Chapter 8
description
Transcript of Chapter 8
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Chapter 8Photosynthesis
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Autotrophs vs. HeterotrophsAutotrophs are organisms that can
make their own food◦Use light energy from the sun to
produce◦Plants are an example
Heterotrophs cannot use the sun’s energy directly◦Obtain energy from the foods they
eat◦Animals and mushrooms are
examples
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Autotrophs vs. Heterotrophs
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EnergyATP – Adenosine triphosphate – is the
molecule cells use to store and release energy. Be able to draw it. Energy is released when the bond is broken between the last two phosphates.
ADP – Adenosine diphosphateAMP – Adenosine monophosphate
Adenosine
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Energy
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EnergyAdding a phosphate group to ADP
allows the organism to store energy◦ATP is like a fully charged battery◦ADP is like a partially charged
battery
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EnergyEnergy is used for:1. Active transport: Na+ is pumped
out and K+ into the cell2. Motor proteins that move organelles3. Synthesis of proteins, nucleic acids,
lipids,…4. Produce light (firefly)5. Cell reproduction and more
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EnergyGlucose is better for long term
storage than ATPA single molecule of glucose stores 90
times the chemical energy of a molecule of ATP
Most cells only have a small amount of ATP, only enough to last for a few seconds of activity
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What is Photosynthesis?Photosynthesis is the process in
which light, water, and carbon dioxide (CO2) is made into sugar and oxygen (O2)
Carbon dioxide + water sugar + oxygen
6CO2 + 6H2O C6H12O6 + 6O2
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PhotosynthesisChlorophyll a
and Chlorophyll b are pigments in the chloroplast that absorb light of the visible spectrum, except for green light. They reflect green, thus the leaf looks green.
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PhotosynthesisPhotosynthesis takes place in the
chloroplasts◦Chloroplasts have stacks of
thylakoids (saclike photosynthetic membranes)
◦Proteins in thylakoids organize chlorophyll and other pigments into photosystems, which are the light-collecting units
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Light-dependent reactionsTake place in the thylakoid membranesConvert light energy to ATP and
NADPHSplit H2O and release O2
Electron transport chain connects the two photosystems to make an H+ gradient across the thylakoid membrane (ATP synthase uses this force to make ATP). Uses a proton (H+) pump.
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Light-dependent reactions
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Calvin cycle reactionsTake place in the stromaUse ATP and NADPH to convert CO2 to
sugarReturn ADP, inorganic phosphate, and
NADP+ to the light reactions
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Calvin cycle reactions
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Photosynthesis
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Factors affecting photosynthesis
Water (required raw material)◦Plants in dry climates have a waxy
coating to prevent water lossCO2 concentration (required raw
material)Temperature: enzymes function best
between 0o C and 35o CLight intensity
◦Plants can reach a maximum rate of photosynthesis with light intensity (varies between plant type)
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Chapter 9 Cellular Respiration
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Chemical EnergyHow much energy is in food?
◦One molecule of glucose contains 3811 calories of heat energy
◦A calorie is the amount of energy needed to raise the temperature of one gram of water one degree Celsius
◦The Calorie (food labels) is actually 1000 calories
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Chemical EnergyThe beginning of turning food into
energy is glycolysis (produces small amount of energy)
If oxygen is present 2 other pathways occur to produce more energy
If oxygen is not present, 1 different pathway occurs
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Energy PathwaysAerobic – requires oxygen
◦Also called cellular respirationAnaerobic – does not need oxygen
◦Fermentation – name for anaerobic pathway following glycolysis (if oxygen is not present). (The term fermentation includes glycolysis).
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What is Cellular Respiration?Cellular Respiration (video)Cellular respiration - the process
that releases energy by breaking down glucose and other food molecules in the presence of oxygen.
Glucose + oxygen carbon dioxide + water + energy
C6H12O6 + 6O2 6CO2 + 6H2O + ATP
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What is Cellular Respiration?
Carbondioxide
Water
Oxygen
Carbondioxide
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Cellular RespirationSteps of cellular respiration:1. Glycolysis – one glucose is broken in
half to make 2 pyruvic acids. Anaerobic. Occurs in cytoplasm.
2. Krebs cycle – pyruvic acid is broken down into CO2 and energy. Aerobic. Occurs in mitochondrion. Also called citric acid cycle.
3. Electron transport chain – using a series of proteins, the electrons from the Krebs Cycle and glycolysis to convert ADP to ATP.
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GlycolysisNADH passes energy from glucose to
the electron transport chain
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Energy PathwaysAerobic – requires oxygen
◦Also called cellular respirationAnaerobic – does not need oxygen
◦Fermentation – name for anaerobic pathway following glycolysis (if oxygen is not present). (The term fermentation includes glycolysis).
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FermentationTwo types of fermentation:Alcoholic fermentation: yeasts and
some bacteriaPyruvic acid + NADH alcohol + CO2 + NAD+
Lactic acid fermentation: most organisms including us and many bacteria
Pyruvic acid + NADH lactic acid + NAD+
Both processes regenerate NAD+
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Lactic Acid Fermentation
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Kreb’s Cycle and ETCDuring the Kreb’s cycle pyruvic acid is
down into carbon dioxide◦Occurs in the mitochondrion◦NADH and ATP is produced
In the electron transport chain (ETC) high energy electrons (NADH, FADH2) is converted into ATP◦Hydrogen ions are pumped across
membrane◦ATP synthase – enzyme (protein)
that makes ATP using H+ gradient
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Cellular Respiration1 glucose results in the production of
36 ATP net◦34 more ATP than anaerobic
processes◦38% of the total energy in glucose,
the other 62% is “lost” through heat◦More efficient than an automobile
(25%-30%) 70-75% is lost to heat
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Energy Pathway
Glycolysis
No Oxygen Oxygen
Anaerobic respiration Aerobic respiration
36 ATP2 ATP, lactate oralcohol and CO2
Fermentation Cellular respiration
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Cellular Respiration
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Cellular Respiration
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Energy Pathway
Photosynthesis
Cellular Respiration
Fermentation
Function
Energy storage Energy release Energy release
Location
Chloroplasts Mitochondria Cytoplasm
Reactants
CO2 and H2O Glucose and O2 Glucose & NAD
Products
Glucose and O2 CO2 and H2O & ATP
Alcohol & CO2
& ATP orLactic acid & ATP
Comparing photosynthesis, cellular respiration, & fermentation: