1) The Calvin cycle fixes carbon from carbon dioxide into organic molecules like glucose. It uses energy from light reactions to convert CO2 into glyceraldehyde-3-phosphate in chloroplasts.
2) The key enzyme is RuBisCO, which catalyzes the carboxylation of ribulose-1,5-bisphosphate with CO2 to form two molecules of 3-phosphoglycerate. These are then reduced and regenerated into more ribulose-1,5-bisphosphate in a cyclic process.
3) The cycle requires ATP and NADPH from light reactions. It is regulated by light and dark conditions that affect enzyme activation and pH levels in the chloroplast.
Photorespiration - Introduction, why is it occur in plants, pathway of photorespiration, Enzymes names, pathway step by step explanation, Benefits of photorespiration, additional information related to photorespiration, Rubisco enzyme, Oxygenase enzyme, Oxygen concentration higher leads to photorespiration, problem to carry out calvin cycle.
Synthesis of Sucrose and starch very easy way to learn.
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And
Photorespiration - Introduction, why is it occur in plants, pathway of photorespiration, Enzymes names, pathway step by step explanation, Benefits of photorespiration, additional information related to photorespiration, Rubisco enzyme, Oxygenase enzyme, Oxygen concentration higher leads to photorespiration, problem to carry out calvin cycle.
Synthesis of Sucrose and starch very easy way to learn.
If you want to get more updated information According to your desires comment and like share this information with your friends to spread more knowledge.
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and Instagram ( rahee413)
And
it is bypass cycle of citric acid cycle.
it give the brief description of glyoxylate cycle.
it is the summary of glyoxylate cycle for m.sc, bsc, science students.
it is very important topic for entrance exam of biology stream.
Pentose phosphate pathway is also called Hexose monophosphate pathway/ HMP shunt/ Phosphogluconate pathway.
It is an alternative route for the metabolism of glucose.
It is more complex pathway than glycolysis.
It is more anabolic in nature.
It takesplace in cytosol.
The tissues such as liver, adipose tissue, adrenal gland, erythrocytes,testes and lactating mammary gland are highly active in HMP shunt.
It concern with the biosynthesis of NADPH and pentoses.
Dr.S.KARTHIKUMAR
Associate Professor
Department of Biotechnology
Kamaraj College of Engineering and Technology, K.Vellakulam-625701, TN, India
Email: skarthikumar@gmail.com
Sulphate assimilation which takes place mainly in chloroplasts in higher plants leads to the formation of cysteine. cysteine is the central compound in sulphur assimilation.
it is bypass cycle of citric acid cycle.
it give the brief description of glyoxylate cycle.
it is the summary of glyoxylate cycle for m.sc, bsc, science students.
it is very important topic for entrance exam of biology stream.
Pentose phosphate pathway is also called Hexose monophosphate pathway/ HMP shunt/ Phosphogluconate pathway.
It is an alternative route for the metabolism of glucose.
It is more complex pathway than glycolysis.
It is more anabolic in nature.
It takesplace in cytosol.
The tissues such as liver, adipose tissue, adrenal gland, erythrocytes,testes and lactating mammary gland are highly active in HMP shunt.
It concern with the biosynthesis of NADPH and pentoses.
Dr.S.KARTHIKUMAR
Associate Professor
Department of Biotechnology
Kamaraj College of Engineering and Technology, K.Vellakulam-625701, TN, India
Email: skarthikumar@gmail.com
Sulphate assimilation which takes place mainly in chloroplasts in higher plants leads to the formation of cysteine. cysteine is the central compound in sulphur assimilation.
Carbocations and factors affecting their stabilitykoskal
A carbocation is a species where a carbon atom bonds to three carbon atoms and has a positive charge. Carbocations are electron deficient species and therefore very reactive and unstable. Anything which donates electron density to the electron-deficient center will help to stabilize them.
