Chap 8 .Cellular Transport and
the Cell Cycle
• To help keep you healthy,
–materials must be transported through
cell membranes, and
CHAPTER OBJECTIVES
• Be able to explain these processes :
• diffusion, passive transport, active transport, endocytosis
and exocytosis.
• Be able to explain why these are important to living cells
• Be able to predict the effect of a hypertonic, hypotonic or
isotonic solution on a cell.
• Be able to explain why cell size is limited
• Be able to sequence the events of the cell cycle.
• Be able to describe and illustrate the four stages of Mitosis
• Be able to explain how the Cell Cycle is Regulated.
• How are Cell Cycle Control and cancer related?
Section 8.1 Cellular
Transport
1. Osmosis
2. Passive Transport
3. Active transport
4.Endocytosis
5.Exocytosis
Diffusion
Fig. 5.8, p. 80
Osmosis
•Diffusion of water molecules
across a selectively
permeable membrane
Water in cells
• In a cell, water always moves to
balance concentration on both
sides of the cell.
• Helps maintain Homeostasis
.
• What affects osmosis?
• Solids
• solution:__________+ __________
• Concentration gradient: unequal
distribution of ______ on both sides of
a membrane.
Tonicity: Comparing solute
concentrations
Isotonic solutions:
equal
Hypertonic –more
Hypotonic - less
Tonicity and Osmosis
2%
sucrose
water
10% sucrose
2% sucrose
There is a concentration gradient
here
• .
compartment
1
compartment
2
HYPOTONIC
SOLUTION
HYPERTONIC
SOLUTION
membrane permeable to
water but not to solutes
fluid volume increases
In compartment 2
Fig. 5.23, p. 89
Osmotic Pressure
• Water enters cell –swells
• Exerts pressure on the cell
membrane
•
How does a plant cell
withstand this pressure?
• Animal cell?
WORK WITH YOUR SHOULDER PARTNER
FOR THE NEXT 5-7 MIN TO ANSWER THE
FOLLOWING 6 QUESTIONS.
1. What happens to cells (plant and animal) in a hypotonic solution?
2. Why does an animal cell burst?
3. What keeps a plant cell from bursting?
4. Why do plants wilt (hint, read p. 197 and 198)
5. What happens to cells (plant and animal) in a hypertonic solution?
6. What happens to cells (plant and animal) in an isotonic solution?
Follow directions for the foldable on
p. 195
• Using your text-p. 197, draw pictures in
your foldable of animal and plant cells in
• Isotonic solution
• Hypotonic solution
• Hypertonic solution
• Describe what is happening in each.
prepare a table in your notes
Type of Transport Transport Protein
Used?
SIMPLE
DIFFUSION
FACILITATED
DIFFUSION
ACTIVE
TRANSPORT
ENDOCYTOSIS
EXOCYTOSIS
Direction of
Movement
Requires Energy
Input From Cell?
Classification of
Transport
(active/passive)
Facilitated Duffusion
prepare a table in your notes
Type of Transport Transport Protein
Used?
Direction of
Movement
Requires Energy
Input From Cell?
Classification of
Transport
(active/passive)
SIMPLE
DIFFUSION
no
High to low conc
no
passive
FACILITATED
DIFFUSION
Yes
Channel or
carrier
High to low conc
no
passive
ACTIVE
TRANSPORT
Yes, carrier
(pump)
Low to high conc Yes
Yes
ENDOCYTOSIS
No
Active
Neither
Both
yes
EXOCYTOSIS
no
both
neither
2. Passive Transport
NO ENERGY NEEDED; DIFFUSION DOWN
CONC. GRADIENT.
2 TYPES:
• 1. Simple Diffusion: through lipid bilayer:
nonpolar (O2, CO2), water(small)
• 2. Facilitated Diffusion: using a transport
protein—2 kinds:
1. Channel Proteins
2. Carrier Proteins (change shape)
Carrier Protein : Facilitated diffusion
solute
Active Transport
•Solutes go against
concentration gradient
(from less conc. to more)
•Requires Energy
•Through a Carrier
Protein (called a pump)
Active Transport
• 1. Sodium Potassium PumpEnables cells to conduct nerve
impulses
• 2. Proton Pumps—These are the
key to cell metabolism—
(mitochondria and chloroplasts)
animation
Transport of Large Particles:
These both require energy.
•1.
Endocytosis- a cell surrounds and
brings in particles, or even whole cells.
2.
