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Photosynthesis
Method of converting sun energy into chemical energy usable by cells
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Autotrophs
self feeders, capable of making their own food
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Photoautotroph's
use sun energy e.g. plants photosynthesis - makes organic compounds (glucose) from light
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Chemoautotroph:
use chemical energy e.g. bacteria that uses sulfide or methane.
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Chemosynthesis:
makes organic compounds from chemical energy contained in sulfide or methane
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Photosynthesis takes place in specialized structures inside plant cells called?
chloroplasts.
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Light absorbing pigment molecules e.g.
chlorophyll
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Pigment
substace able to absorb light
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Light energy -> electromagnetic energy ->
photons (may or may not contain matter)
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Photosynthesis
explains as if light behaves as a photon
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Light has a double nature
(photon & electromagnetic wave)
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Photosynthesis equation
6CO2 + 12 H2O + light energy ? C6H12O6 + 6O2+ 6H2O
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The carbohydrate made is
glucose
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Water appears on both sides because ___ H2O molecules are required and ___ new H2O molecules are made
12, 6
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Water is split as a source of electrons from hydrogen atoms releasing ___ as a byproduct
O2
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Electrons increase potential energy when moved from water to sugar therefore ______ is required
energy
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Plants contain a lot of
salt and sugar
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Light-dependent Reactions
Overview: light energy is absorbed by chlorophyll molecules
this light energy excretes electrons and boosts them to a higher energy level.
They are trapped by electron acceptor molecules that a poised at the start of a neighboring transport system.
The electrons fal to a lower energy state, releasing energy that is harnessed to make ATP.
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Carbon fixation is fixing CO2, making
a molecule of glucose.
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Need __CO2 for one glucose
6
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Energy Shuttling - Recall ATP: cellular energy-nucleotide based molecule with 3 phosphate groups bonded to it, when removing the third phosphate group, lots of energy is
liberated = superb molecule for shutting energy around with in cells.
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Other energy shuttles-coenzymes (nucleotide based molecules): move electrons and protons around within the cell
NADP+, NADPH NAD+, NADP FAD, FADH2
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Light-dependent Reactions - Photosystem:
light capturing unit, contains chlorophyll, the light capturing pigment
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Electron transport system:
sequence of electron carrier molecules that shuttle electrons, energy released to make ATP
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Electrons in chlorophyll must be replaced so that cycle may continue - these electrons come from _______ _______ Oxygen is liberated from the light reactions
water molecules,
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Light reactions yield ____ and ____ used to fuel the reactions of the Calvin cycle (light independent or dark reactions)
NADPH and ATP
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Calvin Cycle (light independent or dark reactions)
ATP and NADPH generated in light reactions used to fuel the reactions which take CO2 and break it apart, then reassemble the carbons into glucose.Called?
- carbon fixation: taking carbon from an inorganic molecule (atmospheric CO2) and making an organic molecule out of it (glucose)
- Simplified version of how carbon and energy enter the food chain
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Light-dependent reactions, (photophosphorylation) - Generates ATP and NADPH and Occurs where?
in the Thylakoid membranes of the chloroplast
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Light-independent (Calvin cyclee) Uses ATP and electron from the light reactions. Occurs where?
outside the Thylakoid membrane.
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Sunlight is a mixture of many wavelengths, some living organisms have evolved _____ that absorb certain wavelengths of light and reflect them.
pigments
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Light made of particles called
photons.
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Other pigments help absorb
wavelength
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Visible light is only a small portion of the
electromagnetic spectrum.
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Visible light ranges from about
390 nm to about 760 nm.
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To our eyes 400nm light appears
violet.
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Remember what we see is light
REFLECTED off objects.
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Because the earths atmosphere absorbs more infrared and ultraviolet light. Most of the light reaches the earths surface is
visible light.
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The visible light is then used in photosynthesis to build
complex molecules.
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Mechanisms of photosyntheses - Substances needed:
- Photons - sunlight,
- CO2 - atmosphere,
- H2O - soil, rain,
- Chlorophyll - chloroplasts
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Light-dependent reactions occur in two steps:
- 1.Conversion of solar enegrgy (photons) to chemical energy (high energy ATP) phosphorylation
- 2. ATP is used to join CO2 and H2O --> PGAL (trios) --> Glucose
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Light Dependant Reactions Are carried out by molecules in the
thylakoid membranes.
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Convert light energy to the chemical energy which are
ATP and NADPH
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Photosystem I
absorbs light at 700nm and is called P700.
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Split H2O and release
O2 atmosphere.
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Photosystem II
absorbs light at 680nm and is called P680
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Antenna pigments
absorb photons and pass the energy to nearby chlorophyll molecules or accessory igments by resonance energy transfer
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Purpose of light reaction?
To make ATP & NADPH
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__ molecules of CO2 are needed..
6... 6 carbons in glucose
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Calvin cycle reactions Occur
only after the light-dependent reactions are completed.
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Calvin cycle reactions May occur in ____ or _____ but does NOT require light.
light or dark
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Calvin cycle Occur in the _____ of the chloroplasts.
Stroma
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Calvin cycle Transforms CO2 into sugar in ____ stages.
Three
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Calvin cycle Return what to the lght reaction?
ADP, inorganic phosphate, and NADP+ to the light reaction.
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Calvin cycle Use ATP and NADPH to convert CO2 to the sugar ___.
G3P
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How many CO2 molecules does a chloroplast need to make one molecule of glucose?
6molecules of CO2
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As the cycle turns 6 times it produces 12 molecules of 3-carbon GP3.Of these two form a molecule of glucose and the remaining ten regenerate molecules of
ribulose bisphosphate
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Take C from CO2 how many molecules of CO2
need 3 molecules of CO2.. 2 molecules of trios
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How man ATP and NADPH are needed?
9ATP & 6NADPH are needed
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Rubisco fixes CO2 which is the only enzyme that can take
CO2 from atmosphere.
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Part 1. Capturing the Carbon - CO2 is added to a five-carbon compound called ribulose bisphosphate, which then splits into two three-carbon molecules. The enzyme that catalyzes this reaction is called
Rubisco.
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Part 2. Making sugar - the three-carbon molecules changes into a true
three-carbon sugar (GP3).
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Part 3. Regenerating ribulose biphosphate - more ribulose biphosphate is made for part 1 and the cycle
continues.
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