The oxygenase activity of Rubisco produces 2-phosphoglycolate. This .pdfpasqualealvarez467
The oxygenase activity of Rubisco produces 2-phosphoglycolate. This is a wasteful pathway in
photosynthetic cells because:
(Choose the TWO best answers)
Question 5 options:
Rubisco is much slower when catalyzing the oxygenation reaction than the carboxylation, and
therefore the enzyme gets bogged down with O2 and catalytic activity is reduced.
The O2 that could have been used as an electron acceptor in the mitchondrial electron transport
chain has been used up and wasted.
CO2 is lost without the production of any ATP, NADPH or other energy-rich compounds, and
therefore is considered wasted.
The rubisco reaction requires ATP, which is wasted if 2-phosphoglycolate is produced.
During the process of converting 2-phosphoglycolate into a useful metabolite, a molecule of
CO2 is lost. The Calvin cycle reactions are required to get this carbon \"back\" via carbon
fixation.
In the process of converting 2-phosphoglycolate to 3-phosphoglycerate, NAD+ is consumed
when converting serine to glycine.
Rubisco is much slower when catalyzing the oxygenation reaction than the carboxylation, and
therefore the enzyme gets bogged down with O2 and catalytic activity is reduced.
The O2 that could have been used as an electron acceptor in the mitchondrial electron transport
chain has been used up and wasted.
CO2 is lost without the production of any ATP, NADPH or other energy-rich compounds, and
therefore is considered wasted.
The rubisco reaction requires ATP, which is wasted if 2-phosphoglycolate is produced.
During the process of converting 2-phosphoglycolate into a useful metabolite, a molecule of
CO2 is lost. The Calvin cycle reactions are required to get this carbon \"back\" via carbon
fixation.
In the process of converting 2-phosphoglycolate to 3-phosphoglycerate, NAD+ is consumed
when converting serine to glycine.
Solution
CO2 is lost without the production of any ATP, NADPH or other energy-rich compounds, and
therefore is considered wasted.
During the process of converting 2-phosphoglycolate into a useful metabolite, a molecule of
CO2 is lost. The Calvin cycle reactions are required to get this carbon \"back\" via carbon
fixation..
What are rubisco and RuBP And what do they do Briefly list 4 simil.pdfforecastfashions
What are rubisco and RuBP? And what do they do? Briefly list 4 similarities in how ATP is
made in mitochondria and in chloroplasts. A. How does the second law of thermodynamics
explain why diffusion occurs across a membrane? B. Describe how oxidative phosphorylation,
substrate-level phosphorylation, and photo phosphorylation differ in the way ATP is made.
Solution
RuBisCO , is an enzyme Which is used in the Calvin cycle for catalyzing the first step of carbon
fixation, a process by which the atoms of atmospheric carbon dioxide are made available to
organisms in the form of energy-rich molecules such as sucrose. RuBisCO catalyzes either the
carboxylation or oxygenation of ribulose-1,5-bisphosphate (also known as RuBP) with carbon
dioxide or oxygen.
Ribulose-1,5-bisphosphate (RuBP) is an important 5-carbon intermediate in the Calvin cycle
taking place during photosynthesis. It is the substrate, which is used by the enzyme to fix CO2 to
create a highly unstable 6 Carbon PO4 which decays into two molecules of glycerate 3-
phosphate.
In both i.e. Mitochindria as well as in Chloroplast ATP synthesis takes place via a proton
gradient-
Both have ATP synthatases
Both have Electron Transport Chains
Both have 70s ribosomes.
The second law is a trend towards the randimization or increasing entropy. When the
concentration of a substance on both sides of a membrane are equal, the distribution is more
random than when they are unequal. Diffusion of a substance to a region, where it is initially less
concentrated increases entropy, making it energetically favourable (SPONTANEOUS) process.
-Substrate level phosphorylation occurs in the cytoplasm during Glycolysis and Mitochondria
during Krebs cycle.
