cell energy: atp, photosynthesis & cellular respiration chapters 8 & 9
TRANSCRIPT
Cell Energy: ATP, Cell Energy: ATP, Photosynthesis & Photosynthesis &
Cellular RespirationCellular Respiration
Chapters 8 & 9
Energy for the Cell
ATP= Adenosine Triphosphate
3 major parts to ATP:
1. Adenine
2. Ribose (sugar)
3. Three phosphates
Adenosine
Adenosine Triphosphate
adenine
ribose
three phosphates
How is energy released from ATP?Break a bond between 2nd & 3rd phosphates
This releases ENERGY to be used by cells!
3rd phosphate is broken off
ATP breaking down to ADP and releasing ENERGY!
ADP= Adenosine Diphosphate• Only 2 phosphates instead of 3• ADP is recycled to make ATP [add a phosphate]
• If ADP/ATP is not reused, we would eat 24/7 just to have enough energy!
ADP being recycled to create ATP once again.
PHOTOSYNTHESIS
Photosynthesis = process trapping light energy to make GLUCOSE [chemical (food) energy]
6CO2 + 6H2O + sunlight
6 carbon dioxide
6 water
C6H12O6 + 6O2
1 glucose
6 oxygen
Where does photosynthesis take place?
• PLANTS only; in the LEAVES
• In plant cell, inside CHLOROPLASTS
• Chlorophyll = pigment that captures light energy from sun
found in THYLAKOID DISCS in chloroplasts
http://www.nicerweb.com/doc/class/bio100/Locked/media/ch06/DB06100.jpg
Why are Plants Green?
• Chlorophyll absorbs all wavelengths of light EXCEPT for green.
• Green wavelengths are REFLECTED most
Green wavelength
Green not absorbed so it gets reflected – that’s why plants look green!
Photosynthesis occurs in 2 phases:
1. Light Dependent Reactions
2. Light Independent Reactions
1.Light DEPENDENT rxns (Occurs in thylakoids)
• takes light energy to make ATP & NADPH (needed for light indep. rxns)
• converts H2O to O2
Three Processes:a. Electron transport chain (ETC)
1) light hits chlorophyll & energizes e-
2) e- move down a chain to make NADPH (a form of energy)
b. Photolysis = splits water to make oxygen , hydrogen ions & electrons (to replace e- used in ETC)
2H2O 4H+ + 4e- + 02
c. Chemiosmosis
• moves H+ (made in photolysis) to stroma (space inside chloroplast) to make ATP
http://www.mun.ca/biology/singleton/Topic%2012/lPlantNutrition&Metabolism.htm
2. Light INDEPENDENT Reactions (CALVIN CYCLE) = makes glucose from CO2 using NADPH & ATP made in light dep. rxns
a. Occurs in light or dark
c. Glucose has 6 carbons & CO2 has only 1 carbon
b. Occurs in stroma
Calvin cycle must go around 6 times to make 1 glucose
Light
O2
Sugars
CO2
NADPH
ATP
ADP + P
NADP+Chloroplast
Light Dependent Reactions
Calvin Cycle
CELLULAR RESPIRATIONCELLULAR RESPIRATION
= process that breaks down glucose to make ATP
• occurs PLANT & ANIMAL cells
C6H12O6 + 6O2
1 glucose
6 oxygen
6CO2 + 6H2O + ATP 6 carbon dioxide
6 water
Glucose
Glycolysis
Oxygen present
No oxygen present
Aerobic Respiration
Fermentation
Glycolysis – breaking down glucose into pyruvic acid
• occurs in cytoplasm
• ANAEROBIC = does not require oxygen (can still occur if O2 present)
Makes : 4 ATP Uses: 2 ATP
NET TOTAL: 2 ATP
• 2 major stages (after glycolysis)
A. Aerobic Respiration = breaks down glucose to make ATP when O2 is available
• occurs in MITOCHONDRIA
• occurs in MATRIX [space within mitochondria]• AEROBIC = requires oxygen • makes 2 ATP
1) Citric Acid Cycle (Kreb’s Cycle) – uses pyruvic acid (from glycolysis) to make ATP & CO2
2) Electron Transport Chain (ETC) – Makes H2O & ATP
from O2 and H+
• Occurs in CRISTAE (inner membrane)
• AEROBIC• makes 34 ATP
ENERGY MADE FROM AEROBIC RESPIRATION:
Glycolysis = 2 ATP Citric Acid Cycle = 2 ATP
(Kreb’s Cycle)
ETC = 34 ATP
From 1 glucose 38 ATP!
Glucose Glycolysis
Cytoplasm
Pyruvic acid
Electrons carried in NADH
Krebs Cycle
Electrons carried in NADH and
FADH2
Electron Transport
Chain
Mitochondrion
B. B. FERMENTATIONFERMENTATION (Anaerobic Respiration)(Anaerobic Respiration)
= breaks down glucose to make ATP when no O2 is
available• begins after glycolysis
2 major types:
1) Lactic acid fermentation –glucose breaks down to make lactic acid & CO2
• makes 2 ATP (including glycolysis)
• occurs in bacteria
• occurs in human muscle cells
[under heavy exercise, not enough O2 – lactic acid builds up in muscles & makes you sore]
[yogurt, cheese, etc.]
2) Ethyl alcohol fermentation –glucose breaks down to make ethyl alcohol & CO2
• makes 2 ATP (including glycolysis)• occurs in yeast[bread rises because CO2
bubbles formed in dough]