BELL RINGER 8-13-14
1.
A prediction or statement that can be tested is a(n) ______.
a.
b.
c.
d.
2.
A sample that is treated exactly like the other experimental groups
except that the variable is not applied to it is a(n) __________.
a.
b.
c.
d.
3.
Conclusion
Observation
Control
Hypothesis
Observation
Variable
Control
Hypothesis
What is the only difference between the control group and the
experimental group in a controlled experiment?
a.
b.
c.
d.
The test
The prediction
The variable
The hypothesis
AGENDA
Standard
 Cell Theory Notes
 Endosymbiotic Theory Video
 Eukaryotic/Prokaryotic Venn Diagram

Independent
 Whole class

STANDARD

Students will analyze the nature of the
relationships between structures and functions in
living cells

Explain the role of cell organelles for both
prokaryotic and eukaryotic cells, including the cell
membrane, in maintaining homeostasis and cell
reproduction.
BEFORE WE GET GOING…
A theory in everyday language implies that
something is unproven or speculative
 A theory in science is

A widely accepted explanation of things observed in
nature
 It must be supported by evidence (including
evidence gained through experimentation and
observation)

CELL THEORY

Some random cell facts:
The average human being is composed of around 100
Trillion individual cells
 It would take as many as 50 cells to cover the area of a dot
on the letter “i”

Red blood cells
DISCOVERY OF CELLS
1665 – English scientist, Robert Hooke,
discovered cells while looking at a thin slice
of cork.
 He described the cells as tiny boxes or a
honeycomb
 He thought that cells only existed in plants and
fungi

ANTON VAN LEUWENHOEK

1673 – used a handmade microscope to
observe pond scum and discovered single-celled
organisms

He called them “animalcules”
He also observed blood cells from fish, birds, frogs,
dogs, and humans
 Therefore, it was known that cells are found in
animals as well as plants

150-200 YEAR GAP?
Between the Hooke/Leuwenhoek discoveries and the
mid 19th century, very little cell advancements were
made.
 This is probably due to the widely accepted traditional
belief in “spontaneous generation”
 Example


Maggots from rotting meat
MATTHIAS SCHLEIDEN
1838 – concluded that all plant parts are made of cells
 He was a German botanist

THEODOR SCHWANN
1839 – concluded that all animal tissues are composed of
cells
 He was a German physiologist and close friend of
Schleiden

LOUIS PASTEUR

1859 - Disproved spontaneous generation
RUDOLF VIRCHOW

1858 – studied cellular pathology and concluded that
cells must arise from preexisting cells


“Where a cell exists, there must have been a preexisting cell.”
He was a German physician
THE CELL THEORY

3 Basic Components:
All organisms are composed of one or more cells.
 The cells is the basic unit of life in all living things.
 All cells are produced by the division of preexisting cells.

Roundworm embryo
undergoing cell
division
THE MODERN INTERPRETATION OF CELL THEORY
All known living things are made up of one or more cells
 All living cells arise from preexisting cells through division
 The cell is the fundamental unit of structure and function
in all living organisms
 The activity of an organism depends on the total activity of
independent cells
 Energy flow occurs within cells
 Cells contain hereditary information which is passed from
cell to cell during cell division
 All cells are basically the same in chemical composition in
organisms of similar species

WHY IS CELL THEORY IMPORTANT?
Helps us to differentiate between living and non-living
things.
 Unifies all living things – no matter how different one
organism is from the next they are both composed of cells
 Foundational for biology!

Mouse kidney cells
Onion cells
PROKARYOTES
The first organisms on Earth
 May have lived 3.5 billion years ago and for millions of
years they were the only organisms on Earth
 Eukaryotes evolved from prokaryotes, but how?


Endosymbiotic theory
E. coli, prokaryote
Amoeba, eukaryote
PROKARYOTIC/EUKARYOTIC VENN DIAGRAM
Use Chapter 7 in your textbook to complete a Venn
Diagram comparing and contrasting prokaryotic and
eukaryotic cells
 Work for 20-25 minutes on your own, then we will fill out a
class Venn diagram based on your input
