Cells. Levels of Organization Cells produce tissues Tissues produce organs Organs produce organ...
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Transcript of Cells. Levels of Organization Cells produce tissues Tissues produce organs Organs produce organ...
Cells
Levels of Organization
• Cells produce tissues• Tissues produce organs
• Organs produce organ systems• Organs systems produce organisms
Levels of Organization
3
Introduction• The basic organizational structure of the human body is the cell.
• There are 50-100 trillion cells in the human body.
• Differentiation is when cells specialize.
• As a result of differentiation, cells vary in size and shape due to their unique function. http://
www.natgeoeducationvideo.com/film/1080/the-human-cell
4
3.2: A Composite Cell
• Also called a ‘typical’ cell• Major parts include:
• Nucleus• contains DNA
• Cytoplasm• cellular contents
between plasma membrane &nucleus
• Plasma membrane• selective barrier
Microtubules
Flagellum
Nuclear envelope
Basal body
Chromatin
Ribosomes
Cell membrane
Mitochondrion
Cilia
Microtubules
Microtubule
Centrioles
Microvilli
Lysosomes
Nucleolus
Nucleus
Phospholipid bilayer
SmoothEndoplasmicreticulum
RoughEndoplasmicreticulum
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Golgiapparatus
Secretoryvesicles
http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP11403
5
Cell Membrane(aka Plasma Membrane)
• Outer limit of the cell• Controls what moves in and out of the cell• Selectively permeable• Phospholipid bilayer
• Water-soluble “heads” form surfaces (hydrophilic)• Water-insoluble “tails” form interior (hydrophobic)• Permeable to lipid-soluble substances
• Cholesterol stabilizes the membrane• Proteins:
• Receptors• Pores, channels and carriers• Enzymes• Self-markers
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Cell Membrane
Cell membraneCell membrane
(b)(a)
“Heads” ofphospholipid
“Tails” ofphospholipid
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a: © Biophoto Associates/Photo Researchers, Inc.
Fibrous proteinCarbohydrateGlycolipidGlycoprotein
Extracellular sideof membrane
Cytoplasmic sideof membrane
Cholesterolmolecules
Globularprotein
Doublelayer ofPhospholipidmolecules
Hydrophobicfatty acid“tail”
HydrophilicPhosphate“head”
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cell MembraneElectrochemical Gradient
• due to selective permeability
• difference in concentration of chemicals across membrane
• difference in distribution of charges across the membrane
• difference is the membrane potential
Cell MembraneElectrochemical Gradient
Cell Membrane• Boundary of the cell• Made of a phospholipid bilayer
Cell Membrane
Cell Organelles
• Organelle= “little organ”• All the stuff in between
the organelles is cytosol• Everything in a cell
except the nucleus is cytoplasm
Cell Organelles
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Cytoplasm
• Cytosol = water
• Organelles = solids
Cytoplasm is really like a Jello fruit salad where the Jello is the cytosol and the fruits (oranges, grapes, bananas,
maybe walnuts, etc.) are the organelles.
Cytoplasm
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Organelles
Endoplasmic Reticulum (ER)• Connected, membrane-bound
sacs, canals, and vesicles• Transport system• Rough ER
• Studded with ribosomes• Smooth ER
• Lipid synthesis• Added to proteins
arriving from rough ER• Break down of drugs
Ribosomes• Free floating or connected to ER• Provide structural support and enzyme activity
to amino acids to form protein (protein synthesis)
Membranes
Ribosomes
Membranes
(b) (c)
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Organelles
Endoplasmic Reticulum
• A.k.a. “ER”• Connected to nuclear
membrane• Highway of the cell• Rough ER: studded with
ribosomes; it makes proteins
• Smooth ER: no ribosomes; it makes lipids
Endoplasmic Reticulum (ER)
Ribosome• Site of protein synthesis• Found attached to
rough ER or floating free in cytosol
• Produced in a part of the nucleus called the nucleolus
Remember where ribosomes are found in the cell and why?
Ribosomes
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Organelles
Golgi apparatus• Stack of flattened, membranous sacs• Modifies, packagesand delivers proteins
Vesicles• Membranous sacs• Store substances
Inner membrane
Outer membrane
Cristae
(a) (b)
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a: © Bill Longcore/Photo Researchers, Inc.
Mitochondria• Membranous sacs with inner partitions• Generate energy
Golgi Apparatus
Golgi Apparatus• Looks like a stack of
plates• Stores, modifies and
packages proteins• Molecules transported
to and from the Golgi by means of vesicles
Golgi Apparatus
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Organelles
Lysosomes• Enzyme-containing
sacs• Digest worn out cell
parts or unwanted substances
Peroxisomes• Enzyme-containing
sacs• Break down organic
molecules
Centrosome• Two rod-like centrioles• Used to produce cilia
and flagella• Distributes
chromosomes during cell division
(a) (b)
Centriole(cross-section)
Centriole(longitudinal section)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a: © Don W. Fawcett/Visuals Unlimited
Organelles
Lysosomes• Garbage disposal of
the cell• Contain digestive
enzymes that break down wastes
Which organelles do lysosomes work with?
