Biology 112 Unit 3 · 2010. 3. 29. · Title: Biology 112 Unit 3.pdf Author: macuser Created Date:...
Transcript of Biology 112 Unit 3 · 2010. 3. 29. · Title: Biology 112 Unit 3.pdf Author: macuser Created Date:...
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Biology 112Unit Three
Chapter Four
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Cell Sizes
• Smallest ‐ Bacteria• Largest ‐ Bird egg• Longest ‐ Giraffe’s Nerve Cell• Most Cells ‐ Diameter of 0.7µm to
105 µm
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Human height
Length of somenerve andmuscle cells
10 m
Frog egg
Chicken egg
Una
ided
eye
1 m
100 mm(10 cm)
10 mm(1 cm)
1 mm
Ligh
t mic
rosc
ope
Elec
tron
mic
rosc
ope
100 nm
100 µm
10 µm
1 µm
Most plant and animal cells
Viruses
NucleusMost bacteriaMitochondrion
10 nm
Lipids
Ribosome
Proteins
Mycoplasmas(smallest bacteria)
1 nmSmall molecules
0.1 nm Atoms
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How big can a cell get?
• Cells are limited by natural laws• They must be able to house organelles(minimum size)
• They must stay within a certain surface areato volume raRo (maximum size)
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Surface Area
• L x W
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Volume
• L x W x H
• Large cell = smaller SA/Vol raRo
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30 µm
30 µm 10 µm
10 µm
Surface areaof one large cube= 5,400 µm2
Total surface areaof 27 small cubes= 16,200 µm2
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Cell Structure
• Minimal Cell1. Plasma membrane
2. Cytoplasm
3. GeneRc informaRon
4. Ribosomes
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Two Types of Cells
• ProkaryoRc• EukaryoRc
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ProkaryoRc Cells
• Average 2 µm to 8 µm long• No nucleus– Nucleoid (nuclear region)
• Most have a bacterial cell wall– PepRdoglycan
• Limited organelles– Ribosomes
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ProkaryoRc Cells
• Variety of structures– Capsule
• Some have sRcky outer coat– Pili or flagella
• Used for movement
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Nucleoid
Ribosomes
Plasma membrane
Cell wall
Capsule
Flagella
Bacterialchromosome
A typical rod-shapedbacterium
Pili
A thin section through thebacterium Bacillus coagulans(TEM)
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EukaryoRc Cells
• Average 10x bigger and 1000x in volume asprokaryoRc
• Nucleus present• Variety of membranous cellular organelles• Vary in cellular metabolism
– Dependent on internal cellular membranes– Increase areas of specializaRon
• Increase in SA allows for more reacRons to takeplace at one Rme
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Unicellular
• ProRsta– The kingdom being reorganized
• Fungi– Yeast
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MulRcellular
• Plant– No centrioles– Cell wall (cellulose)– Chloroplast– Central vacuole
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Smooth endoplasmicreticulum
Rough endoplasmicreticulum
CYTOSKELETON:
NUCLEUS:Nuclear envelopeChromosomeNucleolus
Ribosomes
Golgiapparatus
Plasma membrane
Mitochondrion
Peroxisome
Cell wall
Central vacuoleMicrotubule
Intermediatefilament
Microfilament
Cell wall ofadjacent cell
Chloroplast
Plasmodesmata
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MulRcellular
• Animal– Paired centrioles– No cell wall– Flagella in some (movement)– ContracRle vacuole
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Smooth endoplasmicreticulum
Roughendoplasmicreticulum
CYTOSKELETON:
NUCLEUS:Nuclear envelopeChromosomesNucleolus
Ribosomes
Golgiapparatus
Plasma membrane
Mitochondrion
Peroxisome
Centriole
Lysosome
MicrotubuleIntermediatefilamentMicrofilament
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Organelles and FuncRons
• Four Categories1. Manufacturing
2. Breakdown
3. Energy Processing
4. Support, Movement and CommunicaRon
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Manufacturing
• Nucleus – control center of the cell– Nuclear Envelope
• Double membrane• Perforated (pores)• Material movement
– DNA• ChromaRn strands• Strands make up chromosomes
– Nucleolus• Contains chromaRn, RNA and protein• Manufactures ribosome
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Two membranes ofnuclear envelope Nucleus
Nucleolus
Chromatin
Pore
Endoplasmicreticulum
Ribosomes
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Ribosomes
• Assemble amino acids into polypepRdes• Every cell has ribosomes!
