THE CELL THE CELL CELL THEORY,STRUCTURE AND CELL THEORY,STRUCTURE AND

FUNCTIONFUNCTION

Discovery of the CellDiscovery of the Cell The invention of the The invention of the microscopemicroscope

made the discovery of the cell made the discovery of the cell possible. possible.

16651665: Robert : Robert HookeHooke used an early used an early compound microscope to observe a compound microscope to observe a thin piece of thin piece of corkcork (plant material). He (plant material). He observed empty chambers, which he called observed empty chambers, which he called ““cellscells.”.”

16771677: Anton van : Anton van LeeuwenhoekLeeuwenhoek used a used a single lens microscope to observe pond single lens microscope to observe pond water. He saw tons of water. He saw tons of microorganismsmicroorganisms (bacteria, protists), even in the water he (bacteria, protists), even in the water he drank!drank!

Discovery of the CellDiscovery of the Cell

18381838: : SchleidenSchleiden concluded that plants are made of cells. concluded that plants are made of cells. 18391839: : SchwannSchwann concluded that animals are made of cells. concluded that animals are made of cells. 18581858: : VirchowVirchow concluded that new cells came only from concluded that new cells came only from

other living cells.other living cells.

Discovery of the CellDiscovery of the Cell

These discoveries were confirmed by other These discoveries were confirmed by other scientists & are summarized in the scientists & are summarized in the CELL CELL THEORYTHEORY::

1.1. All living things are made of one or All living things are made of one or more cellsmore cells..

2.2. Cells are the basic units of structure & Cells are the basic units of structure & function in living thingsfunction in living things..

3.3. New cells are produced from existing New cells are produced from existing cellscells..

Prokaryotes & EukaryotesProkaryotes & Eukaryotes

While all cells share 3 While all cells share 3 characteristics,characteristics,

• Surrounded by a cell membraneSurrounded by a cell membrane• Contain genetic material (DNA)Contain genetic material (DNA)• Have ribosomesHave ribosomes

They are divided into 2 broad They are divided into 2 broad categories:categories:1. 1. ProkaryoticProkaryotic Cells (prokaryotes) Cells (prokaryotes)

2. 2. EukaryoticEukaryotic Cells (eukaryotes) Cells (eukaryotes)

Prokaryotes & EukaryotesProkaryotes & Eukaryotes Prokaryotic Cells (Prokaryotic Cells (prokaryotesprokaryotes))

Do not have a nucleusDo not have a nucleus or any membrane- or any membrane-bound organellesbound organelles

Average Size: Average Size: 1 micrometer1 micrometer Example: Example: bacterial cellsbacterial cells

Prokaryotes & EukaryotesProkaryotes & Eukaryotes Eukaryotic Cells (Eukaryotic Cells (eukaryoteseukaryotes))

Have a nucleusHave a nucleus and membrane-bound and membrane-bound organellesorganelles

Average size: Average size: 10-100 micrometers10-100 micrometers Example: Example: animal & plant cellsanimal & plant cells, amoeba, amoeba

Prokaryotes & EukaryotesProkaryotes & Eukaryotes Both prokaryotes & eukaryotes…Both prokaryotes & eukaryotes…

• ……have cell have cell membranesmembranes..

• ……contain contain chromatinchromatin (condensed (condensed DNA).DNA).

• ……contain contain ribosomesribosomes..

Prokaryotes & EukaryotesProkaryotes & Eukaryotes Both prokaryotes & eukaryotes have cell membranes:Both prokaryotes & eukaryotes have cell membranes: Function of the cell membrane:Function of the cell membrane:

• Protective Protective barrierbarrier from the outside environment from the outside environment• Controls what Controls what goes in and comes outgoes in and comes out of the cell of the cell

“selective permeability”“selective permeability”

Prokaryotes & EukaryotesProkaryotes & Eukaryotes Both prokaryotes & eukaryotes have cell Both prokaryotes & eukaryotes have cell

membranes:membranes: Structure of the cell membrane:Structure of the cell membrane:

• Phospholipid Phospholipid bilayerbilayer• ProteinsProteins & cholesterol in it & cholesterol in it

Prokaryotes & EukaryotesProkaryotes & Eukaryotes Both prokaryotes & eukaryotes contain chromatin:Both prokaryotes & eukaryotes contain chromatin:

chromatin

Prokaryotes & EukaryotesProkaryotes & Eukaryotes Both prokaryotes & eukaryotes contain ribosomes:Both prokaryotes & eukaryotes contain ribosomes:

PART II CELL STRUCTUREPART II CELL STRUCTURE

What membrane-bound organelles What membrane-bound organelles characterize the characterize the eukaryoticeukaryotic cell? cell?

What is the function of these What is the function of these organelles, and what relationships organelles, and what relationships

exist between their form & function?exist between their form & function?

CytoplasmCytoplasm Structure: Structure:

• Thick, watery substance (cytosol)Thick, watery substance (cytosol)• All the cellular contents between the plasma All the cellular contents between the plasma

membrane and nucleus membrane and nucleus Function: Function:

• Contains all the Contains all the organellesorganelles

• Where most Where most chemical reactions chemical reactions occur occur

Eukaryotic Cell StructureEukaryotic Cell Structure

OrganellesOrganelles are specialized structures are specialized structures that perform specific functions vital that perform specific functions vital to the life of a cell. to the life of a cell.

Cellular organelles can be thought of Cellular organelles can be thought of as little as little organsorgans. .

Just as organs function to keep the Just as organs function to keep the body body alivealive, organelles perform the , organelles perform the functions of the cell.functions of the cell.

NucleusNucleus Structure: Structure:

• Bound by a nuclear membraneBound by a nuclear membrane• Location of chromatin (DNA) which holds all Location of chromatin (DNA) which holds all

instructions for making proteinsinstructions for making proteins• Nucleolus = region of highly condensed DNA, Nucleolus = region of highly condensed DNA,

where ribosomes are made.where ribosomes are made. Function: Function:

• Control center of Control center of the cell the cell

RibosomesRibosomes

Structure: Structure: • Small particles of RNA and proteinSmall particles of RNA and protein• Found floating in the cytoplasm or attached Found floating in the cytoplasm or attached

to the rough endoplasmic reticulumto the rough endoplasmic reticulum Function:Function:

• Make proteins (protein “orders” from the Make proteins (protein “orders” from the nucleus)nucleus)

Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER) Structure:Structure:

• System of membrane channelsSystem of membrane channels• Rough ER (studded with ribosomes)Rough ER (studded with ribosomes)• Smooth ERSmooth ER

Function:Function:• Channels serve as paths for the synthesis Channels serve as paths for the synthesis

& transport of materials through & out of & transport of materials through & out of the cell the cell

• Chemical reactions occur on the Chemical reactions occur on the membranesmembranes

Rough ERRough ER: site of protein synthesis: site of protein synthesis Smooth ERSmooth ER: site of lipid synthesis: site of lipid synthesis

Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER)

Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER)

Golgi ComplexGolgi Complex Structure:Structure:

• Stack of flat membranesStack of flat membranes Function:Function:

• ““Post office” of the cellPost office” of the cell• Modifies, sorts, packages, & Modifies, sorts, packages, &

ships proteinsships proteins• Products received from ER Products received from ER

are modified, tagged, & sent are modified, tagged, & sent through & out of the cellthrough & out of the cell

• Produces vesicles used for Produces vesicles used for transport throughout celltransport throughout cell

Golgi ComplexGolgi Complex

LysosomesLysosomes Structure:Structure:

• membrane-bound sacsmembrane-bound sacs• filled with enzymesfilled with enzymes

Function:Function:• Enzymes break down carbs, lipids, & Enzymes break down carbs, lipids, &

proteins into smaller piecesproteins into smaller pieces• Break down old organellesBreak down old organelles• Where harmful foreign materials Where harmful foreign materials

can be destroyed can be destroyed• Basically get rid of the junkBasically get rid of the junk

