Name: water as a biological solvent
Uploaded: 2019-03-11T09:21:00.000Z
Duration: 1 min 12 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

Earth and Environmental Science

Earth's Systems

ESS.EES.3.1

Solvents

溶媒とは分子を分解する 物質のことで 分解される物質は溶質と呼ばれます 例えば、細胞の細胞質内にある 水は生命の存続に必要な 様々な栄養素を分解・伝達してくれます 細胞内の化学物質は水の持つ極性により 水素原子の+と 酸素原子の-の性質を持ち合わせています 例えば、塩や塩化ナトリウムなどのイオン化合物があると それぞれのイオンは水に引き寄せられ 水素結合します そうすると、水は物質の周りを取り囲み、溶質が拡散して水和状態となり 溶液と呼ばれる均一的な混合物となります

溶媒

溶媒とは、たいていは液体であり、他の物質を溶かすことができる物質です。溶かされる物質は溶質と呼ばれます。溶媒と溶質が結合すると、分子レベルで溶媒と溶質の両方が均質に混在した溶液となります。水は普遍的な生物学的溶媒です。その極性構造により、他の多くの極性化合物を溶解することができます。水の溶解能力は、水分子同士の結合と溶質との結合のバランスによって決定されます。
 
 飽和溶液は、溶解可能な溶質の最大量を含みます。例えば、塩（NaCl）は簡単に水に溶解し、塩水（食塩水）となります。これは、塩がそれぞれのイオンであるナトリウムイオン（Na+）と塩化物イオン（Cl-）に解離するからです。水は極性があるので、わずかに負に帯電した酸素原子が正に帯電したナトリウムイオンに引きよせられます。1つのナトリウムイオンに複数の水分子が結合し、水和層を形成します。同様に、水の水素原子はわずかに正に帯電しているため、負に帯電した塩化物イオンに引きよせられ、再び塩化物イオンの周りに水和層を作ります。これら水和殻によって、溶質粒子が分離・分散状態に保たれ、溶液が作られるのです。
 
 食塩水の飽和溶液には、室温で約26％の塩化ナトリウムが含まれます。さらに塩が加わると、余剰分は溶液に溶け込むことができず、底で沈殿物となります。アメリカのユタ州にあるグレートソルト湖の塩分含有量は5〜27％です。イスラエル、ヨルダン、ヨルダン川西岸地区に接する死海の塩分含有量は～34％になります。これは、水の塩分飽和量よりもかなり高いものです。余剰分の塩は沈殿析出し、驚くような塩の結晶を形成します。 
 
 溶質の溶解度（水に溶ける能力）は、生物学的機能にとって重要です。例えばタンパク質やアミノ酸は細胞に入るために溶解していなければなりません。同様に、数ある中でもナトリウムイオン、塩化物イオン、カリウムイオン、カルシウムイオンは細胞の機能に必要です。タンパク質、イオン、その他の栄養素は、血液に溶けており、水分の約79％にあたります。腎臓は、浸透圧調節と呼ばれるろ過の際に、これらの溶質を、取り除いたり加えたりすることで、血液中に溶けた溶質を適切な量に保っています。

溶媒は、他の物質を溶解できる物質、ほとんどの場合は液体です。ここでは、溶解する物質を溶質と呼びます。溶剤が...

Education

JoVE Core

Biology

生物学

Fundamentals

基礎

Chemistry of Life

生命の化学

KEY TERMS AND CONCEPTS

主要用語と概念

water as a biological solvent

Water acts as a biological solvent in many living systems. A solvent is a substance, usually a liquid, that dissolves another substance called a solute. When a solvent and a solute mix, they form a solution, which is a uniform mixture of both parts.

Water is called a universal biological solvent because its polar structure helps it dissolve many other polar compounds. Polarity means that one side of the molecule has a slight positive charge and the other side has a slight negative charge. Water’s ability to dissolve substances depends on a balance between water molecules sticking to each other and sticking to the solute.

A saturated solution holds the maximum amount of solute that can dissolve. Table salt, or sodium chloride (NaCl), dissolves readily in water to make salt water, also called saline. When salt dissolves, it breaks apart into sodium ions (Na+) and chloride ions (Cl-).

Water molecules then surround these ions. The oxygen atom in water is slightly negative, so it is attracted to sodium ions. The hydrogen atoms are slightly positive, so they are attracted to chloride ions. Several water molecules can cluster around each ion and form a sphere of hydration. These hydration shells keep the particles separated and dispersed, which allows a solution to form.

At room temperature, saturated salt water contains about 26% sodium chloride. If more salt is added, the extra salt cannot dissolve. It settles out as a precipitate at the bottom. The Great Salt Lake in Utah has a salt content that ranges from 5% to 27%. The Dead Sea, bordered by Israel, Jordan, and the West Bank, has about 34% salt. That is well above the saturation level of salt in water, so excess salt precipitates and forms striking salt crystals.

