Download Introduction to Cells

Introduction to Cells
Dragonfly Book: Chapter 7-1
Ms. McCaughan
LSHS
The Discovery of Cells
Cells were not
described until
1665……….WHY?
Scientists did not begin
to use microscopes until
the mid-1600’s
Most cells are too small
to see without the
microscope!
The Discovery of Cells
Robert Hooke (1665)
English Biologist
Observed a thin slice
of cork (plant material)
using an early
microscope
Saw thousands of
tiny chambers which
he called “cells”
The Discovery of Cells
Anton van Leeuwenhoek (1674)
Matthias Schleiden (1838)
German botanist concluded all plants are made of cells
Theodor Schwann (1839)
Dutch biologist
Observed tiny living organisms in drops of pond water
through a simple microscope.
German biologist stated all animals are made of cells
Rundolph Virchow (1855)
Russian proposed all cells come from existing cells
Cell Theory
The discoveries of all of the mentioned
biologists formed a fundamental concept
in biology called the CELL THEORY:
All living things are made up of cells
The cell is the basic unit of life.
All cells come from existing cells
Cells have common characteristics
DNA
Genetic material
Found in the nucleus of eukaryotic cells and the nucleoid
region in prokaryotes
Cell Membrane
Lipid bi-layer that seperates the inside of the cell from its
external environment
Selective barrier that controls what goes into and out of
the cell
Ribosomes
Structures used in protein synthesis
Cytoplasm
The interior of the cell
Cytoskeleton
Fibers that give cells structure
Prokaryotic Cells
“Pro” = before, “karyotic” = nucleus
At least 3.5 billion years old
Simplest and smallest cells
No nucleus
No specialized organelles
Nucleiod region in the center to hold DNA
DNA is a circular single strand
Still function as living: grow, reproduce and respond to
environment
Examples: bacteria and blue-green algae
Prokaryotic
Cells
Eukaryotic Cells
“Eu” = true, “karyotic” = nucleus
Perhaps evolved about 1.5 billion years ago
Larger and more complex than prokaryotes
Nucleus
DNA is a double-stranded and packaged in chromosomes
Many specialized organelles
Examples: plants, animals, protists and fungi
Eukaryotic Cells
Plant Cell
Animal Cell
Comparison Chart
All Cells
•Found
in living
things
•Basic unit of life
•Produced from
existing cells
Contain:
•Cell
membrane
•DNA
•Ribosomes
•Cytoplasm
•Cytoskeleton
Prokaryotes
Eukaryotes
•Older
•Newer
•Smaller
•Larger
•Simple
•Complex
•No
•Nucleus
nucleus
Nucleoid region
•No
specialized
organelles
•Examples:
bacteria, algae
•Many
specialized
organelles
•Examples:
plants, animals,
protists, fungi