Cell Structure Revised by Bryant Wong. Cell Theory All organisms are composed of one or more cells Cells are the smallest living things Cells come.

Cell StructureCell Structure

Revised by Bryant WongRevised by Bryant Wong

Cell TheoryCell Theory

All organisms are composed of one or All organisms are composed of one or more cellsmore cells

Cells are the smallest living thingsCells are the smallest living things Cells come from other cellsCells come from other cells

Does Size Really MatterDoes Size Really Matter

YesYes Surface area to volume ratioSurface area to volume ratio

Surface Area to Volume Video

MicroscopesMicroscopes

Resolution: the minimum distance two Resolution: the minimum distance two points can be apart and still be points can be apart and still be distinguished as two separate itemsdistinguished as two separate items

Light Microscope< Compound Light Microscope< Compound Microscope< Electron Microscope< Microscope< Electron Microscope< Scanning Electron Microscope Scanning Electron Microscope <Transmission Electron Microscope<Transmission Electron Microscope

Descriptions of Microscopes

What do all cells have?What do all cells have?

Centrally located genetic materialCentrally located genetic material CytoplasmCytoplasm Plasma membranePlasma membrane Chromosomes (carry genes)Chromosomes (carry genes) Ribosomes (make proteins)Ribosomes (make proteins) CytosolCytosol

Eukaryotic cells have internal Eukaryotic cells have internal membranes that compartmentalize their membranes that compartmentalize their functionsfunctions

The basic structural and functional unit of The basic structural and functional unit of every organism is one of two types of every organism is one of two types of cells: prokaryotic or eukaryoticcells: prokaryotic or eukaryotic

Only organisms of the domains Bacteria Only organisms of the domains Bacteria and Archaea consist of prokaryotic cellsand Archaea consist of prokaryotic cells

Protists, fungi, animals, and plants all Protists, fungi, animals, and plants all consist of eukaryotic cellsconsist of eukaryotic cells

Prokaryotic CellsProkaryotic Cells

Plant CellPlant Cell

Animal CellAnimal CellLE 6-9a

Flagellum

Centrosome

CYTOSKELETON

Microfilaments

Intermediate filaments

Microtubules

Peroxisome

Microvilli

ENDOPLASMIC RETICULUM (ER

Rough ER Smooth ER

MitochondrionLysosome

Golgi apparatus

Ribosomes:

Plasma membrane

Nuclear envelope

NUCLEUS

In animal cells but not plant cells: LysosomesCentriolesFlagella (in some plant sperm)

Nucleolus

Chromatin

Peptido…who?Peptido…who?

Archeabacteria lack peptidoglycanArcheabacteria lack peptidoglycan Gram Positive Vs Gram NegativeGram Positive Vs Gram Negative

Comparing Prokaryotic Comparing Prokaryotic and Eukaryotic Cellsand Eukaryotic Cells

Prokaryotic cellsProkaryotic cells Have no nucleusHave no nucleus DNA is in an unbound region called the DNA is in an unbound region called the

nucleoidnucleoid Lack membrane-bound organellesLack membrane-bound organelles

Comparing Prokaryotic Comparing Prokaryotic and Eukaryotic Cellsand Eukaryotic Cells

Eukaryotic CellsEukaryotic Cells Have DNA in a nucleus that is bounded by a Have DNA in a nucleus that is bounded by a

membranous nuclear envelopemembranous nuclear envelope Have membrane-bound organellesHave membrane-bound organelles Generally much larger than prokaryotic cellsGenerally much larger than prokaryotic cells The logistics of carrying out cellular The logistics of carrying out cellular

metabolism sets limits on the size of cellsmetabolism sets limits on the size of cells

EukaryotesEukaryotes

Archeabacteria seem to be more related Archeabacteria seem to be more related to eukaryotes than prokaryotes….what to eukaryotes than prokaryotes….what might this imply?might this imply?

The eukaryotic cell’s genetic The eukaryotic cell’s genetic instructions are housed in the nucleus instructions are housed in the nucleus and carried out by the ribosomesand carried out by the ribosomes

The nucleus contains most of the DNA in The nucleus contains most of the DNA in a eukaryotic cella eukaryotic cell

Ribosomes use the information from the Ribosomes use the information from the DNA to make proteinsDNA to make proteins

OrganellesOrganelles

Nucleus Ribosomes Organelles of the endomembrane system

The Nucleus: Genetic The Nucleus: Genetic Library of the CellLibrary of the Cell

The nucleus contains The nucleus contains most of the cell’s most of the cell’s genes and is usually genes and is usually the most conspicuous the most conspicuous organelleorganelle

The nuclear envelope The nuclear envelope encloses the nucleus, encloses the nucleus, separating it from the separating it from the cytoplasmcytoplasm

LE 6-10

Close-up of nuclearenvelope

Nucleus

Nucleolus

Chromatin

Nuclear envelope:Inner membraneOuter membrane

Nuclear pore

Porecomplex

Ribosome

Pore complexes (TEM) Nuclear lamina (TEM)