-2ATP/GTP are produced by conversion of ADP or GDP
OXIDATIVE PHOSPHORYLATION
-Occurs in Mitochondria
Occurs during respiration
pigment systems are not involved
ATP is produced from ADP and iP
Molecular O2 is required for terminal oxidation.
PHOTOPHOSPHORYLATION
Occurs during photosynthesis inside the chloroplasts.
Pigment systemt I & II are involved
Sunlight is the external source of energy
Molecular Oxygen is not required.
Photosynthesis has two types of reaction, first one is light reaction (Hill's reaction) and the other one is dark reaction (Blackman's reaction). In this presentation you learn full mechanism of how plants produce energy for their survival by photosynthesis.
Photosynthesis has two types of reaction, first one is light reaction (Hill's reaction) and the other one is dark reaction (Blackman's reaction). In this presentation you learn full mechanism of how plants produce energy for their survival by photosynthesis.
Cellular Energy Transfer (Glycolysis and Krebs Cycle) and ATPmuhammad aleem ijaz
This presentation is all about Cellular Energy Transfer with reference to Glycolysis and Kreb Cycle with all their stages involved.
It also includes ATP production in the body, its importance, structure.
Also contains a comparison of energy production in Krebs and Glycolysis cycle.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Palestine last event orientationfvgnh .pptxRaedMohamed3
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We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
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The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
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Sectors of the Indian Economy - Class 10 Study Notes pdf
Calvin cycle and regulation
1. Calvin CycleCalvin Cycle
and its regulationand its regulation
Iqbal rashid mir
Msc botany 3rd
sem
HT. NO.
100714502053
2. Light reactions: Energy of light is conserved as
“high energy” phosphoanhydride bonds of ATP
reducing power of NADPH.
Proteins & pigments responsible for the light
reactions are in thylakoid (grana disc) membranes.
Light reaction pathways will be not be presented
here.
Photosynthesis
takes place in
chloroplasts.
It includes light
reactions and
reactions that are
not directly
energized by light.
3. The free energy of cleavage of ~P bonds of ATP, and
reducing power of NADPH, are used to fix and
reduce CO2
to form carbohydrate.
Enzymes & intermediates of the Calvin Cycle are
located in the chloroplast stroma, a compartment
somewhat analogous to the mitochondrial matrix.
Calvin Cycle,
earlier designated
the photosynthetic
"dark reactions,"
is now called the
carbon reactions
pathway:
4. Ribulose Bisphosphate Carboxylase (RuBP Carboxylase),
catalyzes CO2
fixation:
ribulose-1,5-bisphosphate + CO2
2 3-phosphoglycerate
Because it can alternatively catalyze an oxygenase
reaction, the enzyme is also called RuBP
Carboxylase/Oxygenase (RuBisCO). It is the most
abundant enzyme on earth.
Ribulose-1,5-bisphosphate
(RuBP)
OH
H2C
CH
C
C
OHH
H2C OPO3
2-
OPO3
2-
O
3-Phosphoglycerate
(3PG)
OH
H2C
CH
C
OO
OPO3
2-
-
5. RuBP Carboxylase - postulated mechanism:
Extraction of H+
from C3 of ribulose-1,5-bisphosphate
promotes formation of an enediolate intermediate.
Nucleophilic attack on CO2
leads to formation of a
β-keto acid intermediate, that reacts with water
and cleaves to form 2 molecules of 3-
phosphoglycerate.
OH
H2C
CH
C
C
OHH
H2C OPO3
2−
OPO3
2−
O
OH
H2C
CH
C
C
OH
H2C OPO3
2−
OPO3
2−
−
O
H+
OH
H2C
CH
C
C
O
H2C OPO3
2−
OPO3
2−
HO CO2
−
CO2
OH
H2C
CH
C
OPO3
2−
O−
O
H2O
1
5
4
3
2
ribulose-1,5- enediolate β-keto 3-phosphoglycerate
bisphosphate intermediate intermediate (2)
6. Transition state analogs of the postulated β-keto acid
intermediate bind tightly to RuBP Carboxylase and
inhibit its activity.