Solubility is important for biology because many molecules must stay dissolved to work in the body. Proteins and amino acids need to be dissolved to reach cells. Ions such as sodium, chloride, potassium, and calcium are also needed for cell function. Proteins, ions, and other nutrients stay dissolved in the blood. The kidneys help control the right levels of these dissolved solutes by removing or adding them during filtration. This process is called osmoregulation.

Water as a Biological Solvent

the periodic table and organismal elements

the-periodic-table-and-organismal-elements

Periodic Table Basics for Living Things

The periodic table helps explain which elements living things need and how those elements are related. Elements are the smallest units of matter that cannot be broken down further by chemical processes. There are 118 known elements, but not all occur naturally, and even fewer are essential for life. Living matter is made mostly of carbon, nitrogen, hydrogen, and oxygen. Together, these elements make up most of the human body and are also found in all life on Earth. Smaller amounts of calcium,...

atomic structure

Atoms and Their Subatomic Particles

Atoms are the smallest units of elements, and they make up all matter. Each atom contains three subatomic particles: protons, neutrons, and electrons. These particles give an atom its mass and its charge. The idea that matter is made of tiny particles goes back to Democritus, a Greek philosopher around 450 B.C. He used the word atomos, which means “indivisible.” The idea was not accepted at the time, but it returned many centuries later. In the 19th century, John Dalton proposed an atomic...

isotopes

Atomic Mass and Isotope Basics

Atomic mass and isotopes are linked by the number of protons and neutrons in an atom. The number of protons sets an element’s atomic number, or Z. For example, every atom with eight protons is oxygen. Atoms of the same element can still differ because they can have different numbers of neutrons. The mass number, or A, is the total of protons and neutrons. Atoms with the same atomic number but different mass numbers are called isotopes. Elements can have several isotopes. Carbon-12, carbon-13,...

electron behavior

Electron Shells and Valence Electrons

Electrons are negatively charged subatomic particles that occupy regions around the positively charged nucleus of an atom. Their location is linked to energy levels called shells. They are also grouped into sub-shells and orbitals within each shell. An electron’s shell shows its general energy level. Electrons closer to the nucleus have less energy, while electrons farther away have more energy. The sub-shell gives a more exact location and energy level. An orbital is the shape of the region...

electron orbital model

Electron Orbitals and Energy Levels

Electron orbitals show where electrons are most likely to be found around the atomic nucleus. They also help explain energy levels, orbital shapes, and three-dimensional orientation. In an atom, electron location is described first by a shell, or principal energy level. It is then described by a subshell within that shell and by the individual orbitals inside each subshell. The first shell is closest to the nucleus. It has only one subshell and one spherical orbital, called the 1s orbital.

covalent bonds

Electronegativity and Covalent Bond Polarity

Covalent bonds form when two atoms share electrons to fill their valence shells. The way those shared electrons are pulled depends on electronegativity, which is an atom’s ability to attract electrons in a bond. When atoms have similar electronegativities, they form nonpolar covalent bonds. When their electronegativities differ, the bond is polar because the electrons are shared unevenly. The number of covalent bonds an atom can make depends on its valence electrons. Oxygen has six valence...

ionic bonds

Ionic Compounds and Electrolytes

Ionic compounds form when atoms gain or lose electrons to reach a more stable electron configuration. The charged particles that result are called ions. Ionic bonds are electrostatic attractions between oppositely charged ions. The most reactive elements include those with one valence electron, such as potassium, and those that need one more valence electron, such as chlorine. Ions that lose electrons become positive cations. Ions that gain electrons become negative anions. Cations and anions...

hydrogen bonds

Hydrogen Bonds in Water

Hydrogen bonds in water are weak attractions between atoms that are already part of other chemical bonds. One atom is electronegative, such as oxygen, and carries a partial negative charge. The other is a hydrogen atom that is bonded to another electronegative atom and has a partial positive charge. These attractions form because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom like oxygen or nitrogen. The electrons in that bond are shared unequally.

van der waals interactions

Intermolecular Forces in Polar Solutions

Intermolecular forces are the attractions and repulsions that act between atoms and molecules. These electrostatic forces come from particles with permanent, partial, or temporary charges. For neutral atoms and molecules, the main types are ion-dipole, dipole-dipole, and dispersion forces, which are together called van der Waals forces. Polar molecules have a partial positive end and a partial negative end. That separation of charge creates a dipole. In water, oxygen is more electronegative...

