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Transcript of Chapter 4 Cells: The Basic Units of Life. Chapter 4: Cells Are All Cells Alike? All living things...
Chapter 4Chapter 4Cells: The Basic Units of LifeCells: The Basic Units of Life
Chapter 4: CellsChapter 4: CellsAre All Cells Alike?Are All Cells Alike?
All living things are made up of cells. Some All living things are made up of cells. Some organisms are composed of only one cell. organisms are composed of only one cell. Other organisms are made up of many Other organisms are made up of many cells.cells.
Amoeba Axolliti
Chapter 4: CellsChapter 4: CellsAre All Cells Alike?Are All Cells Alike?
1.1.What are the advantages of a one-celled What are the advantages of a one-celled organism? Disadvantages?organism? Disadvantages?
Advantage : Very small and high Advantage : Very small and high SA:V ratio, nutrients enter easily and SA:V ratio, nutrients enter easily and reproduce very quicklyreproduce very quickly
Disadvantage: If cell is injured, death Disadvantage: If cell is injured, death of organism may result.of organism may result.
Chapter 4: CellsChapter 4: CellsAre All Cells Alike?Are All Cells Alike?
1.What are the advantages of an organism 1.What are the advantages of an organism that is made up of many cells?that is made up of many cells?
Advantages: specialized cells Advantages: specialized cells increase capability of organism, more increase capability of organism, more complex. complex.
Disadvantages: require more energyDisadvantages: require more energy
A. The Discovery of the CellA. The Discovery of the Cell
Cells Cells are the basic unit of structure and function and in living things.are the basic unit of structure and function and in living things.
Cell TheoryCell Theory states that: states that:
– All living things are composed of cells.All living things are composed of cells.
– Cells are the basic units of structure and function in living things.Cells are the basic units of structure and function in living things.
– All cells come from preexisting cells. All cells come from preexisting cells.
A. Discovery of the CellA. Discovery of the CellHow did early scientists come to these How did early scientists come to these conclusions?conclusions?
1665 Hooke – observed 1665 Hooke – observed cork “cells” using an cork “cells” using an early microscopeearly microscope
A. Discovery of the CellA. Discovery of the CellHow did early scientists come to these How did early scientists come to these conclusions?conclusions?
1674 Van Leeuwenhoek 1674 Van Leeuwenhoek Observed first living cellsObserved first living cells
A. Discovery of the CellA. Discovery of the CellHow did early scientists come to these How did early scientists come to these conclusions?conclusions?
1838 Schleiden – All plants have cells.1838 Schleiden – All plants have cells.
1839 Schwann – All animals have cells.1839 Schwann – All animals have cells.
A. Discovery of the CellA. Discovery of the CellHow did early scientists come to these How did early scientists come to these conclusions?conclusions?
1855 Virchow – All cells come from existing 1855 Virchow – All cells come from existing cells.cells.
B. Exploring the CellB. Exploring the Cell
Light microscopeLight microscope
Electron microscopesElectron microscopes
B. Exploring the CellB. Exploring the Cell
1.1. What are the advantages of using a light What are the advantages of using a light microscope? Disadvantages?microscope? Disadvantages?
Advantage: Ability to observe living organismsAdvantage: Ability to observe living organisms
Disadvantage: lower resolution of detailsDisadvantage: lower resolution of details
B. Exploring the CellB. Exploring the Cell
2.2. What are the advantages of using an electron What are the advantages of using an electron microscope?microscope? Advantage: higher resolutionAdvantage: higher resolution Disadvantage: non-living organismDisadvantage: non-living organism
C. Cell Structure and FunctionC. Cell Structure and Function
All Cells Share Certain Common Features:All Cells Share Certain Common Features:• Cell membraneCell membrane• DNADNA• Cytoplasm - portion of the cell outside the Cytoplasm - portion of the cell outside the
nucleusnucleus• RibosomesRibosomes
C. Cell Structure and FunctionC. Cell Structure and Function
All Cells Share Certain Common Features:All Cells Share Certain Common Features:
MUST obtain energy and nutrientsMUST obtain energy and nutrients
MUST convert DNA into proteinsMUST convert DNA into proteins
MUST keep certain biochemical reactions MUST keep certain biochemical reactions separateseparate
C. Cell Structure and FunctionC. Cell Structure and Function
ALL cells are classified as either:ALL cells are classified as either:• Prokaryotic CellsProkaryotic Cells• Eukaryotic CellsEukaryotic Cells
Prokaryotic and Eukaryotic Cells
Prokaryotes Eukaryotes
•NO nucleus•NO membrane-enclosedorganelles•Small (MOST 1-10 μm)•Unicellular•Bacteria
Cell membraneContain DNARibosomesCytoplasm
Prokaryotes Eukaryotes
•NO nucleus•NO membrane-enclosedorganelles•Small (MOST 1-10 μm)•Unicellular•Bacteria
Cell membraneContain DNARibosomesCytoplasm
•Nucleus•Membrane-enclosedorganelles•Larger than prokaryotes(MOST 5-50 μm)•Some unicellular•Multicellular•Protists, Fungi, Animals, and Plants•Cytoskeleton
Prokaryotes Eukaryotes
•NO nucleus•NO membrane-enclosedorganelles•Small (MOST 1-10 μm)•Unicellular•Bacteria
Animal Cell
Centrioles
Nucleolus
Nucleus
Nuclearenvelope
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Golgi apparatus
Mitochondrion
CellMembrane
Ribosome(free)
Ribosome(attached)
Figure 7-5 Animal Cell
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 Cell
NucleusNucleusStructureStructure– Surrounded by a Surrounded by a nuclear envelopenuclear envelope composed of two composed of two
membranes with thousands of membranes with thousands of nuclear poresnuclear pores
FunctionFunction– Contains cell’s DNA and with it the Contains cell’s DNA and with it the ccoded instructions oded instructions
for making proteins and other important moleculesfor making proteins and other important molecules– Nuclear pores Nuclear pores allow material to move in and out of allow material to move in and out of
the nucleusthe nucleus
BOTH plant and animals cellsBOTH plant and animals cells
NucleolusNucleolus
StructureStructure– Small, dense region inside the nucleusSmall, dense region inside the nucleus
FunctionFunction– Assembly of ribosomesAssembly of ribosomes
BOTH plant and animal cellsBOTH plant and animal cells
nuclearenvelope
nuclearpores
nucleolus
chromatin
nucleus
nuclearpores
Chromatin and Chromosomes Chromatin and Chromosomes
RibosomesRibosomes
StructureStructure– Small particles of RNA and proteinSmall particles of RNA and protein– Found in cytoplasm or attached to Rough ERFound in cytoplasm or attached to Rough ER
FunctionFunction– Assembly of proteinsAssembly of proteins
BOTH plant and animal cellsBOTH plant and animal cells
0.05 micrometers
mRNA
ribosomes
Rough Endoplasmic ReticulumRough Endoplasmic Reticulum
StructureStructure– Internal membrane system that is continuous Internal membrane system that is continuous
with the nuclear envelope with the nuclear envelope with with attached attached ribosomes ribosomes appears “rough” appears “rough”
FunctionFunction– Site where lipid components of cell membrane Site where lipid components of cell membrane
