CellsCells

Chapter 7Chapter 7

How many cells do humans have?How many cells do humans have?

About 10 TRILLION cells!About 10 TRILLION cells!

If you tried counting them at a rate of If you tried counting them at a rate of 1cell/sec, it would take over 2000 years to 1cell/sec, it would take over 2000 years to do it.do it.

Discovery of CellsDiscovery of Cells

Robert Hooke (1665)Robert Hooke (1665)

Used microscope to look at thin slice of cork Used microscope to look at thin slice of cork treetree

Named structures “cells” like the small Named structures “cells” like the small rooms monks lived in.rooms monks lived in.

Anton van LeeuwenhoekAnton van Leeuwenhoek

1673- Used a simple microscope to 1673- Used a simple microscope to observe pond scum & discovered observe pond scum & discovered livingliving single-celled organismssingle-celled organisms

He called them “animalcules”He called them “animalcules”

1838- Matthias Schleiden- all plant parts are made 1838- Matthias Schleiden- all plant parts are made of cellsof cells

1839- Theodor Schwann- all animal tissues are 1839- Theodor Schwann- all animal tissues are composed of cells.composed of cells.

Development of Cell TheoryDevelopment of Cell Theory

1858- Rudolf Virchow, concluded that cells must 1858- Rudolf Virchow, concluded that cells must arise from preexisting cells.arise from preexisting cells.

The Cell Theory The Cell Theory

1. All living things are composed of one or more 1. All living things are composed of one or more cells. cells.

2. The cell is the basic unit of structure and function 2. The cell is the basic unit of structure and function in all living things. in all living things.

3. All cells are produced from pre-existing cells. 3. All cells are produced from pre-existing cells.

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Sizes of Living ThingsSizes of Living Things

10 m1 m0.1 m1 cm1 mm100 nm10 nm1 nm0.1 nm

mousefrog egg

human eggmost bacteria

virus

protein

atomant

electron microscope

light microscope

human eye

humanblue whale

chloroplastrose

1 km100 m100 m10 m1 m

plant and animal

cellsaminoacid

ostrichegg

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Types of MicroscopesTypes of Microscopes

1. Compound light 1. Compound light microscopemicroscope

Light passes Light passes through lenses to through lenses to magnify image up magnify image up to 1000Xto 1000X

Can observe Can observe living cells living cells

Types of MicroscopesTypes of Microscopes

2. 2. Electron Electron microscopemicroscope

Uses a beam of Uses a beam of electrons to electrons to magnify image magnify image

> 1000X> 1000X Kills cells being Kills cells being

observed observed

Scanning Electron MicroscopeScanning Electron Microscope

Produces 3-dimensional images of cell Produces 3-dimensional images of cell surfacesurface

Transmission Electron MicroscopeTransmission Electron Microscope

Electrons pass through only thin samples Electrons pass through only thin samples

Explores cell internal structures and large Explores cell internal structures and large proteinsproteins

Prokaryotes and EukaryotesProkaryotes and Eukaryotes

ProkaryotesProkaryotes

Prokaryotes: Prokaryotes: ((pro-pro- means means beforebefore, and , and

karyotekaryote means means nucleusnucleus));first type of cells to ;first type of cells to evolve evolve Very small, the size of mitochondriaVery small, the size of mitochondria UnicellularUnicellular Kingdoms: Archaea and BacteriaKingdoms: Archaea and Bacteria Reproduce asexually via Binary FissionReproduce asexually via Binary Fission

ProkaryotesProkaryotes

Structures:cell membranecell wallribosomesflagella or cilianucleoidcytoplasmcapsuleNo membrane bound organelles - only eukaryotes have

A day in the life of BacteriaA day in the life of Bacteria

Can only move in two directions forward Can only move in two directions forward (swimming) and tumbling, and at one speed.(swimming) and tumbling, and at one speed.