elements and compounds

Elements, Compounds, and Bonding

Elements and compounds are the two main kinds of pure substances. A pure substance contains only one kind of matter. An element contains only one type of atom. A compound contains two or more types of atoms joined by a chemical bond. Elements can be atomic or molecular, depending on their basic units. They are unique forms of matter with specific chemical and physical properties. Ordinary chemical reactions cannot break an element into a smaller substance. There are 118 elements, but only 98...

molecular shapes

Electron Geometry and Lone Pairs

Electron geometry and lone pairs help explain why molecules take specific shapes. The arrangement of electron groups around a central atom controls the molecular geometry. Valence electrons form bonding pairs, which sit mainly between bonded atoms, or lone pairs, which belong to one atom only. Electron pairs in the valence shell spread out to reduce repulsion. They do this by maximizing the distance between one another. A diatomic molecule has two regions of electron density, and these are...

pH Scale in Everyday Solutions

pH measures how acidic or basic a water-based solution is. It depends on the concentration of hydronium ions, H3O+, in the solution. In one liter of pure water at neutral pH, there are 1×10−7 moles of hydronium ions. Because hydronium ion levels can vary over a very wide range, measuring pH directly in moles is not practical. The pH scale converts hydronium ion concentration into a negative logarithm. Pure water has a pH of 7 and is neutral. Most solutions fall between 0 and 14, but some, such...

chemical reactions

Atoms, Bonds, and Chemical Reactions

Chemical reactions rearrange atoms to form new substances. In a reaction, the starting materials are called reactants, and the new substances are called products. The atoms stay the same type and number, but their bonds change, so the substances become different compounds. During a chemical reaction, bonds between atoms break and form again. This means the shared electrons are rearranged. Some reactions happen on their own, while others need an energy source such as heat or light. In biology,...

redox reactions

Electron Transfer in Redox

Redox reactions are chemical reactions that involve electron transfer between atoms or molecules. When one particle gains electrons, another must lose them at the same time. That is why oxidation and reduction always happen together. The two roles in a redox reaction are linked. The atom that is oxidized acts as the reducing agent, or reductant. The atom that is reduced acts as the oxidizing agent, or oxidant. A simple way to remember the ideas is OIL-RIG, which means oxidation is losing...

cohesion

Water Molecules and Surface Tension

Water molecules stick to each other through cohesion. Water is neutral overall, but it is a polar molecule. The oxygen atom in one water molecule has a partial negative charge, and it can bind with a hydrogen atom that has a partial positive charge in another water molecule. This forms a hydrogen bond. Each water molecule can form up to four hydrogen bonds with other water molecules, and these bonds give water its cohesive nature. Cohesion helps water form droplets on a surface. Water does not...

adhesion

Water Climbing by Adhesion

Water can climb or stick to surfaces because of adhesion, which is the attraction between different kinds of molecules. In water, this is easy to see on polar surfaces such as glass or cellulose in plants. The positive hydrogen side of water is more attracted to the negative oxygen in silica than to nearby water molecules. This attraction helps explain capillary action. If a narrow glass tube is placed in a beaker of water, water molecules attach to the tube’s surface and the water level rises.

states of water

Water Phase Changes and Ice Density

Water changes between solid, liquid, and gas states as temperature and molecular motion change. In this lesson, the focus is on how water freezes, melts, vaporizes, and returns to liquid or solid form. The balance between intermolecular forces, which pull molecules together, and kinetic energy, which pushes them apart, controls each state. Water freezes when intermolecular forces become stronger than kinetic energy. Unlike most substances, ice is less dense than liquid water. This happens...

specific heat

How Specific Heat Affects Temperature

Specific heat capacity describes how much energy a substance needs to rise by 1 degree Celsius for each gram. It is often written with calories, grams, and degrees Celsius, but it can also be shown in joules, kilograms, and Kelvin. For water, 1 gram needs 1 calorie to increase by 1°C, which is also written as 1 cal/g-°C or 4186 J/kg/K. Water has a high specific heat capacity, so it takes in a large amount of heat before its temperature changes much. It also gives off a lot of heat when it...

vaporization

Vaporization, Boiling, and Evaporation

Vaporization changes a liquid into vapor when temperature adds enough kinetic energy to overcome intermolecular forces. It is a surface phenomenon, which means it starts at the liquid’s surface. The energy needed to vaporize a set amount of liquid at a given pressure and constant temperature is called the heat of vaporization. Water shows this process clearly. When liquid water is vaporized, it becomes steam. One way this happens is boiling, which occurs when vapor bubbles form beneath the...

solvents

Water acts as a biological solvent in many living systems. A solvent is a substance, usually a liquid, that dissolves another substance called a solute. When a solvent and a solute mix, they form a solution, which is a uniform mixture of both parts. Water is called a universal biological solvent because its polar structure helps it dissolve many other polar compounds. Polarity means that one side of the molecule has a slight positive charge and the other side has a slight negative charge.

key terms and concepts

Explore how water dissolves salt, forms hydration shells, and reaches saturation. Learn why dissolved ions matter for cells, blood, and kidney regulation.

