Name: glycolysis: how cells break down glucose
Uploaded: 2019-03-11T09:21:10.000Z
Duration: 56 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Biology

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

From Molecules to Organisms- Structures and Processes

LS.Bio.3.3

What is Glycolysis?

당분해는 신진대사 과정으로서설탕을 분해하여 에너지를 발생시킨다글루코스가 먼저 세포의 세포질로 들어가서두 주요 단계를 거쳐 변형된다첫째 단계는 ATP의 형태로 에너지를 요구하는데글루코스 분자를 안에 가두고일련의 단계를 통해서 수정한다둘째 단계는 전자로부터 에너지를 추출하고그것을 고에너지 NADH와 더 많은 ATP분자로 그것을 이용한다여러 개의 효소 단계를 거친 후에탄소 셋인 설탕 피루빈산염이 두 개 생성되고미토콘드리아로 이송될 준비가 되는데구연산 회로로 들어가기 위한 것이다

해당과정이란 무엇인가?

<h4>개요</h4>
 
 세포는 고분자(macromolecule)를 분해하여 에너지를 만듭니다. 세포호흡은 “음식 에너지”를 (고분자 화학 결합에서) 아데노신삼인산(adenosine triphosphate, 줄여서 ATP) 형태의 화학 에너지로 변환하는 생화학적 과정입니다. 이 엄격히 조절되는 복잡한 과정의 첫 번째 단계는 해당과정(glycolysis)입니다. 해당과정의 영어단어 glycolysis는 라틴어 glyco(당)과 lysis(용해)에서 유래합니다. 해당과정은 ATP 생성과 다른 대사 경로(metabolic pathway)로 공급되는 중간대사물질(intermediate metabolite)의 생성, 이 두 가지 세포 내 주요기능을 수행합니다. 해당과정 경로(glycolytic pathway)는 1개의 헥소스(hexose; 6탄당; 6탄소 탄수화물)를 피루브산(pyruvate) 같은 트리오스(triose; 3탄당; 3탄소 탄수화물) 분자 2개, ATP분자 2개, 그리고 니코틴아마이드 아데닌 다이뉴클레오타이드(nicotinamide adenine dinucleotide, 줄여서 NADH) 분자 2개로 변환합니다.
 
 <h4>해당과정의 발견</h4>
 
 여러분은 해당과정이 최초로 발견된 생화학 경로라는 것을 알고 있었나요? 1800년대 중반 루이 파스퇴르 (Louis Pasteur)는 미생물이 산소가 없을 때 포도당의 분해를 일으킨다고 판단했습니다 (즉 발효작용). 1897년 에두아르트 부흐너 (Eduard Buchner)는 세포를 부수고 가용성(soluble) 분자와 세포기관(organelle)이 있는 세포질(cytoplasm)을 추출해 이 효모 추출물에 세포가 없어도 발효 반응이 가능한 것을 발견했습니다. 이어 1905년 아서 하든 (Arthur Harden)과 윌리엄 영 (William Young)은 무기 인산(inorganic phosphate; Pi)을 첨가하지 않으면 발효 속도가 감소하고, 발효는 열에 민감한 구성요소(나중에 여러 효소를 포함하는 것으로 확인됨)와 낮은 분자 중량(low molecular weight), 열안정 요소(무기 이온, ATP, ADP, 그리고 NAD와 같은 보조효소)를 모두 필요로 한다는 것을 발견했습니다. 1940년쯤엔 많은 사람들(구스타프 엠덴(Gustav Embden), 오토 마이어호프(Otto Meyerhof), 야콥 카롤 파르나스(Jakub Karol Parna) 등)의 노력으로 해당과정의 완전한 경로가 확립되었습니다. 현재 해당과정은 EMP 경로로 알려져 있습니다.
 
