Photosynthesis
The process through which plants use solar energy to convert CO2 and H2O to suhars and other orgsnjc molecules and they release O2 as a by-product
Autotrophs
Plants (make their own food), they are the ultimate source of organic molecules for almost all other organisms
Photoautotrophs
Plants and other photosynthesizers Use the energy of light
Who are the producers of the biosphere?
Photoautotrophs because they produce the food supply
Heterotrophs
Feed off of producers because they cannot make their own food but must consume plants or animals or decompose organic material
how do photoautotrophs help?
Feed us, clothe us, house us, provide energy for warmth, light, transport, and manufacturing
Producers in aquatic environments
Unicellular and multicellular algae
Organization of plants that do photosynthesis
Pigments and enzymes are grouped together in membranes or compartments that facilitate photosynthesis
Chlorophyll
A light-absorbing pigment in the chloroplasts that play a central role in converting solar energy to chemical energy; give leafs their green color
Mesophyll
The green tissue in the interior of the leaf; chloroplasts are concentrate in the cells of this
Stomata
Tiny pores where carbon dioxide entered the leaf and oxygen exits
How is water absorbed by roots put in plants?
Veins
Purpose of veins?
Take in water and opportunity sugar to the roots and other parts of the plant
Typical amount of chloroplasts?
30-40
Stroma
Fluid of the chloroplast that is enclosed by two membranes
Thylakoids
Interconnected membranous sacs that are suspended in the stroma
Thylakoid space
Enclosed by the thylakoids
Grana (s. granum)
Stacks of thylakoids
thylakoid membrane
House chlorophyll molecules and machinery that converts light energy to chemical energy which is used to make sugar in the stroma
Bubbles on plants?
O2 produced during photosynthesis
Basic equation for photosynthesis
6CO2 + 6H2O -> C6H12O6 + 6O2
C.B. Van Niel
Proposed that H2O s
Photosynthesis
The process through which plants use solar energy to convert CO2 and H2O to suhars and other orgsnjc molecules and they release O2 as a by-product
Autotrophs
Plants (make their own food), they are the ultimate source of organic molecules for almost all other organisms
Photoautotrophs
Plants and other photosynthesizers Use the energy of light
Who are the producers of the biosphere?
Photoautotrophs because they produce the food supply
Heterotrophs
Feed off of producers because they cannot make their own food but must consume plants or animals or decompose organic material
how do photoautotrophs help?
Feed us, clothe us, house us, provide energy for warmth, light, transport, and manufacturing
Producers in aquatic environments
Unicellular and multicellular algae
Organization of plants that do photosynthesis
Pigments and enzymes are grouped together in membranes or compartments that facilitate photosynthesis
Chlorophyll
A light-absorbing pigment in the chloroplasts that play a central role in converting solar energy to chemical energy; give leafs their green color
Mesophyll
The green tissue in the interior of the leaf; chloroplasts are concentrate in the cells of this
Stomata
Tiny pores where carbon dioxide entered the leaf and oxygen exits
How is water absorbed by roots put in plants?
Veins
Purpose of veins?
Take in water and opportunity sugar to the roots and other parts of the plant
Typical amount of chloroplasts?
30-40
Stroma
Fluid of the chloroplast that is enclosed by two membranes
Thylakoids
Interconnected membranous sacs that are suspended in the stroma
Thylakoid space
Enclosed by the thylakoids
Grana (s. granum)
Stacks of thylakoids
thylakoid membrane
House chlorophyll molecules and machinery that converts light energy to chemical energy which is used to make sugar in the stroma
Bubbles on plants?
O2 produced during photosynthesis
Basic equation for photosynthesis
6CO2 + 6H2O -> C6H12O6 + 6O2
C.B. Van Niel
Proposed that H2O split rather than CO2 and then released O2
confirmed by later scientists who used the isotope oxygen - 18
What is oxidized in cellular respiration?
Sugar
How did scientists trace the process of photosynthesis?
By the use of isotopes
What kind of reaction is photosynthesis?
Redox reaction
Redox
Oxidation-reduction
What kind of reaction is cellular respiration?
redox reaction
What is reduced in photosynthesis?
CO2
What is oxidized in photosynthesis?
Oxygen
What is reduced in cellular respiration?
O2 and H2O
two stages of photosynthesis
light reactions and calvin cycle
Light reactions
-First part of photosynthesis
-occurs in the thylakoids
-Convert light energy to chemical energy and releases O2
-light energy is used to drive the transfer of electrons from H+ to NADP+ which is reduced to NADPH which stores electrons and hydrogen ions a
NADP+
electron acceptor; accepts electrons in the light reactions
NADPH
reduced from NADP+; temporarily stores electrons and hydrogen ions and provides reducing power for Calvin cycle
Light reactions
Absorb solar energy and convert it into chemical energy stored in ATP and NADPH
When is sugar made?