Water as a Biological Solvent | 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.

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JoVE Core シリーズは、生物学の重要な概念を説明する 300 を超える簡潔でわかりやすいアニメーション ビデオ レッスンに加え、今日の研究室で行われる実際の研究実験を示す 150 以上の科学者の活動ビデオを通じて、生物学に命を吹き込みます。

Pennsylvania State Academic Standards

Earth and Space Science

3.3.9-12.K

Alabama Course of Study Science

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

From Molecules to Organisms: Structures and Processes

9-12.B.1.4.b

Florida Department of Education

High School

Life Science

SC.912.L.18

SC.912.L.18.12

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

South Carolina College and Career Ready Science Standards

Earth and Space Science (ESS)

Earth’s Systems

E-ESS2-5.

myJoVE Corporation

Igneous Volcanic Rock

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The Carbon Cycle

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Igneous Intrusive Rock

Source: Laboratory of Alan Lester - University of Colorado Boulder
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Using Topographic Maps to Generate Topographic Profiles

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Determining Spatial Orientation of Rock Layers with the Brunton Compass

Source: Laboratory of Alan Lester - University of Colorado Boulder
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Making a Geologic Cross Section

Source: Laboratory of Alan Lester - University of Colorado Boulder
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Use models to explain how mantle convection powers plate tectonics.

ESS.EES.2.1

Analyze and interpret data to predict locations of volcanoes and earthquakes based on plate boundaries.

ESS.EES.2.2

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An Overview of Alkenone Biomarker Analysis for Paleothermometry

Source: Laboratory of Jeff Salacup&#160;- University of Massachusetts Amherst
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Topographic Surveying and Contours

Topographic surveying is critical for documenting the Earth's surface, focusing on capturing elevations, slopes, and natural and man-made features. It is ...

Plotting of Topographic Maps

Topographic maps represent the Earth's surface features using contour lines, which connect points of equal elevation to create a two-dimensional ...

Methods of Obtaining Topography

Topography involves measuring and mapping land elevations, natural features, and artificial structures to create accurate representations of the terrain. ...

Use models to explain how plate tectonics influence topography.

ESS.EES.2.3

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 ...

Conditions on Early Earth

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 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, ...

The Nitrogen Cycle

Nitrogen atoms, present in all proteins and DNA, are recycled between abiotic and biotic components of the ecosystem. However, the primary form of ...

The Phosphorus Cycle

Unlike carbon, water, and nitrogen, phosphorus is not present in the atmosphere as a gas. Instead, most phosphorus in the ecosystem exists as compounds, ...

The Sulfur Cycle

Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found in the ...

Bioremediation

Bioremediation is the use of prokaryotes, fungi, or plants to remove pollutants from the environment. This process has been used to remove harmful toxins ...

Carry out investigations to explain how the rock cycle and rates of weathering, erosion, and soil formation influence Earth's systems.

ESS.EES.2.4

What is Climate?

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What is Weather?

Overview

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Variation of Atmospheric Pressure

Change in atmospheric pressure with height is particularly interesting. The decrease in atmospheric pressure with increasing altitude is due to the ...

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Analyze and interpret data to explain how volcanic activity influences changes in Earth's atmosphere, geosphere, biosphere, and hydrosphere.

ESS.EES.2.5

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 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+). ...

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 ...

Redox Reactions

Oxidation-reduction or redox reactions involve the transfer of electrons from one molecule or atom to another. When an atom gains an electron, another ...

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 ...

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 ...

Specific Heat

The specific heat capacity of a substance refers to the energy required to increase the temperature of one gram of that substance by one degree Celcius. ...

Vaporization

The physical form of a substance changes by changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize ...

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 ...

solubility-equilibria-ionic-product-of-water

Solubility Equilibria: Ionic Product of Water

Water is a weak electrolyte and undergoes a small amount of self-ionization.
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Carry out investigations to explain the properties of water.

Energy

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Energy Basics

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Climate Change

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Enthalpy

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Mechanism of heat transfer

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Use models to explain how water is an agent of energy transfer.

ESS.EES.3.2

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 ...

Measuring Tropospheric Ozone

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
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an-overview-of-bgdgt-biomarker-analysis-for-paleoclimatology

An Overview of bGDGT Biomarker Analysis for Paleoclimatology

Analyze and interpret data to explain how major greenhouse gases influence climate.

ESS.EES.3.3

Analyze how the geosphere is shaped by plate tectonics and the rock cycle.

Water as a Biological Solvent

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