1 µm

Rough ER

Nucleus1 µm

0.25 µm

Surface of nuclear envelope

Ribosomes: Protein Ribosomes: Protein Factories in the CellFactories in the Cell

Ribosomes are particles Ribosomes are particles made of ribosomal RNA made of ribosomal RNA and proteinand protein

Ribosomes carry out Ribosomes carry out protein synthesis in two protein synthesis in two locations:locations: In the cytosol (free In the cytosol (free

ribosomes)ribosomes) On the outside of the On the outside of the

endoplasmic reticulum (ER) endoplasmic reticulum (ER) or the nuclear envelope or the nuclear envelope (bound ribosomes)(bound ribosomes)

LE 6-11

Ribosomes

0.5 µm

ER Cytosol

Endoplasmicreticulum (ER)

Free ribosomes

Bound ribosomes

Largesubunit

Smallsubunit

Diagram ofa ribosome

TEM showing ERand ribosomes

The endomembrane system regulates The endomembrane system regulates protein traffic and performs metabolic protein traffic and performs metabolic functions in the cellfunctions in the cell

Components of the endomembrane Components of the endomembrane system:system: Nuclear envelopeNuclear envelope Endoplasmic reticulumEndoplasmic reticulum Golgi apparatusGolgi apparatus LysosomesLysosomes VacuolesVacuoles MicrobodiesMicrobodies Plasma membranePlasma membrane

These components are either These components are either continuous or connected via transfer continuous or connected via transfer by vesiclesby vesicles

The endomembrane system is a The endomembrane system is a complex and dynamic player in the complex and dynamic player in the cell’s compartmental organizationcell’s compartmental organization

LE 6-16-3

Nuclear envelope

Nucleus

Rough ER

Smooth ER

Transport vesicle

cis Golgi

trans Golgi

Plasma membrane

The Endoplasmic Reticulum: The Endoplasmic Reticulum: Biosynthetic FactoryBiosynthetic Factory

The endoplasmic reticulum The endoplasmic reticulum (ER) accounts for more (ER) accounts for more than half of the total than half of the total membrane in many membrane in many eukaryotic cellseukaryotic cells

The ER membrane is The ER membrane is continuous with the nuclear continuous with the nuclear envelopeenvelope

The are two distinct regions The are two distinct regions of ER:of ER: Smooth ER, which lacks Smooth ER, which lacks

ribosomesribosomes Rough ER, with ribosomes Rough ER, with ribosomes

studding its surfacestudding its surface

LE 6-12

Ribosomes

Smooth ER

Rough ER

ER lumen

Cisternae

Transport vesicle

Smooth ER Rough ER

Transitional ER

200 nm

Nuclearenvelope

Smooth ERSmooth ER

FunctionsFunctions Synthesizes lipidsSynthesizes lipids Metabolizes carbohydratesMetabolizes carbohydrates Stores calciumStores calcium Detoxifies poisonDetoxifies poison

Rough ERRough ER

FunctionsFunctions Has bound ribosomesHas bound ribosomes Produces proteins and membranes, which Produces proteins and membranes, which

are distributed by transport vesiclesare distributed by transport vesicles Membrane factory for the cellMembrane factory for the cell

The Golgi Apparatus: The Golgi Apparatus: Shipping and Receiving Shipping and Receiving CenterCenter

The Golgi apparatus consists of The Golgi apparatus consists of flattened membranous sacs called flattened membranous sacs called cisternaecisternae

FunctionsFunctions Modifies products of the ERModifies products of the ER Manufactures certain macromoleculesManufactures certain macromolecules Sorts and packages materials into Sorts and packages materials into

transport vesiclestransport vesicles

LE 6-13

trans face(“shipping” side ofGolgi apparatus) TEM of Golgi apparatus

0.1 µm

Golgiapparatus

cis face(“receiving” side ofGolgi apparatus)

Vesicles coalesce toform new cis Golgi cisternaeVesicles also

transport certainproteins back to ER

Vesicles movefrom ER to Golgi

Vesicles transport specificproteins backward to newerGolgi cisternae

Cisternalmaturation:Golgi cisternaemove in a cis-to-transdirection

Vesicles form andleave Golgi, carryingspecific proteins toother locations or tothe plasma mem-brane for secretion

Cisternae

Lysosomes: Digestive Lysosomes: Digestive CompartmentsCompartments

A lysosome is a membranous sac of A lysosome is a membranous sac of hydrolytic enzymeshydrolytic enzymes

Lysosomal enzymes can hydrolyze Lysosomal enzymes can hydrolyze proteins, fats, polysaccharides, and proteins, fats, polysaccharides, and nucleic acidsnucleic acids

Lysosomes also use enzymes to recycle Lysosomes also use enzymes to recycle organelles and macromolecules, a organelles and macromolecules, a process called autophagyprocess called autophagy

