Cells and the Cell Theory
Academic Biology
I.
II.
III.
Name_______________
Intro
A. Most organisms are made of billions or trillions of cells.
Adult human has 35 trillion cells.
B. Organisms differ from each other in cell structure.
1. certain features common to all: cell membrane, cytoplasm
2. certain processes are necessary for all cells: metabolism,
reproduction, creating energy, removing wastes, getting nutrients
Invention of the microscope enabled scientists to view cells.
A. Anton von Leeuwenhoek (dutch merchant)
1. developed first working microscope
2. first to view microorganisms and living cells
B. British scientist Hook viewed cork cells
1. coined the term cells as they looked like monastery cells.
C. Schleiden
1. German botanist – 1838
2. studied plant cells
3. discovered that all organisms are made of fully individualized,
independent, separate beings (cells)
D. Schwann
1. German zoologist – 1939
2. studied animal cells
3. found that the cell is the cellular basis of all life
E. Virchow
1. Discovered that the animal only arises from an animal and the
plant only from a plant
2. contradicted the idea of spontaneous generation
Cell Theory
A. The combined work of Schleiden, Schwann, and Virchow led to the Cell
Theory
1. Cells are the basic unit of life.
2. All organisms are made of cells.
3. All cells arise from pre-existing cells.
IV.
Parts of a cell
A. Cell membrane
1. thin double layer of lipids and proteins separating the cell’s
contents from its environment
2. microns thick (10,000 cell membranes is as thick as a piece of
paper)
3. Mostly made of phospholipids
a. polar molecule
b. hydrophilic
c. hydrophobic
4. Fluid mosaic model – proteins are embedded in the cell
membrane that allow materials to come in and out. They move in
through the proteins which can move around and change shape
for all materials to enter through. (Find a cell membrane and
draw it and label it.)
B. Nucleus
1.
2.
3.
4.
V.
control center of the cell
prokaryotic cell – no nucleus, DNA is found in the center
eukaryotic cell – has a membrane bound nucleus
surrounded by a double layer membrane called a nuclear
envelope.
5. lots of pores are found in the membrane
6. contains DNA
a. long thin strands are called chromatin
b. condenses into thick strands called chromosomes
during cell division
c. contains coded blueprints that control cell activity
7. has at least one nucleolus which make ribosomes which build
proteins
C. cytoplasm
1. everything between the cell membrane and the nuclear
membrane
2. Two main components
a. cytosol which is jellylike, mostly water, with
proteins, carbohydrates, and organic compounds –
biological reactions occur
b. Organelles are structures that work like miniature
organs that carry out specific functions in a cell
Organelles
A. ribosomes
1. make proteins
2. found free floating or attached to the endoplasmic reticulum
B. Endoplasmic reticulum
1. intracellular transport (highway)
2. connects nuclear membrane to cell membrane
3. detoxifies chemicals in cytoplasm
4. rough ER is studded with ribosome’s – processes proteins
5. smooth ER has no ribosomes – processes lipids and
carbohydrates
C. Golgi Apparatus
1. packages and secretes cell products
D.
E.
F.
G.
VI.
2. series of flat, membrane-bound sacs stacked like pancakes called
cristae
mitochondria
1. powerhouse of the cell
2. releases energy contained in food
3. folded inner membrane increases the surface area
4. makes ATP through cellular respiration
lysosomes
1. contains enzymes to digest food particles inside the cell
2. enzymes are produced by the golgi apparatus
vacuoles
1. membrane bound sac in cell membrane
2. stores food, cell products, or wastes
Other cell parts:
Cell Diversity
Structure
Cell membrane
Cell wall
nucleus
chromosomes
ribosomes
ER
Golgi apparatus
lysosomes
vacuoles
mitochondria
chloroplasts
cytoskeleton
Prokaryotic cells
No
Yes
No
Yes
No
No
No
No
No
No
No
Yes
eukaryotic
Animal
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
eukaryotic
plant
yes
yes
Yes
yes
yes
Yes
Yes
Yes
Yes
Yes
yes
No
A. Plant cells
1. have a cell wall and a cell membrane
2. cell wall has cellulose which makes it rigid.
3. Plastids: chromoplasts, chloroplasts, leucoplasts, and other
plastids.