Name: carbon fixation in photosynthesis
Uploaded: 2025-08-11T09:30:18.000Z
Duration: 1 min 40 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Earth and Space Science

Earth's Systems

3.3.9-12.L

The Calvin Cycle

- [Anlatıcı] Ototrof bitkilerde Calvin döngüsü, atmosferdeki karbondioksidin kloroplastın stromasına girmesiyle başlar.
 Burada karbondioksitin bir karbon atomu, ribuloz bifosfat karboksilaz oksijenaz ile, kısaca RuBisCo adlı enzimle katalize edilen bir reaksiyonla beş karbon alıcı şeker molekülüne eklenir veya bağlanır.
 Ortaya çıkan altı karbonlu molekül çok kararsızdır ve iki adet üç karbonlu moleküle bölünür.
Bunlar 3-fosfogliserik asit, 3-PGA'dır.
 ATP enerjiyi sağlar ve NADPH her birine bir hidrojen bağlar.
 3-PGA zincirleri gliseraldehit-3-fosfat adı verilen başka bir üç karbonlu ara maddeye çevrilir.
Sonra bir G3P döngüden çıkar ve altı karbon atomuyla glikoz oluşturmak için bir başkasını bekler.
 Bu sırada kalan G3P dört döngü daha beklemelidir.
 Bekleme süresince karbonlar birikir ve ATP, RuBP alıcılarını yenilemek için daha fazla enerji sağlar.
Toplamda altı tur Calvin döngüsü atmosferden altı karbondioksit bağlar.
 18 ATP'nin enerjisini ve 12 NADPH'nin indirgeme gücünü, döngüye devam amacıyla bir molekül glikoz yenileme ve yeniden RuBP yapmak için kullanır.

Michelet, Laure, Mirko Zaffagnini, Samuel Morisse, Francesca Sparla, María Esther Pérez-Pérez, Francesco Francia, Antoine Danon ve ark. "Calvin-Benson Döngüsünün Redoks Düzenlemesi: Eski Bir Şey, Yeni Bir Şey." Bitki Biliminde Sınırlar 4 (2013). [<a href="https://doi.org/10.3389/fpls.2013.00470" target="__blank">Kaynak</a>]

Sharkey, Thomas D. ve Sean E. Weise. "Calvin-Benson Döngüsü Etrafındaki Glikoz 6-Fosfat Şant." Deneysel Botanik Dergisi 67, no. 14 (1 Temmuz 2016): 4067–77. [<a href="https://doi.org/10.1093/jxb/erv484" target="__blank">Kaynak</a>]

calvin döngüsü

<h4>Genel Bakış</h4>

Oksijenik fotosentez, yılda yaklaşık 200 milyar ton karbondioksiti (CO2) organik bileşiklere dönüştürür ve yaklaşık 140 milyar ton atmosferik oksijen üretir (O2). Fotosentez, bir kişinin tüm gıda ve oksijen ihtiyacının temelidir.

Fotosentetik süreç, bitki kloroplastlarının farklı bölgelerinde meydana gelen iki reaksiyon setine ayrılabilir: ışığa bağlı reaksiyon ve ışığa bağlı olmayan veya karanlık reaksiyonlar. Işığa bağlı reaksiyon, kloroplastın tilakoid membranında gerçekleşir. Işık enerjisini ATP ve NADPH olarak depolanan kimyasal enerjiye dönüştürür. Bu enerji daha sonra, Calvin-Benson döngüsünün ışıktan bağımsız reaksiyonları yoluyla atmosferik karbondioksiti kompleks karbonhidratlara indirgemek için kloroplastın stroma bölgesinde kullanılır.