are assembled, along with proteins and other are assembled, along with proteins and other materials that are exported from the cellmaterials that are exported from the cell
BOTH plant and animal cellsBOTH plant and animal cells
Smooth Endoplasmic ReticulumSmooth Endoplasmic Reticulum
StructureStructure– Internal membrane system Internal membrane system – NO ribosomes on its surface NO ribosomes on its surface appears appears
“smooth”“smooth”
FunctionFunction– Contains enzymes that synthesize membrane Contains enzymes that synthesize membrane
lipids and detoxify drugslipids and detoxify drugs
BOTH plant and animal cellsBOTH plant and animal cells
Endoplasmic ReticulumEndoplasmic Reticulum
Golgi ApparatusGolgi Apparatus
StructureStructure– Stack of closely apposed membranesStack of closely apposed membranes
FunctionFunction– Modifies, sorts, and packages proteins and Modifies, sorts, and packages proteins and
other materials from the ER for storage in the other materials from the ER for storage in the cell or secretion outside the cellcell or secretion outside the cell
BOTH plant and animal cellsBOTH plant and animal cells
Golgi ApparatusGolgi Apparatus
The Endomembrane SystemThe Endomembrane System
Protein Modification
LysosomesLysosomes
StructureStructure– Small organelles filled with digestive enzymesSmall organelles filled with digestive enzymes
FunctionFunction– Digestion, or breakdown, of lipids, Digestion, or breakdown, of lipids,
carbohydrates, and proteins into small carbohydrates, and proteins into small molecules that can be used by the rest of the molecules that can be used by the rest of the cellcell
– Breaking down organelles that have outlived Breaking down organelles that have outlived their usefulnesstheir usefulness
BOTH plant and animal cellsBOTH plant and animal cells
LysosomesLysosomes
Food vacuole
Lysosome
VacuolesVacuoles
StructureStructure– Saclike structuresSaclike structures
FunctionFunction– Store materials such as water, salts, proteins, Store materials such as water, salts, proteins,
and carbohydratesand carbohydrates
BOTH plant and animal cellsBOTH plant and animal cells
contractilevacuole
centralreservoir
pore
collectingducts
Paramecium – Contractile Paramecium – Contractile VacuoleVacuole
Contractile Vacuole
cytoplasm centralvacuole
cell wall plasma membrane
MitochondriaMitochondria
StructureStructure– Enclosed by 2 membranes – outer and a highly Enclosed by 2 membranes – outer and a highly
folded inner membranefolded inner membrane– Contain DNAContain DNA
FunctionFunction– Convert the chemical energy stored in food Convert the chemical energy stored in food
(glucose) into compounds that are more (glucose) into compounds that are more convenient for cell use (ATP) convenient for cell use (ATP) Cellular Cellular RespirationRespiration
BOTH plant and animal cellsBOTH plant and animal cells
outermembrane
innermembrane
intermembranecompartment
matrix
cristae
0.2 micrometer
ChloroplastChloroplast
StructureStructure– Surrounded by 2 membranes – outer and inner Surrounded by 2 membranes – outer and inner
membranemembrane– Inside - large stacks of thylakoid membranes that Inside - large stacks of thylakoid membranes that
contain chlorophyllcontain chlorophyll– Contain DNAContain DNA
FunctionFunction– Capture the energy from sunlight and convert it into Capture the energy from sunlight and convert it into
chemical energy (glucose) chemical energy (glucose) Photosynthesis Photosynthesis
ONLY found in plant cells ONLY found in plant cells
outer membrane
inner membrane
stroma
thylakoid
channelinterconnecting
thylakoids
granum(stack of thylakoids)
1 micrometer
Organelle DNAOrganelle DNA
Why do mitochondria and chloroplasts Why do mitochondria and chloroplasts contain DNA but other organelles do contain DNA but other organelles do NOT?NOT?