 <h4>포도당의 운명</h4>
 
 포도당(glucose)은 두 가지 방법으로 세포에 들어갈 수 있습니다. 첫째, 포도당은 GLUT(glucose transporter; 포도당 수송체)라 불리는 내재단백질(integral protein)군에 의해 촉진 확산(facilitated diffusion)을 통해 세포질(cytosol)로 운반됩니다. GLUT 단백질군의 구성원은 인체의 특정 조직에 존재합니다. 둘째, 포도당은 막관통 동시수송체 단백질(transmembrane symporter protein)을 통한 2차 능동수송(secondary active transport)으로 농도구배(concentration gradient)를 거슬러 세포에 들어갑니다. 여기서 동시수송체(symporter)는 음이온을 펌프질하며 발생하는 전기화학적 에너지를 사용합니다 (예: 소장, 심장, 뇌, 콩팥(신장)에 있는 나트륨-포도당 공동수송체(sodium-glucose linked transporter)).
 
 유산소(aerobic; 산소가 풍부)와 무산소(anaerobic; 산소가 부족) 조건 모두에서 포도당이 세포의 세포질에 들어가면 해당과정이 시작됩니다. 해당과정에는 두 가지 주요 단계가 있습니다. 첫 번째 단계는 에너지가 필요한 단계로 준비 단계로 간주하는데, 이 단계에선 세포 내 포도당을 가두어 효율적으로 분해될 수 있도록 6탄소 뼈대를 재구성합니다. 두 번째 단계는 에너지를 방출하여 피루브산을 생성하는 보상 단계(pay-off phase)입니다.
 
 <h4>피루브산의 운명</h4>
 
 산소의 농도와 미토콘드리아의 존재에 따라 피루브산은 두 가지 운명을 따를 수 있습니다. 미토콘드리아가 존재하는 유산소 조건에서 피루브산은 미토콘드리아로 들어가 구연산회로(citric acid cycle; 시트르산회로)와 전자전달계(electron transport chain)를 거쳐 CO2, H2O, 그리고 훨씬 더 많은 ATP로 산화됩니다. 반면 무산소 조건(예: 움직이는 근육) 또는 미토콘드리아 부족(예: 원핵생물(prokaryote))에서, 피루브산은 유산 발효(lactate fermentation)에 들어갑니다 (즉, 무산소 조건에서는 유산으로 환원됩니다). 흥미롭게도 효모와 몇몇 박테리아는 무산소 조건에서 알코올 발효로 알려진 과정을 통해 피루브산을 에탄올(ethanol)로 변환할 수 있습니다.
 
 <h4>해당과정의 조절</h4>
 
 해당과정 같은 효소 매개 대사 경로(enzyme-mediated metabolic pathway)의 엄격한 통제와 조절은 유기체가 제대로 기능하는 데 매우 중요합니다. 통제는 기질 제한(substrate limitation) 또는 효소결합 조절(enzyme-linked regulation)을 통해 이뤄집니다. 기질 제한은 세포 내 기질과 생성물의 농도가 평형에 가까울 때 발생합니다. 따라서 기질의 가용성(availability)이 화학 반응 속도를 결정합니다. 효소결합 조절에선 기질과 생성물의 농도는 평형과는 거리가 멉니다. 효소의 활동이 반응 속도를 결정하고 그 경로 전체의 흐름을 제어합니다. 해당과정에서 세 가지 조절 효소(regulatory enzyme)는 헥소인산화효소(hexokinase; 헥소키네이스; 헥소키나아제), 포스포프룩토인산화효소(phosphofructokinase; 포스포프룩토키네이스; 포스포프룩토키나아제), 피루브산 인산화효소(pyruvate kinase; 피루브산키네이스)입니다.

개요
세포는 거대분자를 분해하여 에너지를 만듭니다. 세포 호흡은 "음식 에너지"를 변환하는 생화학적 과정입니다.

Education

교육

JoVE Core

생물학

Cellular Processes

세포 과정

Cellular Respiration

세포 호흡

KEY TERMS AND CONCEPTS

주요 용어 및 개념

glycolysis: how cells break down glucose

Glycolysis is the first stage of cellular respiration and a key way cells break down glucose to make energy. Cellular respiration converts food energy from macromolecules into ATP, the cell’s main energy currency. Glycolysis also creates intermediate molecules that can feed into other pathways.