<h4>Calvin-Benson Döngüsü</h4>

Calvin-Benson döngüsü, ışıktan bağımsız fotosentetik reaksiyonlar kümesini temsil eder. Atmosferik CO2 ' yi kompleks karbonhidratlara dönüştürmek için ışığa bağımlı reaksiyonlar sırasında üretilen adenosin trifosfat (ATP) ve nikotinamid-adenin dinükleotid fosfat (NADPH) kullanır. Calvin-Benson döngüsü ayrıca ışığa bağımlı reaksiyon için adenosin difosfat (ADP) ve NADP+ rejenere eder.

Calvin-Benson döngüsünün başlangıcında, atmosferik CO2 yaprağa stoma adı verilen açıklıklardan girer. Kloroplastın stroma bölgesinde, ribuloz-1,5-bifosfat karboksilaz/oksijenaz (RuBisCO) enzimi, CO2 ' dan bir 5-karbon (5C) alıcı şeker molekülüne, ribuloz-1,5-bifosfat (RuBP) bir karbon atomu ekler. Elde edilen 6C molekülü oldukça kararsızdır ve iki molekül 3-fosfogliserik aside (3-PGA) bölünür. Enzim 3-fosfogliserat kinaz, bu 3-PGA moleküllerini 1,3-bifosfogliserat oluşturmak için fosforile etmek için ATP kullanır. Gliseraldehit 3-fosfat dehidrojenaz gliseradehit 3-fosfat (G3P), bir 3C şeker oluşturmak için bu molekülleri azaltmak için NADPH kullanır. Bu nihai ürün, Calvin-Benson döngüsü için bir takma ad olan C3 karbon fiksasyonu adını doğurur.

Altı CO2 molekülünü düzeltmek için, Calvin-Benson döngüsü 12 NADPH ve 18 ATP molekülünü azaltır. Bu enerji kaynakları, ışığa bağlı fotosentez reaksiyonları ile yenilenir. Altı CO2, 12 adet 3C molekülüne (G3P) ayrılan altı 5C molekülüne (RuBP) bağlanır. Bu G3P moleküllerinden on tanesi, döngüye devam etmek için RuBP alıcısının altı molekülünü yeniden üretir. İki G3P molekülü bir glikoza dönüştürülür. G3P ayrıca diğer karbonhidratları, amino asitleri ve lipitleri sentezlemek için de kullanılabilir.

Calvin Döngüsü

Genel bakış

Oksijenli fotosentez, yılda yaklaşık 200 milyar ton karbondioksiti (CO2) organik bileşiklere dönüştürür ve yaklaşık ...

Education

JoVE Core

Biology

Biyoloji

Cellular Processes

Hücresel Süreçler

Photosynthesis

Fotosentez

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

carbon fixation in photosynthesis

Photosynthesis uses light energy to turn carbon dioxide into carbohydrates. It also releases oxygen as a by-product. These products help support most food webs and make aerobic life possible.

Photosynthesis has two main stages, and they happen in different parts of the chloroplast. The light-dependent reactions take place in the thylakoid membranes. Chlorophyll absorbs light energy there and helps split water molecules. This releases O2 and makes ATP and NADPH.

The light-independent reactions happen in the stroma, where the Calvin-Benson cycle operates. This cycle uses ATP and NADPH to reduce atmospheric CO2 into carbohydrates. After they are used, ADP and NADP+ return to the thylakoids so the light reactions can recycle them.

The Calvin-Benson cycle has three phases: carbon fixation, reduction, and regeneration of the CO2 acceptor, RuBP. CO2 enters the leaf through stomata. In the stroma, the enzyme RuBisCO attaches each CO2 molecule to ribulose-1,5-bisphosphate, or RuBP. This forms an unstable six-carbon intermediate that quickly splits into two molecules of 3-phosphoglycerate, or 3-PGA.

During reduction, each 3-PGA molecule is phosphorylated by ATP to form 1,3-bisphosphoglycerate. NADPH then reduces it to glyceraldehyde-3-phosphate, or G3P, a three-carbon sugar. For every six CO2 molecules fixed, two G3P molecules leave the cycle. These molecules help form glucose and other organic compounds.

