Chapter 4: The Internal
Environment of Organisms
Section 1: Cell
Structure
Eukaryote
animal cells
Prokaryote
bacteria cells
Eukaryote
plant cells
Bacterial cell
• Prokaryotic—what’s missing?
• NUCLEUS and MEMBRANE BOUND
ORGANELLES
Human
Animal Cell - Eukaryotic
Cell Organelles
5. Nucleus—brain of cell,
DNA, genetic code
6. Nuclear membrane—
surrounds the nucleus
7. Nucleolus—makes the
ribosomes
8. Ribosomes—make the
proteins
9. Proteins—product of
the cell
Cell Organelles
mitochondria
9. Cell membrane—surrounds the cell
10. Mitochondria—powerhouse of the cell
11. Lysosomes—get rid of waste products
More Organelles
12. Golgi apparatus—
packages and
distributes
13. Microtubule—
hollow tube that helps
define the shape of
the cell
14. Cytoplasm—all of
the fluid in the cell
and organelles except
for the nucleus
More Organelles
15. Vacuole—holds
fluids
a. Plants have a
large central vacuole
b. Protists have a
food vacuole (digests
food) and a
contractile vacuole
(expels wastes)
More cell organelles
16. Endoplasmic reticulum—highway of the
cell
a. Smooth ER—no ribosomes
b. Rough ER—with ribosomes
ER
Plant Cells
Plant Cell
chloroplast
Plant Cell Organelles
17. Cell Wall—support, allows plants to
grow
18. Chloroplast—site of photosynthesis
• Cells: The Basic Units of Life
Section 2: The Cell
Membrane and Cell Transport
Cell Membrane
• Continuous membrane that completely
surrounds the cell
• Thin, nearly invisible
• Surrounds the cytoplasm
• Creates structure
It’s like a big plastic
bag with some tiny
holes.
Membrane structure
• Phospholipid bilayer
– Fat molecules are arranged in 2 layers
– Two regions:
Hydrophilic =
water-loving
Hydrophobic =
water-fearing
Phospholipids
• Hydrophilic head – “water loving”
– Likes polar substances
– Example: water
• Oxygen wins the tug-of-war with the
electrons, H becomes slightly positive.
Phospholipids
• Hydrophobic tail – “water fearing”
– Likes non-polar substances
– Ex: Fats
Electrons are the same on all sides.
Draw the phospholipid bilayer
Membrane Structure
• Embedded within the phospholipids there
are functional proteins and transport
proteins.
There are two types of
Functional Proteins
a. Marker Proteins
- identify the cell to other cells
- used by the immune system to identify self cells from
foreign invaders
- important in organ transplants
Functional Proteins
b. Receptor Proteins
- used in communication between cells
- allow the cell to receive instructions
When a hormone binds
to the receptor the
receptor protein
releases a signal to
perform some action.
Transport Proteins
a. Channel Proteins
- Move materials through the cell
- Acts as a passive pore (NO energy)
- Molecules move randomly in and out
- Facilitated diffusion
- must use a protein channel to move molecules!
Transport Proteins
b. Carrier Proteins
- does NOT require energy
- do not extend through the membrane
- bond and drag molecules through the lipid bilayer
- one molecule at a time
Transport Proteins
c. Active Transport Pumps
- require energy (ATP)
- move molecules from area of low concentration to an
area of high concentration
- working against diffusion
Example: Sodium-potassium pump
ATP
Na+ (moving out)
K+ (coming in)
Other Membrane Transports
• Phospholipid bilayer is Semi-permeable
– allows small non-polar molecules and ions to
pass freely through the cellular membrane
• Semi-permeability allows two additional
types of membrane transport:
– Diffusion
– Osmosis
Diffusion
• Passive movement of
molecules without
assistance from
membrane proteins
– does NOT use energy
• Molecules must be
traveling from an area
of high concentration to
an area of lower
concentration.
