Get your notebook out, Get your notebook out, copycopy and answer the and answer the following questions (don’t use the book):following questions (don’t use the book):1.1. What are the 3 main types of What are the 3 main types of

microscopes?microscopes?2.2. Which one(s) enable the greatest Which one(s) enable the greatest

magnification?magnification?3.3. What is the smallest unit of organization What is the smallest unit of organization

that has all of the characteristics of life?that has all of the characteristics of life?4.4. Where do you find the Where do you find the prologueprologue in a book in a book

– in the beginning or at the end?– in the beginning or at the end?

Check (& correct) your Check (& correct) your answers!answers!1. What are the 3 main types of microscopes?1. What are the 3 main types of microscopes?

2. Which one(s) enable the greatest 2. Which one(s) enable the greatest magnification?magnification?

3. What is the smallest unit of organization that 3. What is the smallest unit of organization that has all of the characteristics of life?has all of the characteristics of life?

4. Where do you find the 4. Where do you find the proprologuelogue in a book – in in a book – in the beginning or at the end?the beginning or at the end?

Light microscope, SEM (scanning electron microscope), and TEM (transmission electron microscope)

SEM and TEM: Up to 500,000xLight microscopes only go to ~1,500x

The cell

In the beginning, Pro = “before” in Greek

The The Story Story

of of CellsCells

What are cells?What are cells?The Building Blocks of The Building Blocks of

LifeLife

Remember: The Remember: The cellcell is the smallest is the smallest structural unit capable of performing life structural unit capable of performing life functions. functions.

Examples of CellsExamples of Cells

Amoeba

Plants

Red Blood Cell

Nerve Cell

Bacteria

Cell TriviaCell Trivia The average human being is composed of The average human being is composed of

around 100 Trillion individual cells!!!around 100 Trillion individual cells!!! The egg yolk from an ostrich egg is the The egg yolk from an ostrich egg is the

largest cell. They are about a half foot long. largest cell. They are about a half foot long. It would take as many as 50 cells to cover the It would take as many as 50 cells to cover the

area of a dot on the letter “i” on your paperarea of a dot on the letter “i” on your paper

Ostrich egg Chicken egg

Discovery of CellsDiscovery of Cells16651665- English Scientist, - English Scientist, Robert HookeRobert Hooke, discovered cells , discovered cells

while looking at a thin slice of cork (bark of tree)while looking at a thin slice of cork (bark of tree)– He described the cells as tiny boxes or a honeycombHe described the cells as tiny boxes or a honeycomb– He thought that cells only existed in plants and fungiHe thought that cells only existed in plants and fungi

The Microscope! (pg 171)The Microscope! (pg 171)1673- Anton von Leuwenhoek, invented the microscope and observed pond scum and discovered single celled organisms

•He called them “animalcules”He called them “animalcules”•He also observed blood cells from fish, birds, frogs, dogs, He also observed blood cells from fish, birds, frogs, dogs, and humansand humans•Therefore, it was known that cells are found in animals as Therefore, it was known that cells are found in animals as well as plantswell as plants

The Compound Light The Compound Light MicroscopeMicroscope

Developed in the Developed in the 1600’s1600’s Maximum magnification of Maximum magnification of

1,500x1,500x Uses Uses lightlight to magnify to magnify

specimensspecimens

The Electron MicroscopeThe Electron Microscope Developed in the Developed in the 1930’s-1930’s-

1940’s1940’s Maximum magnification of Maximum magnification of

500,000x500,000x Uses Uses a beam of electrons a beam of electrons to to

magnify specimensmagnify specimens 2 types:2 types:

– SEM (scanning electron SEM (scanning electron microscope)microscope) Used to scan the Used to scan the surfacesurface of of

cellscells 3D image3D image

– TEM (transmission electron TEM (transmission electron microscope)microscope) Used to study the Used to study the internal internal

structuresstructures of cells of cells

The Cell Theory (pg 172)The Cell Theory (pg 172)Memorize this!Memorize this!

1. All organisms are composed of one 1. All organisms are composed of one (unicellular) or more cells (multi-(unicellular) or more cells (multi-cellular).cellular).

2. The cell is the basic unit of structure, 2. The cell is the basic unit of structure, function, and organization of function, and organization of organisms.organisms.

3. All cells come from pre-existing cells.3. All cells come from pre-existing cells.

Let’s investigate the 3Let’s investigate the 3rdrd idea: idea: Where does life come from?Where does life come from?

Old TheoryOld Theory - - Spontaneous Spontaneous GenerationGeneration– Life Life spontaneouslyspontaneously happens: happens:

Life comes from non-life Life comes from non-life Examples: Examples:

– Mice from cloth sacks and grains.Mice from cloth sacks and grains.– Maggots from rotting meat.Maggots from rotting meat.

REALLY?

Where does life come Where does life come from?from? 1858- Rudolf Virchow, German physician, after 1858- Rudolf Virchow, German physician, after

extensive study of cellular pathology, concluded thatextensive study of cellular pathology, concluded that cells must arise from preexisting cells.cells must arise from preexisting cells.

Biogenesis – Life can only be formed from existing life.

We will be investigating this further when we cover Evolution (Ch. 14), for now just understand the main ideas, no dates or names necessary.

Two Types of CellsTwo Types of Cells

ProkaryotiProkaryoticc

EukaryoticEukaryotic

REMEMBER US

Types of Cells (p.173)Types of Cells (p.173)

1. Prokaryotes1. Prokaryotes = bacteria cells= bacteria cells– No true nucleus, not membrane boundNo true nucleus, not membrane bound– NucleoidNucleoid = unbound ball of DNA= unbound ball of DNA

2 Domains2 Domains– ArchaeaArchaea = similar to 1 = similar to 1stst forms on life on forms on life on

earthearth– EubacteriaEubacteria = more closely related to = more closely related to

eukaryotic cellseukaryotic cells

2. Eukaryotes2. Eukaryotes = plant & animal = plant & animal cells with a cells with a true membrane bound true membrane bound nucleusnucleus– Organisms made up of one or more cellsOrganisms made up of one or more cells– Membrane bound organellesMembrane bound organelles– OrganellesOrganelles = well-defined structures, = well-defined structures,

perform specific functions, usually perform specific functions, usually surrounded by membranesurrounded by membrane

– Larger than prokaryotic cellsLarger than prokaryotic cells

Basic Parts of A CellBasic Parts of A Cell

Plasma MembranePlasma Membrane = cell = cell membrane, barrier between outside membrane, barrier between outside & inside& inside

CytoplasmCytoplasm = = – fluid (fluid (cytosolcytosol))– organelles inside the cellorganelles inside the cell

NucleusNucleus = membrane bound organelle = membrane bound organelle containing DNAcontaining DNA

Logic-based classification Logic-based classification exerciseexercise

You will get a yellow sheet that contains You will get a yellow sheet that contains characteristics of both prokaryotic and characteristics of both prokaryotic and eukaryotic cells eukaryotic cells

Work with your partner, and your partner Work with your partner, and your partner ONLY, to classify the characteristics listedONLY, to classify the characteristics listed

Read the instructions carefully and Read the instructions carefully and complete the assignment in your complete the assignment in your notebook. (If you don’t finish, there is a notebook. (If you don’t finish, there is a digital copy on the HW page)digital copy on the HW page)

Return yellow half sheet to the front at Return yellow half sheet to the front at the end of classthe end of class