Examples: 2-carboxyarabinitol-1,5-bisphosphate (CABP,
above right) & carboxyarabinitol-1-phosphate (CA1P).
2-Carboxyarabinitol-1,5-
bisphosphate (inhibitor)
OH
H2C
CH
C
C
OHH
H2C OPO3
2−
OPO3
2−
HO CO2
−
Proposed β-keto acid
intermediate
OH
H2C
CH
C
C
O
H2C OPO3
2−
OPO3
2−
HO CO2
−
7. 8 large catalytic subunits (L, 477 residues, blue, cyan)
8 small subunits (S, 123 residues, shown in red).
Some bacteria contain only the large subunit, with
the smallest functional unit being a homodimer, L2.
Roles of the small subunits have not been clearly
defined. There is some evidence that interactions
between large & small subunits may regulate
catalysis.
RuBisCO PDB 1RCXRuBisCO PDB 1RCX
RuBP
Carboxylase
in plants is a
complex
(L8S8) of:
8. Large subunits within
RuBisCO are arranged as
antiparallel dimers, with
the N-terminal domain of
one monomer adjacent to
the C-terminal domain of
the other.
Each active site is at an
interface between
monomers within a dimer,
explaining the minimal
requirement for a dimeric
structure.
The substrate binding site is at the mouth of an αβ-barrel
domain of the large subunit.
Most active site residues are polar, including some
charged amino acids (e.g., Thr, Asn, Glu, Lys).
ribulose-1,5-
bisphosphate
PDB 1RCX
2L & 2S
subunits
of RuBisCO
9. "Active" RuBP Carboxylase has a carbamate that binds
an essential Mg++
at the active site.
The carbamate forms by reaction of HCO3
−
with the
ε-amino group of a lysine residue, in the
presence of Mg++
.
HCO3
−
that reacts to form carbamate is distinct from
CO2
that binds to RuBP Carboxylase as substrate.
Mg++
bridges between oxygen atoms of the carbamate
& substrate CO2
.
Carbamate Formation
with RuBP Carboxylase Activation
Enz-Lys NH3
+ H
N C
O
O−
+ HCO3
−
+ H2O + H+Enz-Lys
10. Binding of either RuBP or a transition state analog
to RuBP Carboxylase causes a conformational
change to a "closed" conformation in which
access of solvent water to the active site is
blocked.
RuBP Carboxylase (RuBisCO) can spontaneously
deactivate by decarbamylation.
In the absence of the carbamate group, RuBisCO
tightly binds ribulose bisphosphate (RuBP) at the
active site as a “dead end” complex, with the
closed conformation, and is inactive in catalysis.
In order for the carbamate to reform, the enzyme
must undergo transition to the open
conformation.
11. RuBP Carboxylase Activase is an ATP hydrolyzing
(ATPase) enzyme that causes a conformational change
in RuBP Carboxylase from a closed to an open state.
This allows release of tightly bound RuBP or other sugar
phosphate from the active site, and carbamate
formation.
Since photosynthetic light reactions produce ATP, the
ATP dependence of RuBisCO activation provides a
mechanism for light-dependent activation of the
enzyme.
The activase is a member of the AAA family of
ATPases, many of which have chaperone-like roles.
RuBP Carboxylase Activase is a large multimeric protein
complex that may surround RuBisCO while inducing the
conformational change to the open state.
12. When O2
reacts with ribulose-1,5-bisphosphate, the
products are 3-phosphoglycerate plus the 2-C
compound 2-phosphoglycolate.
This reaction is the basis for the name RuBP
Carboxylase/Oxygenase (RuBisCO).
OH
H2C
CH
C
OO
OPO3
2−
−
H2C
C
OPO3
2−
O−
O
3-phospho- phosphoglycolate
glycerate
Photorespiration:
O2
can compete with CO2
for binding to RuBisCO,
especially when [CO2
] is
low & [O2
] is high.
