2. 2
HISTORY OF THE CELL
1664 - Robert Hooke:
• made a simple microscope
• Looked at the dead cells of bark.
• He named the “boxed-shaped” structures “cell”
3. HISTORY OF THE CELL
1600s - Leeuwenhoek:
• 1st to view living things
• Pond water & scrapings from his teeth
• Designed his own microscope
3
4. Co-founders of the Cell Theory
1838 –M. Schleiden:
all plants are made of cells
1839 – T. Schwann - all
animals are made of cells
1855 - Rudolph Virchow –
cell comes from other cells.
4
5. CELL THEORY:
Includes the following three principles:
1. All living things are made of one or more
cells.
2. Cells are the basic unit of life
3. Cells come from pre-existing cells.
6. Theory vs. Scientific Law
Theory: an explanation of the
observed phenomenon.
Law: description of an observed
phenomenon.
Similarities: supported by
considerable data and widely accepted
by the scientific community.
Ex.: Kepler's Laws describe (how) the
motions of planets but do not provide an
explanation (why) for their movements.
9. Transmission Electron Microscope:
• TEMs produce high-resolution, 2-dimensional
images. It allows you to zoom in to see organelles.
• Disadvantage: specimens are dead
• Advantage: magnifies objects up to 500,000x.
Mitochondrion inside a cell
Teacher’s Notes:
TEM are tools used for
medical and biological
research. Most powerful
microscope!
10. Scanning Electron Microscope:
It’s a type of electron microscope that
produces images of a sample by scanning it
with a focused beam of electrons.
Advantage: creates 3D images
Disadvantage: Specimens are dead
13. GENERAL CHARACTERISTICS OF ALL
CELLS
A plasma cell membrane
Genetic material (RNA, DNA)
Break bonds to release energy
ATP
14. Organisms may be:
• Unicellular – composed of one cell
• Multicellular- composed of many cells
14
15. In Multicellular Organisms:
15
Cells take on different shapes & functions
through cell differentiation.
Differentiation occurs numerous times
during the development of a multicellular
organism as the organism changes from a
simple zygote to a complex system of
tissues and cell types.
16. How do cells specialize?
• Cells can turn different genes on and off
allowing a cell to change into a different
cell with a specific function (job)
20. TWO TYPES OF CELLS
PROKARYOTES:
• Lack a nucleus
• Simple & Smaller
• Unicellular
• Circular DNA
• Reproduce by binary
fission
Ex: bacteria
EUKARYOTES:
- Have a nucleus
- Complex
- Single or multi-celled
Ex. Algae, yeast,
plants and animals
21. Main Structures in Prokaryotes:
•Cell wall (or capsule)
•Cell membrane
•Ribosomes
•Circular DNA
called plasmid
21
Teacher’s Note: There are no
mitochondria in prokaryotes
22. Plant vs Animal Cells (eukaryotes)
Structures found in plant cells only:
• Cell wall
• Central vacuole
• Chloroplast
Structures found in animal cells only:
• Centrioles (used in cell division)
• Lysosomes (rare in plants)
23. Examples of Eukaryotes
24
Single celled organism Paramecium
(protista)
Plant cell
Animal cell
25. Integral Protein are
embedded
Peripheral
Protein
Cholesterol for
flexibility
Inside of cell
Carbohydrate
chains for ID
The Fluid Mosaic Model
26. Why do we mean by fluid mosaic
model?
FLUID- phospholipids and proteins can move around freely
within the layer
MOSAIC- the pattern produced by the scattered protein
27. Function of the plasma membrane:
• Involved in cell ID.
• Controls what goes in and out of cell
• Binding site for enzymes.
• Protective barrier
• Anchors cytoskeleton (shape)
• Attach to other cells (tissue)
28. Structure of the plasma membrane
• Made of two layers
• Surrounds outside of all cells
• Made of many phospholipids units
31
Outside of cell
Cell
membrane
Inside of cell
(cytoplasm)
Proteins
Carbohydrate
chains
Protein
channel Lipid bilayer
29. Essential Components:
• PHOSPHOLIPID: Units that make up the lipid
bilayer.
