Chapter 7: Cell Structure Chapter 7: Cell Structure and Functionand Function

Robert HookeRobert Hooke (1635-1703) (1635-1703)

• English ScientistEnglish Scientist• First to use the First to use the

microscope to microscope to observe cellsobserve cells

• Coined the term Coined the term “cell”“cell”

• Looked at cork Looked at cork cellscells

Anton van LeeuwenhoekAnton van Leeuwenhoek1632-17231632-1723

• Dutch scientistDutch scientist• Invented the first Invented the first

compound compound microscopemicroscope

• First to observe First to observe LIVING cellsLIVING cells

• Blood cells and Blood cells and protistsprotists

Robert BrownRobert Brown1773-18581773-1858

• Scottish botanistScottish botanist• In 1831 he was In 1831 he was

the first person to the first person to observe the observe the nucleus of a cellnucleus of a cell

Schleiden & SchwannSchleiden & Schwann1804-1881 1810-18821804-1881 1810-1882

Developing Cell TheoryDeveloping Cell Theory 1838 1838

• SchleidenSchleiden• Said “all Said “all

plants are plants are made up of made up of cells”cells”

• SchwannSchwann• Said “all Said “all

animals are animals are made up of made up of cells”cells”

JohannesJohannes RudolphRudolphPurkinjePurkinje VirchowVirchow

• Coined the term Coined the term “protoplasm” to “protoplasm” to refer to the refer to the jellylike material jellylike material that fills the cell.that fills the cell.

• Said “all cells Said “all cells arise only from arise only from preexisting cells”preexisting cells”

Cell Theory OverviewCell Theory Overview

1.1. All organisms are made of one or All organisms are made of one or more cells.more cells.

2.2. All cells carry on life activities.All cells carry on life activities.

3.3. New cells arise only from other New cells arise only from other living cells.living cells.

Prokaryotic vs Eukaryotic Prokaryotic vs Eukaryotic

• PROKARYOTICPROKARYOTIC• Simplest formSimplest form• Lack membrane Lack membrane

bound structuresbound structures• Example: bacteria Example: bacteria

and some protistsand some protists

• EUKARYOTICEUKARYOTIC• Most commonMost common• Possess Possess

membrane bound membrane bound structures and a structures and a nucleusnucleus

• Found in most Found in most living thingsliving things

Sizes of CellsSizes of Cells

• Eukaryotic are Eukaryotic are usually larger usually larger than prokaryoticthan prokaryotic

• Both nutrients and Both nutrients and wastes are wastes are constantly constantly entering and entering and exiting cells exiting cells

• Vary in size and Vary in size and shapeshape

Cell Structures and Cell Structures and OrganellesOrganelles

Organelles = specialized Organelles = specialized internal structures of internal structures of eukaryotic cellseukaryotic cells

CELL WALLCELL WALL

• Found in most bacteria and all Found in most bacteria and all plant cellsplant cells

• Gives cell its shape and provides Gives cell its shape and provides protectionprotection

• Allows passage of materialsAllows passage of materials• In plant cells, it is made of In plant cells, it is made of cellulosecellulose• http://www.http://www.cellsalivecellsalive.com/.com/

THE NUCLEUSTHE NUCLEUS

• Control center or “ Control center or “ city hall ” of cell.city hall ” of cell.

• Largest organelleLargest organelle• Controls Controls

metabolism and metabolism and cell reproductioncell reproduction

Structure of nucleusStructure of nucleus

• Nuclear envelope = membrane Nuclear envelope = membrane that surrounds the nucleus that that surrounds the nucleus that acts in manner similar to the cell acts in manner similar to the cell membranemembrane

• NucleolusNucleolus = dense are in center of = dense are in center of nucleus where DNA,RNA, and nucleus where DNA,RNA, and proteins are found.proteins are found.*site where ribosomes are produced*site where ribosomes are produced

Picture of nucleus:Picture of nucleus:

MICROFILAMENTSMICROFILAMENTS

• Long, solid, Long, solid, threadlike threadlike structuresstructures

• Made of actinMade of actin• Involved in Involved in

muscle muscle contraction and contraction and cyclosiscyclosis– Movement of Movement of

cytoplasmcytoplasm

MICROTUBULESMICROTUBULES

• Hollow, cylindrical Hollow, cylindrical structuresstructures

• Helps to give cell Helps to give cell its shapeits shape

• Made of tubulinMade of tubulin• Involved in Involved in

mitosismitosis• More informationMore information

CytoplasmCytoplasm

• Watery material lying within the Watery material lying within the cell between the cell membrane cell between the cell membrane and the nucleusand the nucleus

