Chapter #6 and 7
Photosynthesis and Cellular Respiration
The Need For Energy

Heterotrophs get energy from food

Heterotrophs require energy for all of
life’s processes
-digest food
-grow
-maintenance
-repair
-synthesis
ENERGY

All energy ultimately comes from the sun

Autotrophs
-producers

Heterotrophs
-consumers
ENERGY (2)
Photosynthesis
-stores the energy
 Respiration
-releases the energy
 Both photosynthesis and respiration
have an ATP-ADP Cycle
-provides the energy to the cells

ATP

Adenosine Triphosphate

Components:
-adenine, ribose, 3 phosphates
 Phosphorylation:
-process of freeing a phosate from ATP
(enzyme ATPase) making ADP
-ATP synthetase then reattaches the
phosphate group making ATP
ATP-ADP Cycle
Respiration

Process that releases chemical energy
from food

Occurs in ALL cells

Reactants
glucose, oxygen
 Products
carbon dioxide, energy, water
Photosynthesis

Process that converts radiant solar energy
into chemical energy stored in organic
molecules

Occurs in cells of autotrophs

Reactants
carbon dioxide, water, light
 Products
carbohydrates, oxygen
Basis of Photosynthesis

Absorption of Sunlight

Light Dependent Reactions

Light Independent Reactions (CalvinBenson Cycle)
(all occurs within the chloroplast)
Chloroplast

Chlorophyll
-light absorbing pigments

3 membrane system
-granum (stacks of thylakoid)
-stroma (fluid)
-increases the surface area for light
absorption
Light Dependent Reactions

Occurs in the Thylakoids (grana)

First Stage
-convert light to electrical energy using
electron transport chain (photosystem I)
-uses water, releases oxygen

Second Stage
-convert electrical energy to chemical energy
(ATP) (phtotsystem II)
Light Independent Reactions
(Calvin-Benson Cycle)





CO2 and ATP enter the stroma
Binds to RuBP(5 carbon molecule)
RuBP splits into PGAL (3 carbon sugar made
with the addition of Hydrogen from NADPH
and ATP)
PGAL generates 1 glucose and regenerates
RuBP to start the cycle over again
Completes 6 turns to get glucose (6 carbon
sugar)
Alternative Pathways

C4 (corn, sugarcane, crabgrass)
-more efficient at fixing carbon to form sugars
 CAM (desert plants)
-close stomata during the day to prevent
water loss
-trap carbon dioxide for the Calvin-Benson
Cycle at night
Cellular Respiration
Aerobic
-in the presence of oxygen
 Anaerobic
-occurs when oxygen is not present
-causes fermentation (alcoholic and
lactic acid)

Three Parts of Cellular
Respiration…
Glycolysis
 Kreb’s Cycle
 Electron Transport Chain

Three Parts of Cellular
Respiration…
Glycolysis
 Kreb’s Cycle
 Electron Transport Chain

GLYCOLYSIS
Occurs in the cytoplasm
 Turns glucose into pyruvic acid
 Net 2 ATP
-4 are made and two are used
 2 NADH
-electron carrier to be used during the
last step of respiration

KREB’S CYCLE
Pyruvic acid turns into Acetyl-CoA
-Produces 2 NADH
 Enters the mitochondria
 Produces
-2 ATP
-2 FADH2
-6 NADH

Products so far…
4 ATP
 10 NADH
 2 FADH2

Electron Transport Chain
2 FADH2 and 10 NADH enter the ETC
 1 FADH2 yields 2 ATP
 1 NADH yields 3 ATP


Total
-4 ATP from FADH2
-30 ATP from NADH
How many ATP from
respiration?
38 ATP
TOTAL
Fermentation
Occurs in the cytoplasm
 Lactic Acid
-muscle cells
 Alcoholic
-Yeasts
-Bacteria

Anaerobic Respiration
Respiration w/o oxygen
 Glycolysis

– Glucose broken down to pyruvic acid
(2ATP)
– Oxygen is needed for pyruvic acid to enter
the mitochondria so the process stops
• Pyruvic Acid breaks down to Lactic Acid
(animals)
• Pyruvic Acid breaks down to Alcohol (yeast)
CHROMATOGRAPHY