Levels of Structural Organization Figure 1.1, step 1 Molecules Atoms Chemical level Atoms combine to form molecules.

Levels of Structural Organization Figure 1.1, step 1 Molecules Atoms Chemical level Atoms combine to form molecules

Table 2.1 Common Elements Making Up the Human Body (1 of 3).

© 2015 Pearson Education, Inc. Biochemistry: the Chemical Composition of Living Matter  The molecules of the human body can be divided into the following groups: 1.Inorganic compounds  Lack carbon  Tend to be small, simple molecules  Include water, salts, and some acids and bases 2.Organic compounds  Contain carbon  All are large, covalently bonded molecules  Include carbohydrates, lipids, proteins, and nucleic acids

© 2015 Pearson Education, Inc. I. Inorganic Compounds 1. Water  Most abundant inorganic compound in the body  66% of your body weight  Vital properties 1.High heat capacity 2.Polarity/solvent properties 3.Chemical reactivity 4.Cushioning

© 2015 Pearson Education, Inc. Polarity/solvent properties- water is often called the “universal solvent”  Solvents are liquids or gases that dissolve smaller amounts of solutes  Solutes are solids, liquids, or gases that are dissolved or suspended by solvents  A mixture of solutes and solvents are called solutions  Many nutrients and respiratory gases dissolve in water and water is a good transport molecule in the body

© 2015 Pearson Education, Inc. Chemical reactivity-  Water is an important reactant in some chemical reactions  Reactions that require water are known as hydrolysis reactions  Example: water helps digest food or break down biological molecules

2.Salts  Compounds that dissociate (break apart) into ions in the presence of water  Vital to many body functions  Example: sodium and potassium ions are essential for nerve impulses; iron ions are important in the blood  All salts are electrolytes- ions that conduct electrical currents  If electrolyte balance is off in the body, many processes will not work © 2015 Pearson Education, Inc.

Figure 2.11 Dissociation of salt in water. δ–δ– δ+δ+ δ+δ+ H H O Water molecule Na + Cl – Salt crystal Ions in solution

3.Acids and Bases  Acids  Release hydrogen ions (H + ) when dissolved in water  Also called proton donors, since hydrogen ions are essentially a hydrogen nucleus  Example: HCl  H +  Cl –  Hydrochloric acid- stomach acid  Carbonic acid- carbon dioxide is converted into this to make it less toxic in the blood stream before it reaches the lungs © 2015 Pearson Education, Inc.

 Neutralization reaction  Type of reaction in which acids and bases react to form water and a salt  Example: NaOH  HCl  H 2 O  NaCl  pH- measure of the concentration of hydrogen ions in a solution  Cells are very sensitive to changes in pH;  pH balance is controlled by the kidneys, lungs, and buffers- chemicals present in bodily fluids and resist changes in pH to protect cells © 2015 Pearson Education, Inc.

Figure 2.12 The pH scale and pH values of representative substances. pH 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Acidic solution Neutral solution Basic solution OH – H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ Increasingly basic Increasingly acidic Neutral [H + ]=[OH – ] Examples 1M Sodium hydroxide (pH 14) Oven cleaner, lye (pH 13.5) Household ammonia (pH 10.5–11.5) Household bleach (pH 9.5) Egg white (pH 8) Blood (pH 7.4) Milk (pH 6.3–6.6) Black coffee (pH 5) Wine (pH 2.5–3.5) Lemon juice, gastric juice (pH 2) 1M Hydrochloric acid (pH 0)

© 2015 Pearson Education, Inc.  Polymer: chainlike molecules made of many similar or repeating units (monomers)  The main organic compounds in the body are carbohydrates, proteins, lipids, and nucleic acids. They are all polymers. II. Organic Compounds

© 2015 Pearson Education, Inc. Monomers linked by covalent bond (a) Dehydration synthesis Monomer 1Monomer 2 Monomers are joined by removal of OH from one monomer and removal of H from the other at the site of bond formation. H2OH2O Dehydration synthesis—monomers are joined to form polymers through the removal of water molecules. Monomers unite, and water is released

© 2015 Pearson Education, Inc. (b) Hydrolysis Monomer 2Monomer 1 Monomers linked by covalent bond Monomers are released by the addition of a water molecule, adding OH to one monomer and H to the other. H2OH2O Hydrolysis—polymers are broken down into monomers through the addition of water molecules. As a water molecule is added to each bond, the bond is broken, and the monomers are released

© 2015 Pearson Education, Inc. II. Organic Compounds  Carbohydrates  Contain carbon, hydrogen, and oxygen  Include sugars and starches  Classified according to size  Monosaccharides—simple sugars  Disaccharides—two simple sugars joined by dehydration synthesis  Polysaccharides—long-branching chains of linked simple sugars