In the final regeneration phase, the remaining G3P molecules are rearranged to rebuild RuBP. This step uses additional ATP. Regenerating RuBP lets the cycle continue fixing CO2.

Carbon Fixation in Photosynthesis

what is photosynthesis?

Photosynthesis in Chloroplasts and Leaves

Photosynthesis happens in plants and in some bacteria. It is the process that captures carbon dioxide and solar energy to make glucose. Glucose stores chemical energy as carbohydrates. The overall biochemical equation is 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2. Photosynthesis also releases oxygen into the atmosphere and helps maintain Earth’s atmospheric oxygen content. Photosynthetic reactions take place in chloroplasts, which are specialized membrane-enclosed parts of the plant cell.

light as energy

How Plant Pigments Capture Light

Photosynthesis uses light energy from the sun, which is a form of electromagnetic radiation. The full range of possible wavelengths is called the electromagnetic spectrum. Light is made of photons, which are small packets of energy. Photons act like waves and are described by frequency, wavelength, and amplitude. Waves with higher frequencies carry more energy and have shorter wavelengths. Waves with lower frequencies carry less energy and have longer wavelengths. For most organisms,...

anatomy of chloroplasts

Chloroplasts and Photosynthesis in Plant Cells

Chloroplasts are the organelles where photosynthesis takes place in green algae and plants. They are also found in green stems and unripe fruit. In plants, mesophyll cells in the leaf contain the highest density of chloroplasts. Each chloroplast has a double membrane. The outer membrane faces the plant cell cytoplasm on one side and the chloroplast intermembrane space on the other. The inner membrane separates that narrow space from the stroma, which is the watery interior of the chloroplast.

photosystem ii

Photosystem II and Water Splitting

Photosystem II is a multi-protein complex that captures light energy and begins the flow of electrons in photosynthesis. It uses bound pigments to harvest photons and send that energy to its reaction center. From there, the energy continues through the electron transport chain and on to photosystem I. The pigments in photosystem II include chlorophyll a, chlorophyll b, and carotenoids. They are arranged in two parts of the photosystem: the antenna complex and the reaction center. The antenna...

photosystem i

Photosystem I and NADPH Formation

Photosystem I helps convert light energy into NADPH during photosynthesis. It works with photosystem II in the thylakoid membrane of the chloroplast, but it uses a different electron supplier and a different electron acceptor. Electrons excited in photosystem II move to photosystem I through an electron transport chain. That chain includes plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As the electrons travel between the two photosystems, they lose energy and must be...

the calvin cycle

Photosynthesis uses light energy to turn carbon dioxide into carbohydrates. It also releases oxygen as a by-product. These products help support most food webs and make aerobic life possible. Photosynthesis has two main stages, and they happen in different parts of the chloroplast. The light-dependent reactions take place in the thylakoid membranes. Chlorophyll absorbs light energy there and helps split water molecules. This releases O2 and makes ATP and NADPH. The light-independent reactions...

c4 pathway and cam

Plant Carbon Fixation in Hot Climates

Plant carbon fixation in hot climates can follow the C4 pathway or the CAM pathway. These alternative pathways help some plants reduce energy loss from photorespiration. Photorespiration happens when oxygen levels are high and rubisco, the enzyme in the Calvin cycle, binds O2 instead of CO2. When that happens, photosynthesis slows and energy is used up. The C4 pathway is used by plants such as corn and sugarcane. In mesophyll cells, CO2 first joins with PEP, or phosphoenolpyruvate, through the...

key terms and concepts

Explore how the Calvin-Benson cycle fixes carbon dioxide into sugars, using ATP and NADPH in the chloroplast stroma during photosynthesis.

Carbon Fixation in Photosynthesis | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

JoVE Core serisi, biyolojinin ana konseptlerini açıklayan 300 adet kısa ve kolay anlaşılabilir olan video dersleriyle ve günümüz laboratuvarlarında yürütülen gerçek araştırmaları gösteren 150'den fazla \"bilim insanları iş başında\" videolarıyla biyolojiye hayat vermektedir.