• CHOLESTEROL: Maintains flexibility
• CARBOHYDRATE CHAINS: Involved in cell
recognition
Outside of cell
Inside of cell
(cytoplasm)
Cell
membrane
Proteins
Carbohydrate
chains
Protein
channel Lipid bilayer
30. Proteins in the Cell Membrane
Integral proteins
• help move ions and other
molecules that can’t cross the
membrane.
• They are embedded completely
through the membrane.
• Ex.: carrier proteins & channel
proteins
Peripheral proteins: attached on
the surface (inner or outer). Used
for anchoring & binding site.
31. Glycoproteins:
• Proteins with attached carbohydrate
tails that act as markers for cell
recognition/identification.
34
32. 35
PHOSPHOLIPIDS:
• Can move sideways to allow small molecules to
squeeze through the lipid bilayer.
Made of:
• Head: water loving (hydrophilic)
• Tail: water fearing, points inward (nonpolar)
36. Types of Passive Transports
Moves molecules from a higher to lower
concentrations without the use of energy.
1. Diffusion: Moves tiny molecules such as oxygen
2. Osmosis: Moves water molecules. Will make
cells lose or gain water.
3. Facilitated Diffusion: Moves ions and other
molecules with the help of a transport protein (aka
channel protein)
38. Three types of passive transports
DIFFUSION
(ex. oxygen)
FACILITATED DIFFUSION
(ex. glucose)
OSMOSIS
(water)
39. Active Transport:
• Uses a carrier protein that change shapes.
• Requires energy.
Other active transports used for larger
molecules include:
• Endocytosis (moves substances in)
• Exocytosis (moves substances out)
40. Other types of Active Transports:
Endocytosis: allows for large particles to enter the cell.
Exocytosis: allows for substances and toxic to exit the cell.
42. Passive vs. Active Transport
PASSIVE
TRANSPORT:
“going down the
concentration
gradient”
ACTIVE TRANSPORT:
“Going against the
concentration
gradient”
43. Types of Solutions:
• Hypotonic: water rushes into the cell.
Makes plant cells firm up but animal cells
burst. Ideal condition for plant cells.
• Isotonic: equal amount of water goes in
and out of cell. Ideal for animal cells.
• Hypertonic: water leaves the cell. Makes
cells shrivel.
44. Effects of Hypotonic Solution on Plant Cells
Shrinks Soft Firm up
*ideal*
Teacher’s Notes: Hypotonic solutions are ideal for plant cells, but will
make an animal cell burst due to osmotic pressure on its cell
membrane
45. Effects of Osmosis on Animal Cells:
Teacher’s Note: Isotonic solution is ideal
for animal cells.
49. Summary of transport
52
Transport Description Energy?
Diffusion Tiny molecules squeeze thru cell
membrane Ex: Oxygen
No
Osmosis The diffusion of water No
Facilitated
Diffusion
An integral protein (channel
protein) is used to transport
molecules across.
No
Active
Transport
A carrier protein changes its
shape as it lets in molecules.
YES!!
(ATP)
50. PARTS OF AN
EUKARYOTIC CELL
ORGANELLES – ch7 pg.190-200
52. Function of organelles
• Nucleus – control center,
• Cell membrane – barrier where
transports take place
•Ribosomes – builds proteins.
•ER – helps assembles and transports
proteins
• Golgi – packs and exports proteins.
53. Functions of Organelles
• Lysosome – breaks down parts, contains enzymes
• Cell Wall – rigid, for support
• Central Vacuole – for storage
• Chloroplast – makes food for the plant (solar panel),
holds green pigment.
• Mitochondria – makes ATP (energy) from food
• Cytoplasm – holds organelles, where chemical reactions
take place
61. 64
Living Levels
CELLS – life starts here TISSUES – Similar cells working
together
62. More Living Levels
ORGANS
ORGAN
SYSTEMS ORGANISM
Different tissues
working together
Different organs
working together
Complete
multicellular
individual