Download 9.1 Energy in Living Systems

9.1 Energy in Living Systems
I. Chemical Energy
A. Almost all the energy in organic
compounds comes from the sun
B. Photosynthesis
1. creates organic compounds from CO2 &
H 2O
2. Used by plants, algae, & prokaryotes
C. Autotrophs
1. make their own food so long as sunlight
is available
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2. Organisms that cannot make their own
food must eat autotrophs
II. Metabolism and the Carbon Cycle
A. Metabolism involves using energy to build
organic molecules
B. The carbon cycle makes carbon
compounds continuously available in an
ecosystem
C. Photosynthesis
1. Takes place in chloroplasts
2. Converts CO2 & sunlight into glucose
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D. Cellular Respiration
1. Cells make the carbon in glucose into
stable carbon dioxide molecules &
produce energy used to make ATP.
III. Transferring Energy
A. ATP
1. an organic molecule that is the
main energy source for cell
processes
2. It can be created in one place & used
in another
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3. ATP converts into ADP
a. ATP ADP + P + energy
b. very little energy is needed to start
this reaction. Much more energy is
released
4. ATP synthase – an enzyme that
calalyzes the synthesis of ATP
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9.2 Photosynthesis
I. Harvesting Light Energy
A. Chloroplasts
1. Organelles that convert light energy
into chemical energy
2. Has two membranes (outer & inner)
a. both allow light to pass through
3. Inner membrane contains thylakoids
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B. Electromagnetic Radiation
1. Forms = visible light, x-rays, radio, &
microwaves
2. All have different wavelengths
a. the space between peaks
C. Pigments
1. Substance that absorbs certain colors
& reflects all of the others
2. Chlorophyll is a green pigment in
chloroplasts that absorbs light energy
a. absorbs mostly blue & red light,
reflects green & yellow.
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a. contain molecules that absorb light
& are arranged in stacks
3. Two types of chlorophyll (a & b)
4. Pigments called carotenoids
a. absorb blue & green, reflect
yellow, orange, & red light
b. when chlorophyll fades in the fall
the carotenoids are exposed
D. Two Electron Transport Chains
1. During photosynthesis, one transport
chain provides energy to make ATP,
while the other provides energy to make
NADPH
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E. Producing Sugar
1. ATP & NADPH are used to produce
energy storing sugar molecules from
the carbon in carbon dioxide
2. Calvin Cycle – the most common
method of carbon dioxide fixation
F. Factors that Affect Photosynthesis
1. light intensity, CO2 concentration, &
temperature
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9.3 Cellular Respiration
I. Glycolysis
A. Def – enzymes break down one 6-carbon
molecule of glucose into two 3-carbon
pyruvate molecules
B. Glucose is the primary fuel for respiration
1. Formed when carbs like starch are
broken down
2. When no carbs are available cells use
fats
a. 1 gram of fat releases more energy
than 2 grams of carbs
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C. Steps of Glycolysis
1. Breaking down glucose
2. NADPH production
3. Pyruvate production
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D. Glycolysis is an anaerobic process
1. takes place without oxygen
E. Aerobic process
1. metabolic process that takes place
with oxygen
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II. Aerobic Respiration
A. Humans can use oxygen to produce ATP
B. Krebs cycle
1. a series of reactions that produce
electron carriers.
C. Up to 34 ATP molecules can be produced
from one glucose molecule
III. Fermentation
A. the process in which carbohydrates are
broken down in the absence of oxygen
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B. Lactic Acid Fermentation
1. Can occur in humans & some animals
during vigorous exercise when the
muscles must operate without oxygen
C. Alcoholic Fermentation
1. an enzyme removes carbon from the 3
carbon pyruvate
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