VacuolesVacuoles Structure:Structure:

• In plants, there is one In plants, there is one large central vacuolelarge central vacuole

• Membrane-bound sacMembrane-bound sac Function:Function:

• Stores water, salts, proteins, carbsStores water, salts, proteins, carbs• Plants: maintains rigidity (turgor pressure)Plants: maintains rigidity (turgor pressure)• Unicellular: contractile vacuole used to Unicellular: contractile vacuole used to

pump excess water out of the cellpump excess water out of the cell• Maintaining water content is part of Maintaining water content is part of

homeostasishomeostasis

Large Central VacuoleLarge Central Vacuole

MitochondriaMitochondria Structure:Structure:

• Double layer membraneDouble layer membrane• Inner membrane has lots of folds which Inner membrane has lots of folds which

increases surface areaincreases surface area

MitochondriaMitochondria Function:Function:

• ““Powerhouse” of the eukaryotic cellPowerhouse” of the eukaryotic cell• Where glucose is broken down in order to Where glucose is broken down in order to

produce useable energy for your body (ATP)produce useable energy for your body (ATP)

CC66HH1212OO66 + 6 O + 6 O22 --> 6H --> 6H22O + 6COO + 6CO2 2 + + energyenergy exothermic or endothermic reaction?exothermic or endothermic reaction?

MitochondriaMitochondria Interesting Fact:Interesting Fact:

• Mitochondria are only passed down to Mitochondria are only passed down to offspring by women (men do not pass offspring by women (men do not pass down mitochondria)down mitochondria)

• So your mitochondria in your cells all So your mitochondria in your cells all came from your mom!came from your mom!

Another interesting fact:Another interesting fact:• The DNA in your mitochondria is The DNA in your mitochondria is

different from the DNA in your different from the DNA in your chromosomes. Your mitochondrial chromosomes. Your mitochondrial DNA also came from your mother.DNA also came from your mother.

ChloroplastChloroplast Structure:Structure:

• Surrounded by a double membraneSurrounded by a double membrane• Inside, stacks of membranes (grana) --Inside, stacks of membranes (grana) --

> increased surface area > increased surface area • Where chlorophyll is storedWhere chlorophyll is stored

ChloroplastChloroplast Function:Function:

• Site of photosynthesis: where energy Site of photosynthesis: where energy from sun is captured & converted into from sun is captured & converted into chemical energy (glucose)chemical energy (glucose)

6CO6CO22 + 6H + 6H22O + sunlight O + sunlight C C66HH1212OO66 + 6O + 6O22

exothermic or endothermic reaction?exothermic or endothermic reaction?

CytoskeletonCytoskeleton Structure:Structure:

• Made of microtubules (tubulin), Made of microtubules (tubulin), intermediate filaments, microfilaments intermediate filaments, microfilaments (actin)(actin)

CytoskeletonCytoskeleton Function:Function:

• Gives shape and Gives shape and organization to the organization to the cell. cell.

• Aids in cell movement Aids in cell movement Assembly of actinAssembly of actin Cilia/flagellaCilia/flagella

• Involved in cell division Involved in cell division (centrioles)(centrioles)

Cilia and FlagellaCilia and Flagella

Organelles with the capacity for movementOrganelles with the capacity for movement Extend from surface of the cellExtend from surface of the cell

CentriolesCentrioles Structure:Structure:

• Pair of microtubule bundlesPair of microtubule bundles Function:Function:

• Used in cellular division in ANIMAL Used in cellular division in ANIMAL cellscells

• Not present in plant cellsNot present in plant cells

Cell WallCell Wall Made of cellulose Made of cellulose

• What kind of molecule is cellulose?What kind of molecule is cellulose? Provides plant cells w/ more rigidity Provides plant cells w/ more rigidity

than animal cellsthan animal cells

Plant vs. Animal CellsPlant vs. Animal Cells Create a Venn Diagram to Create a Venn Diagram to

compare and contrast the compare and contrast the structure of plant and animal cells.structure of plant and animal cells.