unit 3: cell processes union academy charter school
TRANSCRIPT
UNIT 3: CELL PROCESSES
Union Academy Charter School
Cells must maintain homeostasis
Cells maintain homeostasis by letting specific things in or out of the cell.
The cell membrane is selectively permeable!
O2, CO2, non-polar (fat soluble) molecules
Glucose, water, ions (Na+), polar (water soluble) molecules
Outside the cell
Inside the cell
Transport protein
Why aren’t cells big?
Surface area to volume ratio! The higher the better!
More membrane per unit of cytoplasm allows molecules to move throughout the cell
much faster.
Diffusion of molecules
Diffusion – when molecules move from high to low concentration without using energy.
Other examples?
Cells use diffusion
Diffusion – when molecules move from high to low concentration without using energy.
High concentration
Low concentration
Cells use diffusion
Since diffusion uses no energy we call it passive transport. Some diffusion is facilitated (helped) by proteins.
Osmosis - diffusion of water
Osmosis – when water moves from high to low concentration without using energy. Sometimes other molecules are too big so water
has to move!water sugar
The volume
increases on the right!
What would this do to a
cell??
Osmosis in the cell
Cells can be exposed to 3 types of solutions: Isotonic – same amount of solute on both
sides. Hypotonic – less solute outside the cell. Hypertonic – more solute outside the cell.
Osmosis in the cellRed blood cells
Plant cells
Isotonic solution
normal cell
normal cells
Hypotonic solution
normal turgid cell
cells swell, burst
This is why we
use saline!
Hypertonic solution
cytoplasm shrinks from cell wall
shriveled cells
This is why we can’t
drink salt water!
Diffusion/osmosis problem setup Some problems will use a U-tube.
This could be used for diffusion or osmosis. There is a semipermeable membrane.
Sometimes molecules can fit through, sometimes only water.
membrane
TimeH2O
red dye
Diffusion Osmosis
Diffusion/osmosis problem setup If osmosis occurs, what will move, and in
which direction?
Diffusion/osmosis problem setup If diffusion occurs, what will move, and in
which direction?
Diffusion/osmosis problem setup If osmosis occurs, what will move, and in
which direction?
Diffusion/osmosis problem setup If osmosis occurs, what will move, and in
which direction?
10% salt
60% salt
50% salt
40% salt
90% water
40% water
50% water
60% water
What if the cell wants to move something from low to high concentration?
Active transport – cells use energy (ATP) to move molecules from low to high concentration. Ex. Stomach acid.
Active transport in action!
Bulk transport: Endocytosis: Using energy to bring something
into the cell. Phagocytosis: Cell eating Pinocytosis: Cell drinking Receptor-mediated endocytosis: Cell surface receptors bind to
something and pull it in.
Exocytosis: Using energy to push something out of the cell.
plasma membrane
Inside
Exocytosis
Active transport in action!
A paramecium lives in fresh water but likes to be salty inside! Uses a contractile vacuole to pump water out.
Passive vs. active transport
No energy used High to low Ex: O2 into blood
cells.
Energy used Low to high Ex. Stomach acid.
Passive Active
Photosynthesis – in the chloroplast Light + 6H2O + 6CO2 C6H12O6 + 6O2
Reactants Products
Cellular respiration – in the mitochondria
C6H12O6 + 6O2 6H2O + 6CO2 + 36ATP
cristae
doublemembrane
outer membrane
inner membrane
matrixglucose
oxygen
carbon dioxide
water
energy (ATP)
Notice that this is the photosynthesis equation flipped!
Reactants Products
Aerobic respiration – use of oxygen to make energy.
WARM UP 2/23/15 Write the photosynthesis equation using
words. Write the photosynthesis equation using
chemical formulas (ex: 6CO2 instead of carbon dioxide).
Write the cellular respiration equation using words.
Write the cellular respiration equation using chemical formulas.
How do we use ATP?
ATP (adenosine triphosphate): our energy currency. We use it by breaking one phosphate from
the end. This leaves ADP and Pi (inorganic phosphate).
These pieces are recycled!
Photosynthesis and respiration work together!Energy Conversions
chloroplast
mitochondrion
ATPChemical work Transport work Mechanical work
solarenergy
heat
CO2 and H2O
O2
Chemical energy (carbohydrate)
heat
What if there isn’t any oxygen? Even without oxygen, organisms can
break down glucose and make energy – anaerobic respiration.
glucoseLactic acid fermentation Alcoholic fermentation
2Lactic acid + 2ATP 2Ethanol + CO2 + 2ATP
Aerobic vs. Anaerobic recap
Aerobic respiration – uses oxygen. Carried out by most eukaryotes when they have
sufficient oxygen. Aerobic respiration: C6H12O6 + 6O2 6H2O + 6CO2 + 36ATP
Anaerobic respiration – does not use oxygen. Carried out by prokaryotes and some eukaryotes like
yeast. Lactic acid fermentation: C6H12O6 2Lactic acid + 2ATP Alcoholic fermentation: C6H12O6 2Ethanol + 2CO2 + 2ATP
WARM UP 2/24/15 Which organism is most likely to use
anaerobic respiration?a. Mouse b. bird c. tree d. yeast
Which produces more ATP, aerobic or anaerobic respiration?
If you have more CO2 in the air, how will that affect the rate of photosynthesis?
We use fermentation to make products
yeast