Introduction to CellsDragonfly Book: Chapter 7-1

Ms. McCaughanLSHS

The Discovery of Cells Cells were not

described until 1665……….WHY?

1. Scientists did not begin to use microscopes until the mid-1600’s

2. Most cells are too small to see without the microscope!

The Discovery of CellsA. Robert Hooke (1665)

1. English Biologist

2. Observed a thin slice of cork (plant material) using an early microscope

3. Saw thousands of tiny chambers which he called “cells”

Draw what he saw in the box

The Discovery of Cells

B. Anton van Leeuwenhoek (1674)1. Dutch biologist2. Observed tiny living organisms in drops of pond water

through a simple microscope.

C. Matthias Schleiden (1838)1. German botanist concluded all plants are made of cells

D. Theodor Schwann (1839)1. German biologist stated all animals are made of cells

E. Rundolph Virchow (1855)1. Proposed all cells come from existing cells

Cell Theory

The discoveries of all of the mentioned biologists formed a fundamental concept

in biology known as CELL THEORY

1. All living things are composed of cells

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

3. New cells are produced from existing cells

Cells have common characteristicsA. DNA

Genetic material

B. Cell Membrane Lipid bi-layer that controls what goes into and out

of the cell

C. Ribosomes Structures used in protein synthesis

D. Cytoplasm The interior of the cell

E. CytoskeletonFibers that give cells structure

Prokaryotic Cells “Pro” = before, “karyotic” = nucleus At least 3.5 billion years old Simplest and smallest cells No nucleus (Nucleiod region in the center to hold DNA)

No specialized organelles(Still function as living: grow, reproduce and respond to environment)

Examples: Bacteria and blue-green algae

ProkaryoticCells

Eukaryotic Cells

A. “Eu” = true, “karyotic” = nucleus

B. Evolved about 1.5 billion years ago

C. Larger and more complex than prokaryotes

D. Nucleus (DNA packaged in chromosomes)

E. Many specialized organelles

F. Examples: Plants, Animals, protist & fungi

Eukaryotic Cells

Animal Cell

Plant Cell

Comparison ChartAll Cells Prokaryotes Eukaryotes

•Found in living

things•Basic unit of life•Produced from

existing cellsContain:

•Cell membrane•DNA•Ribosomes•Cytoplasm•Cytoskeleton

•Older•Smaller•Simple•No nucleus

Nucleoid region

•No specialized organelles•Examples: bacteria, algae

•Newer•Larger•Complex•Nucleus•Many specialized organelles

•Examples: plants, animals, protists, fungi