Exocytosis-The expulsion or
secretion of materials from a cell.
EXOCYTOSIS
The vacuole formed moves inside
the cell.
Section 8.2 Cell Growth and
Reproduction
• Cell Size Limitations
• Why can’t you be just one BIG CELL???
1.Diffusion
– Within the cell nutrients and waste move by
__________
• Not so effiecient over long distances!
More limitations…
• 2. DNA
– Cell can’t survive unless there is enough of it to
support the protein needs.
– WHAT DOES DNA HAVE TO DO WITH
PROTEINS ANYWAY?
Yet More Limitations!!
• 3. Surface area to volume ratio.
– As a cell’s size increases, the volume increases
at a much faster rate than its surface area.
1 mm cube
2mm cube
S.A
6x1x1= 6mm2
6 x 2x2=
V.
1mm 3
4 mm cube
Mitosis
• A type of nuclear
division.
• The process by which
2 daughter cells are
formed, each
containing a complete
set of chromosomes.
1. Prophase
• Longest phase
• Chromatin coils to form visible
chromosomes
• Nuclear envelope breaks apart
• Nucleolus disappears
• Centrioles (in animals) migrate
to opposite sides
• Spindle Forms;
• Aster visible in animal cells.
Sister chromatids become
attached to spindle fibers
at their centromere.
Sister Chromatids line up
at spindle equator.
Metaphase
Anaphase
• Sister chromatids
pulled apart
Telophase
• Chromosomes
unwind—back into
chromatin.
• New nuclear
envelopes form
around each set of
chromatin.
• Cytoplasmic division
CYTOKINESIS
• Different in plants and animals
• In Animals: a furrow forms and the cell pinches in 2
• In plants, a cell plate forms across the middle, them
membranes, then cell walls.
Results of Mitosis
• 2 new cells with chromosomes that are
identical to parent cell.
• Function identically to the parent cell.
Importance of Mitosis
• Single-celled organisms: reproduce this
way.
• Multicellular organisms:
– Enables formation of tissues and organs, and
organ systems
Section 8.3 CONTROL OF THE
CELL CYCLE
2 types of proteins involved in control:
1. Controlled by cyclins ( a protein)
2. A type of enzyme activates the cyclin.
Together, this activated cyclin regulates the cell
cycle.
Uncontrolled cell growth
• Tumor
– 1. Benign
– 2. Malignant
Cancer
•
•
•
•
Malignant tumor
Results from uncontrolled cell division
Cell cycle controls not functioning normally.
Results from changes in one or more genes
involved in production of proteins involved in
the cell cycle.
• May metestasize: travel via blood to other parts
of the body.
Causes
• Environmental
• Genetic
• Viral Infections (virus
may damage genes)
Cancer Prevention
• A healthy diet
• Fiber—reduce incidence
of colon cancer
• Fat moderation
• Vitamins A,C,E, bets
carotene (all
antioxidants)
• Minerals: calcium
• Exercise
Fluid-Mosaic Model
Cell recognition protein
..\Unit 3\Interactive
Animations.htm
..\unit 2 documents\animationsNa
K pump.htm
Example: Glucagon
• In this role, glucagon
is a Ligand
Fig. 5.24, p. 89
Protein Hormone binds with
surface receptor
GLUCAGON-Why does it not
just pass through the cell
membrane?
• Made of Protein—so it is
• Unable to pass through lipid
layer.
• Binds with cell receptor, but
does NOT enter cell.
Gated Channel
2. Voltage-Gated:
Respond so change in
Electrical current
:Sodium/Potassium- Nerve
Impulse Transmission
Concentration gradient
low
lipid
bilayer
.
P energy
input
high
DIFFUSION ACROSS
LIPID BILAYER
PASSIVE TRANSPORT
facilitated diffusion
ACTIVE
TRANSPORT
Lipid-soluble
molecules and
water molecules
diffuse across
Water-soluble molecules
and ions diffuse through
interior of transport proteins.
No energy boost required.
Specific solutes pumped
across, through transport
proteins against gradient;
requires energy boost
Fig. 5.25a, p. 91
Cell Membrane Semi-permeabl
• Permeable to :Small molecules:
H2O, O2, CO2, hydrophobic
molecules, small lipids
• Impermeable to : large polar
molecules,ions K=, Na+,
glucose, macromolecules,
proteins, carbs., DNA
Diffusion
Movement of molecules
from higher conc. to lower
concentration until =