© 2015 Pearson Education, Inc. Carbohydrates  Monosaccharides—simple sugars Structure  Single chain or single-ring structures  Contain 3 to 7 carbon atoms Function  Cellular fuel  Builds part of a nucleic acid molecule Examples: glucose (blood sugar), fructose, galactose, ribose, deoxyribose

© 2015 Pearson Education, Inc. Carbohydrates  Disaccharides Structure  two simple sugars joined by dehydration synthesis Function  Found mainly in foods; too large to be moved into cells so must be broken down by hydrolysis Examples: sucrose, lactose, and maltose

© 2015 Pearson Education, Inc. Polysaccharides Structure  long, branching chains of linked simple sugars  Large, insoluble molecules Function  Molecules are used for storing energy and can be harvested for energy Examples  Starch (plants) and glycogen (animals, stored in muscles and liver)

© 2015 Pearson Education, Inc. Lipids  Most abundant are the triglycerides, phospholipids, and steroids  Sources include meats, egg yolks, dairy, and oils  Contain carbon, hydrogen, and oxygen  Carbon and hydrogen outnumber oxygen  Insoluble in water, but soluble in other lipids

© 2015 Pearson Education, Inc. Lipids Triglycerides Structure  Composed of three fatty acid chains (long chains of carbon and hydrogen) and one glycerol molecule Function  Source of stored energy; stored in fat deposits under the skin and around organs  Insulate the body and protect body from heat loss Examples  Saturated fats, Unsaturated fats, Trans fats, Omega 3 fatty acids

© 2015 Pearson Education, Inc. Figure 2.15a Lipids. Glycerol (a) Formation of a triglyceride. Fatty acid chains are bound to glycerol by dehydration synthesis. 3 fatty acid chains Triglyceride, or neutral fat 3 water molecules 3H 2 O

© 2015 Pearson Education, Inc. Figure 2.16a Examples of saturated and unsaturated fats and fatty acids. (a) Saturated fat. At room temperature, the molecules of a saturated fat such as this butter are packed closely together, forming a solid. Structural formula of a saturated fat molecule.

© 2015 Pearson Education, Inc. Figure 2.16b Examples of saturated and unsaturated fats and fatty acids. (b) Unsaturated fat. At room temperature, the molecules of an unsaturated fat such as this olive oil cannot pack together closely enough to solidify because of the kinks in some of their fatty acid chains. Structural formula of an unsaturated fat molecule.

© 2015 Pearson Education, Inc. Lipids  Trans fats  Oils that have been solidified by the addition of hydrogen atoms at double bond sites  Increase risk of heart disease  Omega-3 fatty acids  Found in cold-water fish and plant sources, including flax, pumpkin, and chia seeds; walnuts and soy foods  Appears to decrease risk of heart disease

© 2015 Pearson Education, Inc. Lipids Phospholipids Structure  Contain two fatty acids rather than three  Contains a phosphorus containing molecule that is attached to the glycerol Function  Form cell membranes; help control what goes in and out of the cell

© 2015 Pearson Education, Inc. Figure 2.15b Lipids. Polar “head” Nonpolar “tail” (schematic phospholipid) 2 fatty acid chains (nonpolar tail) Glycerol backbone Phosphorus-containing group (polar head) (b) Typical structure of a phospholipid molecule (phosphatidylcholine). Two fatty acid chains and a phosphorous-containing group are attached to a glycerol backbone.

Lipids Steroids Structure  Formed of four interlocking rings  Some cholesterol is ingested from animal products. The liver also makes cholesterol  Cholesterol is the basis for all steroids made in the body Function  Wide range of functions: found in cell membranes, builds Vitamin D, build hormones Examples: Include cholesterol, bile salts, vitamin D, and some hormones © 2015 Pearson Education, Inc.

Figure 2.15c Lipids. (c) Cholesterol. Simplified structure of cholesterol, a steroid, formed by four interlocking chains.

