2. Discovery of Cells
• Robert Hooke (1600’s) discovered “little
chambers” (cells) in cork plant
• Anton van Leeuwenhoek (1600’s)used
microscope to view living things in pond
water. Saw things swimming around!
3. Discovery of Cells, cont.
• Matthias Schleiden (1838) concluded
plants made of cells
• Thoedor Schwann (1839) concluded all
animals made of cells
4. Cell Theory
1. All living things are made up of cells.
2. Cells are the smallest working units of all
living things.
3. All cells come from preexisting cells
through cell division.
5. Definition of Cell
A cell is the smallest unit that is
capable of performing life
functions.
7. Two Types of Cells
•Prokaryotic
“pro-” means “before” (like “pre”)
“karyon” means “nut” or kernel”
No nucleus
•Eukaryotic
“eu-” means “true”
Has nucleus
8. Prokaryotic
• Do not have
organelles
surrounded by
membranes
• Few internal
structures
• One-celled
organisms,
Bacteria
http://library.thinkquest.org/C004535/prokaryotic_cells.html
9. Eukaryotic
• Contain organelles surrounded by membranes
• Most living organisms
Plant Animal
http://library.thinkquest.org/C004535/eukaryotic_cells.html
14. Cell Membrane
• Outer membrane of cell
that controls movement
in and out of the cell
• Double layers of fat
“”phospholipid bilayer”
http://library.thinkquest.org/12413/structures.html
15. Cell Wall
• Most commonly found
in plant cells &
bacteria & fungi
• Supports & protects
cells
• Made of carbohydrate
http://library.thinkquest.org/12413/structures.html
17. Nucleus
• Directs cell activities
• Separated from cytoplasm by nuclear
membrane
• Contains genetic material - DNA
18. Nuclear Membrane
• Surrounds nucleus
• Made of two layers
• Openings allow
material to enter and
leave nucleus
http://library.thinkquest.org/12413/structures.html
19. Chromatin
• Form DNA takes
most of the time.
• Like spaghetti
• Made of DNA
wrapped up
w/proteins
20. Chromosomes
• In nucleus
• DNA wrapped up tight
by proteins called
“histones”
• Contain instructions
for traits &
characteristics
http://library.thinkquest.org/12413/structures.html
23. Ribosomes
• Each cell contains
thousands
• Make proteins
• Found on
endoplasmic
reticulum & floating in
the cytoplasm
http://library.thinkquest.org/12413/structures.html
24. Endoplasmic Reticulum
• Moves materials around
in cell
• Smooth type: lacks
ribosomes
• Rough type (pictured):
ribosomes embedded in
surface
http://library.thinkquest.org/12413/structures.html
25. Mitochondria
• Produces energy through
chemical reactions –
breaking down fats &
carbohydrates
• Controls level of water and
other materials in cell
• Recycles and decomposes
proteins, fats, and
carbohydrates
http://library.thinkquest.org/12413/structures.html
26. Golgi Bodies
• Protein 'packaging
plant'
• Move materials within
the cell
• Move materials out of
the cell
http://library.thinkquest.org/12413/structures.html
27. Lysosome
• Digestive 'plant' for
proteins, fats, and
carbohydrates
• Transports undigested
material to cell
membrane for removal
• Cell breaks down if
lysosome explodes
http://library.thinkquest.org/12413/structures.html
28. Vacuoles
• Membrane-bound
sacs for storage,
digestion, and waste
removal
• Contains water
solution
• Help plants maintain
shape
http://library.thinkquest.org/12413/structures.html
29. Chloroplast
• Usually found in plant
cells (not in animal)
• Contains green
chlorophyll
• Where
photosynthesis takes
place
http://library.thinkquest.org/12413/structures.html
32. Cell Boundaries
• Cell Membrane
1. Controls what
goes in & out
2. Support &
protection
• Cell Wall
1. Support &
protection
33. Diffusion through Cell
Boundaries
• Every cell lives in a
liquid environment
• Membrane controls
movement of
dissolved
molecules back &
forth (in & out of
cell)
• (Remember a
solution contains a
– Solvent: the
substance that
dissolves the other
stuff (often water)
– solute: the
substance that gets
dissolved (salt,
sugar, ions, etc.)
34. Concentration of Solutions
• The greater the ratio of solute to solvent,
the higher the concentration.
• Ex:
• Solution #1: dissolve 5 g of salt in 1L of
water. Concentration= 5g/L
• Solution #2: dissolve 10 g of salt in 1L of
water. Concentration=10g/L
35. Diffusion
• In solution, particles move
constantly, colliding & spreading out.
• Diffusion is the movement of
particles from area of greater to
lesser concentration (b/c of random
motion.)
• Requires no energy to move
substances across a membrane (b/c
moved by random motion)
37. Osmosis
• The diffusion of water through a
membrane
• Some molecules are too large to move
through a membrane
38. How Osmosis Works
see Fig 7-15 on p 185
• If there is a selectively permeable
membrane separating 2 solutions
w/differing concentrations of solute,
• Water will move from the side where it is in
greater concentration to where it is in
lesser concentration. (R to L in picture)
39. Concentration of Solutions
• Isotonic: when the
concentration of
particles is the
same on both
sides of membrane
• Hypertonic: “above
strength”- the
stronger of the 2
solutions (L side)
• Hypotonic: “below
strength”- the less
concentrated of the
2 solutions (R side)
40. How Osmosis Works in Cells
see p 186 of text, Fig 7-16
• Isotonic: Cell
maintains its shape
• Hypertonic