Chapter 7Chapter 7

Cell Structure & FunctionCell Structure & Function

Section 7-1Section 7-1

Life is CellularLife is Cellular

What led to the discovery of the cell?What led to the discovery of the cell?– The MicroscopeThe Microscope

Remember!Remember!– CellsCells make up all living things. make up all living things.

The Discovery of the CellThe Discovery of the Cell

Early Microscopes:Early Microscopes:– Scientists didn’t use microscopes until Scientists didn’t use microscopes until

the 1600’s.the 1600’s.– Robert HookeRobert Hooke -one of the 1st to look at -one of the 1st to look at

cells under a microscope.cells under a microscope.Gave cells their name.Gave cells their name.P. 169, fig. 7-1P. 169, fig. 7-1He was looking at He was looking at deaddead cork cells. cork cells.

Cork Cells (Hooke)Cork Cells (Hooke)

Robert HookeRobert Hooke

At about the same time as Hooke, At about the same time as Hooke, Anton van LeeuwenhoekAnton van Leeuwenhoek used a tiny used a tiny microscope to look at pond water.microscope to look at pond water.

He discovered the new world of He discovered the new world of microorganisms.microorganisms.

The Cell TheoryThe Cell Theory

In 1838, In 1838, Matthias SchleidenMatthias Schleiden stated that all stated that all plantsplants are made of cells. are made of cells.

In 1839, In 1839, Theodore SchwannTheodore Schwann stated that all stated that all animalsanimals were made of cells. were made of cells.

In 1855, In 1855, Rudolf VirchowRudolf Virchow stated that cells stated that cells could only come from other cells.could only come from other cells.

The Cell Theory:The Cell Theory:P. 170P. 170

1.1. All living things are made of cells.All living things are made of cells.

2.2. Cells are the basic units of Cells are the basic units of structurestructure & & functionfunction in living things. in living things.

3.3. New cells are produced from existing New cells are produced from existing cells.cells.

Exploring the CellExploring the Cell

Today, modern biologists use more Today, modern biologists use more powerful microscopes & techniques.powerful microscopes & techniques.

Some of the tools they use:Some of the tools they use:– Fluorescent labels & light microscopyFluorescent labels & light microscopy

Able to follow molecules moving through a cell.Able to follow molecules moving through a cell.

– Confocal light microscopyConfocal light microscopy Scans cells w/ a laser to make 3D images of cells & Scans cells w/ a laser to make 3D images of cells &

their parts.their parts.

– High-resolution videoHigh-resolution video Enables us to make movies of cells as they grow, Enables us to make movies of cells as they grow,

divide, & develop.divide, & develop.

http://www.kent.edu/projects/cell/http://www.kent.edu/projects/cell/video/fatheadminnow2.mpgvideo/fatheadminnow2.mpg

Another New MethodAnother New Method

Electron Microscopes (EM):Electron Microscopes (EM):– Can view things Can view things 1 million1 million times smaller times smaller

than that of a light microscope.than that of a light microscope.– 22 types of EM’s: types of EM’s:

Transmission Electron Microscopes (Transmission Electron Microscopes (TEMTEM))Scanning Electron Microscopes (Scanning Electron Microscopes (SEMSEM))

TEM:TEM:– Lets us see cell structures & large Lets us see cell structures & large

protein molecules.protein molecules.

– Cells & tx’s must be cut into ultra-thin Cells & tx’s must be cut into ultra-thin slices before they are examined.slices before they are examined.

– 2D2D cross sectionalcross sectional image. image.

TEMTEM

SEM:SEM:– 3D3D images of cells images of cells– Objects don’t have to be thinly sliced to Objects don’t have to be thinly sliced to

view.view.

SEMSEM

Remember!Remember!– EM’s can only view the EM’s can only view the nonlivingnonliving..

In the 1990’s, researches perfected a In the 1990’s, researches perfected a new class of microscope.new class of microscope.

– The The Scanning Probe MicroscopeScanning Probe Microscope– Produces images by tracing the surfaces Produces images by tracing the surfaces

of samples w/ a fine probe.of samples w/ a fine probe.– Can observe single atoms.Can observe single atoms.– Used to see DNA & protein molecules.Used to see DNA & protein molecules.

Scanning Probe Scanning Probe MicroscopeMicroscope

Prokaryotes & EukaryotesProkaryotes & Eukaryotes

Cells come in all shapes & sizes.Cells come in all shapes & sizes.

But, all cells have But, all cells have 22 characteristics characteristics in common:in common:

1.1. They have a They have a cell membranecell membrane at some point at some point in their lives.in their lives.

2.2. They They contain DNAcontain DNA..

Cells fall into Cells fall into 22 categories based on if categories based on if they have a they have a nucleusnucleus..– NucleusNucleus –large membrane bound –large membrane bound

organelle.organelle.Contains cell’s DNA.Contains cell’s DNA.Controls many of the cell’s activities.Controls many of the cell’s activities.

– OrganelleOrganelle –specialized structure that –specialized structure that performs important functions w/in the performs important functions w/in the cell.cell.““Tiny organs”Tiny organs”

The The 22 categories are: categories are:

– ProkaryotesProkaryotesCells don’t contain a nucleus.Cells don’t contain a nucleus.

– EukaryotesEukaryotesCells do contain a nucleus.Cells do contain a nucleus.

– ProPro = before = before– Eu Eu = true= true– KaryonKaryon =kernel=kernel

ProkaryotesProkaryotes Generally smaller & simpler than eukaryotic Generally smaller & simpler than eukaryotic

cells.cells. Prokaryotes have DNA, but it’s not Prokaryotes have DNA, but it’s not

contained in a nucleus.contained in a nucleus. All are unicellular.All are unicellular. Despite their simplicity, prokaryotes:Despite their simplicity, prokaryotes:

– GrowGrow– ReproduceReproduce– Respond to their env.Respond to their env.– Some are mobile.Some are mobile.

Ex:Ex:– BacteriaBacteria

EukaryotesEukaryotes Generally larger & more complex than Generally larger & more complex than

prokaryotes.prokaryotes. Eukaryotes contain membrane bound Eukaryotes contain membrane bound

organelles & a nucleus (DNA).organelles & a nucleus (DNA). Eukaryotes can be Eukaryotes can be unicellularunicellular or or

multicellularmulticellular.. Ex:Ex:

– PlantsPlants– AnimalsAnimals– FungiFungi– ProtistsProtists

Pro-k vs. Eu-kPro-k vs. Eu-k

Prokaryotes Eukaryotes

Cell membraneContain DNA

NucleusEndoplasmic reticulum

Golgi apparatusLysosomesVacuoles

MitochondriaCytoskeleton

Plant vs. Animal CellPlant vs. Animal Cell

Centrioles

Cell membraneRibosomes

NucleusEndoplasmic reticulum

Golgi apparatusLysosomesVacuoles

MitochondriaCytoskeleton

Cell WallChloroplasts

Animal Cells Plant Cells

Section 2Section 2

Eukaryotic Cell StructureEukaryotic Cell Structure

Comparing the Cell to a FactoryComparing the Cell to a Factory

OrganellesOrganelles –literally means “ –literally means “little little organsorgans”.”.– Specialized structures that carry out Specialized structures that carry out

specific functions in a cell.specific functions in a cell.

Cell biologist divide cells into Cell biologist divide cells into 22 parts: parts:– The nucleusThe nucleus– The cytoplasmThe cytoplasm

CytoplasmCytoplasm –portion of the cell –portion of the cell outside the nucleus.outside the nucleus.– Cytoplasm is a gelatinous-like material.Cytoplasm is a gelatinous-like material.

Cytoplasm:Cytoplasm:

NucleusNucleus

The nucleus is the control center of the The nucleus is the control center of the cell.cell.– It contains almost all the cell’s DNA & w/ it It contains almost all the cell’s DNA & w/ it

the coded instructions for making proteins the coded instructions for making proteins & other important molecules.& other important molecules.

Surrounding the nucleus is a double Surrounding the nucleus is a double membrane called the membrane called the nuclear envelopenuclear envelope..