In this pathway, one six-carbon sugar such as glucose is split into two three-carbon molecules, including pyruvate. The process produces a net gain of two ATP molecules, since four ATP are made and two are used. It also generates two molecules of NADH, a carrier used in later energy reactions.

The history of glycolysis began with studies of fermentation. In the mid-1800s, Louis Pasteur showed that microorganisms break down glucose without oxygen. In 1897, Eduard Buchner found that fermentation could still happen in cell-free yeast extracts, which showed that the cytoplasm contains the needed soluble components.

Later, Arthur Harden and William Young found that fermentation slows without inorganic phosphate. They also showed that the process needs both a heat-sensitive part, later linked to enzymes, and a heat-stable part with small molecules such as inorganic ions, ATP, ADP, and coenzymes like NAD. By 1940, Gustav Embden, Otto Meyerhof, Jakub Karol Parnas, and others had established the full pathway, which is now also called the EMP pathway.

Glucose can enter cells in two main ways before glycolysis begins. GLUT proteins move glucose into the cytosol by facilitated diffusion. Transmembrane symporter proteins can also bring glucose in against its concentration gradient by secondary active transport, using energy from ion pumping. Sodium-glucose-linked transporters are examples found in the small intestine, heart, brain, and kidneys.

Glycolysis can begin after glucose enters the cytosol under both aerobic and anaerobic conditions. The pathway has two main phases. The first is an energy-requiring preparatory phase that traps glucose in the cell and rearranges its six-carbon backbone so it can be split efficiently. The second phase releases energy and forms pyruvate.

Pyruvate can follow different paths depending on oxygen and mitochondria. Under aerobic conditions with mitochondria, pyruvate enters the mitochondria and continues through the citric acid cycle and the electron transport chain, where it is oxidized to carbon dioxide, water, and more ATP. Under anaerobic conditions, such as in working muscles, or in cells without mitochondria, such as prokaryotes, pyruvate undergoes lactate fermentation. Yeast and some bacteria can instead convert pyruvate to ethanol through alcohol fermentation.

Glycolysis is tightly regulated because metabolic pathways must be controlled for proper cell function. Regulation can depend on substrate limitation, which occurs when substrate and product levels are near equilibrium and the available substrate sets the reaction rate. It can also depend on enzyme-linked regulation, where the pathway is controlled by key enzymes. Hexokinase, phosphofructokinase, and pyruvate kinase are three enzymes that help determine the overall flux of glycolysis.

Glycolysis: How Cells Break Down Glucose

what is glycolysis?

Glycolysis is the first stage of cellular respiration and a key way cells break down glucose to make energy. Cellular respiration converts food energy from macromolecules into ATP, the cell’s main energy currency. Glycolysis also creates intermediate molecules that can feed into other pathways. In this pathway, one six-carbon sugar such as glucose is split into two three-carbon molecules, including pyruvate. The process produces a net gain of two ATP molecules, since four ATP are made and two...

energy-requiring steps of glycolysis

Glycolysis: Glucose Trapping and Splitting

Glycolysis begins in the cytosol, where glucose is prepared for use as energy. This process has two phases: an energy-requiring phase and an energy-releasing phase. The first phase changes glucose into a more reactive, unstable form before it can move into later steps. In the first step, glucose is phosphorylated, which means a phosphate group is added from ATP. This produces glucose 6-phosphate. The added phosphate is negatively charged, so it cannot cross the hydrophobic cell membrane. As a...

energy-releasing steps of glycolysis

Glycolysis: ATP and NADH Formation

Glycolysis produces ATP and NADH during its energy-releasing phase. These reactions are the last steps of glycolysis and convert glyceraldehyde-3-phosphate, or G3P, into pyruvate. The phase is often described as steps 6 to 10, and it happens twice because two 3-carbon sugars are made earlier in glycolysis. The sixth step begins with two linked events. G3P is oxidized, which means it loses hydrogen, and it is phosphorylated, which means a phosphate group is added. NAD+ acts as the electron...

