Download cell theory and structure

CELL THEORY AND STRUCTURE
Discovery of cells
•Cells were first seen in 1665 by the early microscopist Robert Hooke.
•Hooke was examining cork wood, and noticed that the wood was divided into
little squares or “cells”
Other scientists made further discoveries of cells:
•Anton VonLeeuwenhoek – c.1680 – discovered blood cells, bacteria and other
single-celled organisms which he named “animacules.”
•Matthias Schleiden – 1838 - theorized that all plants are made of cells
•Theodor Schwann – 1839 – theorized that all animals are made of cells.
•Rudolph Virchow – 1855 – stated that all living cells come only from other
living cells
Modern Cell Theory
(Three components)
I.
All living things are made of cells
II.
Cells are the basic units of living things. (i.e. Nothing less than a cell is
living).
III.
Living cells come only from other living cells.
Cell Structure
Two basic cell types:
I.
Prokaryotic Cells:
–Organisms with prokaryotic cells are called “prokaryotes”
–Prokaryotes have no true nucleus or organelles. (organelles are small internal
cell components that perform life-functions for the cell).
–Have a single strand of “looped” DNA
–Most prokaryotes are single-celled microscopic organisms.
II.
Eukaryotic Cells:
–Organisms composed of eukaryotic cells are called “eukaryotes.”
–Have a nucleus which contains the cell’s DNA.
–Compose some single-celled organisms and ALL multicellular organisms.
–Have organelles, each of which is surrounded by a bound in a “plasma
membrane.”
Prokaryotes
•Very simple cells
•Always single-celled
•No nucleus
•DNA arranged in one single loop
•Found only in bacteria
vs
Eukaryotes
•Complex cells
•Can be single-celled or multicellular
•Have a nucleus
•DNA arranged in many separate
strands
•Found in Animal, Plant, Protist, and
Fungi kingdoms