Download Photosynthesis and Cellular Respiration

Energy and Life
Energy= the ability to do work
Autotrophs= use sunlight, CO2 , and water to
make their own food (sugars) 
PHOTOSYNTHESIS
Heterotrophs= can’t make their own food, they
have to eat autotrophs to stay alive!
ATP
ATP= (Adenosine Tri-Phosphate) the energy
storage molecule used by most organisms
It is the usable version of a cells energy
ATP gets broken down to release energy in the
Mitochondria
Photosynthesis
CO2 + H2O + Sunlight ----------- C6H12O6 + O2
Chlorophyll= pigment inside the chloroplast
that absorbs sunlight
Light Reactions= Convert light energy to
ATP (during the day)
Dark Reactions= Convert CO2 + H2O to
sugars (at night)
Light Reactions
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Light Reactions = (Photophosphorylation)
Convert light energy to ATP (during the day);
takes the energy in light and the electrons in
water to make the energy rich molecules ATP
and NADPH
H20 + ADP + Pi + NADP+ + light  ATP +
NADPH + O2 + H
Dark Reactions
●
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Dark Reactions = (Calvin – Benson Cycle)
Convert CO2 + H2O to sugars (at night); takes
CO2 from the atmosphere and the energy in
ATP & NADPH to create a glucose molecule.
6CO2+18ATP+12NADPH +H+ 18ADP+18 Pi
+12NADP+ +1 glucose
Cellular Respiration
C6H12O6 + O2 ----------- CO2 + H2O + Energy
The breakdown of food molecules to release energy needed
for work.
Step 1: Glycolysis = converts glucose (6-carbon sugar) to
pyruvate (2, 3-carbon sugars) & releases energy  2 ATP
Step 2: Aerobic Respiration= breakdown of Pyruvate in the
presence of Oxygen  NO ATP made!
Step 3: Krebs Cycle= Produces coenzymes (NADH) to
speed up the last step  2 ATP
Step 4: Electron Transport Chain= Uses the coenzymes
(NADH) to crank out mass amounts of ATP  32 ATP!
Total ATP Production
CELLULAR RESPIRATION PRODUCES A
TOTAL OF 36 ATP MOLECULES!
Anaerobic Respiration: Chemical reactions that
release the energy from foods in the absence of
oxygen (O2)
Cells (active muscle cells) or organisms (bacteria,
yeast) that use this process to get their energy
needs live on the small amount of ATP that is
provided by Glycolysis (2 ATP)
Anaerobic Respiration
Alcoholic Fermentation: Converts pyruvate (3carbon sugar) to CO2 and ethanol (alcohol)
● Bakers use the fermentation of yeast cells to
make breads ( the CO2 makes the dough rise)
● Also used industrially in the manufacturing of
beer & wine
● Ethanol is added to gasoline to make gasohol
Anaerobic Respiration
Lactic Acid Fermentation: converts pyruvate to
Lactic Acid
● During strenuous exercise you deplete your
muscle cells of oxygen so they enter the
anaerobic cycle
● Lactic acid is a waste product produced from
this
● Lactic acid build up in the muscles causes
muscle cramping
● Lactic acid made in the muscles diffuses into the
bloodstream , then goes to the liver, where it is
converted back into pyruvate
Aerobic vs. Anaerobic
Aerobic
vs.
1. Oxygen required
required
2. Produces 36 ATP
Anaerobic Respiration
1. No Oxygen
2. Produces 2 ATP
ATP provided through the complete Aerobic breakdown
of glucose provides energy for activities such as: eating,
sleeping, exercising, & STUDYING BIOLOGY!
Aerobic Respiration is relatively inefficient !!  36 ATP
is only about half the energy contained in a glucose
molecule!
Question: Where does the rest of the
energy go?
Answer: Lost as heat
Organelles where these events
occur...
●
Photosynthesis: Occurs in the Chloroplasts



●
Both the Light and Dark reactions
Stroma = fluid inside chloroplast (Dark reactions)
Thylakoids = individual membrane layer (“pancake”);
(Light reactions)
Granum (Grana) = an entire stack of thylakoids
●
Cellular Respiration: Occurs in the
Mitochondria, Cytoplasm



Glycolysis = occurs in the cytoplasm, products get
shipped to the Mitochondria
Aerobic Respiration + Krebs Cycle = occurs in the
Mitochondria Matrix
Electron Transport Chain = occurs on the Cristae
Enzymes & Catalysts
Key Terms
Catalyst: A chemical agent that accelerates a
chemical reaction without being permanently
changed in the process
Enzyme: A protein molecule that acts as a
Biological Catalyst
Substrate: the molecule that the enzyme binds
to; the molecule that undergoes the reaction
5 Things All Enzymes Have in
Common
1. They don’t make anything happen that could
not happen on its own
2. They are NOT permanently altered or used up
by a reaction (they are re-used)
3. The same enzyme usually works for the
forward and reverse directions of a reaction
4. All enzymes work on specific substrates
5. Enzymes function to lower the Activation
Energy of a chemical reaction
Activation Energy
Activation Energy: The extra energy required to
destabilize existing chemical bonds and initiate a
chemical reaction
Enzymes increase the rate of reactions by
lowering the Activation Energy!
Active Site: “Pocket” on the enzyme in
which the substrate binds to forming an
Enzyme-Substrate Complex (lock and key)
Products: what the substrate is turned into
after binding to the enzyme; gets released
Factors That Affect Enzyme Activity
1. Temperature: rate increases with temp.
increase only until the temperature optimum is
reached; maximizes random molecular movement
Optimal temp range for most human enzymes =
35-40 C (94-99 F )
2. pH: pH optimum = pH 4 to 6; pepsin (a
digestive enzyme) works best at pH 2
Factors That Affect Enzyme Activity
3. Ionic Concentration: high ion concentrations
(salt) slow down enzyme activity
4. Cofactors & Coenzymes: presence of small
non-protein molecules required for proper enzyme
catalysis
Cofactors = inorganic (Zn, Cu, metals)
Coenzymes = organic (vitamins)
Factors That Affect Enzyme Activity
5. Enzyme Inhibitors: substance that binds to an enzyme
and decreases its activity
Competitive Inhibition= resemble an enzymes normal
substrate, compete with it for the active site, block it
●
Noncompetitive Inhibition = binds to another part of the
enzyme besides the active site; causes the enzyme to
change shape so the active site can’t bind to the substrate
●
6. Allosteric Regulation: receptor site on some part of the
enzyme other than the active site; serve as a chemical
“on/off” switch (activator/inhibitor)
7. Feedback Inhibition: the product of one metabolic
pathway can become the inhibitor for another