Download Objective for today

Objective for today
Metabolism
 Photosynthesis
 Cellular Respiration

Metabolism
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What is metabolism?
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Why do we need all those chemical reactions?
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The sum of all chemical reactions occurring in the
body.
There are lots of jobs that must be done to keep us
alive! Breathing, digestion, movement, thinking,
immunity, growth, etc.
All those reactions require energy. Where do
we get the energy from?
ENERGY:

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We get the majority of our energy from our
FOOD
Energy is released from the GLUCOSE in food
Every time a bond is broken ENERGY is
RELEASED
Glucose is broken down into 2 molecules of
pyruvic acid in the cytoplasm of the cell
2 Molecules of Pyruvic Acid move into the
mitochondria and are broken down into
Carbon Dioxide
2 Laws of Thermodynamics

1st Law: Energy cannot be created or
destroyed, but it can change from one form to
another.
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Solar, chemical, mechanical, heat energy, etc.
2nd Law: When energy changes forms, some
of the energy is wasted or lost as…

HEAT!
Living things depend on the Sun!
(wasted energy)
(wasted)
(stored in
glucose)
(wasted)
(Used for
Movement)
Two Types of
organisms

Autotrophs

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Make their own energy containing
molecules
Two types:
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Photosynthetic: use the sun
Chemosynthetic: use inorganic chemical
reactions
Heterotrophs

Can’t make their own food; do “take out”
Photosynthesis

Solar energy + 6CO2 + 6H2O  C6H12O6 + 6O2
(carbon (water)
dioxide)

(glucose)
(oxygen)
Reactants: solar energy, carbon dioxide and water

CO2 and H2O diffuse into the plant cell.

Products: high energy glucose and oxygen

Photosynthesis transforms solar energy into
the chemical energy of a carbohydrate.

The photosynthetic process takes place with
organelles called chloroplasts.
Photosynthesis:
2 sets of reactions

Light reactions

Solar energy
Chemical energy
(ATP, NADPH)

Calvin Cycle reactions (aka Dark reactions)

Chemical energy
Chemical energy
(ATP, NADPH)
(carbohydrate)
C6 H12 O6
Sun + 6CO2 + 6H2O  C6H12O6 + 6O2
Solar energy can be
converted to chemical
energy.
Spot the Dog: See Spot Run
This chemical energy
can be stored in the
covalent bonds that
hold together the
atoms in a molecule of
glucose.
Chemical energy can
be converted to
mechanical energy.
See Spot run! 
Chemical energy is
stored in each of
these covalent
bonds.
Before an organism can use the
chemical energy in glucose, the
energy must be stored in ATP.
 ATP is the “currency” of cellular
energy.
 ATP directly supplies the energy
necessary for nearly all chemical
reactions in the body.

ATP:

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Adenosine
Triphosphate
nucleotide
Very high energy bonds between
phosphate groups (like charges repel)
ATP

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Chemical energy is stored in the high energy
bonds that hold the phosphate groups together
in the ATP molecule.
When ATP is broken down, a phosphate group
is released along with free energy that can be
used for metabolism.
Functions of ATP
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Chemical work: ATP supplies the energy needed to
build organic molecules in the cell.
Transport work: ATP supplies the energy to pump
substances across the cell membrane.
Mechanical work: ATP provides energy for
movement. (muscle contraction, flagella,
chromosome movement during mitosis, etc.)
Exergonic =
releases energy
So how & where is ATP formed?
Outside the mitochondria…

Glycolysis:

Glucose (6 carbons) is converted to pyruvate (3 carbons)
Energy input 2 ATP  4 ATP made  net gain of 2 ATP

P.S. Don’t
memorize this
diagram!
(glyco = sugar; lysis= breakdown)
Inside the mitochondria…

Krebs cycle (aka Citric Acid cycle or TCA cycle)
Big Picture:
Organic molecules from glycolysis
enter the mitochondria. These
molecules are processed in the
Krebs cycle. The products of the
Krebs cycle are:
• Carbon Dioxide (waste product)
• ATP (used for energy)
• etc.
•Net gain of 2 ATP
Don’t memorize this diagram!
Cellular Respiration
Cellular
respiration is
the process of
breaking down
glucose to
produce
carbon dioxide
, water and
ATP.
Aerobic
respiration
requires
oxygen and
produces 32
ATP molecules
per glucose.
Anaerobic
respiration (aka
fermentation) does
not require oxygen.
It is a less efficient
process than aerobic
respiration,
producing only 2 net
ATP.
The products of
fermentation include
either lactate or
alcohol.
When our muscles
need more oxygen
than they are
supplied, cellular
respiration becomes
anaerobic. Lactic
acid is released as a
waste product.
Fermentation
(AKA anaerobic respiration)
What happens to the products of the
Krebs cycle?
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ATP is used as an energy source.
Carbon dioxide exits the cell by diffusion.
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Eventually, it will diffuse into the bloodstream.
After that, CO2 will diffuse from the bloodstream
into the alveoli of the lungs.
Then, it is released into the atmosphere by
exhalation.
Plants will absorb the carbon dioxide to use in the
photosynthetic process all over again.
Big Picture

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Organisms require energy for metabolism.
That energy ultimately comes from the sun’s
energy stored in the chemical bonds of
glucose, produced by photosynthesis.
Mitochondria within cells have the machinery
necessary to turn that glucose into ATP that the
cell can use for energy.
Living things depend on the Sun!
(wasted energy)
(wasted)
(stored in
glucose)
(wasted)
(Used for
Movement)
Hmmmmmmmmm

Photosynthesis
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CO2 + H2O + sunlight energy > glucose + O2
Cellular respiration
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Glucose + O2 > CO2 + H2O + ATP energy
Bromothymol Blue

Used to test for the presence of carbon dioxide
(CO2)

If CO2 is present it is a yellow color

If CO2 is NOT present it is a blue color