Chapter 7Chapter 7

Cell Structure and FunctionCell Structure and Function

Anton van LeeuwenhoekAnton van Leeuwenhoek

Father of the microscope - Father of the microscope - 1600’s1600’s– used lens technologyused lens technology– fabric qualityfabric quality– telescope same timetelescope same time

1st to see life in a drop of 1st to see life in a drop of waterwater

Robert HookeRobert Hooke

16651665

1st to examined plant 1st to examined plant

tissuetissue

Resembled monastery’s Resembled monastery’s

tiny rooms tiny rooms

““Cells” Cells”

Matthias SchleidenMatthias Schleiden

1838 - all plants are made of cells1838 - all plants are made of cells

Theodor SchwannTheodor Schwann

1839 - All animals are made of cells1839 - All animals are made of cells

Rudolf VirchowRudolf Virchow

1855 - Cells come from other 1855 - Cells come from other preexisting cellspreexisting cells

The Cell TheoryThe Cell Theory

All living things are composed of cellsAll living things are composed of cells

Cells are the basic units of structure and Cells are the basic units of structure and function in living thingsfunction in living things

New cells are produced from existing New cells are produced from existing cellscells

What do all cells have in What do all cells have in common?common?

Cell membraneCell membrane– thin, flexible barrier surrounding the cellthin, flexible barrier surrounding the cell

CytoplasmCytoplasm– fluid within the cellfluid within the cell

Genetic MaterialGenetic Material

Basic Cell Basic Cell TypesTypes

Prokaryotic CellsProkaryotic Cells– cell membranecell membrane– cytoplasmcytoplasm– genetic material genetic material

(lack a nucleus)(lack a nucleus)– all bacteria all bacteria

Cell membrane

cytoplasm

Genetic Material

Eukaryotic Eukaryotic CellsCells

Contain cell Contain cell membrane, membrane, cytoplasmcytoplasm

nucleusnucleus

organellesorganelles

all animal, plant, all animal, plant, fungi and fungi and protistsprotists

A Closer Look at the CellA Closer Look at the Cell

Your objective is to…Your objective is to…

Describe the main functions of each Describe the main functions of each

cell structurecell structure

Cell WallCell WallPlants, bacteria, Plants, bacteria, fungi, algaefungi, algae

Provides structure Provides structure and protectionand protection

Gas and water Gas and water exchangeexchange

Plants - made of Plants - made of the polysaccharide the polysaccharide cellulosecellulose

NucleuNucleuss

Controls cell Controls cell processesprocesses

Contains DNAContains DNA– deoxyribose deoxyribose

nucleic acidnucleic acid– codes for protein codes for protein

and other and other moleculesmolecules

ChromatinChromatin– DNA bound to proteinDNA bound to protein

ChromosomesChromosomes– chromatin condenses chromatin condenses

during cell division during cell division

NucleolusNucleolus– make ribosomesmake ribosomes

Nuclear EnvelopeNuclear Envelope– 2 layers with pores 2 layers with pores

that allow for the that allow for the passage of materialpassage of material

CytoskeletonCytoskeleton

Network of protein filamentsNetwork of protein filaments

(microtubules and microfilaments)(microtubules and microfilaments)

Maintains cell shapeMaintains cell shape

Cell MovementCell Movement

Intracellular MovementIntracellular Movement– moves organellesmoves organelles– important during cell divisionimportant during cell division

Tracks for organelle movement

Cell membrane

Endoplasmicreticulum

Microtubule

Microfilament

Ribosomes Mitochondrion

Figure 7-11 Cytoskeleton

Transportation

The OrganellesThe Organelles

Specialized structures within Specialized structures within the cytoplasm of the cell that the cytoplasm of the cell that

perform specific jobsperform specific jobs

Endoplasmic Endoplasmic ReticulumReticulum

2 types2 types– Rough and SmoothRough and Smooth– membrane assemblagemembrane assemblage

RoughRough– contain ribosomescontain ribosomes– certain proteins are modified certain proteins are modified

SmoothSmooth– synthesis of lipidssynthesis of lipids

RibosomesRibosomes

Use genetic information to make proteinUse genetic information to make protein

found free in cytoplasm or on RERfound free in cytoplasm or on RER

Golgi Golgi ApparatusApparatus

Receive proteins from RERReceive proteins from RER

Use enzymes to attach Use enzymes to attach carbohydrates and lipids to carbohydrates and lipids to proteinsproteins

Sent to final destinationSent to final destination

Construct LysosomesConstruct Lysosomes

LysosomesLysosomes

Contain enzymes that breakdown large Contain enzymes that breakdown large molecules into smaller moleculesmolecules into smaller molecules

Recycle old organelles and debrisRecycle old organelles and debris

Enzyme

Recycling

VacuoleVacuoless

Storage units for water, salts, proteins Storage units for water, salts, proteins and carbohydratesand carbohydrates

Provide support for plants “water”Provide support for plants “water”

