Download Photosynthesis and Cellular Respiration

Photosynthesis and Cellular Respiration
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 = (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
Process of converting energy from sunlight to energy in chemical
bonds:
CO2 + H2O + Sunlight ----------- C6H12O6 + O2
Chlorophyll = pigment inside the chloroplast that absorbs sunlight
 Light absorbed by pigments gets incorporated into electrons
 Energized electrons are unstable and re-emit the absorbed
energy
 Energy gets reabsorbed by electrons of a nearby pigment
molecule
 This absorption re-emission cycle continues
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 = (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
1
CELLULAR RESPIRATION
C6H12O6 + O2 ----------- CO2 + H2O + Energy
The breakdown of food molecules to release energy needed for work,
occurs in the Mitochondria.
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, CO2 given off (exhale)  2 ATP
Step 4: Electron Transport Chain = Uses the coenzymes (NADH)
to crank out mass amounts of ATP  32 ATP!
Q. How many ATP are made from the energy released from the
breakdown of 1 glucose?
A. 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)
1. Alcoholic Fermentation: Converts pyruvate (3-carbon
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
 Occurs in plants, fungi, and bacteria
2
2. Lactic Acid Fermentation: converts pyruvate to Lactic
Acid (Lactate)
 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
1. Oxygen required
2. Produces 36 ATP
vs.
Anaerobic Respiration
1. No Oxygen required
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!
Q: Where does the rest of the energy go?
A: Lost as heat
3
ORGANELLES
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
Insert fig 3-2
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
Insert fig 4-2
4