Name: plant carbon fixation in hot climates
Uploaded: 2019-03-11T09:21:13.000Z
Duration: 1 min 27 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Environmental Science

Earth’s Systems

HS-ESS2-6

C4 Pathway and CAM

- [Narratore] Alcune
piante come il granturco

hanno sviluppato metodi
alternativi per fissare il carbonio

in modo più efficiente in
ambienti caldi e aridi.

In uno, il percorso C4,

durante il primo passaggio
di fissazione del carbonio,

l'anidride carbonica, CO2,
penetra le cellule del mesofillo

e attraverso l'enzima PEP
carbossilasi si combina

con il composto PEP formato
da 3 atomi di carbonio

per formare il composto a 4
atomi di carbonio, ossalacetato,

che viene poi convertito
in un altro acido organico,

in questo caso, il malato.

Il malato viene trasportato nelle cellule

della guaina del fascio

in profondità della foglia
dove l'ossigeno è limitato

e scomposto, rilasciando CO2,

che può procedere attraverso
il ciclo di Calvin

e interagire con il rubisco
per produrre zuccheri.

Altre piante, come l'ananas,

usano il metabolismo
dell'acido delle Crassulacee

o il percorso CAM, per
fissare il carbonio.

Le piante CAM aprono
gli stomi solo di notte

per prevenire la perdita
di acqua durante il giorno.

Come nel percorso C4,

il CO2 viene fissato con la PEP
carbossilasi in ossalacetato

che poi è convertito in malato.

Invece di trasportare il
malato a un'altra parte

della foglia, le piante
CAM conservano il composto

in vacuoli della cellula del mesofillo

rilasciandolo durante il giorno

perché il ciclo di Calvin possa procedere

insieme alle reazioni alla
luce nella fotosintesi.

<ol>
	<li>Edwards, E.J. Traiettorie evolutive, accessibilità e altre metafore: il caso della fotosintesi C4 e CAM. Nuovo fitologo. 223 (4), 1742-1755 (2019).</li>
</ol>

via metabolica c4 e cam nelle piante

<h4>Panoramica</h4>

Alcune piante, come la canna da zucchero e il mais, che crescono in condizioni calde, utilizzano un processo alternativo chiamato percorso C4 per fissare il carbonio. Il ciclo inizia con CO2 dall'atmosfera che entra nelle cellule mesofille dove viene utilizzato per generare ossalacetato, una molecola a quattro carbonio, da fosfoenolpiruvate (PEP). L'ossaloacetato viene poi convertito in malato e trasportato in cellule di ottaia, dove la concentrazione di ossigeno è bassa. Lì, CO2 viene rilasciato dal malate ed entra nel ciclo Calvin dove viene convertito in zuccheri. Il percorso CAM viene effettuato in piante come i cactus che hanno anche bisogno di conservare l'acqua durante il giorno. Le piante CAM lasciano CO2 nelle foglie di notte e producono malate che vengono conservati in vacuoli fino al giorno successivo. Il malata viene poi rilasciato dai vacuoli e lavorato nel ciclo Calvin. Il percorso C4 separa i diversi processi localmente, mentre il percorso CAM li separa in ordine cronologico.

<h4>Ilsentiero C 4</h4>

Alcune piante, come il mais e la canna da zucchero, hanno sviluppato modi alternativi per fissare il carbonio che aiutano a evitare la perdita d'acqua in ambienti caldi e secchi. Uno di questi metodi è il percorso C4. Nella prima fase, CO2 entra nelle cellule di mesofia, e l'enzima di fosfolpigilpyruvate (PEP) carboxylase lo aggiunge al PEP composto a 3 carbonio per formare l'osloatoacetate composto a 4 carbonio. L'oxaloacetate viene poi convertito in un acido organico chiamato malata.

Successivamente, il malato viene trasportato in cellule di faunpe in profondità nella foglia dove la concentrazione di ossigeno è bassa. Malate è ripartito, rilasciando una molecola di CO2 che poi entra nel ciclo di calvin dove l'enzima rubisco lo converte in zucchero. Il percorso C4 offre un vantaggio in condizioni calde e aride, in quanto le piante chiuderanno i loro stomi per conservare l'acqua. Di conseguenza, possono mantenere bassa la concentrazione di ossigeno e quindi favorire il legame di CO2 al rubisco piuttosto che o2. Quando la concentrazione di ossigeno è più alta, il rubisco lega O2 invece di CO2,un processo chiamato fotorespirazione, che arresterebbe la fotosintesi e consuma energia.

<h4>Il percorso CAM</h4>

Altre piante, come cactus e ananas, utilizzano il percorso del metabolismo acido crassulaceo (CAM) per fissare il carbonio. Le piante CAM aprono principalmente gli stomi di notte per prevenire la perdita d'acqua durante la giornata calda. Di notte CO2 entra nelle cellule del mesofillo, dove si combina con PEP per formare ossalacetato e infine malato. Malato viene poi conservato in vacuoli fino al giorno successivo quando viene rilasciato dai vacuoli ed entra nel Ciclo di Calvin. Le prime fasi della fotosintesi procedono durante il giorno in quanto sono dipendenti dalla luce, mentre le reazioni indipendenti dalla luce del ciclo di calvin si svolgono durante la notte. In questo modo, le piante CAM separano la fissazione di CO2 e la sintesi dello zucchero utilizzando diversi momenti della giornata.

Via metabolica C4 e CAM nelle piante

Most plants use the C3 pathway for carbon fixation. However, some plants, such as sugar cane, corn, and cacti that grow in hot conditions, use alternative ...