ChloroplastsChloroplastsFound in plants and algaeFound in plants and algae

photosynthesisphotosynthesis

2 membranes2 membranes

Contains DNA Contains DNA

MitochondriaMitochondria

Convert food into high-energy Convert food into high-energy compounds (ATP) that the cell uses to compounds (ATP) that the cell uses to power growth, development and power growth, development and movementmovement

2 membranes2 membranes

Contains DNAContains DNA

Animal vs. Plant CellsAnimal vs. Plant Cells

Plant Cell

Nuclearenvelope

Ribosome(attached)

Ribosome(free)

Smooth endoplasmicreticulum

Nucleus

Rough endoplasmic reticulum

Nucleolus

Golgi apparatus

Mitochondrion

Cell wall

CellMembrane

Chloroplast

Vacuole

Figure 7-5 Plant and Animal Cells

Animal Cell

Centrioles

NucleolusNucleus

Nuclearenvelope

Rough endoplasmic reticulum

Golgi apparatus

Smooth endoplasmicreticulum

Mitochondrion

CellMembrane

Ribosome(free)

Ribosome(attached)

Figure 7-5 Plant and Animal Cells

The Cell MembraneThe Cell Membrane

Objectives:Objectives:Describe the structure of the cell Describe the structure of the cell

membranemembraneDescribe how substances move Describe how substances move

through the cellthrough the cell

Cell Membrane Structure

•Lipid bilayer

•Regulates entry and exit of materials

•Protection and support

•Carbohydrate chains act as idenitification cards

Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

Figure 7-12 The Structure of the Cell Membrane

Hydrophobic

•nonpolar

Hydrophilic

•polar

DiffusionDiffusion

Movement of materials from a high Movement of materials from a high concentration to a lower concentration concentration to a lower concentration until equilibrium is reacheduntil equilibrium is reached

requires no energyrequires no energy

What materials diffuse across a cell What materials diffuse across a cell membrane?membrane?

OsmosisOsmosis

Diffusion of water across a selectively Diffusion of water across a selectively permeable membranepermeable membrane

Types of SolutionsTypes of Solutions– hypertonichypertonic - higher concentration of - higher concentration of

dissolved particlesdissolved particles– hypotonihypotonic - lower concentration of c - lower concentration of

dissolved particlesdissolved particles– isotonicisotonic - identical concentration - identical concentration

Figure 7-15 Osmosis

Continues until the concentrations are equal

Solutions outside of the cell…..

Problems in OrganismsProblems in Organisms

PlantsPlants– turgor pressureturgor pressure– rigid vs. wiltingrigid vs. wilting

Antibiotic effects on bacteriaAntibiotic effects on bacteria

Single Celled OrganismsSingle Celled Organisms– contractile vacuole contractile vacuole – homeostasishomeostasis

Animals Animals – cells bathed in isotonic fluids “blood”cells bathed in isotonic fluids “blood”

Facilitated Diffusion• specific protein channels for specific substances that cannot diffuse on their own

•glucose channel

HighConcentration

LowConcentration

CellMembrane

Glucosemolecules

Proteinchannel

Facilitated Diffusion

Active TransportActive Transportmovement of materials from a lower movement of materials from a lower

concentration to a higher concentration, concentration to a higher concentration, requires energy, ATPrequires energy, ATP

Molecule tobe carried

Moleculebeing carried

Energy

Figure 7-19 Active Transport-going against concentration gradient. Natural is from high to low.

Other examples of

active transport

PhagocytosisPhagocytosis

Large particles taken into cellLarge particles taken into cell

Extension of cytoplasm engulfs large Extension of cytoplasm engulfs large particles outside cellparticles outside cell

Pocket folds into cell with contents and Pocket folds into cell with contents and breaks loose from cell membrane forming breaks loose from cell membrane forming vacuole inside cell (in cytoplasm).vacuole inside cell (in cytoplasm).

Unicellular OrganismsUnicellular Organisms

A single cell is the entire organismA single cell is the entire organism

Include prokaryotes and eukaryotesInclude prokaryotes and eukaryotes

Examples include: algae, yeasts, fungi, Examples include: algae, yeasts, fungi, bacteriabacteria

Multicellular OrganismsMulticellular Organisms

Cells are interdependent (like a team)Cells are interdependent (like a team)

Cell specializationCell specialization- separate roles for - separate roles for each type of cell (ex. Blood cell, nerve cell, each type of cell (ex. Blood cell, nerve cell, muscle cell)muscle cell)

Cells are specialized to perform particular Cells are specialized to perform particular functions within organism functions within organism

Levels of OrganizationLevels of Organization

Individual cellsIndividual cellstissuestissuesorgansorgansorgan systemsorgan systemsorganismorganism

Tissue- Tissue- group of similar cells that group of similar cells that perform particular functionperform particular functionOrgan- Organ- groups of tissues working groups of tissues working togethertogetherOrgan Systems- Organ Systems- group of organs group of organs working together to perform specific working together to perform specific function (11 major systems in human function (11 major systems in human body)body)

Muscle cell

Smooth muscle tissueStomach

Digestive system