On the nuclear envelope you will find On the nuclear envelope you will find nuclear poresnuclear pores..– Allow materials to move in & out of the Allow materials to move in & out of the

nucleus.nucleus.Ex:Ex:

– ProteinsProteins– RNARNA– Other moleculesOther molecules

ChromatinChromatin –a granular material –a granular material visible w/in the nucleus.visible w/in the nucleus.– It consists of DNA tightly coiled around It consists of DNA tightly coiled around

proteins.proteins.– Most of the time chromatin is spread Most of the time chromatin is spread

throughout the nucleus.throughout the nucleus.– However, when a cell divides, chromatin However, when a cell divides, chromatin

condenses to form condenses to form chromosomeschromosomes..

Another structure found in most Another structure found in most nuclei is a nuclei is a nucleolusnucleolus..– The nucleolus assembles The nucleolus assembles ribosomesribosomes..

P. 176, fig. 7-7P. 176, fig. 7-7

RibosomesRibosomes

RibosomesRibosomes –small particles of RNA & –small particles of RNA & protein found throughout the cytoplasm.protein found throughout the cytoplasm.

Ribosomes make proteins by following Ribosomes make proteins by following coded instructions that come from the coded instructions that come from the nucleus.nucleus.– These instructions are These instructions are RNARNA..

Cells that are major protein producers Cells that are major protein producers often have numerous ribosomes.often have numerous ribosomes.

Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER)

Endoplasmic ReticulumEndoplasmic Reticulum –an internal –an internal membrane system in cells in which membrane system in cells in which lipid components of the cell lipid components of the cell membrane are assembled & some membrane are assembled & some proteins are modified.proteins are modified.

There are There are 22 portions to an ER: portions to an ER:– The rough ERThe rough ER– The smooth ERThe smooth ER

The rough ERThe rough ER– Involved in the synthesis of proteins.Involved in the synthesis of proteins.– It is said to be rough b/c it has ribosomes found It is said to be rough b/c it has ribosomes found

on its surface.on its surface.– Newly made proteins enter the rough ER & get Newly made proteins enter the rough ER & get

modified.modified.

The Smooth ERThe Smooth ER– No ribosomes found on the surface.No ribosomes found on the surface.– Contains collections of enzymes that Contains collections of enzymes that

perform special tasks such as:perform special tasks such as:Synthesis of membrane lipidsSynthesis of membrane lipidsDetoxification of drugsDetoxification of drugs

– Liver cells tend to have a large amounts Liver cells tend to have a large amounts of smooth ER.of smooth ER.

RERRER SERSER

Golgi Apparatus (GA)Golgi Apparatus (GA)

Proteins made in the ER move to the Proteins made in the ER move to the Golgi Apparatus (GA).Golgi Apparatus (GA).

The GA looks like a stack of closely The GA looks like a stack of closely apposed membranes.apposed membranes.

The GA’s The GA’s modifies, sorts, & packagesmodifies, sorts, & packages proteins & other materials from the proteins & other materials from the ER.ER.– These proteins can be stored in the cell These proteins can be stored in the cell

or secreted out of the cell.or secreted out of the cell.

Kind of like Kind of like UPSUPS.. P. 178, fig. 7-9P. 178, fig. 7-9

LysosomesLysosomes

The clean up crew.The clean up crew.

LysosomeLysosome –small organelles filled w/ –small organelles filled w/ digestive enzymes.digestive enzymes.

Lysosomes are involved in:Lysosomes are involved in:– Breaking down old organelles.Breaking down old organelles.– Digesting foreign matter in the cell.Digesting foreign matter in the cell.

Tay-SachsTay-Sachs -a -a disease is caused by disease is caused by lysosomes that fail to properly do lysosomes that fail to properly do their job.their job.– Fatal by the age of 4.Fatal by the age of 4.– More common in eastern European Jews.More common in eastern European Jews.

