It’s a Cellular WorldIt’s a Cellular WorldUnit 2: CellsUnit 2: Cells

Chapter 7: Cell Structure and FunctionChapter 7: Cell Structure and FunctionSection 7-1 Life is CellularSection 7-1 Life is Cellular

Text- pages -169-173Text- pages -169-173

VocabularyVocabulary

CellCell

Cell theoryCell theory

NucleusNucleus

EukaryoteEukaryote

ProkaryoteProkaryote

ObjectivesObjectives SWBAT explain how microscopes came SWBAT explain how microscopes came

into use and the early observations that into use and the early observations that were made by scientists.were made by scientists.

SWBAT describe the three steps of the Cell SWBAT describe the three steps of the Cell Theory.Theory.

SWBAT describe some modern microscope SWBAT describe some modern microscope techniques used to look at cells and their techniques used to look at cells and their parts.parts.

SWBAT explain how cells are classified.SWBAT explain how cells are classified. SWBAT describe the differences between SWBAT describe the differences between

prokaryotes and eukaryotes.prokaryotes and eukaryotes.

Discovering the CellDiscovering the Cell Mid 1600’s: scientists Mid 1600’s: scientists

began to use began to use microscopes to microscopes to observe living things.observe living things.

1665: Robert Hooke 1665: Robert Hooke (England) compound (England) compound scopescope

1674: Anton van 1674: Anton van Leeuwenhoek Leeuwenhoek (Holland) single lens (Holland) single lens scope.scope.

Cell TheoryCell Theory

Cell Theory states…Cell Theory states…1) All living things are composed of cells.1) All living things are composed of cells.

2) Cells are the basic unit of structure and 2) Cells are the basic unit of structure and function in living things.function in living things.

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

Exploring the Cell TodayExploring the Cell Today

Today’s researchers use microscopes Today’s researchers use microscopes and techniques that are much more and techniques that are much more powerful than those of early powerful than those of early scientists.scientists.

Examples: fluorescent labeling, light Examples: fluorescent labeling, light microscopes, 3-D imaging using microscopes, 3-D imaging using electron microscopeselectron microscopes

Modern TechniquesModern Techniques

3-D imaging3-D imaging

Fluorescent LabelingFluorescent Labeling

Light MicroscopesLight Microscopes

Electron MicroscopesElectron Microscopes

SEM : Scanning Electron MicroscopeSEM : Scanning Electron Microscope– Scanning a pencil-like beam of electrons Scanning a pencil-like beam of electrons

over the surface of an object. Produce a over the surface of an object. Produce a 3-d image3-d image

TEM : TEM : Transmission Electron MicroscopeTransmission Electron Microscope– The transmission electron microscope The transmission electron microscope

(TEM) operates on the same basic (TEM) operates on the same basic principles as the light microscope but principles as the light microscope but uses electrons instead of light.uses electrons instead of light.

TEM resourceTEM resource– http://minerals.caltech.edu/http://minerals.caltech.edu/

Silica_Polymorphs/index.htmlSilica_Polymorphs/index.html– Pictures From The TEMPictures From The TEM

SEM resourcesSEM resources– scharfphoto.com: David Scharf: Homescharfphoto.com: David Scharf: Home– Pictures From The SEMPictures From The SEM

Classifying CellsClassifying Cells

Variety of shapes and sizes.Variety of shapes and sizes. Typical cell 5- 50 µm.Typical cell 5- 50 µm. 2 common characteristics:2 common characteristics:

1)1) Surrounded by barrier- cell membraneSurrounded by barrier- cell membrane

2)2) At some point in the cell lifespan they At some point in the cell lifespan they contain the molecule that carries contain the molecule that carries biological information- DNA. biological information- DNA.

How small is a micrometer How small is a micrometer (um)?(um)?

1 micrometer (um) is one millionth of 1 micrometer (um) is one millionth of a meter 1/1,000,000 ma meter 1/1,000,000 m

or 1 x 10or 1 x 10-6-6

Cell ShapesCell Shapes

Classifying Cells cont’d Classifying Cells cont’d

2 categories of cells- depend upon 2 categories of cells- depend upon whether they contain a nucleus.whether they contain a nucleus.– Eukaryotes: contain nucleiEukaryotes: contain nuclei– Prokaryotes: no nucleusProkaryotes: no nucleus

Nucleus:Nucleus: large membrane-enclosed large membrane-enclosed structure that contains cell’s genetic structure that contains cell’s genetic material (nucleic acids) in the form of material (nucleic acids) in the form of DNA. DNA. – Controls many of the cell’s activities.Controls many of the cell’s activities.

ProkaryotesProkaryotes

Smaller and simpler than eukaryotes.Smaller and simpler than eukaryotes. No nucleus. No nucleus. Some contain organelles.Some contain organelles. Carry out every activity associated Carry out every activity associated

with living things. with living things. – Grow, reproduce, respond to Grow, reproduce, respond to

environment, glide, and swimenvironment, glide, and swim– Example: BacteriaExample: Bacteria

EukaryotesEukaryotes

Larger and more complex than Larger and more complex than prokaryotes.prokaryotes.

Contain dozens of organelles.Contain dozens of organelles. Highly specializedHighly specialized Contain nucleus Contain nucleus Single celled or multi-cellular.Single celled or multi-cellular. Examples: plants, animals, fungi, and Examples: plants, animals, fungi, and

protists.protists.

Review QuestionsReview Questions

What are the 3 statements that What are the 3 statements that make up the cell theory?make up the cell theory?

What’s the difference between What’s the difference between prokaryotes and eukaryotes?prokaryotes and eukaryotes?

Do bacterial cells contain nuclei? Do bacterial cells contain nuclei?