• Formally called the protoplasm by Formally called the protoplasm by PurkinjePurkinje

• Contains all the other organellesContains all the other organelles

RIBOSOMESRIBOSOMES

• Very smallVery small• ““mini factories” of mini factories” of

the cellthe cell• Responsible for Responsible for

protein synthesis protein synthesis with the help of with the help of RNARNA

• Examples: John Examples: John Morrell, GatewayMorrell, Gateway

ENDOPLASMIC RETICULUM ENDOPLASMIC RETICULUM (ER) (ER)

• Fluid filled canalsFluid filled canals• Continuous paths Continuous paths

for transport of for transport of materialsmaterials

• Divides the cell Divides the cell into into compartmentscompartments

ER continuedER continued

• Acts as a “street Acts as a “street system” in a city system” in a city or conveyer at a or conveyer at a factoryfactory

• Rough ER = Rough ER = surface lined with surface lined with ribosomesribosomes

• Smooth ER = no Smooth ER = no ribosomesribosomes

GOLGI BODIES GOLGI BODIES

• Packaging, storage Packaging, storage and processing of and processing of proteinsproteins

• “ “ Post Office ” of the Post Office ” of the cellcell

• Protein arrives from Protein arrives from the ER to be the ER to be packaged in vesicles.packaged in vesicles.

ER, Ribosome, & GolgiER, Ribosome, & Golgi

LYSOSOMESLYSOSOMES

• Many strong digestive enzymesMany strong digestive enzymes• Produced by Golgi BodiesProduced by Golgi Bodies• Involved in digestion of food in the Involved in digestion of food in the

cellcell• Helps break down worn out Helps break down worn out

organelles and wastesorganelles and wastes• “ “ Garbage Truck ”Garbage Truck ”• Recycles cell materialsRecycles cell materials

VACUOLESVACUOLES

• Found mainly in plants but a few Found mainly in plants but a few are found in animal cellsare found in animal cells

• Many different typesMany different types• Examples: Food and contractileExamples: Food and contractile• Act as a storage unit Act as a storage unit

Contractile vacuolesContractile vacuoles

• Location in plant Location in plant cells where cells where excess water excess water collectscollects

ChloroplastsChloroplasts

• A special type of chromoplast that A special type of chromoplast that contains chlorophyllcontains chlorophyll

• Most importantMost important• Contains grana and stromaContains grana and stroma• Contain their own DNAContain their own DNA• Site of photosynthesisSite of photosynthesis

Chloroplast StructureChloroplast Structure

MITOCHONDRIAMITOCHONDRIA

• Release energy used by the cellRelease energy used by the cell• ““power plant”power plant”• Double membrane for extra surface Double membrane for extra surface

areaarea• Responsible for cellular respirationResponsible for cellular respiration

– Process by which energy is released Process by which energy is released using oxygenusing oxygen

Mitochondria structureMitochondria structure

Mitochondria Mitochondria (powerhouse)(powerhouse)

• Act similar to electric Act similar to electric power plantpower plant

• Upto 300 to 800 per Upto 300 to 800 per cellcell

• What advantage is What advantage is their to having its their to having its own DNA?own DNA?

• Can replicate itselfCan replicate itself

Organelle DNAOrganelle DNA

• The only two organelles that The only two organelles that contain their own DNA are contain their own DNA are mitochondria and chloroplastsmitochondria and chloroplasts

• In animals, all of an organisms In animals, all of an organisms organelle DNA is maternal in origin.organelle DNA is maternal in origin.

• Why?Why?

CELL MEMBRANECELL MEMBRANE

• Controls what materials move in Controls what materials move in and outand out

• Helps to maintain homeostasisHelps to maintain homeostasis• Similar to the “city limits”Similar to the “city limits”• Made up of three substances :Made up of three substances :

– Lipids, proteins, and carbohydratesLipids, proteins, and carbohydrates

Fluid-Mosaic ModelFluid-Mosaic Model

Protein functionsProtein functions

1)1) Transport proteins = control Transport proteins = control movement of materials.movement of materials.

2)2) Receptors = act to signal cell Receptors = act to signal cell when to begin or stop when to begin or stop metabolizing.metabolizing.

3)3) Enzymes = start chemical rxns.Enzymes = start chemical rxns.4)4) Binding site for internal Binding site for internal

structures.structures.

Selectively permeableSelectively permeable

Some substances Some substances pass through pass through while others may while others may not.not.