The Calvin cycle
Calvin cycle
-second stage of photosynthesis
-occurs in stroma
-cyclic series of reactions that assembles sugar molecules using CO2 and products of light-reactions
-light independent, dark reactions
carbon fixation
The incorporation of carbon from CO2 into organic compounds (compounds reduced to sugar after this)
What provides the electrons for reducing carbon in the carbon cycle?
NADPH
What provides chemical energy in Calvin cycle?
atp
Electromagnetic energy/radiation
Sunlight
Wavelength
The distance between the crests of electromagnetic waves
Electromagnetic spectrum
The full range of electromagnetic waves from the very short gamma rays to long radio waves
Photon
Packets of energy that have a fixed quantity and a shorter wavelength of light
What happens to visible light in the chloroplast?
Light-absorbing molecules built into the thylakoid membranes absorb some wavelengths of light and reflect other wavelengths so we see the other wavelengths that are not green
Pigments
Light-absorbing molecules in the thylakoid membranes
Chlorophyll a
Participate directly in the light reactions and absorb mainly blue-violet and red light so it looks blue-green because it reflects mainly green light
Chlorophyll b
Absorbs mainly blue and orange light and reflects/appears olive green; broadens the range of light that a plant can use by conveying absorbed energy to chlorophyll a
Carotenoids
Pigments in chloroplasts that are various shades of yellow and orange; survive longer than chlorophyll and broaden the spectrum of colors drive photosynthesis
photoprotection
Driven by carotenoids and is the process by which they absorb and dissipate excessive light energy that would can damage cell molecules
Isolated pigments (chlorophyll)
Emit light as well as heat after absorbing photons; when brightly illuminated, the chlorophyll emits photons of light that produces a reddish afterglow called fluorescence
How do chlorophyll behave in the chloroplast?
they absorb photons to transfer the energy to other pigment molecules and then a special pair of chlorophyll molecules passes off an excited electron to a neighboring molecule
Photosystem
Where chlorophyll molecules are organized along with other pigments and proteins in the thylakoid membrane; consists of a number of light-harvesting complexes surrounding a reaction-center complex
light harvesting complex
consists of various pigment molecules bound to proteins and eventually start the transformation of light energy to chemical energy
Where does chlorophyll a go to the excited state?
By light energy in the reaction center of a photosystem
How is ATP and NADPH produced?
Arrangement of photosystem II and I, photosystem connection to electron transport chain, flows of electrons removed from H2O to NADPH, and synthesis of ATP linked to ETC pumping H+ into membrane compartment
What is the source of the electrons that are moving through the photosystem to NADPH?
Water
Where is O2 produced in the light reactions?
Produced from water and diffused out of the thylakoids, the chloroplast, and the plant cell
How does the flow of electrons produce ATP?
Through the electron transport chain and chemiosmosis
electron transport chain
Helps to produce the concentration gradient of H+ across the thylakoid membrane which drives H+ through ATP synthase and produces ATP
Photophosphorylation
Chemiosmotic production of ATP in photosynthesis. Initial energy input is light energy.
Inputs of Calvin Cycle
CO2, ATP, NADPH
Outputs of Calvin Cycle
G3P (three carbon sugar)
Why is the Calvin cycle a cycle?
The starting material (RuBP) is regenerated after molecules enter and leave the cycle
How many times should the Calvin cycle turn to make G3P?
Three
How many molecules of CO2 must be fixed to make one G3P?
Three
First step of calcium cycle?
Carbon fixation
C3 plants
Plants that use CO2 directly from the air; their first product of carbon fixation is 3-PGA
Rubisco
Enzyme in a leaf that adds O2
Photorespiration
Reaction in which rubisco attaches oxygen instead of carbon dioxide to ribulose bisphosphate and occurs in the light
C4 plants
Found in hot and dry climates because they have altered their modes of carbon fixation to optimize Calvin cycle; first fix CO2 into a 4-carbon compound and close stromata to conserve water
CAM plant species
Aloe, jade, etc; adapted to very dry climates conserve water by opening stomata and taking CO2 only at night and Calvin cycle occurs in the same cells rather than different cells
What is the sugar factory of the chloroplast?
The Calvin cycle
Purpose of carbohydrates produced by photosynthesis?
Fuel for cellular respiration and as a starting material for other organic molecules and make cellulose