Lynn Margulis - Professor in the Lynn Margulis - Professor in the Department of Geosciences Department of Geosciences
University of MassachusettsUniversity of Massachusetts
CytoskeletonCytoskeleton
StructureStructure– Network of protein filamentsNetwork of protein filaments
Microfilaments – threadlike structures made of actinMicrofilaments – threadlike structures made of actin
Microtubules – hollow structures made of tubulinMicrotubules – hollow structures made of tubulin
FunctionFunction– Helps supports the cellHelps supports the cell– Helps the cell to maintain its shapeHelps the cell to maintain its shape– Involved in movementInvolved in movement
BOTH plant and animal cellsBOTH plant and animal cells
Cell membrane
Endoplasmicreticulum
Microtubule
Microfilament
Ribosomes Mitochondrion
microtubules (red)
nucleus
microfilaments (blue)
CentriolesCentrioles
StructureStructure– Composed of tubulinComposed of tubulin– Found in a pair located near the nucleusFound in a pair located near the nucleus
FunctionFunction– Help to organize cell divisionHelp to organize cell division
ONLY found in animal cellsONLY found in animal cells
CentriolesCentrioles
Cell MembraneCell Membrane
StructureStructure– Thin, flexible barrier that surrounds the cellThin, flexible barrier that surrounds the cell– Double-layered sheet composed of a lipid Double-layered sheet composed of a lipid
bilayer, proteins, and carbohydrates – fluid bilayer, proteins, and carbohydrates – fluid “mosaic” model“mosaic” model
FunctionFunction– Regulates what enters and leaves the cellRegulates what enters and leaves the cell– Provides protection and supportProvides protection and support
BOTH plant and animal cellsBOTH plant and animal cells
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel Lipid bilayer
Carbohydratechains
Cell Membrane
Cell WallCell WallStructureStructure– Strong supporting layer that lies outside the cell Strong supporting layer that lies outside the cell
membranemembrane– PorousPorous– Made from fibers of carbohydrate (mostly cellulose) and Made from fibers of carbohydrate (mostly cellulose) and
proteinprotein
FunctionFunction– Provides support and protection for the cellProvides support and protection for the cell
ONLY found in plant cellsONLY found in plant cells
Eukaryotic Cells – Typical Plant CellEukaryotic Cells – Typical Plant Cell
ClosingClosing
Construct a Venn diagram comparing and Construct a Venn diagram comparing and contrasting the structures found in a contrasting the structures found in a typical plant cell and a typical animal cell.typical plant cell and a typical animal cell.
Animal Cells Plant Cells
EUKARYOTIC CELLSAnimal Cells Plant Cells
Cell membraneRibosomes
NucleusEndoplasmic reticulum
Golgi apparatusLysosomesVacuoles
MitochondriaCytoskeleton
Cell WallChloroplasts
Centrioles
In or Out?In or Out?
How is a window screen similar to a cell membrane? How is a window screen similar to a cell membrane? Read on to find out.Read on to find out.
1. What are some things that can pass through a 1. What are some things that can pass through a window screen?window screen?
2. What are some things that cannot pass through a 2. What are some things that cannot pass through a window screen? Why is it important to keep these window screen? Why is it important to keep these things from moving through the screen?things from moving through the screen?
3. The cell is surrounded by a cell membrane, which 3. The cell is surrounded by a cell membrane, which regulates what enters and leaves the cell. Why is it regulates what enters and leaves the cell. Why is it important to regulate what moves into and out of a important to regulate what moves into and out of a cell?cell?
Section 7–3Section 7–3Cell BoundariesCell Boundaries
A.A.Cell MembraneCell Membrane
B.B.Cell WallsCell Walls
C.C. Diffusion Through Cell BoundariesDiffusion Through Cell Boundaries
1.1. Measuring ConcentrationMeasuring Concentration
2.2. DiffusionDiffusion
D.D. OsmosisOsmosis
1.1.How Osmosis WorksHow Osmosis Works
2.2.Osmotic PressureOsmotic Pressure
E.E.Facilitated DiffusionFacilitated Diffusion
F.F.Active TransportActive Transport
1.1. Molecular TransportMolecular Transport
2.2. Endocytosis and ExocytosisEndocytosis and Exocytosis
A. Cell Membrane
StructureStructure– Thin, flexible barrier that surrounds the cellThin, flexible barrier that surrounds the cell– Double-layered sheet composed of a lipid Double-layered sheet composed of a lipid
bilayer, proteins, and carbohydrates – fluid bilayer, proteins, and carbohydrates – fluid “mosaic” model“mosaic” model
FunctionFunction– Regulates what enters and leaves the cellRegulates what enters and leaves the cell– Provides protection and supportProvides protection and support
A. Cell MembranePhospholipid bilayer is shaped by the water inside and outside the cell– Polar phosphate “head” - hydrophilic– 2 nonpolar fatty acid “tails” – hydrophobic
A. Cell MembraneProteins – channels/pumps that move molecules in and out of the cell
Carbohydrates – act as “ID tags” or cell markers
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel Lipid bilayer
Carbohydratechains
A. Cell Membrane
B. Cell Wall
StructureStructure– Strong supporting layer that lies outside the cell Strong supporting layer that lies outside the cell
membrane membrane in many plants, algae, fungi, and prokaryotes
– PorousPorous– Made from fibers of carbohydrate (mostly cellulose) Made from fibers of carbohydrate (mostly cellulose)
and proteinand protein
FunctionFunction– Provides support and protection for the cellProvides support and protection for the cell
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 Cell
What substances are entering and leaving the cell?
