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Introduction to CellsIntroduction to Cells
Ch. 7Ch. 7 Compound Light Compound Light MicroscopeMicroscope: allows : allows light to pass light to pass through a specimen through a specimen and magnifies the and magnifies the image with lensesimage with lenses
Electron microscopesElectron microscopes – use – use beams of electrons to beams of electrons to produce images.produce images.
Three-dimensional images!Three-dimensional images!
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The Discovery of the CellThe Discovery of the Cell
Robert Hooke – first to see and Robert Hooke – first to see and identify cork “cells.”identify cork “cells.”
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The Cell TheoryThe Cell Theory Cell Theory:Cell Theory:
1.1. All living things are All living things are composed of cellscomposed of cells
2.2. Cells are the basic living Cells are the basic living units of all organismsunits of all organisms
3.3. New cells are produced from New cells are produced from existing cellsexisting cells
-a cell divides to form two -a cell divides to form two identical cellsidentical cells
Virchow7-1
Other Inventors of Other Inventors of Cell TheoryCell Theory
Theodore Schwann - all animals Theodore Schwann - all animals are made up of cellsare made up of cells
Matthais SchleidenMatthais Schleiden - all plants are - all plants are made up of cellsmade up of cells
Schwann
Schleiden
Cells are the basic unit of lifeCells are the basic unit of life Unicellular Organisms: BacteriaUnicellular Organisms: Bacteria Multicellular Oganisms: Animal & Multicellular Oganisms: Animal &
Plant CellsPlant Cells
Pancreatic cell Blood cellMuscle cell
All Cells have 3 All Cells have 3 characteristics:characteristics:
1. surrounded by a barrier called a 1. surrounded by a barrier called a cell membranecell membrane
2. have biological information 2. have biological information ((DNADNA))
3. have cytoplasm3. have cytoplasm
Two Main Groups of CellsTwo Main Groups of Cells ProkaryotesProkaryotes
NO membrane bound NO membrane bound organellesorganelles
has circular DNA, no has circular DNA, no nucleusnucleus
cell functions carried out in cell functions carried out in cytoplasmcytoplasm
unicellularunicellular Example: BacteriaExample: Bacteria
Eukaryotes:Eukaryotes: membrane bound organellesmembrane bound organelles DNA is in the nucleusDNA is in the nucleus cell functions carried out by cell functions carried out by
organellesorganelles Most multicellularMost multicellular Example: Animal & Plant Example: Animal & Plant
CellsCells
Eukaryotic Cell StructureEukaryotic Cell Structure
NucleusNucleus – contains DNA that codes – contains DNA that codes for proteinsfor proteins
CytoplasmCytoplasm – the portion of the cell – the portion of the cell outside the nucleus; “jelly-like” fluidoutside the nucleus; “jelly-like” fluid
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Nuclear MembraneNuclear Membrane – surrounds the – surrounds the nucleus.nucleus.
ChromosomesChromosomes – folded and twisted – folded and twisted strands of DNA in the nucleus.strands of DNA in the nucleus.
NucleolusNucleolus – makes ribosomes. – makes ribosomes.
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Inside the NucleusInside the Nucleus
Inside the NucleusInside the Nucleus
Nuclear Envelope
Nucleolus
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RibosomesRibosomes – site where cell makes – site where cell makes enzymes and other enzymes and other Proteins!Proteins!
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Endoplasmic reticulum (ER)Endoplasmic reticulum (ER)– flattened, double-layered flattened, double-layered membranesmembranes site of chemical reactionssite of chemical reactions Rough ER – has ribosomesRough ER – has ribosomes Smooth ER – no ribosomesSmooth ER – no ribosomes
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Endoplasmic Reticulum Endoplasmic Reticulum (ER)(ER)
Rough ER
Smooth ER
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Golgi ApparatusGolgi Apparatus –sorts and packages –sorts and packages proteins.proteins.
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LysosomesLysosomes – contain digestive – contain digestive enzymes.enzymes. Digest food, old organelles, Digest food, old organelles,
viruses/bacteria.viruses/bacteria.
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VacuolesVacuoles – temporary storage – temporary storage
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MitochondriaMitochondria – – produces energy for produces energy for the cellthe cell ““Powerhouse of the Powerhouse of the
Cell!”Cell!”
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ChloroplastsChloroplasts – converts light energy – converts light energy of the sun into sugars of the sun into sugars (Photosynthesis)(Photosynthesis) Found only in plantsFound only in plants..
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CentriolesCentrioles – separates – separates chromatids (DNA) during cell chromatids (DNA) during cell division division Found only in animals.Found only in animals.
CytoskeletonCytoskeleton – provides – provides structure for the cellstructure for the cell
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Cell BoundariesCell Boundaries Plasma membranePlasma membrane – thin, flexible – thin, flexible
membrane that surrounds the cell.membrane that surrounds the cell.
