Cell TheoryCell Theory

• Look closely at a part of a living thing, and what do you Look closely at a part of a living thing, and what do you see?  Hold a blade of grass up against light, and you see?  Hold a blade of grass up against light, and you see tiny lines running the length of the blade.  Examine see tiny lines running the length of the blade.  Examine the tip of your finger, and you see the ridges and the tip of your finger, and you see the ridges and valleys that make up fingerprints.  Place an insect valleys that make up fingerprints.  Place an insect under a microscope, and you see the intricate under a microscope, and you see the intricate structures structures of its wings and the spikes and bristles that protect its of its wings and the spikes and bristles that protect its body.  As interesting as these close-up views may be, body.  As interesting as these close-up views may be, however, they're only the beginning of the story.  Look however, they're only the beginning of the story.  Look closer and deeper with a more powerful microscope, closer and deeper with a more powerful microscope, and you'll see that there is a common structure that and you'll see that there is a common structure that makes up every living thing - the CELL! makes up every living thing - the CELL!

The discovery of the cell…The discovery of the cell…

• "Seeing is believing," an old saying "Seeing is believing," an old saying goes.  It would be hard to find a goes.  It would be hard to find a better example of this than the better example of this than the discovery discovery of the cell.  Without the instruments of the cell.  Without the instruments to make them visible, cells remain to make them visible, cells remain out of sight and out of the minds of out of sight and out of the minds of most of humans though out history. most of humans though out history.

Early MicroscopesEarly Microscopes

The Cell TheoryThe Cell Theory

• 1. All living things are composed of cells  1. All living things are composed of cells  

• 2. Cells are the basic units of structure 2. Cells are the basic units of structure and function in living things.  and function in living things.  

• 3. New cells are produced from existing 3. New cells are produced from existing cells.cells.

Cell membraneCell membrane

• The part of the cell that maintains an The part of the cell that maintains an internal environmentinternal environment

Animal CellAnimal Cell

Prokaryotes (Prokaryotes (the bacteriathe bacteria))

Prokaryotes (Bacteria & Prokaryotes (Bacteria & Archea)Archea)

• ProkaryoticProkaryotic cells are generally smaller and simpler that cells are generally smaller and simpler that eukaryoticeukaryotic cells. cells.

• Prokaryotes contain genetic material (Prokaryotes contain genetic material (DNADNA) that is not ) that is not contained in a nucleus.contained in a nucleus.

• In terms of microorganisms In terms of microorganisms ((living things that are not visible to living things that are not visible to

the un-aided eyethe un-aided eye)) there are currently three groups there are currently three groups ((kingdomskingdoms),), Archea, Bacteria, & ProtistaArchea, Bacteria, & Protista– Prokaryotes: Includes what people normally know as Prokaryotes: Includes what people normally know as – bacteria which actually includes to groupsbacteria which actually includes to groups

• Archea (Archea (microorganisms that live in extreme environmentsmicroorganisms that live in extreme environments))• Bacteria (Bacteria (microorganisms that are found all throughout the planet’s microorganisms that are found all throughout the planet’s

habitatshabitats))– Protists which are eukariotic microorganismsProtists which are eukariotic microorganisms

• Phytoplankton, zooplankton, single-celled algaePhytoplankton, zooplankton, single-celled algae

All other organisms are All other organisms are eukaryoteseukaryotes

• EukaryotesEukaryotes– ProtistsProtists– FungiFungi– PlantsPlants– AnimalsAnimals

Eukaryotic CellEukaryotic Cell

• Eukaryotic cells have little parts like Eukaryotic cells have little parts like organs that are called organellesorgans that are called organelles

• Let’s briefly view them…Let’s briefly view them…

NucleusNucleus

• The nucleus is where DNA is locatedThe nucleus is where DNA is located– 23 strands of DNA from each parent 23 strands of DNA from each parent

called chromosomescalled chromosomes

RibosomesRibosomes

• Where amino acids are put together Where amino acids are put together to make proteinsto make proteins

Rough ER Rough ER (endoplasmic reticulum)(endoplasmic reticulum)

• Where ribosomes are attached Where ribosomes are attached

Golgi ApparatusGolgi Apparatus

• Where cell products are sort, Where cell products are sort, packaged, and shippedpackaged, and shipped

MitochondrionMitochondrion

• Power plant of the cellPower plant of the cell– ATPATP

Plant cellPlant cell

ChloroplastChloroplast

• Site of photosynthesisSite of photosynthesis

VacuoleVacuole

• In plant cells, the central storage siteIn plant cells, the central storage site

The EndThe End