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


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.


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


1674 Van Leeuwenhoek 1674 Van Leeuwenhoek Observed first living cellsObserved first living cells


1838 Schleiden – All plants have cells.1838 Schleiden – All plants have cells.

1839 Schwann – All animals have cells.1839 Schwann – All animals have cells.


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


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


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


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


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



Cell membraneContain DNARibosomesCytoplasm

•Nucleus•Membrane-enclosedorganelles•Larger than prokaryotes(MOST 5-50 μm)•Some unicellular•Multicellular•Protists, Fungi, Animals, and Plants•Cytoskeleton



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


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


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


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


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


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


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


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


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


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


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


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?


Cell membranes are selectively permeable - some substances can pass through the membrane while others cannot

Substances MUST enter and exit the cell by:


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


Hypertonic solution has more solute

Hypotonic solution

Isotonic solutions



Hypotonic solution has less solute

Isotonic solutions



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?


multicellular organism?In unicellular organisms, the organism is a single cell that MUST carry out ALL the functions necessary for life.


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!!!


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


WHY ???


WHY ???

Creates a division of labor that makes multicellular life possible

chapter 4 cells: the basic units of life. chapter 4: cells are all cells alike? all living things...

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cell cells

cork cells

specialized cells

preexisting cells

cell structure

energy slide

early microscope slide

nonliving organism slide