What is the basic unit of all Organisms

What is the basic unit of all Organisms? ? The Cell

Car Breaking down

Hierarchy of living organisms: l Organism l Organ System l Organ l Tissues l Cells –

Today: l We are going to start talking about cells and the cell theory. l We will be filling out the notes I handed you the other day. l I will then hand you the first part of your study guide for your next test. l The second part will be cell organelles once we go over them.

The Basis of Life CELLS

Section 1: Introduction to the Cell

I. Discovery of Cells l The invention of the lens l Robert Hooke (1665): observed a thin slice of cork (dead plant cells) with a microscope. He described what he observed as “little boxes” (cells).

I. Discovery of Cells l Anton van Leeuwenhoek (1675): was the first person to observe living cells.

II. Microscopes l Magnification: refers to the microscope’s power to increase an object’s apparent size l Resolution: refers to the microscope’s power to show detail clearly

1. Light Microscope

Light Microscope Elodea - Aquatic Plant 40 X 400 X

2. Transmission Electron Microscope (TEM)

Transmission Electron Microscope (TEM) Herpes Virus Plant Root Cell

3. Scanning Electron Microscope (SEM)

Scanning Electron Microscope (SEM)

Scanning Electron Microscope (SEM) Mosquito Head 200 X 2000 X

Scanning Electron Microscope (SEM) Fly Eye

Scanning Electron Microscope (SEM) Surface of Tongue Neuron Inside of Stomach

Scanning Electron Microscope (SEM) Pollen Yeast Red Blood Cell, Platelet, and White Blood Cell

TEM vs. SEM Viruses leaving a cell

III. The Cell Theory l Who developed the cell theory? – Matthias Schleiden (1838): concluded that all plants are composed of cells – Theodor Schwann (1839): concluded that all animals are composed of cells – Rudolph Virchow (1855): determined that cells come only from other cells

III. The Cell Theory l What is the cell theory? 1. All living things are composed of one or more cells. 2. Cells are organisms’ basic units of structure and function. 3. Cells come only from existing cells.

IV. Cell Diversity l Size l Shape l Internal Organization

Cell Diversity. Size

Smallest Cells: Cell Diversity- Size Longest Cells: Biggest Cells: 6 inches long, 5 inches wide, 3 pounds Ostrich Egg

Surface Area to Volume Ratio SA = 6 lw V = lwh SA = 6 mm 2 V = 1 mm 3 SA/V = 6: 1 SA = 24 mm 2 V = 8 mm 3 SA/V = 3: 1 V increases faster than SA SA = 96 mm 2 V = 64 mm 3 SA/V = 1. 5: 1

Cell Diversity- Shape l Cells differ widely in shape. l Most cells are roughly cuboidal or spherical.

V. Cell Diversity- Internal Organization l Nucleus: contains DNA which directs the activity of the cell l Organelle: a cell component that performs specific functions in the cell l Eukaryotes: cells that contain a nucleus and membrane-bound organelles l Prokaryotes: cells that lack nuclei and membrane-bound organelles

A. Eukaryotes vs. Prokaryotes l Eukaryotes (animals, plants, fungi, protists) and prokaryotes (bacteria) differ greatly in structure.

Prokaryotic Cell

Structural Organization of Eukaryotic and Prokaryotic Cells

Key Differences:

Eukaryotic cells are differentiated from prokaryotic cells because eukaryotic cells _____. Are much smaller b. Have permeable membranes c. Have a higher rate of reproduction d. Have nuclei a. D