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Photosynthesis vs. Respiration. Free Energy – . Enthalpy (heat of reaction) is the amount of energy released or absorbed during a chemical reaction Symbol is Δ H Think of it as energy needed Entropy is a measure of randomness, tendency toward disorder Symbol is Δ S - PowerPoint PPT Presentation
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Photosynthesis vs. Respiration
Free Energy – Enthalpy (heat of reaction) is the amount of energy
released or absorbed during a chemical reaction Symbol is ΔH Think of it as energy needed
Entropy is a measure of randomness, tendency toward disorder Symbol is ΔS More disorder = more entropy If reaction leads to more disorder, the entropy change
(ΔS) is positive, if it becomes more ordered, ΔS is negative
Example: melting ice, condensing water, cleaning your room (+,-,-)
Temperature – T measured in K (273 + ºC) Free Energy – spontaneity of a reaction
Spontaneous - is negative Not spontaneous - is positive. Would be spontaneous
if reversed.
Things in Common Both photosynthesis and respiration
make ATP. Both involve, CO2, oxygen, sugar
(C6H12O6), and water (H2O) Almost all cells go through respiration
phosphate removed
ATP transfers energy from the breakdown of food molecules to cell functions.– Energy is released when a phosphate group is removed.
– ADP is changed into ATP when a phosphate group is added.
Organisms break down carbon-based molecules to produce ATP.
Carbohydrates are the molecules most commonly broken down to make ATP.
– not stored in large amounts– up to 36 ATP from one glucose
molecule
triphosphateadenosine
adenosine diphosphate
tri=3
di=2
Fats store the most energy.– 80 percent of the energy in your body– about 146 ATP from a triglyceride
• Proteins are least likely to be broken down to make ATP.
– amino acids not usually needed for energy– about the same amount of energy as a carbohydrate
The light-dependent reactions capture energy from sunlight.– take place in thylakoids– water and sunlight are needed– chlorophyll absorbs energy– energy is transferred along thylakoid membrane then to light-
independent reactions– oxygen is released
The light-independent reactions make sugars.– take place in stroma (fluid outside the thylakoids)– needs carbon dioxide from atmosphere– use energy to build a sugar in a cycle of chemical reactions
Photosystem II captures and transfers energy.– chlorophyll absorbs
energy from sunlight– energized electrons enter
electron transport chain– water molecules are split– oxygen is released as
waste– hydrogen ions are
transported across thylakoid membrane
Photosystem I captures energy and produces energy-carrying molecules.– chlorophyll absorbs energy
from sunlight– energized electrons are
used to make NADPH– NADPH is transferred to
light-independent reactions
Summary of Light Dependent Reactions Energy is captured from the sun. Energy goes into electrons into the
electron transport chain. Water is broken down H+ ions are transported and form
NADPH Flow of H+ ions through ATP synthase
makes ATP Electron Transport
Summary of Light Independent Reactions (Calvin Cycle) CO2 enters cycle ATP and NADPH from light-dependent
transfer energy 1 3-carbon molecule made for every 3 CO2 2 3-carbon molecules bonded to make
sugar Products – 6-carbon sugar, NADP+, and
ADP
A molecule of glucose is formed as it stores some of the energy captured from sunlight.– carbon dioxide molecules enter the Calvin cycle (this is what has
sugar as an end product– energy is added and carbon molecules are rearranged– a high-energy three-carbon molecule leaves the cycle
two three-carbon molecules bond to form a sugar– remaining molecules stay in the cycle
o A molecule of glucose is formed as it stores some of the energy captured from sunlight.
Cellular respiration makes ATP by breaking down sugars. Cellular respiration is aerobic, or requires oxygen. Aerobic stages take place in mitochondria.
mitochondrion
animal cell
Glycolysis must take place first.– anaerobic process (does not require oxygen)– takes place in cytoplasm– splits glucose into two three-carbon molecules– produces two ATP molecules
Cellular respiration is like a mirror image of photosynthesis.
The Krebs cycle transfers energy to an electron transport chain. takes place in
mitochondrial matrix breaks down three-carbon
molecules from glycolysis– makes a small
amount of ATP– releases carbon
dioxide– transfers energy-
carrying molecules
6H O2
6CO 2
6O 2
mitochondrionmatrix (area enclosedby inner membrane)
inner membrane
ATP
ATP
energy
energy from glycolysis
1
2
4
3
and
and
and
Krebs Cycle
6H O2
6CO 2
6O 2
mitochondrionmatrix (area enclosedby inner membrane)
inner membrane
ATP
ATP
energy
energy from glycolysis
1
2
4
3
and
and
and
• The electron transport chain produces a large amount of ATP.
– takes place in inner membrane
– energy transferred to electron transport chain
– oxygen enters process– ATP produced
– water released as awaste product
Electron Transport
The Krebs cycle is the first main part of cellular respiration.
Pyruvate is broken down before the Krebs cycle. carbon dioxide
released NADH produced coenzyme A (CoA)
bonds to two-carbon molecule
The Krebs cycle produces energy-carrying molecules.
The electron transport chain is the second main part of cellular respiration.
The electron transport chain uses NADH and FADH2 to make ATP. high-energy electrons enter electron transport chain energy is used to transport hydrogen ions across the
inner membrane hydrogen ions
flow through achannel in themembrane
The electron transport chain is the second main part of cellular respiration.
The breakdown of one glucose molecule produces up to36 molecules of ATP. (2 from glycolysis, 2 from Kreb, 32 from ETC)
– ATP synthase produces ATP
– oxygen picks up electrons and hydrogen ions
– water is released as a waste product
o The electron transport chain uses NADH and FADH2 to make ATP.
ATP Products of Cellular Respiration including glycolysis Glycolysis – uses 2 ATP and make 4 ATP.
Net gain of 2 ATP Kreb Cycle – 2 ATP, 8 NADH, 2 FADH2 Electron Transport Chain – 32ATP Net gain – 36 ATP for every glucose
molecule.
Comparison of Photosynthesis & Cellular Respiration
Photosynthesis Cellular Respiration
Organelle for process
Chloroplast Mitochondrion
Reactants CO2 and H2O Sugars (C6H12O6) and O2
Cycle of chemical reactions
Calvin cycle in stroma of chloroplasts builds sugar molecules
Krebs cycle in matrix of mitochondria breaks down carbon-based molecules
Electron Transport Chain
Proteins within thylakoid membrane
Proteins within inner mitochondrial membrane
Products Sugars (C6H12O6) and O2
CO2 and H2O
Fermentation allows glycolysis to continue when oxygen is unavailable. Fermentation is an anaerobic process.
occurs when oxygen is not available for cellular respiration
does not produce ATP
Fermentation allows glycolysis to continue making ATP when oxygen is unavailable.
• Lactic acid fermentation occurs in muscle cells.– glycolysis splits glucose into two pyruvate molecules– pyruvate and NADH enter fermentation– energy from NADH converts pyruvate into lactic acid– NADH is changed back into NAD+
• NAD+ is recycled to glycolysis
Fermentation is used in food production.– yogurt
– cheese
– bread
Project In teams of 2, students will create a
visual representation (e.g., poster or PowerPoint) to explain the interdependent relationships of cellular respiration and photosynthesis, and how the processes of cellular respiration and photosynthesis affect a runner in a marathon race.
Students should use few words and focus on using graphics to represent the cyclic processes. Visual representations will be peer and teacher reviewed.