Transcript Photosynthesis/Respiration

Photosynthesis/Respiration
Photosynthesis
• Process of converting the energy of
sunlight into the energy in the
chemical bonds of carbohydrates
(sugar and starch).
• Process of converting light energy
into chemical potential energy.
– Carbon dioxide + water  sugar + oxygen
(need light)
– 6CO2 + 6H2O  (CH2O)6 + 6O2
(need light)
Respiration
• Conversion of chemical potential energy
into usable energy (ATP).
– sugar + oxygen  Carbon dioxide + water
– (CH2O)6 + 6O2  6CO2 + 6H2O
Joseph Priestley’s Experiment
• Just mouse inside bell jar
– dead
• Just plant inside bell jar
– dead
• Mouse + plant
– live
Joseph Priestley’s Experiment
• He concluded that mouse produces
something that is required by the plant.
• And, plant produced something the mouse
required.
• What is this “something” that is required by
mouse and plant?
Mouse vs. Plant
• Mouse need to eat, drink, and breathe.
• Plant needs water, soil, and sunlight
(anything else?).
• Mouse needs oxygen (O2)
• Plant needs carbon dioxide (CO2)
Looking back to photosynthesis
and respiration
• Product of photosynthesis is oxygen gas
and sugar.
• Product of respiration is carbon dioxide
and water.
• Therefore, mouse breathes out carbon
dioxide and plant release oxygen.
• Therefore, mouse and plant are
codependent of one another.
Vocabulary
• Autotrophs: make their own food (ex.
Plants).
• Heterotrophs: get energy from food they
eat (ex. Human).
• Pigment: colored substances that absorb
or reflect light.
• Chlorophyll: pigment found in chloroplast that
absorbs red and blue and reflects green.
• NADP+ (nicotinamide adenine dinuceotide phosphate)
(electron carrier): NADP+ could accept two high
charged electrons to form NADPH which could
later form ATP.
• ATP (Adenosine TriPhosphate): electrons could
form ATP by adding phosphate group to ADP or
AMP to form ATP. (adenosine Triphosphate,
Diphosphate, Monophosphate). Energy
trapped in ATP can be used by the cell by
breaking the bond between the phosphate
groups. Forming and breaking of these bonds
Closer look at photosynthesis
• Overall equation
– 6CO2 + 6H2O  C6H12O6 + 6O2
• Photosynthesis is process of converting
light energy into chemical energy
• The process is divided into two separate
stages
– Light reaction
– Dark reaction
Light reaction
• Light reactions include light absorption,
electron transport, oxygen production, and
ATP formation.
Light absorption
• Light reaction occurs in chloroplast within the
photosynthetic membranes where chlorophylls are
located.
• Photosynthetic membranes contain cluster of pigment
molecules, or photosystems, that are able to capture the
energy of sunlight.
• There are two photosystems containing several hundred
chlorophyll molecules as well as a number of accessory
pigments.
– When light energy is absorbed by these pigments, energy is
passed to the reaction center of the photosystem, to a special
pair of chlorophylls, where high energy electrons are released
and are passed to the first of many electron carriers.
Electron Transport
• High energy electrons are passed from
electron carriers to carriers and end up at
NADP+ to form NADPH.
Oxygen production
• Although chlorophylls continuously release
electrons it is replenished by breaking
water molecules to get 4 e- and form 4
hydrogen ions and oxygen molecule.
ATP formation
• Hydrogen ion made from splitting of water
is left inside the photosynthetic membrane.
This allows a chemical gradient where
inside is full of hydrogen (positively
charged) and outside with little/no
hydrogen ion (negatively charged). This
difference is another source of energy to
form ATP.
Dark reaction (Calvin Cycle)
• Derived by Melvin Calvin.
• Do not need light but doesn’t necessarily
occur during dark.
• The Calvin cycle is a metabolic pathway found
in the stroma of the chloroplast in which carbon
enters in the form of CO2 and leaves in the
form of sugar.
Cellular Respiration
(Glycolysis & Respiration)
Cellular Respiration
(Glycolysis & Respiration)
• Conversion of chemical potential energy
into usable energy (ATP).
– sugar + oxygen  Carbon dioxide + water
– (CH2O)6 + 6O2  6CO2 + 6H2O
Glycolysis
• This is anaerobic process (no oxygen)
• Glycolysis: glucose  2ATP + 2NADH +
2 pyruvic acid (total: 6ATP)
• takes place in the cytoplasm
• Glucose + 2ATP  2PGAL
• 2PGAL  4ATP + 2NADH + 2 pyruvic
acid
Respiration
• This is an aerobic process.
• 1 gram of glucose  3811 calories
• Kreb Cycle:
– 2 pyruvic acid  6 CO2 + 6NADH + 2
FADH2 + 2GTP
Citric Acid Cycle
Citric Acid Cycle
Electron Transport
•
•
•
•
2NADH  6ATP
2GTP  2ATP
6NADH  18 ATP
2FADH2  4ATP
• Total of 30 ATP
Mitochondria
Chemiosmotic Pump
Organelles
• Make sure you know the functions of the
following organelles
– Nucleus
– Ribosome
– Mitochondria
– Chloroplast
– Cell membrane
– Endoplasmic reticulum
– Golgi apparatus
Animal cell
Plant cell
Has centrioles
Chloroplast
Cell wall
Central vacuole