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Cellular Respiration & Photosynthesis
Background Information
Producers: are able to convert the sun’s energy into glucose through a process called photosynthesis
Include plants, some protists and bacteria
AKA autotrophs
Photosynthesis requires a special set of pigments called chlorophylls to trap the sunlight in order to make glucose from the water and CO2 from the atmosphere
Background Information (con’t.)
Consumers: eat producers or other consumers in order to get the stored glucose to use for their own needs
Includes animals, some protists & bacteria
Consumers are AKA heterotrophsFungus, bacteria and some protists
are part of a specialized group of consumers AKA decomposers (AKA saprophytes) that eat dead organic material
Food Chain Vocabulary
Food Webs
Food webs are simply overlapping food chains
Food webs are complex diagrams showing the relationships between many different organisms
Energy pp. 138-139
Potential energy is stored energy that could be used for work
The chemical energy stored between the bonds of atoms is a type of PE.
All bonds (ATP, sugar, protein, lipid) store energy
Kinetic energy is energy of motion, work being done
Kinetic energy that does not get work done is called thermal energy (heat)
When bonds are broken, some of the energy is released as heat
Adenosine Triphosphate(ATP) p. 143
ATPATP is broken
down to release the energy between the high energy bonds of the phosphate groups
ATP ADP + Pi
ATP is required for cells to do their work and is made from food
ATP can be made from spare phosphate groups and ADP
ADP + Pi ATP
This process is called cellular respiration and occurs in the mitochondrion of eukaryotic cells
ATP Review
ATP is the energy ‘currency’ of your cells
All foods entering the body convert the chemical energy stored between their bonds into the high energy bonds between the phosphate groups of ATP
The reason for this is that ATP is a very small molecule
This allows a large amount of energy to be used quickly and easily in the cell
ATP’s small size also allows it to travel quickly throughout the cell
Cellular Respiration
Results in ATP production
Occurs in the mitochondrion
The mitochondrion has an inner membrane AKA the cristae (the folds)
The center of the mitochondrion is called the matrix
Cellular Respiration
Aerobic RespirationRequires oxygen which acts as the
‘final electron acceptor’ in the etsRequires a mitochondrionResults in 38 ATP per glucose
moleculeEukaryotes
Anaerobic RespirationDoes not require oxygenDoes not require a mitochondrionResults in 2 ATP per glucose
moleculeProkaryotes (and eukaryotes in
certain situations)
1st Phase: GlycolysisThe 1st stage of
respiration Occurs in the
cytoplasmConverts a 6
Carbon glucose into two 3 Carbon pyruvates
Net gain of 2 ATPElectron carriers
also generated for later use (2 NADH)
Transition step to Kreb’s cycle: the two 3 Carbon pyruvates are converted into two 2 Carbon acetyl-coA molecules
Electrons are generated and transferred to 2 more NADH carriers
Carbon dioxide is released
Glycolysis
Glycolysis
Animation: http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_glycolysis_works.html
2nd Phase: Kreb’s Cycle
Occurs in the matrix of the mitochondrion
The 2 C acetyl-CoA enters the cycle and joins with a 4 C compound
Many different compounds are formed and broken down in the Kreb’s cycle (AKA citric acid cycle)
Each time, electrons are generated and transferred to electron carriers (6 NADH and 2 FADH2)
These electrons are needed for the ets where most of the ATP of respiration will be made
2 ATP are made
Kreb’s Cycle
Kreb’s Cycle
Animation: http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cycle_works__quiz_1_.html
Final Phase: Electron Transport Chain (ets or etc)
Where the bulk of ATP is made in aerobic respiration
Electrons are passed from one protein to the next in the inner membrane (AKA cristae) electron transport chain
As they do, energy is released and used to pump H+ ions into intermembrane space
Electron Transport ChainH+ ions are allowed to flow back into
the matrix through the protein channel of the ATP synthase enzyme
The energy of the falling H+ ions is used by the enzyme to make ATP
Oxygen is AKA the final electron acceptor of the electron transport chain. Without it, the process stops and no more ATP can be made
Electron Transport Chain
32-34 ATP can be generated per glucose molecule through this method
The electron carriers that have left their electrons at the electron transport chain can now return to any of the previous steps to get more electrons to bring back to the etc
Electron Transport Chain
Hydroelectric Power Analogy
Cellular Respiration Summary
Glycolysis yields ATP and NADH, H20 released
Transition step yields NADH, CO2 released
Krebs cycle yields ATP, NADH & FADH2, CO2 released
ETS creates ATP, H20 is formedETS requires the presence of O2 as
the final electron acceptor
Anaerobic Respiration AKA Fermentation
Is simply glycolysis
Occurs in cytoplasm (no mitochondrion required)
Prokaryotic organisms use this process
Eukaryotes may use this process when needed (not enough oxygen)
Creates byproducts: alcohol in yeast or lactic acid in muscle cells
These byproducts act as the final electron acceptor of electrons from the NADH molecules (in aerobic respiration, the FEA is oxygen)
Cellular Respiration & Photosynthesis
Photosynthesis
General Equation for photosynthesis:
CO2 + H20-chlorophyll
Glucose + O2
Notice that the products of photosynthesis are the reactants of aerobic respiration
Chloroplast
Thylakoids are the individual chlorophyll containing structures
A granum is a stack of thylakoids
The stroma is the fluid surrounding the thylakoids
Leaf Cross Section
Photosynthesis
PhotosynthesisLight ReactionsTake place
across the membrane of the thylakoid
Two photosystems (PS I & II) capture sunlight to create ATP in ets and put electrons in electron carriers called NADPH
Dark ReactionsAKA the Calvin
cycleThis process of
‘carbon fixing’ takes place in the stroma of the choloroplast
1 turn of the Calvin cycle produces 1 G3P
2 G3P = 1 glucose molecule
Light Reactions
Chlorophyll in PS I and II traps sunlight
The sunlight excites electrons which are transferred to NADPH electron carriers and taken to the ets
The ETS generates ATP necessary in the Calvin cycle to make G3P (2 G3P = glucose)
Both the ATP and NADPH enter the stroma to complete the Calvin cycle
Water splits to release electrons to replenish the supply at PS II
The electrons used in the ets go to PS I to replenish the electron supply there
Dark Reactions
At the end of the dark reactions, a molecule known as G3P is made
2 G3P joined together forms a glucose molecule
We say that in this phase carbon is ‘fixed’
This means it is taken from a gas state (carbon dioxide) and converted into a solid state (glucose) which can be used by our bodies
Photosynthesis Summary
In the light reactions, electrons from PS II are used in an etc to make ATP needed for the dark reactions.
Electron carriers called NADPH are filled at PS I to be used in the dark reactions
In the dark reactions (Calvin cycle), ATP and NADPH are used to take CO2 and make G3P
2 G3P = 1 glucoseWater and CO2 are used and O2 is
released during the process of photosynthesis
The Carbon Cycle
Carbon is cycled throughout the environment in part through the processes of photosynthesis and cellular respiration
Carbon is stored in organic material, rocks (limestone), and in the atmosphere
The Carbon Cycle