CellsCellsStructure, Function and other stuffStructure, Function and other stuff

GETTIN’ THE JOB DONE:GETTIN’ THE JOB DONE:A Blast from the PastA Blast from the Past

REMEMBER OUR REMEMBER OUR CHARACTERISTICS CHARACTERISTICS OF LIVING THINGS?OF LIVING THINGS? The Toy Lab…The Toy Lab…

EvolutionEvolution ReproductionReproduction Reacting to Reacting to

EnvironmmentEnvironmment Homeostasis Homeostasis

(Balance)(Balance) MovementMovement OrganizationOrganization Energy (getting it, Energy (getting it,

using it)using it)

CELL ORGANELLESCELL ORGANELLES

Each organelle performs specific functionsEach organelle performs specific functionsThe organelle’s function accomplishes one The organelle’s function accomplishes one

or several of the necessary requirements or several of the necessary requirements for life…for life…

e.g., NUCLEUS…e.g., NUCLEUS…a “Two-for-the-price-of-one” speciala “Two-for-the-price-of-one” specialREPRODUCTIONREPRODUCTION Instructions for ORGANIZATION of cellInstructions for ORGANIZATION of cell

A A REALREAL Alien Invasion… Alien Invasion… They come in peace They come in peace

Read Lewis Thomas’ essayRead Lewis Thomas’ essay Answer the following as you read:Answer the following as you read:

What does Thomas mean when he says that “some What does Thomas mean when he says that “some [organelles], and the most important ones at that, are [organelles], and the most important ones at that, are total strangers”?total strangers”?

Which organelles does he suggest are the Which organelles does he suggest are the “strangers”?“strangers”?

What evidence does he provide for this suggestion?What evidence does he provide for this suggestion? In the “master and slave” relationship that Thomas In the “master and slave” relationship that Thomas

alludes to in the reading, in what ways are we “slaves” alludes to in the reading, in what ways are we “slaves” to our organelles?to our organelles?

What is Thomas’s overall emotional reaction to the What is Thomas’s overall emotional reaction to the idea of strangers living inside our cells? How can you idea of strangers living inside our cells? How can you tell?tell?

CELLULAR EVOLUTIONCELLULAR EVOLUTION

A tale of intrigue, suspense, and A tale of intrigue, suspense, and neverending commitment to one another…neverending commitment to one another…

Scene 1: A tale of two cell typesScene 1: A tale of two cell types

Prokaryotes Prokaryotes (used to be Monera in the 5 kingdom classification)(used to be Monera in the 5 kingdom classification)

ArchebacteriaArchebacteria Harshest habitatsHarshest habitats First life forms?First life forms?

EubacteriaEubacteria Most modern bacteriaMost modern bacteria Cyanobacteria (sometimes Cyanobacteria (sometimes

called blue-green algae)called blue-green algae)

EukaryotesEukaryotes All complex cells that have membrane bound organelles.All complex cells that have membrane bound organelles. 10 – 100 X the size of prokaryotic cells10 – 100 X the size of prokaryotic cells May be single cell organisms (still are complex and have membrane bound May be single cell organisms (still are complex and have membrane bound

organelles).organelles). Cells making up all multicellular organisms.Cells making up all multicellular organisms. In multicellular organisms, cells can group together to form a various In multicellular organisms, cells can group together to form a various

“levels of organization“levels of organization

Cell categoriesCell categories

ProkaryotesProkaryotes Smaller than Smaller than

eukaryoteseukaryotes All bacteriaAll bacteria

ArchaebacteriaArchaebacteria eubacteriaeubacteria

No membrane covered No membrane covered organellesorganelles

EukaryotesEukaryotes Much larger than Much larger than

prokaryotesprokaryotes Anything not bacteriaAnything not bacteria

ProtistaProtista PlantaePlantae FungiFungi AnimaliaAnimalia

Membrane bound Membrane bound organelles special organelles special focus on nucleusfocus on nucleus

6 kingdoms connection6 kingdoms connection

BUT…WHY DID THEY DIVERGE?BUT…WHY DID THEY DIVERGE?

