nscu 302 wk 2 1
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Cell Energetics: Photosynthesis & Respiration
Carbon• Carbon forms millions of compounds, both simple
and complex• All living things contain carbon• Living things cycle carbon from the air (inorganic gas
form) to the solid form (organic) and back to the air• Light from the sun provides the energy for
photosynthesis, the process of making organic compounds such as sugar
• The sun’s energy is stored the chemical bonds of sugars and other carbohydrates
• Carbohydrates are used by most living things to provide energy for LIVING
What is the Global Carbon Cycle?
• The movement of carbon between the atmosphere, soil, ocean, living things, and fossil fuels
• Carbon exists primarily as:- Gas, carbon dioxide (CO2), in Earth’s atmosphere - Organic carbon in living and dead organisms.
• Atmospheric carbon is constantly recycled, mostly by green plants and algae, to produce oxygen
The Global Carbon Cycle
CO2 & other greenhouse
gases
Dissolved carbon
Fossil fuel
Green plants
Algae & cyanobacteria
Emissions from burning fossil fuel
respira
tion
Phot
osyn
thes
is
Photosynthesis and Respiration in the Global Carbon Cycle
Carbohydrates&
Oxygen
Carbon dioxide&
Water
PhotosynthesisRespiration
Creates storedEnergy-ATP
A few types of organisms do not need sunlight and photosynthesis as
a source of energy.
• Some organisms live in places that never get sunlight.
• In chemosynthesis, chemical energy is used to build carbon-based molecules.– similar to photosynthesis– uses chemical energy
instead of light energy– occurs where light cannot
penetrate-deep ocean Biology-McDougal Littell 2008
A cell has some remarkable organelles!!! Is this plant or animal?
Chloroplasts
Mitochondrion
Nucleus
The Chloroplast is Remarkable Organelle
Stroma
Thylakoid
Stroma = space/matrix inside the chloroplast where carbohydrate is synthesized
Thylakoid = structures with chlorophyll and light reaction center
The Basic Process of Photosynthesis
CO2 + H2O [C6H12O6] + O2
carbon dioxide water carbohydrate(glucose)
oxygen
light energy
The Light Reactions-Light Dependent
The Dark Reactions-Light Independent
Photosynthesis in chloroplast is divided into…
The Light Reactions-Light Dependent
The Dark Reactions-Light Independent
MUST occur in the presence of light
CAN occur in the presence of light, but works better in the dark
Keeping track of the oxygen atom in photosynthesis
CO2 + H2O [CH2O] + O2
carbon dioxide water carbohydrates oxygen
light energy
Cornelius van Niel (1897-1985)Standford University
Used radioactive-labeled oxygen in water and unlabeled carbon dioxide in photosynthesis experiments
Found that oxygen gas produced comes from water
Postulated that the oxygen atom in carbohydrates must be from carbon dioxide
The Light Reactions
The Dark Reactions
ADP NADP+ NADPH
Carbohydrates CO2 + H2O
H2O O2
ATP
MC.3.B.4
Where do the reactions happen inside the chloroplast?
Light reactionDark reaction
H2O
O2
CO2
Carbohydrates
Light reaction occurs on thylakoid membranes
Dark reaction occurs in the stroma
MC.3.B.4
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