Inorganic Matter

Water is called the [1] because it dissolves more substances than any other liquid. In order for another molecule to dissolve in water, a shell of water molecules called a [2] must form around it. Substances that mix readily with water are called [3], whereas those that do not are called [4]. Water is retained in the body and forms films on organ surfaces due to its [5], the tendency for water molecules to be mutually attracted to each other. This property also gives water a high [6]—the ability to absorb a large amount of heat energy with relatively little change in temperature.

[7] are inorganic molecules and ions extracted from soil and passed through the food chain. The two most significant gases in human physiology are [8] and [9], but recently it has been discovered that many cells contain an enzyme that uses arginine to make [10], a gas widely used as an intercellular messenger.

1._________________________  6._________________________

2._________________________  7._________________________

3._________________________  8._________________________

4._________________________  9._________________________

5._________________________ 10._________________________

Carbon and Organic Molecules

Compounds of carbon are called [11]. They get their unique functional properties mainly from small groups of atoms called [12]. For example, –COOH is one of these called a [13] group, -OH is called a/an [14] group, and –CH3 is called a/an [15] group. Some of these compounds are giant molecules called [16], with very high molecular weights. Usually these are [17], or chains of repetitive subunits called [18]. Such chains are typically formed through [19] reactions, which produce water as a by-product, and they are broken apart by [20] reactions, which consume water.

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Carbohydrates

Carbohydrates are named for the fact that they are made essentially of carbon plus a 2:1 ratio of [21]. The simplest of them are called [22], which literally means "single sugars." Sucrose, lactose, and maltose are the three most common dietary [23], or double sugars. Any compound made of thousands of glucose residues linked together is called a/an [24]. One of these, [25], is indigestible plant fiber important as "bulk" or "roughage" in the diet. [26] is a compound in this category made by liver and muscle cells to store excess glucose. Carbohydrates may be covalently bonded, or [27], with other macromolecules. One example is [28], a protein with one to a few monosaccharide residues attached. Another is a [29], which consists mainly of a long polysaccharide chain bonded to a core protein, and which often forms gels in the intercellular material of tissues. When two different classes of organic compounds are covalently joined to form a large molecule, each chemically different component is called a [30].

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22._________________________ 27._________________________

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Lipids

[31] are usually 16–18 carbon atoms long, with a carboxyl group at one end and a methyl group at the other. They are called [32] if they have one or more C=C double bonds, and [33] if all their carbon-carbon bonds are single covalent and they carry as much hydrogen as possible. When three of these are linked to a glycerol molecule, they form a neutral fat, or [34]. If only two of these are linked to glycerol, and the third carbon of glycerol is linked to a hydrophilic phosphate-containing group, the molecule is called a/an [35]. One of the most important properties of these molecules is that they are [36]—part of the molecule is attracted to water, and part is repelled by it. This property helps determine the structure of cell membranes. Modified 31s with a ring in the middle of the carbon chain are called [37]; they serve as chemical messengers from one cell to another. Lipids with four rings are called [38], and all of these are synthesized from a somewhat notorious compound called [39].

31._________________________ 36._________________________

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Proteins

A protein is a chain of amino acids joined together by [40] bonds. The order in which the amino acids occur is called the [41] of a protein. Most proteins also coil into a spring-like shape called the [42], held together by hydrogen bonds from the C=O group of each amino acid to the –NH group of the third next one. This coiled molecule then tends to fold into a specific shape called the protein’s [43] structure. When a functional protein consists of two or more polypeptides associated with each other, it is said to have a [44] structure. The total three-dimensional shape of a protein, called its [45], is critical to its function. When a structural change destroys a protein’s function, the protein is said to be [46]. When a protein is covalently bonded to a non-protein moiety, it is said to be [47]. Proteins that function as catalysts are called [48].

40._________________________ 45._________________________

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Enzymes

Enzymes work by reducing the [49] of a chemical reaction, enabling it to proceed more rapidly. Molecules that are chemically changed by an enzyme are called its [50]. The site where an enzyme attaches to such a molecule is called the [51]. Just as only one key fits a given lock, a given enzyme can usually bind only to certain 50s, a property called [52]. This limits the chemical reactions they can catalyze. According to the [53] model of enzyme-substrate interaction, a substrate partially determines the shape of the enzyme’s 51. Most enzymes function best at the same [54] because this variable is fairly uniform throughout the body, but [55] varies more from place to place, and different enzymes are adapted to function best at the 55 found in the organ where the enzyme occurs. Some enzymes require inorganic ions called [56] or vitamin derivatives called [57] in order to function. These vitamin derivatives function by transferring electrons from one reaction sequence, or [58], to another.

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Adenosine Triphosphate

The primary purpose of adenosine triphosphate (ATP) is to transfer [59] from one reaction to another. It is composed of three phosphate groups linked to the sugar [60], which in turn is linked to a nitrogenous compound called [61]. In a typical reaction involving ATP, an enzyme called an ATPase hydrolyzes the third [62] from ATP and transfers it to another molecule. That other molecule is then said to be [63]. The synthesis of ATP often begins with a glucose-splitting reaction pathway called [64]. The pyruvic acid generated by this pathway is either converted to lactic acid by a process called [65], or broken all the way down to CO₂ and H₂O by a process called [66]. A major difference between these is that 66 requires [67], whereas 65 does not, but 66 produces a great deal more ATP. The reactions of 66 are carried out in cellular structures called [68]. Some energy transfer reactions use [69] triphosphate, a molecule similar to ATP. ATP is also closely related to the building blocks of the [70] acids, DNA and RNA.

59._________________________ 65._________________________

60._________________________ 66._________________________

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