Transcript Unit 3 Photosynthesis & Cellular Respiration Notes

Unit 3: Cells Processes
(Photosynthesis &
Respiration)
I. Cell Energy
A.
ATP


All cells (plant, animal, bacteria, etc.) need
energy for active transport, cell division,
movement of flagella or cilia, muscle
contraction, etc.
Adenosine triphosphate (ATP) stores energy in
the chemical bonds between the 3 phosphate
groups. The third phosphate bond is weak and
when broken, releases energy
lesser/no energy
•
AMP = one phosphate group
available
•
ADP = two phosphate groups
B. Food you eat is digested to make the ATP you need.
Macromolecule
broken down
Energy released
Carbohydrate *
4 calories/mg
Lipid
9 cal/mg
Protein
4 cal/mg
* most commonly used
II. Photosynthesis

process where autotrophs convert sunlight into
chemical energy & supports virtually all life on Earth
energy stored as sugars which are used by
heterotrophs
occurs in plants and some algae
takes place in the chloroplasts, using chlorophyll

6CO2 + 6H20

Organisms that do NOT require sunlight to make
energy use chemosynthesis (convert chemical energy
to make energy storing carbon compounds). These
include archaebacteria in extreme environments like
deep ocean thermal vents.



C6H12O6 + 6O2
A. Light Dependent Reaction
1. occurs in thylakoid membrane of chloroplast
2. begins when energy from sunlight is absorbed by
pigments in photosystem II
3. H2O molecules are split into O2 (released), H+ and
high energy electrons (e-)
4. H+ ions build up in thylakoid and move through ATP
synthase into stroma, providing energy to make ATP
5. e- go through electron transport chain to photosystem I,
where they are accepted by NADP+ along with H+ to
form NADPH
B. Light Independent Reaction
1. also called Calvin cycle or dark reaction
2. occurs in stroma (fluid outside thylakoid) of
chloroplast
3. light not required
4. CO2 enters undergoes a series of reactions to build
high–energy compounds, (G3P then glucose) using
energy from ATP and NADPH (from the light
dependent reaction)
5. These sugars are either stored (as starch or cellulose)
or used by the plant for growth & development
II. Cellular Respiration
A. Overview/Equation




all organisms must breakdown compounds to
make ATP energy
cellular respiration involves the breakdown of
carbon containing molecules in the presence of O2
to make ATP in the mitochondria of eukaryotic
cells
C6H12O6 + 6O2
6CO2 + 6H20
(MEMORIZE!!)
it is a 3 step aerobic process that begins with
glycolysis
B. Glycolysis – anaerobic process where
glucose is broken down in cytoplasm of cells


Glucose is broken down into 2 simpler 3-carbon
molecules called pyruvate
2 molecules of ATP are also produced (only 2% of
total chemical energy in glucose)
C. Aerobic Respiration
1. Krebs cycle (Citric acid cycle) – if O2 is present, then
pyruvate moves into matrix of mitochondria
 Each pyruvate “turns” the Krebs cycle once,
releasing 3 CO2 and one ATP molecule (a net
of 6 CO2 and 2 ATP)
 Energy is transferred to next step
2. Electron Transport Chain



Occurs in cristae (inner membrane) of
mitochondria
ATP is produced (32 or 34 ATP) which is
used for multiple life processes
O2 is used and reacts with H+ and e- to make
H2O (6 O2 will produce 6 H2O)
D. Anaerobic Respiration (Fermentation)


occurs when not enough/no O2 is present in cells
does NOT make ATP, but allows glycolysis to
continue, which makes small amounts of ATP
1. Lactic acid fermentation – converts pyruvate
to lactic acid
•
occurs when muscles run out of O2 (during
intense exercise, etc.)
•
“burning” of muscles, soreness
•
lactic acid is diffused back into blood and
transported to liver where it is converted
back to pyruvate
2. Alcoholic Fermentation – converts
pyruvate to CO2 and ethanol (ethyl alcohol)
• used by yeast and some plants; CO2
makes breads rise, the ethanol evaporates
during cooking
• produces wines, beers and other ethanol
beverages
 Note: These are the 2 most common types of
fermentation. Bacteria use other types to produce
yogurts, cheeses and aid in digestion