Cell Structure PowerPoint

1. Chp 2-1
The Discovery of Cells
• Why weren’t cells discovered until the
1600’s?
• Describe the contribution of
– Robert Hooke
– Anton van Leeuwenhoek
– Matthias Schleiden
– Theodor Schwann
– Rudolph Virchow
For each, include what year their discovery
was made
1

2. Cell Theory
• Schleiden, Schwann, and Virchow’s
discoveries led to the formation of the
CELL THEORY:
1. All living things are composed of one
or more cells.
2. In organisms, cells are the basic
units of structure and function.
3. Cells are produced only from existing
cells.
2

3. All Cells have:
1. A cell membrane
(a.k.a. “plasma membrane”
2. Ribosomes
3. Genes (DNA)
4. Cytoplasm
- cytoplasm is everything inside a cell
- cytosol is cytoplasm that isn’t inside
an organelle.
3

4. 4
Number of Cells
Organisms may be:
• Unicellular –
composed of one cell
• Multicellular-
composed of many
specialized cells
• Colonial – groups
of cells that lack
specialization

5. 5
Types of CellsTypes of Cells
Prokaryotes - Bacteria
Eukaryotes – Animals, plants, fungi, and
protists.
Eukaryotic CellProkaryotic Cell

6. 6
Prokaryotes
Nucleoid region
contains the DNA
The DNA is circular
No membrane-bound
organelles
Very small: 1-15 μm
in diameter

7. m?μ
7
The symbol “μ” (mu) stands for micron, or
one-millionth of a meter.
A human hair can
vary from 20-180 μm
Those 
Are bacteria on a pin!

8. 8
Eukaryotic Cell
Range from 2-1000 μm
Contain membrane-bound
organelles
Why do you think eukaryotic
cells can be so much larger
than prokaryotic cells?

9. Why are cells so small?
9
Materials must be exchanged
across the cell membrane and then
distributed throughout the cell.
An efficient cell has a large
surface area to volume ratio.
The larger the cell, the smaller
the ratio (inverse relationship)
Size  Ratio 
Why are
some
cells
bigger
than
others?
How do
they get
around
this ratio
thing?

10. 10
Basic Structure of a Cell
Is this a prokaryote or a eukaryote?

11. 11
Outermost part of
animal cells
Found just inside the
cell wall of plant,
fungi, and bacteria
cells
Cell membrane
Surrounding all Cells:Surrounding all Cells:

12. 12
Controls the
movement of
materials into and
out of the cell
“Selectively
permeable”
Cell membrane

13. 13
Jelly-like substance
enclosed by cell
membrane
Cytosol provides a
medium for
chemical reactions
to take place
Cytoplasm
Cytoplasm of a CellCytoplasm of a Cell

14. 14
OrganellesOrganelles
Have specific functions
ex: mitochondria release
stored energy in food
ribosomes make proteins
“membrane-bound” organelles
are surrounded by membranes

15. Eukaryotic Cells
Are not all the same!
Plant cells have a cell wall made of
cellulose
Fungi have cell walls made of chitin
Animal cells don’t even have a cell wall
15

16. 16
There are differentThere are different
kinds of plant cellskinds of plant cells
Onion Epidermal Cells
Root Hair Cell
root hair
Guard Cells

17. 17
There are different kindsThere are different kinds
of “animal” cellsof “animal” cells
white blood cell
red blood cell
cheek cells
sperm
nerve cell
muscle cell
Amoeba
Paramecium

18. 18
Similarities between plantSimilarities between plant
cells and animal cellscells and animal cells
Both have a cell membrane,
ribosomes, cytoplasm, and DNA
Both share many organelles,
including mitochondria

19. 19
Differences between plantDifferences between plant
cells and animal cellscells and animal cells
Animal cells Plant cells
Relatively
smaller in size
No chloroplasts
No cell wall
Relatively
larger in size
Chloroplasts
Cell wall present

20. 20
Animal cells Plant cells
Vacuoles small or
absent
Glycogen as food
storage
Nucleus at the
center
Large central
vacuole
Starch as food
storage
Nucleus near cell
wall
More Differences betweenMore Differences between
Plant Cells and Animal CellsPlant Cells and Animal Cells

21. 21
Levels of organizationLevels of organization
• Cells are
grouped
together and
work as a
whole to
perform special
functions

22. 22
TissueTissue
• A group of similar cells to
perform a particular function
– Animals : epithelial tissue,
muscular tissue, nervous
tissue, and connective tissue

23. 23
OrganOrgan
• Different tissues group together
to carry out specialized functions
– Heart : consists of muscles,
nervous tissue and blood
vessels
– Leaf : consists of epidermis,
mesophyll and vascular tissue

24. 24
Stoma
Air Space
Spongy Mesophyll
Cell
Chloroplast
The Structures of a Leaf
(Plant Organ)
Palisade
Mesophyll Cell

25. 25
SystemSystem
• Several organs and tissues work together
to carry out a particular set of
functions in a co-ordinated way
– Human : digestive, respiratory, excretory,
circulatory and reproductive systems
– Plant : root and shoot systems

26. 26
Human Body SystemsHuman Body Systems
Examples of systems :
 Digestive System
 Respiratory System
 Circulatory System
 Nervous System
 Reproductive System

27. 27
Example of a Human Body System

28. 28
Levels of OrganizationLevels of Organization
CELLS (muscle cells,nerve cells)
TISSUES (muscle, epithelium)
ORGANS (heart, lungs,
stomach)
SYSTEMS (circulatory system)
ORGANISM (human)