What substances are entering and leaving the cell?
Water molecules
Food particles
Ions
Wastes
How do these substances enter and exit the cell?
How do these substances enter and exit the cell?
Cell membranes are selectively permeable - some substances can pass through the membrane while others cannot
Substances MUST enter and exit the cell by:
How do these substances enter and exit the cell?
Cell membranes are selectively permeable - some substances can pass through the membrane while others cannotSubstances MUST enter and exit the cell by:– Diffusion– Osmosis– Facilitated Diffusion– Active Transport
C. Diffusion Through Cell Boundaries
When molecules of a substance move from an area of high concentration to an area of low concentration until equilibrium is reached– Concentration – mass of solute in a given volume of
solution 12 grams of salt in 3 Liters of water 12g/3 L or 4 g/L salt solution70% salt solution 70% salt / 30% water
– Equilibrium – same concentration on both sides of the membrane
C. Diffusion Through Cell Boundaries
Depends on random particle movementsSubstances diffuse across membranes without the use of energy
lipid-soluble molecules(O2, CO2, H2O)
(extracellular fluid)
(cytoplasm)
Simple diffusion
water molecule
drop of dye
D. Osmosis
Diffusion of water molecules through a selectively permeable membrane from an area of high water concentration to an area of low water concentration
Vital to the survival of the cell
Figure 7-15 Osmosis
D. OsmosisWhen comparing solutions, the
Hypertonic solution
Hypotonic solution
Isotonic solutions
D. OsmosisWhen comparing solutions, the
Hypertonic solution has more solute
Hypotonic solution
Isotonic solutions
D. OsmosisWhen comparing solutions, the
Hypertonic solution has more solute
Hypotonic solution has less solute
Isotonic solutions
D. OsmosisWhen comparing solutions, the
Hypertonic solution has more solute
Hypotonic solution has less solute
Isotonic solutions have equal concentrations of solute
Figure 5.8 Osmosis Modifies the Shapes of Cells
D. Osmosis
Osmotic pressure – increase in pressure inside a cell due to osmosis
High osmotic pressure can cause a cell to burst
–Plant cell walls prevent the cell from bursting
–Contractile vacuoles in protists pump out excess water
cytoplasm centralvacuole
cell wall plasma membrane
contractilevacuole
centralreservoir
pore
collectingducts
Paramecium – Contractile Paramecium – Contractile VacuoleVacuole
Contractile Vacuole
E. Facilitated Diffusion
Process in which molecules of a substance are transported across a membrane by a protein
Movement of molecules from an area of high concentration to an area of low concentration through the protein
HighConcentration
LowConcentration
CellMembrane
Glucosemolecules
Proteinchannel
Facilitated Diffusion
Diffusion, osmosis, and facilitated diffusion are forms of passive transport
PASSIVE TRANSPORT – cell transport that does not require the cell to use energy
F. Active Transport
Movement of substances across the cell membrane against the concentration difference from an area of low concentration to an area of high concentration
Requires the use of energy (ATP)
Molecule tobe carried
Moleculebeing carried
Energy
Figure 7-19 Active Transport
F. Active Transport
Sodium-Potassium Pump – moves sodium ions out of cells and potassium ions into cells against the concentration difference
Proton Pumps – move protons across cell membranes causing a large number of protons to accumulate on one side of the membrane
F. Active Transport
Movements of the cell membrane require energy– Endocytosis – process of bringing particles
into a cell using extensions of the cell membrane
Pinocytosis “cell drinking”Phagocytosis “cell eating”
– Exocytosis – material within sacs inside the cell is discharged from the cell
Endocytosis Exocytosis Video
From Simple to More ComplexFrom Simple to More ComplexMany multicellular organisms have structures called organs Many multicellular organisms have structures called organs that have a specific function and work with other organs. that have a specific function and work with other organs. Working together, these organs carry out the life processes Working together, these organs carry out the life processes of the entire organism. of the entire organism.