13. The complex pathway that partly salvages C from
2-phosphoglycolate, via conversion to 3-
phosphoglycerate, involves enzymes of chloroplasts,
peroxisomes & mitochondria.
This pathway recovers 3/4 of the C as 3-
phosphoglycerate.
The rest is released as CO2.
Photorespiration is a wasteful process, substantially
reducing efficiency of CO2 fixation, even at normal
ambient CO2.
OH
H2C
CH
C
OO
OPO3
2−
−
H2C
C
OPO3
2−
O−
O
3-phospho- phosphoglycolate
glycerate
Photorespiration:
Diagram
14. Most plants, designated C3, fix CO2 initially via RuBP
Carboxylase, yielding the 3-C 3-phosphoglycerate.
Plants designated C4 have one cell type in which
phosphoenolpyruvate (PEP) is carboxylated via the
enzyme PEP Carboxylase, to yield the 4-C
oxaloacetate.
Oxaloacetate is converted to other 4-C intermediates
that are transported to cells active in photosynthesis,
where CO2 is released by decarboxylation.
phosphoenolpyruvate oxaloacetate
(PEP)
PEP Carboxylase
→
15. C4 plants maintain a high ratio of CO2
/O2
within
photosynthetic cells, thus minimizing
photorespiration.
Research has been aimed at increasing expression
of and/or inserting genes for C4 pathway enzymes,
such as PEP Carboxylase, in C3 plants.
16. Continuing with Calvin Cycle:
The normal RuBP Carboxylase product, 3-phospho-
glycerate is converted to glyceraldehyde-3-P.
Phosphoglycerate Kinase catalyzes transfer of Pi from
ATP to the carboxyl of 3-phosphoglycerate (RuBP
Carboxylase product) to yield 1,3-
bisphosphoglycerate.
OH
H2C
CH
C
OO
OPO3
2−
−
OH
H2C
CH
C
OPO3
2−
O
OPO3
2−
OH
H2C
CH
CHO
OPO3
2−
ATP ADP NADPH NADP+
Pi
1,3-bisphospho-
glycerate
3-phospho-
glycerate
glyceraldehyde-
3-phosphate
Phosphoglycerate
Kinase
Glyceraldehyde-3-phosphate
Dehydrogenase
17. Glyceraldehyde-3-P Dehydrogenase catalyzes
reduction of the carboxyl of 1,3-bisphosphoglycerate to
an aldehyde, with release of Pi
, yielding
glyceraldehyde-3-P.
This is like the Glycolysis enzyme running backward, but
the chloroplast Glyceraldehyde-3-P Dehydrogenase uses
NADPH as e−
donor, while the cytosolic Glycolysis
enzyme uses NAD+
as e−
acceptor.
OH
H2C
CH
C
OO
OPO3
2−
−
OH
H2C
CH
C
OPO3
2−
O
OPO3
2−
OH
H2C
CH
CHO
OPO3
2−
ATP ADP NADPH NADP+
Pi
1,3-bisphospho-
glycerate
3-phospho-
glycerate
glyceraldehyde-
3-phosphate
Phosphoglycerate
Kinase
Glyceraldehyde-3-phosphate
Dehydrogenase
18. Continuing with Calvin Cycle:
A portion of the glyceraldehyde-3-P is converted
back to ribulose-1,5-bisP, the substrate for
RuBisCO, via reactions catalyzed by:
Triose Phosphate Isomerase, Aldolase, Fructose Bisphosphatase, Sedoheptulose
Bisphosphatase, Transketolase, Epimerase, Ribose Phosphate Isomerase, &
Phosphoribulokinase.
Many of these are similar to enzymes of Glycolysis,
Gluconeogenesis or Pentose Phosphate Pathway,
but are separate gene products found in the
chloroplast stroma. (Enzymes of the other
pathways listed are in the cytosol.)