LE 6-14a

Phagocytosis: lysosome digesting food

1 µm

Plasmamembrane

Food vacuole

Lysosome

Nucleus

Digestiveenzymes

Digestion

Lysosome

Lysosome containsactive hydrolyticenzymes

Food vacuolefuses withlysosome

Hydrolyticenzymes digestfood particles

LE 6-14b

Autophagy: lysosome breaking down damaged organelle

1 µm

Vesicle containingdamaged mitochondrion

Mitochondrionfragment

Lysosome containingtwo damaged organelles

Digestion

Lysosome

Lysosome fuses withvesicle containingdamaged organelle

Peroxisomefragment

Hydrolytic enzymesdigest organellecomponents

Vacuoles: Diverse Vacuoles: Diverse Maintenance CompartmentsMaintenance Compartments

Vesicles and Vesicles and vacuoles (larger vacuoles (larger versions of vacuoles) versions of vacuoles) are membrane-are membrane-bound sacs with bound sacs with varied functionsvaried functions

A plant cell or fungal A plant cell or fungal cell may have one or cell may have one or several vacuolesseveral vacuoles

LE 6-15

5 µm

Central vacuole

Cytosol

Tonoplast

Central vacuole

Nucleus

Cell wall

Chloroplast

VacuolesVacuoles

Food vacuoles are formed by Food vacuoles are formed by phagocytosisphagocytosis

Contractile vacuoles, found in many Contractile vacuoles, found in many freshwater protists, pump excess water freshwater protists, pump excess water out of cellsout of cells

Central vacuoles, found in many mature Central vacuoles, found in many mature plant cells, hold organic compounds and plant cells, hold organic compounds and waterwater

MicrobodiesMicrobodies

Enzyme bearing membrane enclosed Enzyme bearing membrane enclosed vesiclesvesicles Peroxisomes- catalyze the removal of Peroxisomes- catalyze the removal of

electrons associated with hydrogen atomselectrons associated with hydrogen atoms Glyoxysomes- in plants convert fats into Glyoxysomes- in plants convert fats into

carbohydratescarbohydrates

Mitochondria and Mitochondria and ChloroplastsChloroplasts Involved in energy Involved in energy

metabolismmetabolism Both contain their Both contain their

own DNA and own DNA and protein synthesis protein synthesis machinery…what machinery…what does this say?does this say?

Both surrounded by Both surrounded by a double a double membranemembrane

Arrived in the cells Arrived in the cells by endosymbiosisby endosymbiosis

MitochondriaMitochondria

Metabolize sugar to generate ATPMetabolize sugar to generate ATP

Crista

ChloroplastsChloroplasts

Use light to generate ATPUse light to generate ATP

Fibers of The Fibers of The CytoskeletonCytoskeleton

Microfilaments- 2 protein chains loosely Microfilaments- 2 protein chains loosely twinedtwined

Microtubules- largest- hollow tubesMicrotubules- largest- hollow tubes Intermediate filamentsIntermediate filaments

What is the function of What is the function of the cytoskeleton fibers?the cytoskeleton fibers? Modulate cell shapeModulate cell shape Permit cell movementPermit cell movement Move materials within the cytoplasmMove materials within the cytoplasm

Kineson moves towards the outside of the cellKineson moves towards the outside of the cell Dynein moves towards the inside of the cellDynein moves towards the inside of the cell

Extracellular Structures Extracellular Structures and Cell Movementand Cell Movement

Actin fillaments allow some cells to crawl, Actin fillaments allow some cells to crawl, forward movement achieved by myosinforward movement achieved by myosin

Cilia and Flagella- 9+2 structure (fundamental Cilia and Flagella- 9+2 structure (fundamental component of eukaryotic cells)component of eukaryotic cells)

Cell WallCell Wall Provide Protection Provide Protection

and Supportand Support Found in plants, Found in plants,

fungi and protistsfungi and protists Plants and protists Plants and protists

made of cellulosemade of cellulose Fungi made of Fungi made of

chitinchitin Primary walls, Primary walls,

middle lamella, middle lamella, some have some have secondary wallssecondary walls

Extracellular Matrix Extracellular Matrix (ECM)(ECM)

Animals lack cell walls Animals lack cell walls so they have ECM to so they have ECM to protect themprotect them GlycoproteinsGlycoproteins CollagenCollagen Elastin Elastin Fibronectin Fibronectin

IntegrinsIntegrins

Real Life ApplicationReal Life Application

Organelles keep the cell alive and the cells Organelles keep the cell alive and the cells keep organisms alive.keep organisms alive.

We inherit mitochondria from our mother.We inherit mitochondria from our mother. Organelle discoveries suggest that all cells had Organelle discoveries suggest that all cells had

a common ancestor. We all evolved from the a common ancestor. We all evolved from the same thing. Bacteria, eukaryotes, and archaea same thing. Bacteria, eukaryotes, and archaea all had a primitive organelle consisting of little all had a primitive organelle consisting of little polyphosphate. Researchers can track polyphosphate. Researchers can track evolutionary history.evolutionary history.

Relate surface area and volume with cell Relate surface area and volume with cell size and how it effects the cell.size and how it effects the cell.