VacuolesVacuoles VacuolesVacuoles –an organelle that stores –an organelle that stores

materials such as:materials such as:– WaterWater– SaltsSalts– ProteinsProteins– CarbsCarbs

Plants have large central vacuoles Plants have large central vacuoles that can hold, water & wastes.that can hold, water & wastes.– P. 179, fig. 7-10P. 179, fig. 7-10

Mitochondria & ChloroplastsMitochondria & Chloroplasts

The power plants of a cell.The power plants of a cell. Most cells get their energy (E) in Most cells get their energy (E) in 22

ways:ways:– Food (Heterotrophs)Food (Heterotrophs)– Sun (Autotrophs)Sun (Autotrophs)

Mitochondria:Mitochondria:– Can be found in almost all eukaryotic Can be found in almost all eukaryotic

cells.cells. Including plant cells.Including plant cells.

– Converts chemical E into compounds Converts chemical E into compounds that are easy for the cell to use.that are easy for the cell to use.Ex: ATP (Ex: ATP (Adenosine TriphosphateAdenosine Triphosphate))

Mitochondria are enclosed by 2 Mitochondria are enclosed by 2 membranes.membranes.– An outer membraneAn outer membrane– An inner membraneAn inner membrane

Highly folded on itself.Highly folded on itself.Creates more surface area for chemical Creates more surface area for chemical

reactions.reactions.

Chloroplasts:Chloroplasts:– Found in plants & some other orgs.Found in plants & some other orgs.– They capture sunlight & convert it into They capture sunlight & convert it into

chemical E by chemical E by photosynthesisphotosynthesis..This chemical E is then converted to ATP by This chemical E is then converted to ATP by

mitochondria in the plant.mitochondria in the plant.

– Also surrounded by Also surrounded by 22 membranes. membranes.

– Contains a green pigment called Contains a green pigment called chlorophyllchlorophyll..

ChloroplastsChloroplasts

Organelle DNAOrganelle DNA

Chloroplasts & mitochondria contain Chloroplasts & mitochondria contain their own DNA.their own DNA.– No other organelles do.No other organelles do.

It is believed that both of these It is believed that both of these organelles are ancient descendants of organelles are ancient descendants of prokaryotes.prokaryotes.

This is called the This is called the endosymbiotic endosymbiotic theorytheory..

CytoskeletonCytoskeleton CytoskeletonCytoskeleton –a network of protein –a network of protein

filaments that helps the cell maintain filaments that helps the cell maintain its shape.its shape.– It is also involved in movement.It is also involved in movement.

The cytoskeleton is made up of:The cytoskeleton is made up of:– MicrofilamentsMicrofilaments– MicrotubulesMicrotubules

Microfilaments:Microfilaments:– ThreadlikeThreadlike– Made of Made of actinactin– Forms a tough, flexible framework that Forms a tough, flexible framework that

supports the cell.supports the cell.– Also responsible for cytoplasmic Also responsible for cytoplasmic

movement of the cell.movement of the cell.

Microtubules:Microtubules:– Hollow tube-like structuresHollow tube-like structures– Made of Made of tubulintubulin– Critical to maintaining cell shape.Critical to maintaining cell shape.– Also form structures called Also form structures called spindlesspindles

during cell division.during cell division.– Tubulin is also used to make Tubulin is also used to make centriolescentrioles..

Located near the nucleus.Located near the nucleus.Help organize cell division.Help organize cell division.

Microtubules also help w/ movement.Microtubules also help w/ movement.– They make up They make up cilia & flagellacilia & flagella..

P. 181, fig. 7-11P. 181, fig. 7-11

Section 7-3Section 7-3

Cell BoundariesCell Boundaries

All cells are surrounded by a thin All cells are surrounded by a thin barrier called the barrier called the cell membranecell membrane..

Many cells also have a strong Many cells also have a strong supporting layer around that supporting layer around that membrane called the membrane called the cell wallcell wall..

Cell MembraneCell Membrane

Cell membranes regulate what enters & Cell membranes regulate what enters & leaves a cell.leaves a cell.

They also aid in protection & support.They also aid in protection & support.

