Download Photosynthesis and Cellular Respiration

Advanced Biology 11
Energy Transfer; getting energy from the sun
Chemical Formula: 6CO2 + 6H2O
Energy
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C6H12O6 + 6O2
All living organisms use energy.
Energy is needed for metabolism to function.
When organisms use energy they use it in the chemical form, ATP (adenosine triphosphate)
The energy used by living organisms usually originates from the sun.
Green plants convert the sun’s energy into stored chemical energy by the process of
photosynthesis.
Other (non-green) organisms obtain the stored energy by eating or ingesting green organisms.
They will then release this stored energy during the process of cellular respiration.
Photosynthesis
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Is performed by green plants,
cyanobacteria, and some
chlorophyll containing protozoans
(ie, euglena, volvox)
Converts the sun’s energy into
chemical form (C6H12O6: glucose) by
combining water and carbon
dioxide.
Many pigments may be used for
attracting light, chlorophyll A is the
most important in green plants.
Collection of Needed Materials
 H2O is absorbed by the root epidermal cells
 Plants absorb water and carbon dioxide through stoma (a pore surrounded by guard cells)
 Light is absorbed by chlorophyll a (most important for green plants) and chlorophyll b
 Chloroplasts contain chlorophyll (green) and carotenoids (red,orange and yellow)
Light Reactions
 The inner membranes of the chloroplast (called thylakoid membranes) have chlorophyll,
carotenoid and protein molecules embedded in them. The membranes are arranged in stacks
called grana.
 When photons of light enter the chloroplast they excite electrons in the proteins of the
chloroplast.
 This excitement passes electrons along the membranes.
Advanced Biology 11
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The passing of the electron stimulates the production of ATP (useable energy molecule)
Water molecules are split releasing O and allowing H+ to transfer to electron acceptor molecule
NADPH for later use
Dark Reactions
 also called the Calvin Cycle
 This is where the sugars are manufactured
 The ATP and the H+ are used to bind CO2 molecules to a 5 carbon molecule (biphosphate)
making an unstable 6 carbon molecule which breaks down to 2 3Carbon molecules.
 These 3C molecules will be joined to form a simple sugar (C6H12O6)
 The most important sugar for consumer organisms is the sugar form of glucose
 Some of the glucose produced will join to form sucrose (much used table sugar).
 The energy of the sun has now been packaged into a useable chemical form.
Energy transfer to other organisms
 Organisms, as in the kingdom Animalia and Fungi, require energy to survive
 Herbivorous animals, ie. Deer and mushrooms, get this energy as glucose when they digest plant
material
 The glucose the animal has stored is converted to transportable ATP by aerobic and anaerobic
cellular respiration.
Advanced Biology 11
Energy Transfer II: getting energy from photosynthetic organisms
Chemical Formula: C6H12O6 + 6O2
6CO2 + 6H2O
Cellular Respiration
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Two forms:
o Anaerobic: releases energy when oxygen is not present = fermentation
o Aerobic: releases energy using oxygen
Anaerobic Respiration:
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AKA: Fermentation:
o performed by yeast: converts glucose to carbon dioxide and ethanol when releasing
energy.
o 2ATP + Glucose  2 pyruvic acid molecules (3C molecules) + 4ATP
o The pyruvic acid is then converted to ethanol and CO2
 This conversion releases H+ to NAD+ molecules
o Bacteria also perform anaerobic respiration
 Convert pyruvic acid to lactic acid.
 This is a similar reaction that occurs in over stressed muscle cell.
Aerobic Respiration:
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Most efficient for ATP production
Three main processes;
o Glycolysis: cytoplasm
o Krebs Cycle: outer
membrane of
mitochondria
o Electron Transport Chain:
inner membrane of
mitochondria
Reactants: Glucose and oxygen
Products: ATP + CO2 + H2O
Figure 1http://elinowbioreview2.wikispaces.com/file/view/cellular_respiration.jpg/191370366
/360x261/cellular_respiration.jpg
Advanced Biology 11
Glycolysis
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Anaerobic phase
requires 2 ATP
Glucose is converted to pyruvic acid releasing H+
and 4 ATP
H+ is picked up by NAD+ (nicotinamide adenine
dinucleotide) and transported to the electron
transport chain
Kreb’s Cycle
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AKA: Citric Acid Cycle
Changes pyruvic acid to different
carbon molecular forms.
The changing of the molecule
releases H+’s, GTP and CO2.
**Each time CO2 is released,
oxygen was used.
NAD and FAD are ion acceptor
molecules in this stage
NAD and FAD transport H+’s to the
electron transport chain.
GTP is converted to ATP for useable
molecular energy.
2 ATP are formed
Electron Transport Chain
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AKA: oxidative phosphorylation
Electron acceptor molecules transport
electrons (H ions) to the inner membrane of the mitochondria
The electrons are passed from one electron acceptor to another stronger one.
Each time the electron is passed energy is given off, the Energy is collected as ADP joins P to
form ATP.
Approx. 32 ATP are formed
**Not all the energy formed is converted to ATP
o Energy not collected by ATP is released as heat energy.
o This is partly the reason why we are warm blooded organisms.