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Energy and Life
1
Living things need energy to survivecomes from foodenergy in most food comes from the sun
Plants use light energy from the sun to produce food
autotrophs organisms that make their own foodEx - plants
heterotrophs organisms that must obtain energy from the foods they consume animals
9-1 Chemical Pathways
2
Food serves as a source of raw materials for the cells in the body and as a source of energy.
Animal
Plant
Animal Cells
Plant Cells
Mitochondrion
Chemical Energy and ATP
3
Energy – the ability to do workForms: light, heat, electricity, chemical
compoundschemical compound that cells use to store and
release energy is adenosine triphosphate (ATP)ATP - basic energy source for all cells
Chemical Energy and ATP
4
ATP consists of:
adenine
ribose (a 5-carbon sugar)
3 phosphate groups
Adenine
ATP
Ribose 3 Phosphate groups
The three phosphate groups are the key to ATP's ability to store and release energy.
Chemical Energy and ATP
5
Storing EnergyADP has two phosphate groups instead of three.A cell can store small amounts of energy by adding a
phosphate group to ADP.
ADPATP
Energy
Partiallycharged battery
Fullycharged battery
+
Adenosine Diphosphate (ADP) + Phosphate
Adenosine Triphosphate (ATP)
Chemical Energy and ATP
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Releasing EnergyEnergy stored in ATP is released by breaking the
chemical bond between the second and third phosphates.
P
ADP
2 Phosphate groups
Chemical Energy and ATP
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ATP energy uses: - cellular activities: active transport,
protein synthesis - muscle contraction
Most cells have only a small amount of ATP, because it is not a good way to store large amounts of energy.
Cells can regenerate ATP from ADP as needed by using the energy in foods like glucose.
Cellular Respiration
April 21, 2023
So what do our cells do with the Oxygen and why do they give off Carbon Dioxide?
Answer: To make ATP!
April 21, 2023
Cellular Respiration
April 21, 2023
C6H12O6 + 6O2 6CO2 + 6H2O + usable energy
(ATP)
Cellular Respiration (3-stages)
April 21, 2023
GlycolysisKrebs Cycle (Citric Acid Cycle)Electron Transport Chain (ETC)
Overview of Cellular Respiration
12
If oxygen is present: cellular respiration - the process that
releases energy by breaking down glucose and other food molecules in the presence of oxygen
glycolysis Krebs cycle electron transport chain
equation:6O2 + C6H12O6 → 6CO2 + 6H2O + Energyoxygen + glucose → carbon dioxide + water +
Energy
Flowchart
Section 9-2
Glucose(C6H1206)
+Oxygen
(02)
GlycolysisKrebsCycle
ElectronTransport
Chain
Carbon Dioxide
(CO2)+
Water(H2O)
+ATP
Cellular Respiration
April 21, 2023
Glucose
To the electron transport chain
Figure 9–3 GlycolysisGlycolysis:
Step 1
2 Pyruvic acid
Glucose
To the electron transport chain
Figure 9–3 Glycolysis
Section 9-1
2 Pyruvic acid
Glucose
To the electron transport chain
Figure 9–3 Glycolysis
Section 9-1
2 Pyruvic acid
April 21, 2023
Where CytoplasmNO O2 required
Energy Yield net gain of 2 ATP at the expense of 2 ATP
6-C glucose TWO 3-C pyruvatesFree e- and H+ combine with organic ion
carriers called NAD+ NADH + H+
(nicotinamide dinucleotide)
Summary
April 21, 2023
InGlucose (6-C)2 ATP
Out 2 pyruvate; 2(3-C)
2NADHa net of 2 ATP
April 21, 2023
Breakdown of Pyruvic Acid
Where mitochondria
Pyruvate (3-C) Acetic acid (2-C)
3rd C forms CO2
Acetic acid combines with Coenzyme A to form ACETYL-CoA
April 21, 2023
Citric Acid Production
The Krebs Cycle
Section 9-2
Mitochondrion
Krebs Cycle
April 21, 2023
Second Step: Citric Acid Cycle (Krebs Cycle)
April 21, 2023
Where Mitochondrial matrixEnergy Yield 2 ATP and more e-
Acetyl-CoA (2-C) combines with 4-C to form 6-C CITRIC ACID
Citric Acid (6-C) changed to 5-C then to a 4-C
Gives off a CO2 moleculeNAD+ and FAD pick up the released e-
FAD becomes FADH2NAD+ becomes NADH + H+
Cycle ALWAYS reforming a 4-C molecule
ETC
April 21, 2023
Where inner membrane of mitochondriaEnergy Yield Total of 32 ATPO2 combines with TWO H+ to form H2O
Exhale - CO2, H2O comes from cellular respiration
Electron Transport Chain
Section 9-2
Electron TransportHydrogen Ion Movement
ATP Production
ATP synthase
Channel
Inner Membrane
Matrix
Intermembrane Space
Mitochondrion
Summary
GlucoseGlycolysis
Cytoplasm
Pyruvic acid
Electrons carried in NADH
Krebs Cycle
Electrons carried in
NADH and FADH2 Electron
Transport Chain
Mitochondrion
Mitochondrion
Aerobic vs. Anaerobic
April 21, 2023
Anaerobic DOES NOT require oxygenFast, but
produces smaller amounts of energy (ATP)
Aerobic requires oxygenYields large
amounts of energy