Remember their differences?Remember their differences?Where did all of these cell parts come Where did all of these cell parts come

from?from?Scene 2: Intrigue… “Having a friend for Scene 2: Intrigue… “Having a friend for

dinner”…dinner”…

ECOLOGY: INTERACTION WITH ECOLOGY: INTERACTION WITH THE ENVIRONMENTTHE ENVIRONMENT

Living things interact with one anotherLiving things interact with one anotherLots of different kinds of interactionsLots of different kinds of interactions

Predator-preyPredator-preyMutualistsMutualistsEtc…more to come on these laterEtc…more to come on these later

Prokaryote vs Eukaryote sizesProkaryote vs Eukaryote sizes

Phagocytosis(food)/Pinocytosis (liquid)Phagocytosis(food)/Pinocytosis (liquid)same processsame process

Cell interiorCell interior

Endocytosis/ExocytosisEndocytosis/Exocytosis

SO…WHAT SO…WHAT SHOULD SHOULD HAPPEN?HAPPEN?

A cell takes in “prey” using A cell takes in “prey” using the cell the cell membranemembrane

Vesicles form and the food is digested by Vesicles form and the food is digested by the the lysosomeslysosomes, right?, right?

BUT NOT IN THIS CASE… BUT NOT IN THIS CASE… SUSPENSE!SUSPENSE!

REMEMBER: REMEMBER: Prokaryote vs Eukaryote sizesProkaryote vs Eukaryote sizes

What do we know about What do we know about mitochondria and chloroplasts?mitochondria and chloroplasts?

Same size as prokaryotes (A.K.A. Same size as prokaryotes (A.K.A. Bacteria)Bacteria)

Have their own DNAHave their own DNAHave similar structure to prokaryotesHave similar structure to prokaryotesReproduce like prokaryotesReproduce like prokaryotesMembrane structure is like prokaryotesMembrane structure is like prokaryotesDouble membrane makes senseDouble membrane makes sense

Enter…Lynn Margulis…EukaryoteEnter…Lynn Margulis…Eukaryote

Lynn MargulisLynn MargulisHerHer hypothesis hypothesis originally proposed that: originally proposed that:

mitochondria are the result of mitochondria are the result of endocytosis of endocytosis of aerobic bacteria aerobic bacteria

chloroplasts are the result of chloroplasts are the result of endocytosis of endocytosis of photosynthetic bacteria photosynthetic bacteria

in both cases by large in both cases by large anaerobic bacteriaanaerobic bacteria who who would not otherwise be able to exist in an would not otherwise be able to exist in an aerobic environment. aerobic environment.

this arrangement became a mutually beneficial this arrangement became a mutually beneficial relationship for both cells relationship for both cells (symbiotic)(symbiotic). .

HUH?HUH?

Instead of eating your roommate, you let Instead of eating your roommate, you let them live and pay rent…them live and pay rent…

It’s win-win for both of you!It’s win-win for both of you!

Endosymbiotic theoryEndosymbiotic theory

Simply stated, the theory of Simply stated, the theory of endosymbiosisendosymbiosis is the is the concept that:concept that:mitochondria and chloroplasts are the result mitochondria and chloroplasts are the result

of years of evolutionof years of evolution initiated by the initiated by the endocytosisendocytosis of bacteria and of bacteria and

blue-green algae blue-green algae instead of becoming digested, became instead of becoming digested, became

mutualisticmutualistic. . HENCE…A NEVERENDING COMMITMENT HENCE…A NEVERENDING COMMITMENT

TO EACH OTHER!TO EACH OTHER!

BiologicalBiological

levels levels

OfOf

organizationorganization

CELL ENERGYCELL ENERGY

2 PROCESSES:2 PROCESSES: Photosynthesis Photosynthesis

(chloroplast)(chloroplast) Builds sugar using the Builds sugar using the

energy from sunlight energy from sunlight and matter from the and matter from the atmosphereatmosphere

Cell Respiration Cell Respiration (mitochondria & (mitochondria & cytoplasm)cytoplasm)

Releases energy from Releases energy from sugarsugar