Nearly all cell membranes are a Nearly all cell membranes are a flexible,flexible, double double layered sheet called a layered sheet called a lipid bilayerlipid bilayer..– P. 182, fig. 7-12P. 182, fig. 7-12

Along w/ lipids, the cell membrane Along w/ lipids, the cell membrane also has also has proteinsproteins & & carbohydratescarbohydrates embedded in it.embedded in it.

The lipid bilayer is often called a The lipid bilayer is often called a mosaicmosaic, b/c it is made up of many , b/c it is made up of many different parts.different parts.

The proteins form The proteins form channelschannels & & pumpspumps for moving materials across the for moving materials across the membrane.membrane.

The carbohydrates act like The carbohydrates act like IDID cards, cards, allowing individual cells to identify allowing individual cells to identify one another.one another.

http://www.youtube.com/watch?http://www.youtube.com/watch?v=Qqsf_UJcfBc&feature=relatedv=Qqsf_UJcfBc&feature=related

http://www.youtube.com/watch?http://www.youtube.com/watch?v=vh5dhjXzbXcv=vh5dhjXzbXc

Cell Walls (CW’s)Cell Walls (CW’s)

Found in:Found in:– PlantsPlants– Algae (Protists)Algae (Protists)– FungiFungi– Many prokaryotes Many prokaryotes (not all)(not all)

CW’s lie outside the cell membrane.CW’s lie outside the cell membrane.

Most cell walls allow certain Most cell walls allow certain substances to pass through.substances to pass through.

Such as:Such as:– HH2200– COCO22

– OO22

Its main function is to Its main function is to supportsupport & & protectprotect the cell. the cell.

Most CW’s are made of fibers of Most CW’s are made of fibers of carbohydrate & protein.carbohydrate & protein.

Plant CW’s are made of Plant CW’s are made of cellulosecellulose..– Cellulose is a tough carbohydrate fiber.Cellulose is a tough carbohydrate fiber.– The fiber in your diet.The fiber in your diet.

Diffusion Through Cell BoundariesDiffusion Through Cell Boundaries

The movement of molecules from The movement of molecules from one side of the cell membrane to the one side of the cell membrane to the other.other.

Measuring ConcentrationMeasuring Concentration Recall what a solution is.Recall what a solution is.

– What’s a solute?What’s a solute?– What’s a solvent?What’s a solvent?

ConcentrationConcentration –the mass of solute in –the mass of solute in a given volume of solution, or a given volume of solution, or mass/volume.mass/volume.

Lets figure concentration of a Lets figure concentration of a solution.solution.– If you dissolved If you dissolved 12g12g of salt in of salt in 3L3L of of

water, the concentration would be: water, the concentration would be: 12g/3L12g/3L = = 4 g/L4 g/L

DiffusionDiffusion DiffusionDiffusion –process of molecules –process of molecules

moving from an area of moving from an area of highhigh concentration to an area of concentration to an area of lowlow concentration.concentration.– EquilibriumEquilibrium –when the concentration of –when the concentration of

a solute is the a solute is the samesame throughout a throughout a solution.solution.

Diffusion will go on until EQ is Diffusion will go on until EQ is reached.reached.

What does diffusion have to do w/ a What does diffusion have to do w/ a cell membrane?cell membrane?– P. 184, fig. 7-14P. 184, fig. 7-14

Diffusion requires Diffusion requires no E no E output by the output by the cell.cell.– It’s It’s freefree!!

OsmosisOsmosis Biological membranes are Biological membranes are selectively selectively

permeablepermeable..– Some substances can pass & some can’t.Some substances can pass & some can’t.

Water passes very easily.Water passes very easily.

However, many solutes can’t.However, many solutes can’t.

OsmosisOsmosis –the diffusion of –the diffusion of waterwater through a through a selectively permeable membrane.selectively permeable membrane.

How Osmosis WorksHow Osmosis Works

HH22O moves from an area of O moves from an area of highhigh H H22O O concentration to an area of concentration to an area of lowlow H H22O O concentration.concentration.

Water moves across the membrane Water moves across the membrane until EQ is reached.until EQ is reached.