Divide every 20 minutesDivide every 20 minutes

Long family history….. 3.5 billion years ago to be Long family history….. 3.5 billion years ago to be exact (The earth formed 4.6 billion years ago)exact (The earth formed 4.6 billion years ago)

From Prokaryotes to From Prokaryotes to EukaryotesEukaryotes

EUKARYOTESEUKARYOTES

Emerged 1.6-2.1 Billion years agoEmerged 1.6-2.1 Billion years ago

Kingdoms: Animals, Plants, Fungi, and Kingdoms: Animals, Plants, Fungi, and ProtistsProtists

Characteristics: Characteristics: Complex structure with Nucleus and Membrane-Complex structure with Nucleus and Membrane-

Bound OrganellesBound Organelles

Unicellular and MulticellularUnicellular and Multicellular

If all cells originate from other If all cells originate from other cells, how do you think cells, how do you think

eukaryotes came about?eukaryotes came about?

EndosymbiosisEndosymbiosis Endosymbiotic theoryEndosymbiotic theory - -

states that some states that some eukaryotic organelles eukaryotic organelles evolved from evolved from prokaryotes.prokaryotes.

The host and prokaryotic The host and prokaryotic cells benefited from cells benefited from each other and each other and eventually resulted in eventually resulted in this evolutionary change this evolutionary change of eukaryote cells.of eukaryote cells.

Plant and Animal CellsPlant and Animal Cells• Plant CellPlant Cell

Cell WallCell Wall ChloroplastsChloroplasts Rigid Shape (Cell Wall)Rigid Shape (Cell Wall) Large Central VacuoleLarge Central Vacuole

•Animal Cell•No Cell Wall•Irregular/ round shape

Plant and Animal Cell Structures: Plant and Animal Cell Structures: Nucleus, Nucleolus, Nuclear EnvelopeNucleus, Nucleolus, Nuclear Envelope

NucleusNucleus - stores - stores genetic informationgenetic information

NucleolusNucleolus - - ribosome productionribosome production

Nuclear envelopeNuclear envelope - - protective layer protective layer controlling what controlling what enters and leavesenters and leaves

Plant and Animal Cell Structures: Plant and Animal Cell Structures: Cytoplasm and CytosolCytoplasm and Cytosol

CytoplasmCytoplasm – everything – everything inside cell membraneinside cell membraneCytosolCytosol - gel like material - gel like material within the cell, includes within the cell, includes proteins, dissolved proteins, dissolved molecules, water, etc.molecules, water, etc.

Cell MembraneCell MembranePhosphoPhospholipidlipid bibilayerlayer

FlexibileFlexibile

Regulates what goesRegulates what goes

in and out of cellin and out of cell

Cell WallCell WallLocated outside Located outside membrane in membrane in plantplant and and prokaryoticprokaryotic cells, cells, NOT in animal cells.NOT in animal cells.

Rigid, porousRigid, porous

Plant and Animal Cell Structures: Plant and Animal Cell Structures: RibosomesRibosomes

Also found in ProkaryotesAlso found in Prokaryotes

Protein synthesisProtein synthesis (makes proteins) (makes proteins)

Plant and Animal Cell Structures: Plant and Animal Cell Structures: CytoskeletonCytoskeleton

MicrofilamentsMicrofilaments: : carry out cellular movements carry out cellular movements including including gliding, contraction, and cytokinesis.gliding, contraction, and cytokinesis.

MicrotubulesMicrotubules: : Cell shapeCell shape

• Helps move things within the cell (tracks)Helps move things within the cell (tracks)• Form the spindle fibers for separating Form the spindle fibers for separating

chromosomes during mitosischromosomes during mitosis

Plant and Animal Cell Plant and Animal Cell Structures: Flagella and CiliaStructures: Flagella and Cilia

Hairlike structures that aid Hairlike structures that aid in movement (motility) of in movement (motility) of the cellthe cell

ORGANELLESORGANELLES

Endoplasmic ReticulumEndoplasmic ReticulumStructure: network of interconnected Structure: network of interconnected

membranes forming channels within cellmembranes forming channels within cellRough Endoplasmic Rough Endoplasmic Reticulum (RER)Reticulum (RER)

