Download Respiration Chapter 12 • Respiration – necessary in all living cells

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Chapter 12
Respiration –
necessary in all living cells
energy = capacity to do work
controlled expenditure of organisms energy reserve to sustain life
opposite of Pn
Similar to combustion (uncontrolled release)
C6H12O6 + 6H2O + 6O2 → 6CO2 + 12 H2O + Energy (ATP)
Glucose can be substituted for starches, fats, proteins &
organic acids
Mitochondria - occurs in mitochondria
Factors influencing Rs
1. Temperature - > temp = >Rs
2. Oxygen Concentration O2 = low Rs
3. Soil Conditions – compacted or water logged = low O2
4. Light – low light = low Pn = low Rs = low growth
5. Metabolic activity - maintenance Rs sustains plant life – Growth Rs
increases biomass (mature plants Rs and Pn are maxed)
Respiration Pathways
1. Glycolysis –
a. (ysis = breakdown) sugar is broken down
b. first stage in all respiration path ways
c. reversible process
d. occurs in cytoplasm
e. glucose is the energy source
f. Produces = 2 pyruvic acids + 2 ATP’s + 2 H atoms (NADH2) and H2O
g. Anaerobic process
h. Pyruvic acid 3 carbon molecule and glucose is a six carbon molecule
i. Pyruvic acid enters the tricarboxilic acid pathway (TCA)
2. Fermentation
a. Fermentation = production of ethyl alcohol and lactic acid
b. Energy source = glucose (pyruvic acid)
c. Produces - lactic acid + 2 CO2 + 2 ATP
d. Anaerobic process – not very efficient
e. Used in baking (yeast) and production of alcohol
3. Krebs Cycle – Citric Acid Cycle - TCA cycle
a. Carbon oxidative process
b. Occurs in mitochondria
c. Energy source = 2 pyruvic acid
d. Produces – 2 CO2 + 4 H atoms + 1 ATP
e. NADH is carrier of electrons from carbon oxidation into ETS system
4. Electron Transport System (ETS)
a. Produces the most ATP (32 or 34)
b. ETS made up of cytochromes and enzymes
Electrons pass from cytochrome to another and energy is given off as heat
and and ATP
c. Final electron acceptor is oxygen and water is end result
Respiration and impact on Agriculture
Need sufficient Rs to meet plants needs
Ideal night temps are 9 degrees F lower than daytime
To hot of night temps will increase Rs
To cool of day and night temps will slow Rs and growth