3.3.9-12.N

Louisiana Student Standards for Science

High School

Earth Science

Earth’s Systems

HS-ESS2-4

HS-ESS2-6

HS-ESS2-7

Environmental Science

Virginia  Standards of Learning

HIgh School

Life Science

LS.4

LS.4.a

LS.4.b

Alabama Course of Study Science

Earth and Human Activity

9-12.EVS.4.8.a

Next Generation Science Standards

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

HS-LS1-5

Texas Essential Knowledge and Skills

BIO.11

BIO.11.A

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

ecosystems-interactions-energy-and-dynamics

Ecosystems: Interactions, Energy, and Dynamics

B-LS2-5.

new-york-state-science-learning-standards

New York State Science Learning Standards

matter-and-energy-in-organisms-and-ecosystems

Matter and Energy in Organisms and Ecosystems

HS-LS1-5.

HS-LS1-6.

Georgia Standards of Excellence

SB1.e

myJoVE Corporation

What is Climate?

Climate refers to the prevailing weather conditions in a specific area over an extended period. As the saying goes, &#8220;Climate is what you expect. ...

Global Climate Change

Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global ...

Ecological Disturbance

An ecological disturbance is a temporary disruption in the environment resulting from abiotic, biotic, or anthropogenic factors, causing a pronounced ...

Climate Change

The certainty of climate change remains a public controversy despite the consensus among approximately 97% of active climate researchers, who not only ...

using-topographic-maps-to-generate-topographic-profiles

Using Topographic Maps to Generate Topographic Profiles

Source: Laboratory of Alan Lester - University of Colorado Boulder
Topographic maps are &#34;plan-view&#34; representations of Earth&#39;s ...

Radiation: Applications

The average temperature of Earth is the subject of much current discussion. Earth is in radiative contact with both the Sun and dark space; it receives ...

Momentum And Radiation Pressure

An object absorbing an electromagnetic wave would experience a force in the direction of propagation of the wave. This force occurs because ...

Radiation Pressure: Problem Solving

The radiation pressure applied by an electromagnetic wave on a perfectly absorbing surface equals the energy density of the wave. The wave&#39;s momentum ...

The Electromagnetic Spectrum

The electromagnetic spectrum consists of all the types of electromagnetic radiation arranged according to their frequency and wavelength. Each of the ...

What is Weather?

Overview

Weather refers to the current state of atmospheric conditions at a specific time and place. Weather is temporary and is influenced by the ...

The Wave Nature of Light

The nature of light has been a subject of inquiry since antiquity. In the seventeenth century, Isaac Newton performed experiments with lenses and prisms ...

Mechanisms of Heat Transfer I

Just as interesting as the effects of heat transfer on a system are the methods by which the heat transfer occur. Whenever there is a temperature ...

Mechanisms of Heat Transfer II

In convection, thermal energy is carried by the large-scale flow of matter. Ocean currents and large-scale atmospheric circulation, which result from the ...

Students who demonstrate understanding can analyze geoscience data to make the claim that one change to Earth's surface can create feedback that causes changes to other Earth systems.  Clarification Statement: Examples should include climate feedbacks, such as how an increase in greenhouse gases causes a rise in global temperatures that melts glacial ice, which reduces the amount of sunlight reflected from Earth's surface, increasing surface temperatures and further reducing the amount of ice.  Examples could also be taken from other system interactions, such as how the loss of ground vegetation causes an increase in water runoff and soil erosion;  how dammed rivers increase groundwater recharge, decrease sediment transport, and increase coastal erosion;  or how the loss of wetlands causes a decrease in local humidity that further reduces the wetland extent.  Assessment Boundary:

3.3.9-12.H

Igneous Intrusive Rock

Source: Laboratory of Alan Lester - University of Colorado Boulder
Igneous rocks are products of the cooling and crystallization of high temperature ...

