Transcript Ch 6: Cells

Ch 6: Cells
History of Cytology
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1665 – Robert Hooke
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1673 – Anton van Leeuwenhoek
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Viewed cork
Named “cells”
Unicellular pond organisms – named
“animalcules”
First to see bacteria and yeast
1833 – Robert Brown discovered nucleus
Cell Theory
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1838 – Matthias Schleiden
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1839 – THeodor Schwann
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All plant parts are composed of cells
All animal tissues are composed of cells
1858 – Rudolph Virchow
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All cells come from other cells
Cell Theory:
1) All living things are composed of 1 or more cells
2) Cells are the basic unit of structure and function
3) All cells are produced from existing cells
Cells
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All cells have:
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Plasma membrane (cell
membrane)
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regulates materials in/out of cell
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Composed of phospholipid
bilayer
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Contains different proteins
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Cytoplasm
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everything inside the cell
membrane
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Medium for chemical rxns
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Cytosol – fluid portion
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Chromosomes (Genes) - DNA
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Ribosomes –site of protein
synthesis
Cell Size – must be small
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To efficiently exchange materials in/out of
cell membrane
Cell surface is the only area of interaction w/
environment
To transport materials inside of cell
Efficiency depends on surface area to
volume ratio
Small cells function more efficiently than
larger cells!
Surface Area to Volume Ratio
Prokaryotic Cells
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DNA is located in nucloid region (NO
NUCLEUS)
Does not contain membrane bound
organelles
Only Eubacteria and Archeabacteria
Kingdoms
Prokaryotic Cell
Evolution of Eukaryotic Cells
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Theory of Endosymbiosis – one
prokaryotic cell engulfed another and did not
digest it, :. Forming a double membrane…
successful relationship
Evidence: Chloroplasts and mitochondria
each have their own separate DNA and can
reproduce on their own, and are similar to
prokaryotic cells
Endosymbiosis
Eukaryotic Organelles
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Nucleus – contains chromosomes
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Nucleolus
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contain materials for RNA
Makes ribosomes
Nuclear Membrane w/ nuclear pores
Nucleoplasm – jelly like material w/in nucleus
Mitochondria
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Powerhouse of the cell
Releases E stored in food
Produces ATP
Eukaryotic Transport System
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Ribosomes – site of protein synthesis
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Free floating in cytoplasm (free)
Attached to ER (bound)
Endoplasmic Reticulum (ER)
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An internal channel system
Rough ER – has ribosomes on surface, aids in
transporting proteins
Smooth ER – involved in making lipids and breaking
down toxic substances
Eukaryotic Transport System
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Vesicles – membrane buds off ER w/
proteins or lipids enclosed
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Lysosome – contains digestive enzymes to
break down macromolecules and worn out cell
parts
Peroxisome - contains enzymes that converts
fat to carbohydrates (from smooth ER)
Golgi body (complex/apparatus) –
packaging and distribution center of the cell
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Cis golgi – arrival side
Trans golgi – departure side
Cytoskeleton
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Cytoskeleton – internal framework
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Mesh-like network of protein fibers
Supports cell shape and anchors organelles
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Microtubules – hollow tubes move chromosomes
during cell division by forming centrioles (animal cells
only)
Actin – long intertwined microfilaments that contract or
expand to determine shape
Intermediate fibers – fibrous protein cables that
anchor ribosomes and enzymes
Cytoskeleton
Cellular Movement
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Flagella – long threadlike microtubules
(whip-like tail)
Cilia – numerous short and tightly
packed microtubules
Intercellular Junctions
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Plants
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Plasmodesmata – perforated channels in plant
cell wall allowing cytosol, water and small
solutes to pass freely
Animals
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Tight junctions – forms tight seal between cells
Desmosomes – anchor cells together in strong
sheets
Gap junctions – cytoplasmic channels between
adjacent cells allowing communication
Animal Cells only
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Extracellular Matrix (ECM)
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Collagen – strong glycoprotein fibers
Proteoglycans – network of glycoproteins
Fibronectin – attaches ECM to Integrins
Integrins – membrane proteins bound to
ECM and interior microfilaments
Centrioles
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composed of microtubules
Aid in moving chromosomes during cell division
Centrosome – 2 centrioles
Plant Cells Only
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Cell Wall
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Central Vacuole
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Extra protective layer
Cellulose - maintains structure
Stores water, ions, nutrients, and waste materials
Controls pressure w/in cell
Tonoplast – membrane surrounding vacoule
Chloroplast
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Contains chlorophyll – photosynthetic pigment
Uses water, carbon dioxide and sunlight to make food in
the form of glucose