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Cell BoundariesCell Boundaries
Cell wallsCell walls – – firmfirm wall around the cell wall around the cell membrane found membrane found only in bacteria and only in bacteria and plants.plants. Protects & gives shape to cellsProtects & gives shape to cells
A
D
G
C
B
FE
3
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6
8
7
Plasma Membrane Plasma Membrane
and Homeostasisand Homeostasis
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Homeostasis – Maintaining a BalanceHomeostasis – Maintaining a Balance
Plasma membrane - Plasma membrane - Semi-permeable, allows only certain materials to move in and out of the cell
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Cell Membrane Cell Membrane StructureStructure
Lipid Lipid BiBilayer – two sheets of lipids layer – two sheets of lipids (phospholipids)(phospholipids)
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Protein channels – help move material Protein channels – help move material across the cell membraneacross the cell membrane
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Cell Membrane Cell Membrane StructureStructure
Fluid Mosaic ModelFluid Mosaic Model
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Cellular TransportCellular Transport movement of material in and out of movement of material in and out of
cellscells
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Solution Solution ConcentrationConcentration::
# of molecules # of molecules per volume of per volume of containercontainer
* ** ** *
* * * * * * * * * ** * * * ** * * * *
High Conc.
Low Conc.
DiffusionDiffusion DiffusionDiffusion – – the movement of molecules the movement of molecules
from an area of from an area of HIGHHIGH concentration to an concentration to an area of area of LOWLOW concentration until concentration until EVENLY EVENLY SPREADSPREAD
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Diffusion of GasesDiffusion of Gases
OsmosisOsmosis Special type of Special type of diffusiondiffusion
The movement of The movement of WATER WATER from where it from where it is in is in high concentrationhigh concentration to where it is to where it is in in low concentrationlow concentration across a across a selectively permeable membraneselectively permeable membrane (cell membrane)(cell membrane)
Osmosis in cellsOsmosis in cells
1% salt solution + H20
10% salt 10% salt solution solution
-H20-H20
H20H20
Water flows from High to Low Concentration
Osmosis PracticeOsmosis Practice
Cell
90% H2O10% NaCl
90% H2O10% NaCl
Concentrations areequal, so no netmovement of water!
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Osmosis PracticeOsmosis Practice
Cell
90% H2O10% NaCl
80% H2O20% NaCl
Concentration ofwater is greater inthe cell than out, sowater will move out!
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Osmosis PracticeOsmosis Practice
Cell
80% H2O20% NaCl
90% H2O10% NaCl
Concentration ofwater is greateroutside the cell than in, so water will move out!
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PlasmolysisPlasmolysis Cell Cell
membranes membranes shrink or shrink or expandexpand
Dependent on Dependent on salt concen-salt concen-trationstrations
Facilitated DiffusionFacilitated Diffusion
Facilitated diffusion – when the Facilitated diffusion – when the plasma membrane “helps” particles plasma membrane “helps” particles pass through protein channels.pass through protein channels. No energy used.No energy used.
Active TransportActive Transport Active transport – when the plasma Active transport – when the plasma
membrane uses energy to move membrane uses energy to move particles against a concentration particles against a concentration gradient.gradient. Uses Transport ProteinsUses Transport Proteins
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EnEndocytosis – process by which docytosis – process by which a cell takes material into the a cell takes material into the cell by infolding of the cell cell by infolding of the cell membranemembrane phagocytosis & pinocytosisphagocytosis & pinocytosis
ExExocytosis – process by which a ocytosis – process by which a cell releases large amounts of cell releases large amounts of materialmaterial
BOTH REQUIRE ATP ENERGY!!!BOTH REQUIRE ATP ENERGY!!!
Moving large particlesMoving large particles
Active or Passive Active or Passive TransportTransport??
Which requires ATP energy?Which requires ATP energy?
Which goes with the Which goes with the concentration gradient?concentration gradient?
Which goes against the Which goes against the gradient?gradient?
Concentration Concentration GradientGradientHigh Concentration Low Concentration
* * * * * * ** * * * * * ** * * * * * *
* * * * * * * * *
* * * ** * * *
* * * *
Passive TransportPassive Transport Diffusion or Diffusion or
OsmosisOsmosis Going with Going with
the gradientthe gradient No ATP No ATP
energy energy requiredrequired * * * * * * * * * *
* * * * * * * * * *
High Conc. To Low Conc.
Active Active TransportTransport Against the Against the
gradientgradient Requires ATPRequires ATP Low to High Low to High
ConcentratioConcentrationsns
* * * * * * * * * * ** * * * * * * * * * ** * * * * * * * * * *
Facilitated Diffusion and Active Facilitated Diffusion and Active TransportTransport
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Organization in Multicellular Organization in Multicellular OrgansismsOrgansisms
Tissues
Organs
Organ System
Organism
Cells
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Plasmolysis in Elodea CellsPlasmolysis in Elodea Cells
Elodea in tap water
Elodea in 10% NaCl
