Download - Cells. Levels of Organization Cells produce tissues Tissues produce organs Organs produce organ systems Organs systems produce organisms Levels of Organization

Levels of Organization

• Cells produce tissues• Tissues produce organs

• Organs produce organ systems• Organs systems produce organisms

Levels of Organization

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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

http://www.natgeoeducationvideo.com/film/1080/the-human-cell



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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

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Golgiapparatus

Secretoryvesicles

http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP11403



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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


a: © Biophoto Associates/Photo Researchers, Inc.

Fibrous proteinCarbohydrateGlycolipidGlycoprotein

Extracellular sideof membrane

Cytoplasmic sideof membrane

Cholesterolmolecules

Globularprotein

Doublelayer ofPhospholipidmolecules

Hydrophobicfatty acid“tail”

HydrophilicPhosphate“head”


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)


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)


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)


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)


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


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)


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






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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


Facilitated Diffusion

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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





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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)


© 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



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Filtration

• Smaller molecules are forced through porous membranes• Hydrostatic pressure important in the body• Molecules leaving blood capillaries


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.


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

http://highered.mcgraw-hill.com/sites/0072495855/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


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


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


Exocytosis

Download - Cells. Levels of Organization Cells produce tissues Tissues produce organs Organs produce organ systems Organs systems produce organisms Levels of Organization

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