Igneous Volcanic Rock

Source: Laboratory of Alan Lester - University of Colorado Boulder
Igneous rocks are the products of cooling and crystallization of magma. Volcanic rocks ...

an-overview-of-alkenone-biomarker-analysis-for-paleothermometry

An Overview of Alkenone Biomarker Analysis for Paleothermometry

Source: Laboratory of Jeff Salacup&#160;- University of Massachusetts Amherst
Throughout this series of videos, natural samples were extracted and ...

Making a Geologic Cross Section

Source: Laboratory of Alan Lester - University of Colorado Boulder
Geologic maps were first made and utilized in Europe, in the mid-to-late 18th century. ...

Conditions on Early Earth

Nuclear Stability

Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10&#8722;15 meters, a nucleus is ...

Radioactivity and Nuclear Equations

Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for ...

Radioactive Decay and Radiometric Dating

Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. ...

Types of Radioactivity

The most common types of radioactivity are &#945; decay, &#946; decay, &#947; decay, neutron emission, and electron capture.
Alpha (&#945;) decay is the ...

Nuclear Power

Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by ...

Isotopes and Radioisotopes

In the early 1900s, English chemist Frederick Soddy realized that an element could have atoms with different masses that were chemically ...

Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

Nuclear Transmutation

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with ...

determining-spatial-orientation-rock-layers-with-brunton

Determining Spatial Orientation of Rock Layers with the Brunton Compass

Source: Laboratory of Alan Lester - University of Colorado Boulder
Most rock units exhibit some form of planar surfaces or linear features. Examples ...

Dynamics of Structures

Source:&#160;Roberto Leon, Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA
It is rare nowadays that a whole year goes by ...

Sound Waves and Doppler Shift

Source: Arianna Brown,&#160;Asantha Cooray, PhD, Department of Physics &#38; Astronomy, School of Physical Sciences, University of California, Irvine, CA
...

Reflection of Waves

When a wave travels from one medium to another, it gets reflected at the boundary of the second medium. A common example of this is when a person yells at ...

Students who demonstrate understanding can develop a model based on evidence of Earth's interior to describe the cycling of matter by thermal convection.  Clarification Statement: Emphasis is on both a one-dimensional model of Earth, with radial layers determined by density, and a three-dimensional model, which is controlled by mantle convection and the resulting plate tectonics.  Examples of evidence include maps of Earth's three-dimensional structure obtained from seismic waves, records of the rate of change of Earth's magnetic field (as constraints on convection in the outer core), and identification of the composition of Earth's layers from high-pressure laboratory experiments.  Assessment Boundary:

3.3.9-12.I

Role of Water in Human Biology

Water is the one of the most significant components of the human body; it plays a crucial role in several physiological activities because of its unique ...

States of Water

Water exists in any one of the three classical states: solid (ice), liquid (water), and gas (steam or water vapor). The state of water depends on i) the ...

The Water Cycle

The Earth&rsquo;s hydrosphere includes all of the areas where the storage and movement of water occurs. Since water is the basis of all living processes, ...

Cohesion

Cohesion is the attraction between molecules of the same type, such as water molecules. Water molecules have an overall neutral charge but are polar ...

physical-and-chemical-properties-of-matter

Physical and Chemical Properties of Matter

The characteristics that enable us to distinguish one substance from another are called properties.

Physical Properties of Matter

A physical property is ...

Chemistry of the Cell

The cell is chemically composed of water, organic molecules and inorganic ions.
Water
The polarity of the water molecule and its resulting hydrogen ...

Water: A Bronsted-Lowry Acid and Base

The reaction between a Br&#248;nsted-Lowry acid and water is called acid ionization. For example, when hydrogen fluoride dissolves in water and ionizes, ...