pyruvate oxidation

How Pyruvate Becomes Acetyl CoA

Pyruvate is prepared for the next stage of cellular respiration inside the mitochondria. After glycolysis, the charged pyruvate molecules enter the mitochondria by active transport. There, they go through three enzymatic reactions so the energy stored in pyruvate can be used by the cell. First, pyruvate dehydrogenase removes the carboxyl group from pyruvate. This step releases carbon dioxide. Next, the stripped molecule is oxidized, and the electrons are picked up by NAD+ to make NADH. The...

the citric acid cycle

Citric Acid Cycle Energy and Products

The citric acid cycle is a key energy-making pathway in cells. It is also called the Krebs cycle or the TCA cycle. In eukaryotic cells, it takes place in the matrix of mitochondria. In prokaryotic cells, it occurs in the cytoplasm. The cycle starts with acetyl CoA, which enters the pathway after pyruvate oxidation. That earlier step makes two acetyl CoA molecules per glucose molecule. For that reason, the citric acid cycle runs twice for each glucose molecule. The pathway includes eight...

electron transport chains

ATP Production by the Electron Transport Chain

ATP production in the electron transport chain is the final stage of cellular respiration. This stage is part of oxidative phosphorylation, which has two steps: the electron transport chain and chemiosmosis. In eukaryotic cells, the electron transport chain sits in the inner mitochondrial membrane. Its main job is to build a proton gradient. That gradient is then used during chemiosmosis to make ATP. The process also regenerates the electron carriers NAD+ and FAD, which are needed again in...

chemiosmosis

ATP Production by Chemiosmosis

ATP production by chemiosmosis is part of oxidative phosphorylation, the efficient stage of cellular respiration that makes most of the cell’s ATP. Oxidative phosphorylation includes two linked processes: the electron transport chain and chemiosmosis. Together, they help generate adenosine triphosphate, or ATP, the main energy molecule used by cells. The electron transport chain is a series of protein complexes in the inner mitochondrial membrane. These complexes pass electrons through a set...

electron carriers

Electron Carriers in Cellular Respiration

Electron carriers help move electrons through cellular respiration. They act like shuttles that can accept electrons, which means they are reduced, or give electrons away, which means they are oxidized. This changing between oxidized and reduced forms is essential for energy production. As glucose breaks down into carbon dioxide and water, it loses electrons at several stages. Electron carriers pick up those electrons and store them temporarily. They then release the electrons into the...

fermentation

Fermentation Pathways Without Oxygen

Fermentation is a metabolic pathway that lets cells make energy without oxygen. It begins after glucose is split into two pyruvate molecules during glycolysis. Glycolysis is the same first step used in aerobic respiration. When oxygen is unavailable, pyruvate does not enter aerobic respiration. Instead, cells convert pyruvate into other organic molecules through pathways that depend on the organism. A key purpose of fermentation is to regenerate NAD+ from NADH so glycolysis can keep running. <br...

dietary connections

How Food Becomes ATP

Food becomes ATP through connected steps in cellular respiration. Carbohydrates, proteins, and lipids all feed into these pathways. The body can use foods such as apples, cheese, and guacamole as sources of energy. Carbohydrate digestion starts with enzymes that break complex carbohydrates into simple sugars. Glucose can enter glycolysis directly. Fructose and galactose must first be converted into sugars that are intermediates of the glycolytic pathway. Proteins are digested into amino acids.

introduction to cellular respiration

Cellular Respiration: ATP Production Steps

Cellular respiration is the process cells use to turn energy from food into ATP. ATP, or adenosine triphosphate, stores energy in chemical bonds that can be released quickly when cells need it. Much of the energy released during respiration becomes heat, but some of it is captured to make ATP. This process depends on oxidation-reduction, or redox, reactions. In these reactions, oxidation means electron loss and reduction means electron gain. The electron carriers NAD+ and FAD, along with their...

products of the citric acid cycle

Citric Acid Cycle Output in Cellular Respiration

The citric acid cycle is a key stage of aerobic respiration in cells. It is also called the Krebs cycle or the tricarboxylic acid (TCA) cycle. Plants and animals use this oxygen-requiring pathway as part of cellular respiration. This cycle happens after glycolysis and pyruvate oxidation. Glycolysis makes two pyruvate molecules from each glucose molecule. During pyruvate oxidation, each pyruvate becomes acetyl-CoA, which is the input for the citric acid cycle. That means one glucose molecule...

