The document discusses photosynthesis and the light-dependent reactions that take place in the thylakoid membranes of chloroplasts. It describes that photosystems absorb light and use the energy to boost electrons to higher energy levels. Photosystem II uses light energy to split water, releasing electrons that are passed through a chain to Photosystem I. Photosystem I further boosts the electrons' energy level and uses them, along with hydrogen ions from water, to reduce NADP+ and generate ATP through non-cyclic photophosphorylation or cyclic photophosphorylation. The overall products of the light reactions are oxygen, ATP, hydrogen ions, and NADPH.
This presentation describes in details how photosynthesis works along with its process. It also explains in details on the light-dependent and light-independent reactions.
This presentation describes in details how photosynthesis works along with its process. It also explains in details on the light-dependent and light-independent reactions.
About how cellular respiration occurs in Mitochondria, it discusses first the parts and functions of mitochondrion then the types of respiration and the 3 processes occurs in aerobic respiration.
what is photosynthesis?-history background-photosynthetic pigmment system-light harvesting complex-photo oxidation of water-photophosphorylation and mechanism of electron transport
Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the sun, into chemical energy that can be used to fuel the organisms' activities. Carbohydrates, such as sugars, are synthesized from carbon dioxide and water.
About how cellular respiration occurs in Mitochondria, it discusses first the parts and functions of mitochondrion then the types of respiration and the 3 processes occurs in aerobic respiration.
what is photosynthesis?-history background-photosynthetic pigmment system-light harvesting complex-photo oxidation of water-photophosphorylation and mechanism of electron transport
Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the sun, into chemical energy that can be used to fuel the organisms' activities. Carbohydrates, such as sugars, are synthesized from carbon dioxide and water.
Any of the chemical reactions that take place during the second stage of photosynthesis and do not require light. During the dark reactions, energy released from ATP (created by the light reactions) drives the fixation of carbon from carbon dioxide in organic molecules. The Calvin Cycle forms part of the dark reactions. As long as ATP is available, the dark reactions can occur in darkness or in light.
brief description about the diversity of living organisms present on earth... this is actually based on a chapter included in NCERT curriculum in class 9th. may be helpful for the students...
Each organism in this world, whether it is a plant, an animal or a microorganism, is unique in itself. This uniqueness of individuals forms the basis of the diversity among the living organisms.
This presentation explores diversity in organisms. How are they classified and how are they studied.
In this ppt, you will learn about photosystem first of photosynthesis, with video and animation such a nice presentation. electron movement by animation, see and understand the system.
2. One can think of the light dependent reactions as
a way to increase the free energy of the system
and the light independent reactions as a way to
convert that new free energy into the bonds of
glucose.
3. Photosystems
Photosystems
• The light-absorbing pigments of thylakoid
membranes and their associated electron
carriers are arranged in functional sets or
clusters.
• These clusters are called photosystems.
• These photosystems can absorb light over the
entire visible spectrum but especially well
between 400 to 500 nm and 600 to 700 nm.
4. When a chlorophyll molecule in the thylakoid membrane is excited by
light, the energy level of an electron in its structure is boosted The
packet of excitation energy now migrated rapidly through the light
harvesting pigment molecules to the reaction centre of the
photosystem where it causes an electron to acquire the large amount
of energy.
5. • The thylakoid
membranes of plant
chloroplasts have
Photosystem I and II
two different kinds of
photosystems each
with its own set of
light harvesting
chlorophyll and
carotenoid molecules
and the
photochemical
reaction centre.
• Photosystem I - is
maximally excited
by light at longer
wavelengths.
(P700)
• Photosystems II - is
maximally excited
by shorter
wavelengths. (Less
the 680)
6. The light reaction
These increase the free energy made available to the
system. This free energy can be used in three ways:
1) To build the chemiosmotic or proton gradient.
2) Generate ATP.
3) Reduce NADP+ to NADPH.
• There are two ways to generate ATP
• 1) Non cyclic photophosphoraltion.
• 2) Cyclic photophosphoralation.
• These two systems differ in the route taken by the "light
activated" electrons and in some of the products formed.
7. Photosystem II
• Light energy is trapped in
photosystem II and
boosts electron to a
higher level.
• The electrons are
received by an electron
acceptor. Thus leaving
the chlorophyll molecule
positive.
• It then splits water by
taking 2e- from it.
• The electrons are passed
from one acceptor
(Plastoquinone and
Cyctochrome) to the next
to photosystem I.
• Along the way the energy
lost reduces ADP-> ATP
8.
9. Photosystem I
• The light energy in
Photosystem I boosts the
electrons to an even higher
level.
• The electrons are received
by another acceptor and
these combine with the
protons from the split water
to reduce NADP called non
cyclic
photophosphorylation.
• Any left over electrons will
return to Photosystem I (via
the electron transport
chain) to produce more
ATP. This is called cyclic
photophosphorylation.
(This is the common
pathway in prokaryotes)
For example: in spinach chloroplasts these photosystems contain about 200 chlorophyll molecules and about 50 carotinoids, arranged in what are called light harvesting antenna .