The process is similar to Pentose Phosphate
Pathway run backwards.
19. Summary of Calvin cycle:
3 5-C ribulose-1,5-bisP (total of 15 C) are
carboxylated (3 C added), cleaved,
phosphorylated, reduced, & dephosphorylated,
yielding
6 3-C glyceraldehyde-3-P (total of 18 C). Of
these:
1 3-C glyceraldehyde-3-P exits as product.
5 3-C glyceraldehyde-3-P (15 C) are recycled back into 3 5-C ribulose-1,5-
bisphosphate.
C3
+ C3
C6
C3
+ C6
C4
+ C5
C3
+ C4
C7
C3
+ C7
C5
+ C5
Overall 5 C3
3 C5
21. 3 CO2
+ 9 ATP + 6 NADPH
glyceraldehyde-3-P + 9 ADP + 8 Pi
+ 6 NADP+
Glyceraldehyde-3-P may be converted to other
CHO:
• metabolites (e.g., fructose-6-P, glucose-1-P)
• energy stores (e.g., sucrose, starch)
• cell wall constituents (e.g., cellulose).
Glyceraldehyde-3-P can also be utilized by plant
cells as carbon source for synthesis of other
compounds such as fatty acids & amino acids.
glyceraldehyde-
3-phosphate
OH
H2C
CH
CHO
OPO3
2−
OCO
carbon
dioxide
Summary of
Calvin Cycle
22. There is evidence for multienzyme complexes of
Calvin Cycle enzymes within the chloroplast stroma.
Positioning of many Calvin Cycle enzymes close to
the enzymes that produce their substrates or utilize
their reaction products may increase efficiency of
the pathway.
grana disks
(thylakoids)
stroma
compartment
2 outer
membranes
Chloroplast
23. Regulation of Calvin Cycle
Regulation prevents the Calvin Cycle from
being active in the dark, when it might
function in a futile cycle with Glycolysis &
Pentose Phosphate Pathway, wasting ATP &
NADPH.
Light activates, or dark inhibits, the Calvin
Cycle (previously called the “dark reaction”) in
several ways.
24. Light-activated e−
transfer is linked to pumping of H+
into thylakoid disks. pH in the stroma increases to
about 8.
Alkaline pH activates stromal Calvin Cycle enzymes
RuBP Carboxylase, Fructose-1,6-Bisphosphatase &
Sedoheptulose Bisphosphatase.
The light-activated H+
shift is countered by Mg++
release
from thylakoids to stroma. RuBP Carboxylase (in
stroma) requires Mg++
binding to carbamate at the active
site.
stroma
(alkaline)
Chloroplast
H2O OH
−
+ H
+
hν
(acid inside
thylakoid disks)
Regulation
by Light.
25. Some plants synthesize a transition-state
inhibitor, carboxyarabinitol-1-phosphate (CA1P),
in the dark.
RuBP Carboxylase Activase facilitates release of
CA1P from RuBP Carboxylase, when it is activated
under conditions of light by thioredoxin.
26. disulfide
Thioredoxin f PDB 1FAA
Thioredoxin is a small protein with a disulfide that
is reduced in chloroplasts via light-activated
electron transfer.
27. During illumination, the thioredoxin disulfide is reduced
to a dithiol by ferredoxin, a constituent of the
photosynthetic light reaction pathway, via an enzyme
Ferredoxin-Thioredoxin Reductase.
Reduced thioredoxin activates several Calvin Cycle
enzymes, including Fructose-1,6-bisphosphatase,
Sedoheptulose-1,7-bisphosphatase, and RuBP
Carboxylase Activase, by reducing disulfides in those
enzymes to thiols.
thioredoxin
−S
−S
thioredoxin
−SH
−SH
|
ferredoxinRed ferredoxinOx
Ferredoxin-
Thioredoxin
Reductase