Light Dependent Reactions
... were passed down the
chain end up in the
reaction centre of
Photosystem I (P700),
and another photon is
needed to re-energize it
so it can be released.
* 5. The chain ends in the
reduction of a molecule
of NADP+ into NADPH.
At this point, there is a
large gradient of H+ across
the membrane, as well ...
PHOTOSYNTHESIS • the light reaction involves three stages: • 1
... photosystem I contain chlorophyll a called P700 (absorption spectrum peaks at a wavelength
photosystem II contain chlorophyll a called P680
the different peaks are due to the proteins associated with them at the reaction centre
What is the Electron Transport Chain?
... The electron transport chain uses electrons temporarily stored in
NADH and FADH2 to reduce a series of membrane associated
protein complexes which use the released energy to pump protons
out of the mitochondrial matrix. The energy stored in the
concentration gradient created is known as the proton m ...
... • Light-dependent reaction: takes place in the thylakoid space and
across the thylakoid membranes.
• Light-independent reaction: takes place in the stroma.
The light reactions
... Not all photosynthetic organisms use H2O as electron donor in
photosynthesis; thus not all of them produce O2 while they produce
ATP and NADPH.
There are two types of photosynthesis: oxygenic (producing
oxygen) photosynthesis and anoxygenic (not producing oxygen)
photosynthesis. Only organisms wit ...
... • Is everywhere (Light is a form of electromagnetic radiation)…
... Evidence of student learning is a demonstrated understanding of each of the following:
1. Electron transport chain reactions occur in chloroplasts (photosynthesis), mitochondria
(cellular respiration) and prokaryotic plasma membranes.
2. In cellular respiration, electrons delivered by NADH and FADH2 ...
... antenna pigments transferring energy to each reaction centre. Plants found in full sunlight will tend
to have antennae with fewer pigments. If the amount of light that is absorbed by plants exceeds
their capacity for electron transfer, part of the photosynthetic electron transfer chain can be shut
the light reactions
... accessory pigments set in a
protein matrix in the
The photon energy of the
ant. pigment molecules
transfer from pigment to
pigment (resonance) until it
reaches a chlorophyll a
molecule in an area called
the reaction centre.
The excited electron of the
chlorophyll a is captured by ...
LEAVES AND PHOTOSYNTHESIS
... ! NADPH adds electrons
! Free energy of NADPH oxidation and ATP
hydrolysis push the reaction forward
T/F 1. Pyruvate, the end product of glycolysis, is processed
... 6. How many molecules of CO2 are produced for each molecule of glucose that passes through
glycolysis and the Krebs cycle?
7. The electrons generated from the Krebs cycle are transferred to ____________ and then are shuttled
a. NAD+ / oxygen
b. NAD+ / electron ...
Microbial Metabolism - ASAB-NUST
• In eucaryotes they are found in the mitochondrial
• The complete cycle appears to be functional in many
aerobic bacteria, free-living protists, and fungi.
Unit 2 Test Review
... o Excited electron is passed through the first series of embedded membrane
proteins Plastoquinone Cytochrome b6-f Complex Plastocyanin. Along the
way, the free energy from the moving electron is used to pump 4 H+ from
outside to inside the thylakoid, per 2 electrons (which travel in pairs always ...
... • Imbedded in the inner mitochondria membrane are a series of
electron carriers. These electron carriers pass electrons from
NADH and FADH to one another down a red-ox stairway. The net
result of this series of step-wise electron exchanges is to pump H+
(protons) out of the matrix into the outer com ...
... 6. In endergonic reactions, __________.
a. the reactants have more potential
energy than the products
b. energy is released
c. a net input of energy is not required
d. all of the above
e. none of the above
7. In most land plants, photosynthesis
occurs in cells of the __________ of the
leaves, becaus ...
