Ch 7 Cell Structure and Function jhgjhgjj.ppt

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1. Chapter 7
Cell Structure & Function
Learning Goal:
I can identify the three parts of
cell theory.
I can describe the structure
and function of cells

2. Exploring the Cell
•Microscopes use lenses to magnify the
image of the object by focusing light or
electrons.
•Compound Light Microscope: allows light
to pass through a specimen and uses two
lenses to form an image.
–1
st
lens, objective lens, located above the
specimen enlarges the image
–2
nd
lens, ocular lens, magnifies this image
further

3. •Electron Microscope: instead of using light
they use a beam of electrons that are
focused by magnetic fields
–Transmission electron microscope: make it
possible to explore cell structure and large
proteins.
•Beams of electrons can only pass through thin
samples
–Scanning electron microscope: pencil-like
beam of electrons is scanned over the surface
of a specimen.
•Produces 3D images

4. CELL THEORY
1. All living things are made of ____________.
2. Cells are the basic unit of structure & function
in an organism.
(cell = basic unit of _____________)
3. Cells come only from the reproduction
of ____________ cells
Cell image: http://waynesword.palomar.edu/lmexer1a.htm
CELLS
existing
life

5. Compare and Contrast
Prokaryotes & Eukaryotes
Prokaryotic Cells
•Have a cell membrane
•Contain DNA
–Not contained in a
nucleus
–DNA is a single circle
(plasmid).
–No nuclei
•No encased organelles
•Example: Bacteria
•All bacteria are
prokaryotes.
•All prokaryotes are
unicellular.
Eukaryotic Cells
•Have a cell membrane
•Contain DNA
–Separated from the rest of the
cell
•Have nuclei
•Have encased organelles
•Examples: single celled
and multi celled living
organisms, plants,
animals, fungi, & protists

6. DO NOW:
Mark and Summary of Cell Theory
notes!
Question: How did the invention of the
microscope eventually lead to the cell
theory?

8. Cells
•All cells
contain:
–Cytoplasm
–Cell
membrane
–Ribosomes
–Genetic
information
(DNA)

10. Eukaryotic Cell Structure

11. Cells
•Unicellular –
organism
made up of
only 1 cell
•ALL
prokaryotes
and SOME
eukaryotes

12. Cells
•Multicellular –
organism made up
of more than 1 cell
•NO PROKARYOTE
IS
MULTICELLULAR

13. Animal Cells
•Eukaryotic cell that
contains organelles
but does not contain
a:
–cell wall
–large vacuole
–Chloroplasts
•Does NOT
photosynthesize.

14. Animal Cells

15. Plant Cells
•Eukaryotic cell
that contains:
–large vacuole
–Cell wall
–chloroplasts
•Photosynthesizes
.

16. Plant Cells

17. Eukaryotic Cell Structure
Two major parts:
1. Nucleus- contains DNA
•Surrounded by the nuclear
envelope
•Chromatin- DNA bound to protein
•Chromosomes- condensed
chromatin before cell division
•Nucleolus- where assembly of
ribosomes begins

18. Eukaryotic Cell Structure
Two major parts:
2. Cytoplasm- portion of
cell outside the nucleus
•Ribosomes- small
particles of RNA that
assemble the proteins

19. Eukaryotic Cell Structure
•Lysosomes- “clean up
crew”
–Digests food
molecules.
–Destroys worn-out
cell parts.
–May destroy the cell.
–‘Suicide sac.’

20. Eukaryotic Cell Structure
•Vacuoles- saclike
structures that store
materials and in plants,
support heavy
structures like leaves
and stems

21. Eukaryotic Cell Structure
•Endoplasmic Reticulum
(ER)- “the factory” where
lipid components of the cell
membrane, proteins, and
other materials are made
–Rough ER- ribosomed
surface where proteins
are modified
–Smooth ER- no
ribosomes, contains
enzymes that perform
specialized tasks such
as making membrane
lipids or detoxifying
drugs

22. Eukaryotic Cell Structure
•Golgi Apparatus:
Modify, sort, and
package proteins and
other materials from ER
for storage in cell or
secretion outside the
cell (acts like a post
office)

23. Eukaryotic Cell Structure
•Mitochondria- converts
the chemical energy
stored in food into
compounds that are
easier for the cell to use
–Site of respiration.