Lysosomes
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__lysosomes.html
Mitochondria• “Powerhouse of the
cell”• Cellular respiration
occurs here to release energy for the cell to use
• Bound by a double membrane
• Has its own strand of DNA
Mitochondria
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Organelles
Cilia• Short hair-like projections• Propel substances on cell
surface
Flagellum• Long tail-like projection• Provides motility to sperm
(a)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a: © Oliver Meckes/Photo Researchers, Inc.
© Colin Anderson/Brand X/CORBIS
Organelles
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Cell Nucleus
• Is the control center of the cell
• Nuclear membrane (envelope)• Porous double membrane• Separates nucleoplasm from
cytoplasm
• Nucleolus• Dense collection of RNA and
proteins• Site of ribosome production
• Chromatin• Fibers of DNA and proteins• Stores information for synthesis of
proteins
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Nucleus
Nucleolus
Chromatin
(a)
Nuclearpores
Nuclearenvelope
Cell Nucleus
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3.3: Movements Into and Out of the Cell
Passive (Physical) Processes
• Require no cellular energy and include:
• Simple diffusion• Facilitated diffusion• Osmosis• Filtration
Active (Physiological) Processes• Require cellular energy and
include:• Active transport• Endocytosis• Exocytosis• Transcytosis
http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html
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Simple Diffusion
• Movement of substances from regions of higher concentration to regions of lower concentration• Oxygen, carbon dioxide and lipid-soluble substances
Time
Solute molecule
Water molecule
A B A B
(2) (3)
Permeablemembrane
A B
(1)
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Simple Diffusion
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Animation:How Diffusion Works
Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html
24
Facilitated Diffusion
• Diffusion across a membrane with the help of a channel or carrier molecule• Glucose and amino acids
Region of higherconcentration
Transportedsubstance
Region of lowerconcentration
Protein carriermolecule
Cellmembrane
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Facilitated Diffusion
25
Animation:How Facilitated Diffusion Works
Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_facilitated_diffusion_works.html
26
Osmosis and Osmotic Pressure
• Osmotic Pressure – ability of osmosis to generateenough pressure to move a volume of water
• Osmotic pressure increases as the concentrationof nonpermeable solutes increases
• Isotonic – same osmotic pressure• Hypertonic – higher osmotic pressure (water loss)• Hypotonic – lower osmotic pressure (water gain)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© David M. Phillips/Visuals Unlimited
(b)
(a)
(c)
Osmosis and Osmotic Pressure
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html
27
Filtration
• Smaller molecules are forced through porous membranes• Hydrostatic pressure important in the body• Molecules leaving blood capillaries
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Capillary wall
Larger molecules
Smaller molecules
Bloodpressure Blood
flow
Tissue fluid
Filtration
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Active Transport
• Carrier molecules transport substances across a membrane from regions of lower concentration to regions of higher concentration• Sugars, amino acids, sodium ions, potassium ions, etc.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Carrier protein Binding site
(a)
(b)
Cel
l mem
bra
ne
Carrier proteinwith altered shape
Phospholipidmolecules Transported
particle
Cellularenergy
Region of higherconcentration
Region of lowerconcentration
Active Transport
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Active Transport:Sodium-Potassium Pump
• Active transport mechanism• Creates balance by “pumping” three (3) sodium (Na+) OUT and two (2) potassium (K+) INTO the cell• 3:2 ratio
Active Transport – Sodium Potassium Na/K Pump
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Animation:How the Sodium-Potassium
Pump Works
Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.http://highered.mcgraw-hill.com/sites/007249585
5/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html
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Endocytosis• Cell engulfs a substance by forming a vesicle around the substance• Three types:
• Pinocytosis – substance is mostly water• Phagocytosis – substance is a solid• Receptor-mediated endocytosis – requires the
substance to bind to a membrane-bound receptor
Nucleus Nucleolus
Particle VesiclePhagocytizedparticle
Cellmembrane
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Endocytosis
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__phagocytosis.html
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Endocytosis
Cytoplasm
Vesicle
(a) (b) (c) (d)
Receptorprotein
Cellmembrane
Moleculesoutside cell
Cellmembraneindenting
Receptor-ligandcombination
Nucleus Nucleolus
Particle VesiclePhagocytizedparticle
Cellmembrane
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Endocytosis
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Exocytosis• Reverse of endocytosis• Substances in a vesicle fuse with cell membrane• Contents released outside the cell• Release of neurotransmitters from nerve cells
Nucleus
Endoplasmicreticulum
Golgiapparatus
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Exocytosis