1.1.Some activities cannot be performed by only one person, Some activities cannot be performed by only one person, but need a team of people. What type of activity requires a but need a team of people. What type of activity requires a team of people to work together in order to complete a task? team of people to work together in order to complete a task?
2.2.What do you think are some characteristics of a successful What do you think are some characteristics of a successful team?team?
3.3.How is a multicellular organism similar to a successful How is a multicellular organism similar to a successful team?team?
Section 7–4Section 7–4The Diversity of Cellular LifeThe Diversity of Cellular Life
A.A.Unicellular OrganismsUnicellular Organisms
B.B.Multicellular OrganismsMulticellular Organisms
1.1. Specialized Animal CellsSpecialized Animal Cells
2.2. Specialized Plant CellsSpecialized Plant Cells
C.C. Levels of OrganizationLevels of Organization
1.1. TissuesTissues
2.2. OrgansOrgans
3.3. Organ SystemsOrgan Systems
Section 7-4:Diversity of Cellular Life
Remember that ALL living things:– Are composed of cells– Reproduce– Contain DNA– Grow and develop– Obtain and use materials and energy– Respond to their environment– Maintain a stable internal environment– Change over time
However, ALL living things are NOT the same.WHY???
A. Unicellular Organisms
Organism composed of only one cell
B. Multicellular Organisms
Organism composed of many cells
How are the cells in a unicellular organism different from the cells in a
multicellular organism?
How are the cells in a unicellular organism different from the cells in a
multicellular organism?In unicellular organisms, the organism is a single cell that MUST carry out ALL the functions necessary for life.
How are the cells in a unicellular organism different from the cells in a
multicellular organism?In unicellular organisms, the organism is a single cell that MUST carry out ALL the functions necessary for life.In multicellular organisms, each cell carries out only one of a few particular functions in the organism. The cells are specialists!!!
How are the cells in a unicellular organism different from the cells in a
multicellular organism?In unicellular organisms, the organism is a single cell that MUST carry out ALL the functions necessary for life.In multicellular organisms, each cell carries out only one of a few particular functions in the organism. The cells are specialists!!!
Cell specialization - cells throughout a multicellular organism can develop in different ways to perform different tasks
Specialized Animal Cells
Red blood cells - carry O2 throughout the bodyPancreatic cells - produce insulin and digestive enzymesMuscle cells - contract and relax to move parts of the body
Specialized Plant Cells
Guard cells - control the exchange of CO2, O2, H2O vapor, and other gases by opening and closing the stomata on the undersides of leaves
Vein
Leaf cross section
Figure 10.3
Mesophyll
CO2 O2Stomata
C. Levels of Organization
Cells Tissues Organs Organ Systems
Tissue – group of similar cells that group together to perform a similar functionOrgan - groups of tissues that work togetherOrgan System - group of organs that work together to perform a specific function
Muscle cell Smooth muscle tissue Stomach Digestive system
Levels of Organization
C. Levels of Organization
WHY ???
C. Levels of Organization
WHY ???
Creates a division of labor that makes multicellular life possible