24. Eukaryotic Cell Structure
•Chloroplasts:
–Found only in plant
cells.
–Site of
photosynthesis.
–Contains the
pigment chlorophyll.
–Appears green

25. Eukaryotic Cell Structure
Cytoskeleton- provides
structure- network of
protein filaments that
helps the cell maintain
its shape and helps in
movement

26. DO NOW:
Mark Notes and Summary to Cell
Structure Notes

27. Cell Membrane
•I can describe the cell membrane and
explain how materials cross the
membrane.
•I can differentiate between active and
passive transport.

28. Cell Boundaries
Cell membrane- the cell border
•Cell Membrane Function
–Separates the cell from its surroundings
–Regulates what enters & leaves the cell
–Provides protection & support
•Cell Membrane Structure
–Flexible, made up of 2 layers of lipids (fats) and is
called a lipid bilayer
–Mosiac- proteins embedded in the bilayer with
carbohydrate molecules attached to them (act as
“identification cards” allowing individual cells to
recognize one another)
www.biology4kids.com

29. Cell Boundaries
Cell Wall- present in many organisms including plants,
algae, fungi, & many prokaryotes.
NOT found in animal cells!
•Located outside the cell membrane
•Cell Wall Function
–Provide support & protection
•Cell Wall Structure
–Made from fibers of carbohydrate & protein (example:
cellulose in plant cell walls)
–Porous (holes) enough to allow water, oxygen, carbon
dioxide, and other substances to pass through easily
www.biology4kids.com
http://www.ucmp.berkeley.edu/plants/cells/elodeacell.jpg

30. Cell Boundaries
Diffusion Through Cell Boundaries
•Diffusion- the random movement of dissolved particles across
the membrane
–Movement from an area more concentrated to the area of
less concentrated
–Requires no energy
–Equilibrium- concentration of solute is same throughout the
system

31. Cell Boundaries
•Osmosis- movement of water through a selectively
permeable membrane (meaning, some substances can
pass through easily and some cannot).
•Water tends to move from high concentration of solvent
(low [solute]) to low concentration of solvent ( high
[solute]) until equilibrium is reached.
However, the water level on each side of the membrane
may not be the same!

32. Cell Boundaries
Osmosis
•Isotonic solution- when the concentration of water and
solute is the same on each side- equilibrium
–Cells placed in an isotonic solution will retain normal shape and
not gain or lose water
•Hypertonic solution- “above strength” meaning water
will move in to the side with the higher concentration
–Cells placed in a hypertonic solution will lose water and shrink.
In plants, you can see this when plants wilt.
•Hypotonic solution- “below strength” meaning water
will move away from the dilute side
–Cells placed in a hypotonic solution will swell. Animal cells may
burst, but plant cells are held by the cell wall
www.biology4kids.com
Plant Cells & Osmotic Pressure

33. Which cells are hypertonic, which are
hypotonic, and which are isotonic?
Hint: normal red blood cells (isotonic) are
slightly concave.
A
B
C

34. Cell Boundaries
Facilitated Diffusion
•The movement of molecules
across the cell membrane
through specific protein
channels
•Requires no energy because it
moves with the concentration
gradient (from high to low)
Active Transport
The movement of materials
against the concentration
gradient (from low to high)
•Requires energy
•Molecular Transport
–Molecules are carried by
proteins in the membrane
that act like “pumps”
•Endocytosis- taking in
–Phagocytosis- “cell eating”,
cytoplasm encloses around
substance
–Pinocytosis- tiny pockets
form at cell membrane and
make vacuoles that are
taken into cell
•Exocytosis- kicking out
–Vacuole surrounds material,
fuses with membrane, and
is forced out of cell

35. Chapter 7 Study Guide
•State the cell theory.
•Distinguish between prokaryotes and
eukaryotes.
•Describe how different microscopes work.
•Describe the structure of animal cells and plant
cells.
•Identify the organelles with a cell.
•Describe the function of the organelles.
•Describe osmosis, diffusion, and active diffusion.
•Describe what happened in a isotonic,
hypertonic, or hypotonic solution.