Chapter 8 and 9 review - Iowa State University
... between the outer and inner
mitochondrial membrane, what would expect to see if there
was an increase in electron transport.
a. The pH would likely go up.
b. The pH would likely go down.
c. The pH would likely remain the same.
4.The proton motive force
a. drives the rotation of the ATP synthase.
SBI 4U photosynthesis 1
... thylakoid membrane with proteins in the centre of them
and make up a photosystem.
Chlorophyll molecules in these photosystems are able to
absorb light energy at various wavelengths.
A pigment absorbs a photon, the molecule passes the
energy to a unique pair of chlorophyll a molecules called
Photosynthesis Part 1
... photon. This high energy electron is then transferred to an electron acceptor via a redox
reaction. The final electron acceptor in this case is NADP+. When it accepts two
electrons it becomes NADPH (very similar to what we learned for NAD+ and NADH).
It takes two photons to excite two electrons to r ...
During the light reactions, there are two possible routes of electron
... photosystem II to photosystem I via an electron transport chain.
3. As the electrons are passed down the ETC, energy is given off. This energy is used to
pump hydrogen ions (protons) from the stroma into the thylakoid lumen, creating a H+
gradient for chemiosmosis. Four protons are translocated into ...
CH 8 Test Review
... 10. An electron carrier is a compound that can accept a pair of high-energy
electrons and transfer them, along with most of their energy, to another
11. One of these carrier molecules is a compound known as NADP+
(nicotinamide adenine dinucleotide phosphate).
12. Photosynthesis uses the en ...
In photosynthesis, the light-dependent reactions take place on the thylakoid membranes. The inside of the thylakoid membrane is called the lumen, and outside the thylakoid membrane is the stroma, where the light-independent reactions take place. The thylakoid membrane contains some integral membrane protein complexes that catalyze the light reactions. There are four major protein complexes in the thylakoid membrane: Photosystem II (PSII), Cytochrome b6f complex, Photosystem I (PSI), and ATP synthase. These four complexes work together to ultimately create the products ATP and NADPH.[.The two photosystems absorb light energy through pigments - primarily the chlorophylls, which are responsible for the green color of leaves. The light-dependent reactions begin in photosystem II. When a chlorophyll a molecule within the reaction center of PSII absorbs a photon, an electron in this molecule attains a higher energy level. Because this state of an electron is very unstable, the electron is transferred from one to another molecule creating a chain of redox reactions, called an electron transport chain (ETC). The electron flow goes from PSII to cytochrome b6f to PSI. In PSI, the electron gets the energy from another photon. The final electron acceptor is NADP. In oxygenic photosynthesis, the first electron donor is water, creating oxygen as a waste product. In anoxygenic photosynthesis various electron donors are used.Cytochrome b6f and ATP synthase work together to create ATP. This process is called photophosphorylation, which occurs in two different ways. In non-cyclic photophosphorylation, cytochrome b6f uses the energy of electrons from PSII to pump protons from the stroma to the lumen. The proton gradient across the thylakoid membrane creates a proton-motive force, used by ATP synthase to form ATP. In cyclic photophosphorylation, cytochrome b6f uses the energy of electrons from not only PSII but also PSI to create more ATP and to stop the production of NADPH. Cyclic phosphorylation is important to create ATP and maintain NADPH in the right proportion for the light-independent reactions.The net-reaction of all light-dependent reactions in oxygenic photosynthesis is:2H2O + 2NADP+ + 3ADP + 3Pi → O2 + 2NADPH + 3ATPThe two photosystems are protein complexes that absorb photons and are able to use this energy to create an electron transport chain. Photosystem I and II are very similar in structure and function. They use special proteins, called light-harvesting complexes, to absorb the photons with very high effectiveness. If a special pigment molecule in a photosynthetic reaction center absorbs a photon, an electron in this pigment attains the excited state and then is transferred to another molecule in the reaction center. This reaction, called photoinduced charge separation, is the start of the electron flow and is unique because it transforms light energy into chemical forms.