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Autotrophs & Heterotrophs
Photosynthesis
&
Cellular Respiration
Autotrophs
Heterotrophs
• Able to use light
• Cannot use the sun’s
energy from the sun
energy directly
to produce food
• Obtain energy from
• EX. plants
the foods they
consume
• EX. Humans
Metabolism
ATP: The Unit of Cellular Energy
CELLULAR
ENERGETICS
The processes of
• ATP (Adenosine triphosphate)
• All of the chemical reactions in a cell
–PHOTOSYNTHESIS
•Light energy from the Sun is converted to
chemical energy for use by the cell.
–CELLULAR RESPIRATION
•Organic molecules are broken down to release
energy for use by the cell.
 Releases energy when the
bond between the second
and third phosphate
groups is broken, forming
a molecule called
adenosine diphosphate
(ADP) and a free
phosphate group.
ATP
ATP: The Unit of Cellular Energy
• ATP is a full battery compared to ADP,
but glucose can store 90 times as much
energy as ATP
• Glucose is the preferred compound to
store energy for longer periods of time.
• ATP
– Adenosine tri phoshate
(contains adenine, ribose, and
3 phosphates)
– Charged battery
• ADP
– Adenosine di phosphate
(contains adenine, ribose, and
2 phosphates)
– Uncharged battery
ATP and Glucose
ATP
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PHOTOSYNTHESIS OVERVIEW
• Photosynthesis occurs in the CHLOROPLAST
• Photosynthesis occurs in two phases:
–Light-dependent reactions
–Light-independent reactions
PHOTOSYNTHESIS - PHASE ONE
• Light-dependent reactions
–The absorption of light is the first step in
photosynthesis
–Chloroplasts capture light energy
• BALANCED chemical equation:
PHOTOSYNTHESIS – PHASE ONE
(continued)
• Electron Transport Chain
–Light energy excited electrons in Photosystem
II and also causes a water molecule to split.
•This releases
–an electron into the electron transport system
–H+ into the thylakoid space
–O2 as a waste product
PHOTOSYNTHESIS – PHASE ONE
(continued)
• Excited electrons move from Photosystem II to an
electron-acceptor molecule in the thylakoid
membrane.
• The electron-acceptor molecule transfers the
electrons along a series of electron-carriers to
Photosystem I.
• Photosystem I transfers the electrons to a protein
called ferrodoxin.
PHOTOSYNTHESIS - PHASE TWO
• Light-independent reactions
(a.k.a DARK reactions)
–The Calvin Cycle
During this phase,
energy is stored in
organic molecules
such as glucose.
– Ferrodoxin transfers electrons to the electron carrier
NADP+ … forming the energy storing molecule NADPH.
2
PHOTOSYNTHESIS - PHASE TWO
(continued)
• The Calvin Cycle Process
 Six CO2 molecules
combine with six 5-carbon
compounds to form twelve
3-carbon molecules called
3-PGA.
 The chemical energy
stored in ATP and NADPH
is transferred to the 3-PGA
molecules to form highenergy molecules called
G3P.
CELLULAR RESPIRATION OVERVIEW
• Cellular Respiration occurs in the
CYTOPLASM & MITOCHONDRIA
• Cellular Respiration occurs in two phases:
PHOTOSYNTHESIS - PHASE TWO
(continued)
• The Calvin Cycle Process
 Two G3P molecules leave
the cycle to be used for the
production of glucose and
other organic compounds.
 An enzyme called rubisco
converts the remaining ten
G3P molecules into 5-carbon
molecules called RuBP.
 These molecules combine
with new carbon dioxide
molecules to continue the
cycle.
CELLULAR RESPIRATION
OVERVIEW
– Glycolysis
– Aerobic Respiration
•Consisting of the Krebs Cycle and the Electron
Transport Chain
• BALANCED chemical equation
•
What do you notice about this equation compared to the balanced chemical equation for Photosynthesis?
CELLULAR RESPIRATION – PHASE ONE
CELLULAR RESPIRATION – PHASE TWO
• Glycolysis
• Aerobic Respiration
–Glucose is broken down IN THE CYTOPLASM
–For each molecule of glucose that is broken
down,
•Two molecules of ATP are formed
•Two molecules of NADH are formed
•Two molecules of pyruvate are formed
– Starts with the Krebs Cycle
•Most of the energy from
the glucose is still
contained in the pyruvate.
•The series of reactions in
which pyruvate is broken
down into carbon dioxide is
called the Krebs cycle.
•The net yield from the
Krebs cycle is six CO2
molecules, two ATP, eight
NADH, and two FADH2.
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CELLULAR RESPIRATION – PHASE TWO
• Aerobic Respiration
–Ends with the Electron Transport Chain
•Final step in the breakdown of glucose
•Point at which ATP is produced
•Produces 32 ATP
ANAEROBIC CELLULAR RESPIRATION
• Anaerobic Respiration
–The anaerobic pathway that follows glycolysis
(when not enough oxygen is present to enter
the Krebs Cycle)
•Two main types
–Lactic acid fermentation
–Alcohol fermentation
ANAEROBIC CELLULAR RESPIRATION
• Lactic Acid Fermentation
– Occurs in animal cells when not enough Oxygen is present
to go through Cellular Respiration
– Occurs in the Cytoplasm
• Pyruvic acid is broken down by enzymes into CO2 and lactic
acid
• Releases 2 ATP molecules
– Lactic acid builds up creating “oxygen debt” and leaving
muscles sore.
• Taking IN O2 breaks down lactic acid causing soreness to
subside.
ANAEROBIC CELLULAR RESPIRATION
• Alcoholic Fermentation
– Occurs in yeast cells when not enough Oxygen is present
to go through Cellular Respiration
– Occurs in the Cytoplasm
• Pyruvic acid is broken down by enzymes into CO2 and
alcohol
• Releases 2 ATP molecules
– Alcohol can build up until it becomes toxic and may kill
the yeast.
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