Objectives
• List scientists who contributed to the cell theory
• List the components of the cell theory
• Compare prokaryote and eukaryote cells
• Label a plant and an animal cell
• Know the functions of cell organelles
Early Contributions
• Robert Hooke - First person to see cells, he was
looking at cork and noted that he saw "a great many
boxes. (1665)
• Anton van Leeuwenhoek - Observed living cells in
pond water, which he called "animalcules" (1673)
• Theodore Schwann - zoologist who observed tissues of
animals had cells (1839)
• Mattias Schleiden - botanist, observed tissues of plants
contained cells ( 1845)
• Rudolf Virchow - also reported that every living thing is made
of up vital units, known as cells. He predicted that cells come
from other cells. (1850 )
The Cell Theory
• 1. Every living
organism is made of
one or more cells.
• 2. The cell is the basic
unit of structure and
function. It is the
smallest unit that can
perform life functions.
• 3. All cells arise from
pre-existing cells.
*Why is the Cell Theory
called a Theory and not a
Fact?
Cell Features
ALL cell have these parts
• Ribosomes – make protein for use by the
organism
• Cytoplasm – fluid material within cell
• DNA – genetic material
• Cytoskeleton – internal framework of cell
• Cell Membrane – outer boundary, some things
can cross the cell membrane
Comprehension Checkpoint
Answer true or false
1.Robert Hooke was the first person to see cells.
2.Bacteria cells have a cell membrane.
3.The Cell Theory was developed by a single scientist.
4.Plant cells have cytoplasm.
5.Cells taken from fungi do not have DNA.
6.Cells can only come from pre-existing cells.
7.It only took five years to develop the Cell Theory.
Prokaryote Cells
•
•
•
•
The first cells to inhabit the earth
Simple cells
Bacteria
These cells do NOT have a nucleus, their DNA is
circular and floats in the cytoplasm
Some bacteria have
a tail-like structure
called a flagella, that
helps it to move.
A capsule surrounds
some bacteria and helps
them avoid the body’s
immune system
Bacteria Images
Bacteria that causes Anthrax
Eukaryotic Cells
• Cells found in plants, animals, protists,
and fungi
• The cell is composed of 4 main parts:
1. Cell membrane
2. Cytoplasm
3. Nucleus – “control center” of cell, houses DNA
4. Organelles – small structures that carry out
specific functions (“little organs”)
Nucleus
• Usually found at center of cell
• Has a nuclear membrane & nuclear pores
• Contains cell’s DNA in one of 2 forms
o chromatin - DNA bound to protein (non-dividing
cell)
o chromosomes - condesed structures seen in
dividing cell
• Also contains an organelle called nucleolus - which
makes the cell’s ribosomes
Cell Organelles
Mitochondria – this is the cell’s energy center. It
turns food into a chemical energy called ATP
The mitochondria is sometimes called the
“powerhouse” of the cell
Cell Organelles
Golgi Apparatus – processes, packages
and secretes proteins. It is comparable to
a factory or a post office.
*A vesicle forms with
Golgi to transport
substances outside
cell.
Cell Organelles
Lysosome – Contains digestive enzymes,
breaks things down, "suicide sac”
Endoplasmic Reticulum –
Transport, "intracellular
highway".
-Rough ER contains many
ribosomes & is involves in
protein synthesis
-Smooth ER ribosomes not
found on surface
Cytoskeleton – Helps cell maintain
support & shape; movement
a. microtubules-hollow structures; also
help build cilia and flagella
b. microfilaments-threadlike
c. centrioles-only in animal cells; used during
cell division (paired)
Vacuole – storage area for water and other
substaces, plant cells usually have a large
central vacuole
Protein Production
The cell is like a factory. Its product is protein which
goes to body to serve different functions.
1.DNA has instructions to build protein
2.These instructions are sent to ribosomes
3.The ribosomes build protein and send it through ER
4.The proteins are delivered to golgi where they are
completed and “tagged” for export outside cell
THE ANIMAL CELL
Cheek Cells Seen Through
Microscope
Plant Cells
• Have additional structures
• CELL WALL – surrounds membrane & provides
additional support
• CHLOROPLASTS – contain green pigment,
function in photosynthesis
• CENTRAL VACUOLE – large water container
in center of cell
PLANT CELL
Can you identify
the parts?
Anacharis Cells Viewed With a
Microscope
Animal Cell vs Plant Cell
Organelles With DNA
• Mitochondria and chloroplasts have their own DNA
(separate from the nucleus)
• This supports the ENDOSYMBIOSIS THEORY
which states that eukaryotic cells evolved when
prokaryote cells engulfed or absorbed other cells.
CELL MEMBRANE
• Selectively permeable ; it regulates what comes into
the cell and what leaves the cell
• It is composed of a double layer of phospholipids
with proteins embedded throughout