outcomes of glycolysis

Glycolysis Products in Cellular Respiration

Glycolysis is the first step of cellular respiration and breaks glucose into smaller molecules. Cells use this process to pull energy from glucose over a series of chemical reactions. Cellular respiration can happen with oxygen or without oxygen. In both aerobic and anaerobic cellular respiration, glycolysis makes a net gain of two pyruvate molecules, two NADH molecules, and two ATP molecules. Four ATP molecules are produced, but two ATP molecules are used earlier in the pathway. Glycolysis...

atp yield

How Cellular Respiration Makes ATP

Cellular respiration makes ATP from glucose in several stages. The process usually produces 30 to 32 ATP per glucose molecule. Most of that ATP comes from oxidative phosphorylation and the electron transport chain, while 4 ATP are made earlier, with 2 from glycolysis and 2 from the citric acid cycle. The electron transport chain, or ETC, sits in the inner mitochondrial membrane. It has four main protein complexes and ATP synthase, the enzyme that makes ATP. NADH and FADH2 deliver electrons to...

key terms and concepts

Learn how glycolysis breaks down glucose, produces ATP and NADH, and connects to pyruvate fate, fermentation, and pathway regulation in cells.

Glycolysis: How Cells Break Down Glucose | 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 시리즈는 생물학의 주요 개념을 설명하는 300개가 넘는 간결하고 이해하기 쉬운 애니메이션 비디오 강의와 오늘날 실험실에서 수행된 실제 연구 실험을 보여주는 150개가 넘는 과학자 활동 비디오를 통해 생물학에 활기를 불어 넣습니다.

Pennsylvania State Academic Standards

Life Science

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

Matter and Energy in Organisms and Ecosystems

3.1.9-12.G

3.1.9-12.J

Louisiana Student Standards for Science

High School

Life Sciences

From Molecules To Organisms: Structures And Processes

HS-LS1-7

ecosystems-interactions-energy-and-dynamics

Ecosystems: Interactions, Energy And Dynamics

HS-LS2-1

Environmental Science

HS-LS2-4

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Cells

Cellular processes

Tennessee Academic Standards

From Molecules to Organisms: Structures and Processes

BIO1.LS1.9

Virginia  Standards of Learning

HIgh School

BIO.2

BIO.2.e

LS.4

LS.4.b

Minnesota Academic Standards in Science

3.1.1 9L.3.1.1.3

3.2.1 9L.3.2.1.1

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Arizona Science Standards

HS.L2

HS.L2U1.21

Alabama Course of Study Science

9-12.B.1.5.c

Next Generation Science Standards

Ecosystems: Interactions, Energy, and Dynamics

HS-LS2-3

Florida Department of Education

SC.912.L.18

SC.912.L.18.8

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

B-LS1-7.

B-LS2-3.

new-york-state-science-learning-standards

New York State Science Learning Standards

HS-LS1-7.

Georgia Standards of Excellence

Botany

SBO1.

Respiration

myJoVE Corporation

Compounds Essential to Human Function

The human body is composed of cells that are fundamentally made up of several different molecules. These molecules are essential to carry out all ...

Macromolecules

Biomolecules
Organisms contain a wide variety of organic molecules with numerous functions which depend on the chemical structures and properties of these ...

Solution Preparation
ExpandCAUTION: It is important to always use care when handling reagents. For example, iodine will stain clothes and skin so wear ...

Identifying Macromolecules with Indicator Solutions
ExpandHYPOTHESES: In this activity, the experimental hypothesis might be that the addition of an ...

pH Regulation in Cells

pH plays a critical role in maintaining normal cellular activities. It helps maintain the structure and function of various proteins, dictates the charge ...

Chemistry of the Cell

Overview of Functional Groups

Functional groups are a group of atoms with characteristic properties, which when linked to the carbon skeleton of a molecule, alter the properties of ...