Education

Didattica

JoVE Core

Biology

Biologia

Cellular Processes

Processi cellulari

Photosynthesis

Fotosintesi

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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 action of PEP carboxylase. This forms the 4-carbon compound oxaloacetate, which is then changed into organic acids, mostly malate.

Malate moves into the bundle sheath cells deep in the leaf, where oxygen levels are low. There, malate is broken down and releases CO2. That CO2 enters the Calvin cycle and is turned into sugar with the help of RuBisCo. In hot, dry conditions, this separation of carbon fixing and sugar production helps the plant close its stomata and save water while keeping oxygen low.

Other plants, such as cacti and pineapple, use the CAM pathway, or crassulacean acid metabolism. CAM plants open their stomata at night to limit water loss during the day. CO2 enters the mesophyll cells at night and combines with PEP to form oxaloacetate and then malate.

The malate is stored in vacuoles until the next day. During the day, it is released so the Calvin cycle can begin. In CAM plants, carbon fixation happens at night, while sugar synthesis follows during the day with energy from the light-dependent reactions. This time-based separation helps these plants survive hot, dry environments.

Plant Carbon Fixation in Hot Climates

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

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...

c4 pathway and cam

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

Learn how C4 and CAM pathways help plants like corn, sugarcane, cacti, and pineapple reduce photorespiration and save water in hot climates.

Plant Carbon Fixation in Hot Climates | 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 Biologia illustra i concetti chiave della biologia grazie a oltre 300 video-lezioni animate, concise e di facile comprensione. Inoltre, negli oltre 150 video di "scienziati in azione", i concetti scientifici vengono applicati e dimostrati da ricercatori attraverso esperimenti in laboratorio.

Virginia  Standards of Learning

HIgh School

Life Science

LS.4

LS.4.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.

Georgia Standards of Excellence

9-12

SB1.e

myJoVE Corporation

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 ...

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 ...

exploring-effects-atmospheric-forcings-on-evaporation-experimental

Exploring the Effects of Atmospheric Forcings on Evaporation: Experimental Integration of the Atmospheric Boundary Layer and Shallow Subsurface

Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study ...

Earth’s systems, being dynamic and interacting, include feedback effects that can increase or decrease the original changes.

HS-ESS2-2

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 ...

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 ...

The geological record shows that changes to global and regional climate can be caused by interactions among changes in the sun’s energy output or Earth’s orbit, tectonic events, hydrosphere circulation, volcanic activity, glaciers, vegetation, and human activities. These changes can occur on a variety of time scales from sudden (e.g., volcanic ash clouds) to intermediate (ice ages) to very long-term tectonic cycles.

HS-ESS2-4

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. ...

physical-properties-of-minerals-i-crystals-and-cleavage

Physical Properties Of Minerals I: Crystals and Cleavage

Source: Laboratory of Alan Lester - University of Colorado Boulder
The physical properties of minerals comprise various measurable and discernible ...

physical-properties-of-minerals-ii-polymineralic-analysis

Physical Properties Of Minerals II: Polymineralic Analysis

Source: Laboratory of Alan Lester - University of Colorado Boulder
The physical properties of minerals include various measurable and discernible ...

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 ...

Igneous Intrusive Rock

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

The abundance of liquid water on Earth’s surface and its unique combination of physical and chemical properties are central to the planet’s dynamics. These properties include water’s exceptional capacity to absorb, store, and release large amounts of energy, transmit sunlight, expand upon freezing, dissolve and transport materials, and lower the viscosities and melting points of rocks.

HS-ESS2-5

The foundation for Earth’s global climate systems is the electromagnetic radiation from the sun, as well as its reflection, absorption, storage, and redistribution among the atmosphere, hydrosphere, and land systems, and this energy’s re-radiation into space.

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 ...

Light as Energy

The energy required to carry out photosynthesis is light&#8212; typically electromagnetic radiation from the sun. The range of all possible wavelengths is ...

Anatomy of Chloroplasts

Green algae and plants, including green stems and unripe fruit, harbor chloroplasts&mdash;the vital organelles where photosynthesis takes place. In ...

Photosystem II

The multi-protein complex photosystem II (PS II) harvests photons and transfers their energy through its bound pigments to its reaction center, and ...

Photosystem I

Although structurally similar to photosystem II (PSII), photosystem I (PSI) is has a different electron supplier and electron acceptor.
Both these ...

The Calvin Cycle

Overview

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

Measuring Tropospheric Ozone

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Ozone is a form of elemental oxygen (O3), a molecule of three oxygen atoms ...

determination-of-nox-in-automobile-exhaust-using-uv-vis-spectroscopy

Determination Of NOx in Automobile Exhaust Using UV-VIS Spectroscopy

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In the troposphere, ozone is naturally formed when sunlight splits nitrogen ...

carbon-and-nitrogen-analysis-of-environmental-samples

Carbon and Nitrogen Analysis of Environmental Samples

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Elemental Analysis is a method used to determine elemental composition of a ...

Gradual atmospheric changes were due to plants and other organisms that captured carbon dioxide and released oxygen.

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 ...

Cyclical changes in the shape of Earth’s orbit around the sun, together with changes in the tilt of the planet’s axis of rotation, both occurring over hundreds of thousands of years, have altered the intensity and distribution of sunlight falling on Earth. These phenomena cause a cycle of ice ages and other gradual climate changes.

Plant Carbon Fixation in Hot Climates

Description

Transcript

Tags

More videos by Standards