus Smooth endoplasmic reticulum Rough endoplasmic reticulum Ribosomes Golgi apparatus Plasma membrane Mitochondrion Flagellum Not in most plant cells Lysosome Centriole Microtubule Cytoskeleton Intermediate filament Microfilament Peroxisome
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