© 2015 Pearson Education, Inc. Proteins  Account for over half of the body’s organic matter  Provide for construction materials for body tissues  Play a vital role in cell function  Contain carbon, oxygen, hydrogen, nitrogen, and sometimes sulfur

Figure 2.17 Amino acid structures. (b) Glycine is the simplest amino acid. (a) Generalized structure of all amino acids. (c) Aspartic acid (an acidic amino acid) has an acid group (—COOH) in the R group. (d) Lysine (a basic amino acid) has an amine group (—NH 2 ) in the R group. (e) Cysteine (a basic amino acid) has a sulfhydryl (—SH) group in the R group, which suggests that this amino acid is likely to participate in intramolecular bonding. Amine group Acid group

Figure 2.18a The four levels of protein structure. (a) Primary structure. A protein’s primary structure is the unique sequence of amino acids in the polypeptide chain. Amino acids Cys Glu Leu Ala Met Lys Arg His Gly Leu Aps

© 2015 Pearson Education, Inc. Figure 2.18b The four levels of protein structure. (b) Secondary structure. Two types of secondary structure are the alpha-helix and beta-pleated sheet. Secondary structure is reinforced by hydrogen bonds, represented by dashed lines in the figure. Hydrogen bonds Alpha- helix -pleated sheet

© 2015 Pearson Education, Inc. Figure 2.18c The four levels of protein structure. (c) Tertiary structure. The overall three- dimensional shape of the polypeptide or protein is called tertiary structure. It is reinforced by chemical bonds between the R-groups of amino acids in different regions of the polypeptide chain. Polypeptide (single subunit)

© 2015 Pearson Education, Inc. Figure 2.18d The four levels of protein structure. (d) Quaternary structure. Some proteins consist of two or more polypeptide chains. For example, four polypeptides construct hemoglobin, the blood protein. Such proteins have quaternary structure. Complete protein, with four polypeptide subunits

© 2015 Pearson Education, Inc. Proteins Fibrous (structural) proteins Structure  Strand-like proteins Function  Appear in body structures  Bind structures together and exist in body tissues  Stable proteins  Examples include collagen and keratin

© 2015 Pearson Education, Inc. Proteins Globular (functional) proteins Structure  Compact, spherical protein molecules Function  Function as antibodies, hormones, or enzymes  Play crucial roles in almost all biological processes Examples  Enzymes, anitibodies, hormones, transport proteins like hemoglobin

© 2015 Pearson Education, Inc. Figure 2.19b General structure of (a) a fibrous protein and (b) a globular protein. Heme group (b) Hemoglobin molecule composed of the protein globin and attached heme groups. (Globin is a globular or functional protein.) Globin protein

© 2015 Pearson Education, Inc. Nucleic acids  Make up genes, which provide the basic blueprint of life  Composed of carbon, oxygen, hydrogen, nitrogen, and phosphorus atoms  Largest biological molecules in the body

© 2015 Pearson Education, Inc. Nucleic Acids Deoxyribonucleic acid (DNA) Structure  Built from 4 nucleotides: Cytosine (C), Guanine (G), Thymine (T), and Adenine (A)  Double helix shape- think spiral staircase; nucleotides bond with each other to form the sides of the helix (A-T, C-G) Function  The genetic material found within every cell’s nucleus  Provides instructions for every protein in the body  Replicates before cell division

© 2015 Pearson Education, Inc. Nucleic Acids Ribonucleic acid (RNA) Structure  Single stranded nucleic acid  Thymine is replaced with Uracil (U) Function  Carries out DNA’s instructions for building proteins in the cell  Created from a template of DNA  Three varieties are messenger, transfer, and ribosomal RNA

© 2015 Pearson Education, Inc. Nucleic Acids Adenosine triphosphate (ATP) Structure  Built from the Adenine (A) base with three phosphate groups attached Function  Chemical energy used by all cells  Created when carbohydrates are broken down in the cell  Energy is released by breaking the high-energy bond between the second and third phosphate group

© 2015 Pearson Education, Inc. Figure 2.22 ATP—structure and hydrolysis. (a) Adenosine triphosphate (ATP) Adenine (b) Hydrolysis of ATP High energy bonds Phosphates Ribose ATP PPP PPP H2OH2O PP Adenosine diphosphate (ADP) PiPi Energy

© 2015 Pearson Education, Inc. Figure 2.23 Three examples of how ATP drives cellular work. (a) Chemical work. ATP provides the energy needed to drive energy-absorbing chemical reactions. ATP PiPi Solute PiPi PiPi P A B B A ADP ATP PiPi ADP P PiPi Membrane protein Relaxed smooth muscle cell Contracted smooth muscle cell (b) Transport work. ATP drives the transport of certain solutes (amino acids, for example) across cell membranes. (c) Mechanical work. ATP activates contractile proteins in muscle cells so that the cells can shorten and perform mechanical work.

Levels of Structural Organization Figure 1.1, step 1 Molecules Atoms Chemical level Atoms combine to form molecules.

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Levels of Structural Organization Figure 1.1, step 1 Molecules Atoms Chemical level Atoms combine to form molecules.

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