– With the concentration
gradient
Osmosis
• Movement of water across a cell
membrane without assistance from
proteins.
– Diffusion of water
• WARNING: OFFICIAL DEFINITION
• Water moves from areas with a low
concentration of solutes to an area with a
high concentration of solutes.
– Solutes cannot freely cross the membrane like water
Osmosis
• EASIER DEFINITION:
• Water moves from high concentrations of
water to low concentrations of water.
• Why does the water move?
– Solutes cannot freely cross the membrane like water
Diffusion and Osmosis Movie
What About Large Molecules?
• Transport proteins, osmosis, and diffusion
can ONLY move small molecules.
• Large molecules can not enter or exit the
cell without disrupting the membrane
• Examples of large molecule movement:
• Steroids (in)
• Waste products (out)
Transport of Large Molecules
• Endocytosis (moving in)
– cell membrane engulfs
structures too large to fit
through the pores or
proteins
– membrane itself wraps
around the particle and
pinches off a vesicle
inside the cell
Transport of Large Molecules
• Exocytosis (moving out)
– Large molecules that
are manufactured in the
cell are enclosed in a
vesicle and released
through the cell
membrane.
– opposite of endocytosis
Venn Diagram
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Fill in the Venn Diagram on types of transport
Exocytosis
Endocytosis
Channel protein
Carrier protein
Facilitated diffusion
High to low concentration
Active transport pump
Diffusion
Osmosis
Moves molecules across membrane
Low to high concentration
Sodium potassium pump
Does not use energy
Uses energy
Onion cell LAB
• Cell wall is sturdy  supports the cell
• Cell membrane within
Onion cell in hypertonic solution
• Hypertonic solution  lots of NaCl
molecules in water
• Water pulled out
• http://www.csun.edu/scied/7microscopy/elodea_plasmolysis/index.htm
Salt on grass
• Salt concentration more outside than
inside.
• To balance it out water is the only
molecule that can come out readily.
• Water comes out and the cells die.
• Salt can not come out on its own.
Animal and plant cell
• Osmotic pressure very important in plants
ANIMAL Cheek cells
• Shape
• Structure
Frog Blood Cells
• What does the frog blood look like?
• Simply Science – Matter and Energy on
the Move
The
Case:
The Coast Guard discovered two bodies, a man
and a woman, in the salt water of the San
Francisco Bay. Both victims apparently drowned;
their lungs were filled with water. Your job as the
coroner will be to determine where the victims
drowned and whether the victims died of
accidental drowning or were victims of murder. To
help you in your determination, you have taken
blood samples from both victims. You must
interpret the findings from these blood samples to
solve the mystery.
What do we know?
- bodies were found in water
What do we want to know?
- was this the water they drowned in?
Let’s Review: Diffusion
• Net movement of particles from an area where there
are many particles of the substance to an area where
there are fewer particles of the substance
• Passive movement from [high]  [low]
• Think of a large room and a crowd of people
v
v
v
v
v
v
v
v
v
v
v
Osmosis
Diffusion of Water Across a
Selectively Permeable
Membrane
- Particles are TOO LARGE to cross
2 Liters water : 4
solutes
2 Liters water : 8
solutes
Diffusion of Water
Osmosis
Water is the only thing
that can cross the
membrane
- Water tries to even out the
“particle concentration.”
(Dilution)
1 Liter water : 4
solutes
2 Liters water : 8
solutes
* Inside and outside of cell
have same concentration of
solute
Isotonic
Iso = equal
-tonic = tension
- Equal tension on the cell
- Which way will water move?
Water
moving
out
Water
moving
in
What effect will this have on the
shape of the cell?
Same size!
* concentration of solute
outside the cell is greater
than concentration
inside cell
Hypertonic
Hyper= more
-tonic = tension
- More tension on the cell
- Which way will water move?
Water
moving
out
What effect will this have on
the shape of the cell?