Introduction to Carbohydrates

Carbohydrates, proteins, and fats are the primary macronutrients in the human diet. However, carbohydrates are the most favored source of energy in the ...

Carbohydrate Metabolism

Sugars as Energy Storage Molecules

What are Lipids?

lipid-derived-compounds-in-the-human-body

Lipid-derived Compounds in the Human Body

Fats and lipids are crucial components in the human body. Some lipid-derived compounds, such as fat-soluble vitamins, eicosanoids, lipoproteins, and ...

Fats as Energy Storage Molecules

What are Proteins?

Protein Organization

Globular Proteins

In organisms, proteins are the most abundant macromolecules. They act as the building blocks of life and play various crucial roles in the body. Proteins ...

Fibrous Proteins

Fibrous proteins are either long and narrow proteins or assemble to form long and thin structures. They contain repetitive units and usually consist of ...

Protein Denaturation

The function of proteins depends on their native three-dimensional structure, which is dictated by the amino acid sequence of the specific protein. ...

Role of Proteins in the Human Body

Proteins are the building block of life. They are also&#160; the most abundant macromolecules with as many diverse roles in the body. They are part of ...

Nucleic Acids and Nucleotides

Nucleic acids are the most important macromolecules for the continuity of life. They carry the cell&#39;s genetic blueprint and have instructions for its ...

Nucleic Acid Structure

The pentose sugar in DNA is deoxyribose, while in RNA the pentose sugar is ribose. The difference between the sugars is the presence of the hydroxyl group ...

ATP Energy Storage and Release

ATP and Macromolecule Synthesis

Biological macromolecules are organic compounds, predominantly composed of carbon atoms. The carbon atoms are covalently bonded with hydrogen, oxygen, ...

Construct an explanation to illustrate relationships between structure and function of major macromolecules essential for life.

LS.Bio.1.1

Introduction to Enzymes

The use of enzymes by humans dates to 7000 BCE. Humans first used enzymes to ferment sugars and produce alcohol without knowing that this was an ...

Enzymes and Activation Energy

The activation energy (or free energy of activation), abbreviated as Ea, is the small amount of energy input necessary for all chemical reactions to ...

Introduction to Enzyme Kinetics

Enzyme kinetics studies the rates of biochemical reactions. Scientists monitor the reaction rates for a particular enzymatic reaction at various substrate ...

Turnover Number and Catalytic Efficiency

The turnover number of an enzyme is the maximum number of substrate molecules it can transform per unit time. Turnover numbers for most enzymes range from ...

Catalytically Perfect Enzymes

The theory of catalytically perfect enzymes was first proposed by W.J. Albery and J. R. Knowles in 1976. These enzymes catalyze biochemical reactions at ...

introduction-to-mechanisms-of-enzyme-catalysis

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple &#34;lock-and-key&#34; fashion. This model stated that the enzyme ...

Ligand Binding and Linkage

Cooperative Allosteric Transitions

Ribozymes

Carry out investigations to illustrate how enzymes act as catalysts for biochemical reactions and how environmental factors affect enzyme activity.

LS.Bio.1.2

What are Cells?

Cells are the smallest and basic units of life, whether it is a single cell that forms the entire organism, e.g., in a bacterium or trillions of them, ...

Cell Size

Cell sizes vary widely among and within organisms. Bacterial cells range between 1-10 micrometers (&#x3BC;m)and are considerably smaller than most ...

Eukaryotic Compartmentalization

One of the distinguishing features of eukaryotic cells is that they contain membrane-bound organelles, such as the nucleus and mitochondria, that carry ...

Prokaryotic Cells

Prokaryotes are small unicellular organisms that include the domains&#x2014;Archaea and Bacteria. Bacteria include many common organisms, such as ...

Cytoplasm

The cytoplasm consists of organelles and a framework of protein scaffolds called the cytoskeleton suspended in an aqueous solution, the cytosol. The ...

Use models to explain how the structure of organelles determines its function and supports overall cell processes.

LS.Bio.1.3

Analyze how the relationship between structure and function supports life processes within organisms.

Glycolysis: How Cells Break Down Glucose

Description

Transcript

Tags

More videos by Standards