An Introduction To Cell An Introduction To Cell BiologyBiology

Chapter 6 in your book

Pages 155-181

--> Why are we on chapter 6 already?!

Objectives For This UnitObjectives For This Unit1. Explain the basic tenets of the cell

theory2. Predict the possible effects of

improved technology on the study of cells

3. Distinguish between prokaryotic and eukaryotic cell structures.

4. Identify the function of the organelles in a typical eukaryotic cell.

Objectives For This UnitObjectives For This Unit

5. Describe the structure of a cell membrane.

6. Compare and contrast the mechanisms for transport of material across the membrane by developing models to illustrate these processes.

Objectives For This UnitObjectives For This Unit

7. Summarize the advantages of multi-cellular organization

What is the basic unit of What is the basic unit of life? life?

BiosphereEcosystemCommunitySpeciesPopulationIndividual

Organ system

Organ

Tissue

Cell

Organelle

What is the basic unit of What is the basic unit of life? life?

BiosphereEcosystemCommunitySpeciesPopulationIndividual

Organ system

Organ

Tissue

CellOrganelle

Discoveries that led to theDiscoveries that led to the CELL THEORY CELL THEORY

1. Robert Hooke - 1665 - slices of cork seen under a microscope.

Discoveries that led to theDiscoveries that led to the CELL THEORY CELL THEORY

2. Anthony Leeuwenhoek

(also memorable for his pioneering microscopy)

looked at yeast, blood cells, algae, which he thought were tiny animals.

Discoveries that led to theDiscoveries that led to the CELL THEORY CELL THEORY

3. Matthias Jakob Schleiden, a botanist, concluded,

“Plants are made of cells!”

Discoveries that led to theDiscoveries that led to the CELL THEORY CELL THEORY

4. Theodor Schwann, a zoologist, concluded,

“Animals are made of cells!”

Discoveries that led to theDiscoveries that led to the CELL THEORY CELL THEORY

Rudolph Virchow, a pathologist, concluded,

“Every living cell comes from a previously living cell!”

Psssst…

August Weismann connected cell biology with evolution.

“All cells can trace their ancestry back to ancient times!”

THE CELL THEORYTHE CELL THEORY

1. Cells, or products made by cells, are the units of structure and function in organisms.

2. All cells come from preexisting cells.

*3. All living things are composed of at least one cell, and cell products

Cell Theory: IntepretationsCell Theory: Intepretations

Energy flow occurs within cells.

Cells contain hereditary information (DNA) which is passed from cell to cell during cell division.

All cells are basically the same in chemical composition.

The activity of an organism depends on the total activity of independent cells.

Macromolecules in the CellMacromolecules in the Cell

1. CarbsCarbs: Structure, energy storage

2. ProteinsProteins: Structure, catalysis, movement, messaging, defense, transport

3. Nucleic acidsNucleic acids:: encoding information(Did you realizeATP is actually a nucleotide?)

4. LipidsLipids: Insulation, concentrated energy and the cellular membrane

(Transparency available upon request)

How Small Are Cells, Anyway?Smallest cells (prokaryotes) - one micronOne micron or micrometer = one-millionth of a

meterMost cells are 10-20 microns in diameter.Human red blood cells - 10 micronsUnicellular organisms - 100 micronsFish egg - 1 millimeterOstrich egg yolk - 100 mm

Giraffe nerve cell - 7 m!!

So How Are We Supposed To See Them!?

“Predict the possible effects of improved technology on the study of cells.”

That is, what do you think we will be able to discover?

Light microscopesTransmission electron microscopesScanning electron microscopes

Electron Microscopes

Drawbacks

Extremely expensive

Specimen can’t be alive

Can’t see moving processes

1. Coat with heavy metals, gold, or carbon

2. Fire electrons at specimen3. Record image on a computer

Electron Microscopes

Transmission EM

Black and white imageMagnification = 250,000XResolution = 1 nm To see inside cells

(INSIDE)

Scanning EM

3D imageryMagnification = 100,00XResolution = 10 nmTo see organs of small organisms (OUTSIDE)

What Have We Covered?What Have We Covered?

Next:

Proks vs Euks

Organelles

Animals vs Plants

Cell Membranes and Membrane Transport

Multicellularity