Cell will shrink!
* concentration of solute
outside the cell is LESS
than concentration
inside cell
Hypotonic
Hypo = less
-tonic = tension
- Less tension on the cell
- Which way will water move?
Water
moving
in
What effect will this have on the
shape of the cell?
Cell will get bigger—maybe burst!
Lose mass
Same mass
Gain mass
How might we use this information
to investigate this case?
• You have blood samples
• Knowledge of Fresh & Saltwater
– Fresh water has _______
Less solutes then RBCs
– Salt water has _______
More solutes then RBCs
• How do we measure osmosis in the body?
– Measure the concentration of solutes in the blood
More water= less solutes
Less water = more solutes
• What solutes might we test to investigate?
– Sodium, Potassium, Chloride
– YOU FIGURE IT OUT NOW! 
BLOOD
SALT
WATER
Hypertonic
Water
BLOOD
SALT
WATER
The Dead Sea
Can this be dangerous?
Hypotonic
FRESH
WATER
BLOOD
Gaining Water = Gaining Mass
By looking at a body how would you be able to tell the
person drowned in fresh water?
• Human Body Systems – The Excretory
System
Section 3:
Urinary System
Multicellular organisms
• What is exchanged
in your body?
– O2
– CO2
– Nutrients
– Waste
• They move by
OSMOSIS &
DIFFUSION!
Need for interconnected cells
• Organ system
– Group of organs that
works together to
perform a common
function
Osmosis in Action
• What happens when
you sweat?
– You lose water and salt
• Why do sweat
glands excrete
salt? Hint: if the
sweat glands
excrete salt, where
will water go?
Osmosis in Action
• Sweat gland control how
much salt they contain in
order to control how much
water is lost in the sweat.
– Less salt = less sweat
– More salt = more sweat
Dispose of wastes
• Metabolic wasteschemical wastes
• Urinary system
Urinary system
• Ammonia- is a toxic
substance in cell waste
produced when protein is
broken down
• If accumulated – life
threatening illness
• Liver- converts ammonia
to urea
• Nontoxic substance now
removed by kidney – lots
of osmosis and diffusion
happening!
Kidneys
•
Main waste
removing organ of
urinary system
1. Filters urea
2. Restores balancewater and salts
3. Produces enzyme
renin that helps
monitor blood
pressure
Inside Kidney
• Renal artery
• Blood cleaned
• Returned to renal
vein
• Urine formednephron
Urine formation
• In nephron—there
are one million
nephrons in each
kidney.
• Filtration
• Reabsorption
• Secretion
Filtration
• In glomerulus
• High blood pressure
in capillary beds –
pushes out solutes
• 125 ml (1/2 cup) of
plasma cleaned
every minute
• No kidney- 2 gallons
water / hour
• 99% of fluid is reabsorbed
Reabsorption
• Proximal tubule
• Active transport of
sodium, sugar, and
vitamin D (to maintain
healthy bones)
• Sets up a
concentration gradient for next step
Loop of Henle
• Water is reabsorbed
into blood by osmosis
– Conc. gradient was
set up by previous
step
Secretion
• Distal tubule &
collecting duct
• Na/K, Na/Ca Pumps
• More water
reabsorbed into blood
• Maintain pH levels
in the body
• Collecting ducts
carry urine to be
excreted
Filtration, Reabsorption, and
Secretion
• All three of these keep the blood at the
right composition and safely removes
wastes in the body to keep you at
homeostasis.
What can damage a kidney?
•
•
•
•
•
Infection
Diabetes
High blood pressure
Autoimmune disease
Household chemicals—paint, varnishes,
furniture oil, lead, or aerosal sprays—
through the gastrointestinal tract, lungs, or
skin.
Dialysis-artificially filter the
blood
• Use if kidneys are
damaged that may
eventually heal or
replaced by a kidney
transplant.
• Works by passive
transport
• Animation