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Cytoplasm
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
RibosomesER
Smallsubunit
Diagram of a ribosome
TEM showing ERand ribosomes
Largesubunit
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• Endoplasmic ReRculum (ER)– Rough ER (due to ribosomes)
• Makes membrane bound proteins• Makes secretory proteins
– Smooth ER• Synthesis of lipids• In the liver, helps regulate blood sugar• Drug breakdown• Storage of calcium
– Amount of Smooth ER or Rough ER in the cells depends onthe funcRon of the cell
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Smooth ER
Nuclearenvelope
Ribosomes
Rough ER
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Transport vesiclebuds off
Secretoryproteininside trans-port vesicle
Glycoprotein
Polypeptide
Ribosome
Sugarchain
Rough ER
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• Golgi Apparatus– Receives and modifies substances manufacturedin the ER
– Finishes, sorts and ships products– # of GA depend on how acRve the cell is insecreRng proteins
– Receiving and Shipping sides (cis and trans)– Contents may either leave the cell or become partof the cell’s organelles or membrane
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Golgi apparatusGolgi apparatus
“Receiving” side ofGolgi apparatus
Transportvesiclefrom ER
New vesicleforming
“Shipping” sideof Golgi apparatus
Transportvesicle fromthe Golgi
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Breakdown• Lysosomes
– DigesRve enzymes (hydrolyRc) in a membranous sac– Only work in a very acidic environment– “Stuff” that needs to be broken down is brought into themembranous sac (recycling)
– Engulfing bacteria– Fusing with food vacuoles– Embryonic development (programmed cell death)
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Digestiveenzymes
Lysosome
Plasmamembrane
Food vacuole
Digestion
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Lysosome
Vesicle containingdamaged mitochondrion
Digestion
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• Peroxisomes– Contains enzymes in a membranous sac thatproduce H2O2
– Help survive environmental toxins includingalcohol
– Help the cell use oxygen to break down faky acids
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• Vacuoles– In plants, can be a large lysosome
• Can store water, chemicals, pigments, poisons or wasteproduct
– In animals, used as a contracRle vacuole tomaintain water balance
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Nucleus
Chloroplast
Centralvacuole
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Nucleus
Contractilevacuoles
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Energy Processing
• Mitochondria– Energy converRng organelle– Cellular RespiraRon
• ConverRng chemical energy in food to chemical energyof ATP for cellular work
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• Mitochondria (conRnued)– Double membrane – two compartments (outer
and inner membranes)
1. Intermembrane space
‐ between the membranes – where H+ build upoccurs
2. Cristae
‐ increase surface area for ATP producRon
‐ ATP Synthase is embedded here
3. Mitochondrial matrix
‐ The Citric Acid Cycle is located here
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Mitochondrion
Intermembranespace
Innermembrane
Cristae
Matrix
Outermembrane
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Support, Movement &CommunicaRon
• Cilia– Microtubule extending from cell– Short and many present– Line trachea to sweep mucous containing debrisout of lungs
– Line oviducts to move the egg toward the uterus
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Cilia
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• Flagella– Fewer in number but longer– Sperm
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Flagellum
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• Both– Dynein arms for movement (9 + 2) arrangement– Anchor in basal body– Are tubular extensions of the plasma membrane– FuncRon is to move either the whole cell or movematerial across cell or into cell
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Centralmicrotubules
Outer microtubuledoublet
Radial spoke
Dynein arms
Plasmamembrane
Triplet
Cross sections:
Flagellum
Basal body
Basal body
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• Animal Cell Surfaces– Animal and other eukaryotes are organized intosingle funcRonal organisms
– These are held together with cell surfaces
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• Extracellular Matrix– Helps hold cells together, affects cell behavior bycontacRng proteins in plasma membrane andcytoskeleton within the cell
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EXTRACELLULAR FLUID
Microfilaments
Collagen fiber
Connectingglycoprotein
Integrin
Plasmamembrane
Glycoproteincomplex with longpolysaccharide
CYTOPLASM
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Binds Cells Together
1. Tight JuncRons‐ leak proof sheet‐ digesRve or nervous system
2. Anchoring JuncRons‐ rivets with cytoskeleton
3. CommunicaRng (Gap) JuncRons‐ allow for flow of water and chemicals‐ also for electrical signals
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Tight junctions
Anchoring junction
Gap junctions
Plasma membranesof adjacent cells
Extracellular matrix