Download Photosynthesis and Cellular Respiration

Photosynthesis and
Cellular Respiration
Energy Use in Living Organisms
 Step 1
 Convert sunlight
energy into chemical
food energy
 Ends in Glucose
 Step 2
 Convert chemical food
energy into chemical
energy that the cell
can use
 Ends in ATP
Adenosine Triphosphate (ATP)
Ribose
Three phosphate
Adenine
groups
Energy Cycle
• ATP is a charged battery for
cell
• Made during cellular
respiration
• Used up to complete activities
for cell
• Energy in ATP is stored in
high energy bonds between
phosphate groups
ATP
• ADP is a used battery for cell
• one phosphate has been
removed
• Phosphate must be added
back on to recharge battery
ADP
ATP and ADP
What do Plants do?
 Plants do step 1
with chloroplasts
 Plants do step 2
with mitochondria
 Because plants
make their own food
and then eat it, they
are called
autotrophs
What do Animals do?
 Only do step 2
with
mitochondria
 Because
animals must
eat food that
others have
made, they are
called
heterotrophs
Step 1: Photosynthesis
 Convert sunlight energy into
glucose
 Chloroplast performs
photosynthesis
 Plants, algae, some bacteria,
and some protists all perform
photosynthesis
 Overall reaction

6CO2 + 6H2O → C6H12O6 + 6O2
 Occurs in two stages
 Light dependent reactions
 Light independent reactions
Chloroplast
 Found only in Plant cells
 Thylakoid- coin-shape structure containing
chlorophyll and proteins; also called photosystems
 Grana- stacks of thylakoids
 Stroma- fluid inside chloroplast (similar to cytoplasm)
Light Dependent Reactions
 Energy from sunlight is absorbed by chlorophyll and other
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pigments in the thylakoid membrane
Water is split into oxygen (given off as waste), H+, and
electrons
Electrons go through a series of proteins in the membrane
called the electron transport chain
Electrons provide energy for hydrogen protein pumps to pump
H+ into the thylakoid
More sunlight energy is absorbed
Electrons are added to NADP+ to create NADPH
Hydrogen ion diffuse through another membrane protein
The diffusion fuels the production of ATP by the enzyme ATP
synthase
Light Dependent Reactions
Light Independent Reactions
 Occurs in the stroma
 Also called the Calvin cycle
 Is a series of reactions controlled by enzymes
 The ATP and NADPH made during the light
dependent reactions are used to fuel the reactions
 CO2 provides the carbon used to make the sugars
 Simple sugars (primarily glucose) are made during
the cycle
Light Independent Reactions
Factors that Affect Photosynthesis
 Water
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Water shortages can slow or stop
photosynthesis
Plants in dry climates
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Waxy coating
Thin leaves (needles on cactus)
 Temperature

Low temps slow or stop photosynthesis

Enzymes do not work well at low temps
Factors that Affect Photosynthesis
(cont)
 Light Intensity/Amount
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Increase in light, increase in photosynthesis
until at maximum level
Plants still perform photosynthesis in periods
without light
 Density of Other Plants
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Crowded plants complete for light and
resources
Reduces photosynthesis
Cellular Respiration
 Convert glucose into ATP
 Mitochondria performs cellular respiration
 All organisms
 Process is called aerobic because it requires
oxygen
 Overall reaction

C6H12O6 + 6O2 → 6CO2 + 6H2O
Mitochondria
 Found in animals
and plants
 Outer and Inner
membrane
 Cristae- folding of
inner membrane
 Matrix- area inside of
inner membrane
Glycolysis
 Occurs in cytoplasm of
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cell
Anaerobic (oxygen not
needed)
2 ATP’s are used to
start the process
Glucose (a 6 carbon
sugar) is broken into
two three carbon sugars
4 ATP’s, 2 NADH’s, and
2 pyruvates are made
What comes next?
 With oxygen
 Other
processes of
cellular
respiration
occur in the
mitochondria
 Without oxygen
 Fermentation
occurs in the
cytoplasm
Krebs Cycle
 Occurs in the matrix
 Pyruvate is broken into a 2 carbon molecule
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producing 2 NADH and CO2
Coenzyme A attaches to the 2 carbon molecule and
enters the Krebs cycle
It is converted into citric acid
Citric acid is broken down through a series of steps
producing 3 more NADH’s. one ATP, one FADH2,
and two more CO2’s
Two turns of the cycle are needed to process the 2
pyruvates from glycolysis
Krebs Cycle
Electron Transport Chain
 Occurs along the inner
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membrane of the
mitochondria
Electrons from NADH and
FADH2 are used
Electrons fuel hydrogen
protein pumps which pump
H+ out of the matrix
H+ diffuses through a
membrane protein and fuels
ATP production by ATP
synthase
Oxygen picks up the
electrons and H+ to form
water
Summary of Cellular Respiration
Fermentation
 Occurs when oxygen in
unavailable
 In humans occurs as
lactic acid fermentaion
(some yeast and plants
do alcohol fermentation)
 Pyruvates are
converted to lactic acid
and NAD+ is formed
 No more ATP are
produced
Comparison
Ps
Rs
Function
Make food for plants
Make energy for ALL
organisms
Location in
cell
Chloroplast
Mitochondria
Uses what?
Water, CO2, Sunlight
Oxygen,
Food/Glucose
Makes what?
Oxygen,
Food/glucose
Water, CO2,
Energy/ATP