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