OsmosisOsmosisSection 7-3

http://www.youtube.com/watch?http://www.youtube.com/watch?v=sdiJtDRJQEc&feature=relatedv=sdiJtDRJQEc&feature=related

33 types of Osmotic Solutions: types of Osmotic Solutions:P. 186, fig. 7-16P. 186, fig. 7-16

IsotonicIsotonic– Concentrations are equal on both sides of the Concentrations are equal on both sides of the

membrane.membrane.– Normal looking cellsNormal looking cells

HypertonicHypertonic– Solution outside the cell has a higher solute Solution outside the cell has a higher solute

concentration than the inside of the cell.concentration than the inside of the cell.– Water leaves the cell.Water leaves the cell.– Cells shrinkCells shrink

HypotonicHypotonic– Solution has a lower solute concentration than the cell.Solution has a lower solute concentration than the cell.– Water enters the cell.Water enters the cell.– Cells swellCells swell

Plant CellsPlant Cells

Plant CellsPlant Cells

http://www.youtube.com/watch?http://www.youtube.com/watch?v=GOxouJUtEhE&feature=relatedv=GOxouJUtEhE&feature=related

Turgid

Flaccid

Red Blood CellsRed Blood Cells

Osmotic PressureOsmotic Pressure Osmosis exerts a pressure known as Osmosis exerts a pressure known as

osmotic pressureosmotic pressure..

Osmotic pressureOsmotic pressure -the pressure exerted by -the pressure exerted by the flow of water through a semi the flow of water through a semi permeable membrane.permeable membrane.

This can cause serious problems for a cell.This can cause serious problems for a cell.– Cells can swell to the point of bursting.Cells can swell to the point of bursting.

Fortunately, animal cells are in a Fortunately, animal cells are in a isotonic solution & don’t come into isotonic solution & don’t come into contact w/ pure Hcontact w/ pure H22O.O.– If they did they would burst.If they did they would burst.

Also, plant cells & bacterial cells Also, plant cells & bacterial cells have cell walls that prevent the cell have cell walls that prevent the cell from bursting.from bursting.

Facilitated DiffusionFacilitated Diffusion

Facilitated diffusionFacilitated diffusion –movement of –movement of specific molecules across CM’s via specific molecules across CM’s via protein channelsprotein channels..– P. 187, fig. 7-17P. 187, fig. 7-17

There are hundreds of protein There are hundreds of protein channels that allow only certain channels that allow only certain substances to cross different substances to cross different membranes.membranes.

This process This process does not does not require E.require E.

It acts just as diffusion.It acts just as diffusion.– It goes from high to low concentrations.It goes from high to low concentrations.

Facilitated DiffusionFacilitated Diffusion http://www.d.umn.edu/~sdowning/http://www.d.umn.edu/~sdowning/

Membranes/diffusionanimation.htmlMembranes/diffusionanimation.html

Active TransportActive Transport

When cells move materials When cells move materials againstagainst the concentration gradient, they are the concentration gradient, they are using using Active TransportActive Transport..

– This process requires E.This process requires E.

Active transport is carried out by Active transport is carried out by transport proteins transport proteins or or pumpspumps found in found in the membrane.the membrane.

Transport of larger molecules can Transport of larger molecules can be done through be done through 22 active transport active transport processes:processes:

1.1. EndocytosisEndocytosis– P. 188, fig. 7-18P. 188, fig. 7-18

2.2. ExocytosisExocytosis

– For each of these processes, the shape For each of these processes, the shape of the membrane changes.of the membrane changes.

Endo & ExoEndo & Exo

http://www.youtube.com/watch?http://www.youtube.com/watch?v=K7yku3sa4Y8&feature=relatedv=K7yku3sa4Y8&feature=related

Molecular TransportMolecular Transport EndocytosisEndocytosis –process of taking material –process of taking material

into the cell by infolding or pocketing of into the cell by infolding or pocketing of the CM.the CM.

– This process forms a vacuole in the cell.This process forms a vacuole in the cell.– This process works for:This process works for:

taking in foodtaking in food larger moleculeslarger molecules other cellsother cells

– 22 examples of endocytosis are: examples of endocytosis are: PhagocytosisPhagocytosis PinocytosisPinocytosis

PhagocytosisPhagocytosis – extensions of – extensions of cytoplasm surround a particle & cytoplasm surround a particle & package it w/in food vesicles.package it w/in food vesicles.– AmoebasAmoebas use this method use this method

Fig. 7-18Fig. 7-18

PinocytosisPinocytosis –the process of taking in –the process of taking in liquids from the surrounding env.liquids from the surrounding env.

Many cells also release large Many cells also release large amounts of material from the cell.amounts of material from the cell.

This process is called This process is called exocytosisexocytosis.. Ex:Ex:

– The removal of water by a contractile The removal of water by a contractile vacuole is an example of this kind of vacuole is an example of this kind of active transport.active transport.

http://highered.mcgraw-hill.com/http://highered.mcgraw-hill.com/sites/0072437316/student_view0/sites/0072437316/student_view0/chapter6/animations.html#chapter6/animations.html#

Section 7-4Section 7-4

The Diversity of Cellular The Diversity of Cellular LifeLife

Unicellular OrganismsUnicellular Organisms

Unicellular orgs.Unicellular orgs. –made of one cell.–made of one cell.

Unicellular orgs. can:Unicellular orgs. can:– growgrow– respond to the env.respond to the env.– reproducereproduce– transform Etransform E

Unicellular orgs. Unicellular orgs. dominatedominate life on life on Earth.Earth.

Examples on Examples on P. 190, fig. 7-20P. 190, fig. 7-20

Multicellular OrganismsMulticellular Organisms

Orgs. made up of many cells.Orgs. made up of many cells.

Multicellular orgs. have cells that are Multicellular orgs. have cells that are specializedspecialized..

Cell SpecializationCell Specialization –process in which cells –process in which cells develop in different ways to perform develop in different ways to perform different tasks.different tasks.– P. 191, fig. 7-21P. 191, fig. 7-21

Specialized Animal CellsSpecialized Animal Cells

Examples of specialized cells in Examples of specialized cells in animals:animals:– Red blood cellsRed blood cells

Transport OTransport O22 throughout the body. throughout the body.

– Pancreatic cellsPancreatic cellsProduce enzymes that aid in digestion.Produce enzymes that aid in digestion.Contain cells specialized for making Contain cells specialized for making

proteins.proteins.– These cells have numerous ribosomes.These cells have numerous ribosomes.

– Muscle cellsMuscle cellsAble to contract & relax, causing movement Able to contract & relax, causing movement

of our bones.of our bones.

Specialized Plant CellsSpecialized Plant Cells

Guard cells of the stomata:Guard cells of the stomata:– Monitor a plants internal conditions, & Monitor a plants internal conditions, &

makes changes accordingly.makes changes accordingly.

Levels of OrganizationLevels of Organization The levels of organization in a The levels of organization in a

multicellular org. are as follows:multicellular org. are as follows:– Individual CellsIndividual Cells– TissuesTissues– OrgansOrgans– Organ systemsOrgan systems– OrganismOrganism

P. 192, fig. 7-22P. 192, fig. 7-22

ExamplesExamples

neurons (nerve cells) neurons (nerve cells) nervous tissue nervous tissue brain brain central nervous system central nervous system human human

TissueTissue –a group of similar cells that –a group of similar cells that perform a specific function.perform a specific function.– Ex:Ex:

The collection of cells in the pancreas that make The collection of cells in the pancreas that make proteins.proteins.

– Most animals have Most animals have 44 types of tx: types of tx: MuscleMuscle EpithelialEpithelial NervousNervous connectiveconnective

OrgansOrgans –many groups of tx’s working –many groups of tx’s working together.together.– Each muscle is an organ.Each muscle is an organ.– However, it also contains nervous tx, & However, it also contains nervous tx, &

connective tx.connective tx.

Organ systemOrgan system –a group of organs –a group of organs working together to perform a working together to perform a specific function.specific function.– Digestive systemDigestive system– Reproductive systemReproductive system– Nervous systemNervous system

Altogether, organ systems make up Altogether, organ systems make up the organism.the organism.

Body SystemsBody Systems