Regulates chemical Regulates chemical compositioncomposition

Maintains Maintains homeostasis homeostasis

DiffusionDiffusion

• Movement of Movement of molecules from a molecules from a region of high region of high concentration to a concentration to a region of low region of low concentrationconcentration

OsmosisOsmosis

• Diffusion of Diffusion of WATERWATER across a across a selectively permeable membrane selectively permeable membrane from a region of high water from a region of high water concentration to a region of low concentration to a region of low water concentration.water concentration.

• Osmotic pressure =Osmotic pressure =– Increased pressure resulting from Increased pressure resulting from

osmosisosmosis

Isotonic solutionIsotonic solution

• Same concentration of dissolved Same concentration of dissolved substances in solution as there is in substances in solution as there is in the cellthe cell

• Same water concentrationsSame water concentrations• Net resultNet result

– No net gain or loss of waterNo net gain or loss of water

Hypotonic solutionHypotonic solution

• Lower concentration of dissolved Lower concentration of dissolved substances in solution than in the substances in solution than in the cellcell

• More water outside the cell than More water outside the cell than inside the cellinside the cell

• Net result :Net result :

Hypertonic pressureHypertonic pressure

• A high concentration of dissolved A high concentration of dissolved substances outside the cellsubstances outside the cell

• More water in the cell than outside More water in the cell than outside the cellthe cell

• Net result :Net result :

Facilitated diffusion vs Facilitated diffusion vs Active transportActive transport

• Facilitated diffusionFacilitated diffusion• No energy neededNo energy needed• Concentration Concentration

gradient determines gradient determines movementmovement

• Uses protein Uses protein channelschannels

• ACTIVEACTIVE• Usually works Usually works

against the conc. against the conc. GradientGradient

• Often a transport Often a transport protein helps the protein helps the movement (ATP)movement (ATP)

Sodium-potassium pumpSodium-potassium pump

EndocytosisEndocytosis

• Transport of material into the cell Transport of material into the cell by means of a vesicleby means of a vesicle

1.1. Pinocytosis = small amounts of Pinocytosis = small amounts of liquid engulfedliquid engulfed

2.2. Phagocytosis = small amounts of Phagocytosis = small amounts of solid ingestedsolid ingested

ExocytosisExocytosis

• Transport of material out of the cell Transport of material out of the cell by means of a vesicleby means of a vesicle

• Exocytosis movieExocytosis movie

Cellular organizationCellular organization

• Simplest form of life: unicellular Ex. Simplest form of life: unicellular Ex. bacteria, protists, algaebacteria, protists, algae

• Multicellular:Multicellular:– The simplest form is that of a colonyThe simplest form is that of a colony– Little if any cellular specializationLittle if any cellular specialization– Example: Volvox (algae)Example: Volvox (algae)

OrganizationOrganization

CELLS TISSUESCELLS TISSUES

ORGAN SYSTEM ORGANSORGAN SYSTEM ORGANS

ORGANISMORGANISM

Tissues:Tissues:

•A group of cells which are A group of cells which are structurally similar and structurally similar and perform the same perform the same function.function.

1. Epithelial Tissue1. Epithelial Tissue

•Tissue that covers surfaces Tissue that covers surfaces inside and outside the bodyinside and outside the body

•Example: skinExample: skin•Sheets of closely packed Sheets of closely packed

cellscells

2. Connective Tissue2. Connective Tissue

• Supports and Supports and binds tissues and binds tissues and organs togetherorgans together

• Widely separated Widely separated cellscells

• EX. bone, bloodEX. bone, blood

3. Nervous Tissue3. Nervous Tissue

• Specialized for Specialized for electrical impulse electrical impulse transporttransport

• Ex. brain, spinal Ex. brain, spinal cords, nervescords, nerves

4. Muscle Tissue4. Muscle Tissue

• Specialized for contractionSpecialized for contraction• Lots of mitochondriaLots of mitochondria

OrgansOrgans

• Group of tissues that work together Group of tissues that work together to perform a specific functionto perform a specific function

• Ex. heart, stomach, flowerEx. heart, stomach, flower

Organ systemOrgan system

• Group of organs that perform a Group of organs that perform a specific taskspecific task

• Ex. digestive, skeletal, circulatoryEx. digestive, skeletal, circulatory

AssignmentAssignment

• Pages 197-198Pages 197-198– 1-10,11,12,15,17,18,22,26,271-10,11,12,15,17,18,22,26,27

Page 199 1-11Page 199 1-11