Covered with ribosomes which Covered with ribosomes which synthesize proteinsynthesize protein

Smooth Endoplasmic Smooth Endoplasmic Reticulum (SER)Reticulum (SER)

A site for synthesis and A site for synthesis and metabolism of lipids (fats).metabolism of lipids (fats).

roughendoplasmic

reticulum

smoothendoplasmic

reticulum

ribosomes

Golgi ApparatusGolgi ApparatusPurpose: Process, Package, SecretePurpose: Process, Package, Secrete

StructureStructure a series of stacked membranesa series of stacked membranes

FunctionFunction Modifies and packages Modifies and packages

macromolecules for transport macromolecules for transport elsewhere in the cell in vesicleselsewhere in the cell in vesicles

transportvesicle

Nucleus

Golgi apparatus

transportvesicle

ER

MitochondriaMitochondriaPurpose: Energy ProductionPurpose: Energy Production

StructureStructure::• Double membrane with a series of Double membrane with a series of

folds called cristae.folds called cristae.

FunctionFunction: : • Cellular respirationCellular respiration- chemical energy - chemical energy

from food converted into usable energy from food converted into usable energy for cellfor cell

• Contains its own DNA Contains its own DNA ““Powerhouse of the cell”Powerhouse of the cell”

Lysosomes (Animals Mostly)Lysosomes (Animals Mostly)

Garbage disposal of Garbage disposal of the cellthe cell

Contain digestive Contain digestive enzymes that break enzymes that break down lipids, down lipids, carbohydrates, carbohydrates, proteins, invaders and proteins, invaders and wasteswastes

Animal Cells Only: Animal Cells Only: CentriolesCentrioles

Organelles used in cell Organelles used in cell reproductionreproduction

Produce microtubulesProduce microtubules

Plants Mostly: VacuolePlants Mostly: Vacuole

Membrane surrounded Membrane surrounded "bags" that contain "bags" that contain water, enzymes and water, enzymes and storage materials in storage materials in plants. plants.

smaller vacuoles in animal cells

Plants Only: ChloroplastsPlants Only: ChloroplastsPhotosynthesis: capture Photosynthesis: capture light energy to produce light energy to produce sugarssugarsDouble outer membraneDouble outer membrane

Human Cell TypesHuman Cell Types

4040

Endomembrane System: A Visual SummaryEndomembrane System: A Visual Summary

lipid

secretion

ribosome

lysosomecontains digestive enzymesthat break down worn-outcell parts or substancesentering the cell at theplasma membrane

transport vesicleshuttles lipids to variouslocations such as theGolgi apparatus

smooth endoplasmicreticulumsynthesizes lipids andalso performs variousother functions

incoming vesiclebrings substances into thecell that are digested whenthe vesicle fuses with alysosome

transport vesicleshuttles proteins tovarious locations such asthe Golgi apparatus

Golgi apparatusmodifies lipids and proteinsfrom the ER; sorts themand packages them invesicles

secretory vesiclefuses with the plasmamembrane as secretionoccurs

RER synthesizes proteins andpackages them in vesicles;vesicles commonly go tothe Golgi apparatus

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Fluid Mosaic ModelFluid Mosaic ModelProteins, carbohydrates are floating among Proteins, carbohydrates are floating among the lipid bilayerthe lipid bilayer

Allows SOME things to enter/exit cell Allows SOME things to enter/exit cell (selectively permeable)(selectively permeable)

Quick ReviewQuick ReviewWhich organelle is the control center of the cell? Which organelle is the control center of the cell? NucleusNucleus

Which organelle holds the cell together?Which organelle holds the cell together?Cell membraneCell membrane

Which organelles are not found in animal cells?Which organelles are not found in animal cells?Cell wall, central vacuole, chloroplastsCell wall, central vacuole, chloroplasts

Which organelle helps plant cells make food?Which organelle helps plant cells make food?ChloroplastsChloroplasts

What does E.R. stand for?What does E.R. stand for?Endoplasmic reticulumEndoplasmic reticulum