The potential of hydrogen (pH) is a measure of the acidity or basicity of a water-based solution determined by the concentration of hydronium ions (H3O+). ...

Solvents

A solvent is a substance, most often a liquid, that can dissolve other substances. Here, the substance being dissolved is called a solute. When a solvent ...

Adhesion

Adhesion occurs when one type of molecule is attracted to a different molecule. Water exhibits adhesive properties in the presence of polar surfaces, such ...

Students who demonstrate understanding can plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes. [cite: 44] Clarification Statement: Emphasis is on mechanical and chemical investigations with water and a variety of solid materials to provide the evidence for connections between the hydrologic cycle and system interactions commonly known as the rock cycle. [cite: 45] Examples of mechanical investigations include stream transportation and deposition using a stream table, erosion using variations in soil moisture content, or frost wedging by the expansion of water as it freezes. [cite: 46] Examples of chemical investigations include chemical weathering and recrystallization (by testing the solubility of different materials) or melt generation (by examining how water lowers the melting temperature of most solids). [cite: 47] Assessment Boundary:

3.3.9-12.K

What are Biogeochemical Cycles?

The most common elements in organic molecules, carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus, are only available in the ecosystem in limited ...

The Carbon Cycle

Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among ...

What is Photosynthesis?

Photosynthesis is a multipart, biochemical process that occurs in plants as well as in some bacteria. It captures carbon dioxide and solar energy to ...

Carbon-dioxide Fixation

Carbon dioxide fixation in prokaryotes enables the assimilation of inorganic carbon into organic molecules, supporting biosynthetic pathways, sustaining ...

Overview

Oxygenic photosynthesis converts approximately 200 billion tons of carbon dioxide (CO2) annually to organic compounds and produces approximately ...

Oxygenic Photosynthesis

Oxygenic photosynthesis is a fundamental process in which light energy is harnessed to drive the oxidation of water, leading to the production of ...

Students who demonstrate understanding can develop a quantitative model to describe the cycling of carbon among the hydrosphere, atmosphere, geosphere, and biosphere. [cite: 154] Clarification Statement: Emphasis is on modeling biogeochemical cycles that include the cycling of carbon through the ocean, atmosphere, soil, and biosphere (including humans), providing the foundation for living organisms. [cite: 155] Assessment Boundary:

What is Evolutionary History?

Scientists record evolutionary history by analyzing fossil, morphological, and genetic data. The fossil record documents the history of life on Earth and ...

The Evidence for Evolution

Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of ...

What is an Ecosystem?

Overview

An ecosystem is the interaction between all abiotic and biotic factors in an environment and can be classified as terrestrial or aquatic. ...

Species Distribution and Biogeography

Species Distribution

Biogeography is the study of species distribution across geographic space and the processes that shape these distributions. This ...

The Soil Ecosystem

Plants obtain inorganic minerals and water from the soil, which acts as a natural medium for land plants. The composition and quality of soil depend not ...

Students who demonstrate understanding can construct an argument based on evidence about the simultaneous coevolution of Earth's systems and life on Earth. [cite: 59] Clarification Statement: Emphasis is on the dynamic causes, effects, and feedbacks between the biosphere and Earth's other systems, whereby geoscience factors control the evolution of life, which in turn continuously alters Earth's surface. [cite: 60] Examples include how photosynthetic life altered the atmosphere through the production of oxygen, which in turn increased weathering rates and allowed for the evolution of animal life; [cite: 61] how microbial life on land increased the formation of soil, which in turn allowed for the evolution of land plants; [cite: 62] or how the evolution of corals created reefs that altered patterns of erosion and deposition along coastlines and provided habitats for the evolution of new life forms. [cite: 63] Assessment Boundary: Assessment does not include a comprehensive understanding of the mechanisms of how the biosphere interacts with all of Earth's other systems. [cite: 64]

Carbon Fixation in Photosynthesis

Description

Transcript

Tags

More videos by Standards