Ch. 2 Chemistry Comes AlivePart II: BIOCHEMISTRY

Biochemistry is the study of the chemical composition and reactions of living matter.

Organic compounds contain carbon and are covalently bonded, such as carbohydrates (sugars and starches).

Inorganic compounds (not organic) include chemicals such as water, salts, acids, and bases.

Water is the most abundant and important inorganic compound in organisms. 60-80 % of cellular volume.

Water has many properties essential to an organisms survival.

High heat capacity- absorbs or releases a large amount of heat before changing its temperature. Important for temp. regulation.

Polarity- water is a polar molecule which makes it an excellent solvent. Many important nutrients, gases, and other compounds are in solution. Metabolic reactions require water

High heat of vaporization- large amount of energy must be absorbed to break the hydrogen bonds holding water molecules together. This heat is released when water evaporates. Provides cooling effect when we sweat.

Reactivity- water is an important in many chemical reactions. (Hydrolysis and dehydration synthesis)

Cushioning- fluid surrounding body organs and tissues provides protection from physical trauma and reduces friction.

Salts are ionic compounds that dissociate into ions in solution.

Salts found in the body include NaCl, KCl, and calcium carbonate. Calcium phosphates make up bones and teeth.

K+ and Na+ ions are important for nerve transmission and muscle contraction.

Acids, bases, and salts are electrolytes because they ionize and dissociate in water.

These solutions can then conduct an electric current.

Acids and bases are covalently bonded molecules that dissociate in solution.

Acids release H+ ions in solution. They are sour and corrosive. pH<7 Acids in the body include HCl (gastric

juice), urine, amino acids, lactic acid, carbonic acid, Vitamin C, fatty acids, saliva

Bases are proton acceptors, some are hydroxides (OH-)

Bases are slippery and bitter, pH > 7.

Bases in the body include blood (7.4), semen, ammonia, and bicarbonate ion.

The relative concentrations of hydrogen [H+] and hydroxyl [OH-] ions in body fluids is measured in pH units.

The pH scale runs from 0 to 14. pH of 7 is neutral, below 7 is considered to be acidic, and above 7 is basic.

Each unit of pH represents a 10x change. For example, a pH of 2 is ten times more acidic than a pH of 3.

Neutralization reactions occur when acids and bases are mixed to form water and salt.

Ex) HCl + NaOH -> H2O + NaCl

Buffers are weak acids or bases that prevent extreme changes in pH.

One buffer system helps maintain pH homeostasis of the blood: carbonic acid/bicarbonate ion

H2CO3 HCO3- + H+

As blood pH rises, the reaction shifts right, causing more carbonic acid dissociate.

As blood pH decreases, the reaction shifts left, causing bicarbonate ions to bond with protons (H+) to reform carbonic acid.

Carbohydrates contain carbon, hydrogen, and oxygen in a ratio of 1:2:1.

Carbohydrates include sugars and starches, and are important for energy. A few carbohydrates are used for structural purposes.

Larger molecules, such as starch, are less soluble in water.

Monosaccharides (simple sugars) are single-chain or single ring structures containing 3-7 carbon atoms. Ex) glucose, fructose, and galactose

Disaccharides are made up of two sugar units. Ex) lactose and maltose

Polysaccarhides- chains of monosaccharides forming a polymer.

Ex) starch, cellulose,

glycogen

Contain carbon, hydrogen, and oxygen. Structure often includes fatty acids and glycerol.

Phosphorus is found in some more complex lipids.

Insoluble in water, but dissolve in other lipids and organic solvents.

Formed by fatty acids and glycerol in a 3:1 ratio. Also called triglycerides. Concentrated source of energy.

Fats when solid, and oils when liquid. Saturated fats have only single bonds.

Meat fat and butter fat are examples. Unsaturated fats contain double bonds.

Olive oil and peanut oil are examples. Usually considered to be healthier.

Modified triglyceride with phosphorus containing group.

Has hydrophobic tail (nonpolar) and hydrophilic (polar) head. Amphipathic molecule.

Chief component of cell membranes, also found in nervous tissue

Flat molecules made up of four interlocking hydrocarbon rings.

Fat soluble and contain little oxygen.

Examples: cholesterol, sex hormones, bile

salts, and important for cell membranes

Cholesterol-structural basis for all body steroids

Bile salts- released by the liver into the digestive tract, where they assist in fat digestion and absorption

Vitamin D- produced in the skin on exposure to sunlight, needed for healthy bone growth and function

Sex hormones- estrogen and testosterone produced in the gonads, needed for reproduction

Cortisol- metabolic hormone needed for maintaining normal blood glucose levels

Some vitamins are not water-soluble. These nonpolar vitamins can accumulate in fat tissues if consumed in excess.

Vitamin A- found in orange fruits and vegetables, part of the photoreceptor pigment involved in vision

Vitamin E- found in green leafy vegetables, important in wound healing, has antioxidant properties

Vitamin K- made available by the action of intestinal bacteria, prevalent in many foods, necessary for blood clotting

Diverse group of lipids formed from a 20-carbon fatty acid found in cell membranes.

As a group of compounds, they play diverse roles in the body; such as in blood clotting, regulating blood pressure, inflammatory response, secretory activity, and labor contractions

Protein-based substances that transport fatty acids and cholesterol in the bloodstream; major varieties are high-density lipoproteins (HDLs) and low-density lipoproteins (LDLs)

Contain carbon, hydrogen, oxygen, and nitrogen. Many contain phosphorus and sulfur.

Composed of chains of 20 amino acid types, joined by peptide bonds

Basic structural material of the body, making up 10-30% of cell mass.

Includes enzymes, hemoglobin, and contractile proteins of muscles

Amino acids arethe building blocks

of protein.

Proteins have a complex structure on four levels:

Primary-sequence of amino acids Secondary- chain bends or twists (B-

pleated sheet or alpha-helix) Tertiary- secondary structure folds to

produce a compact, globular structure Quaternary- two or more polypeptide

chains group to form a complex protein such as hemoglobin

Overall structure of a protein determines its biological function.

Fibrous proteins (structural proteins) are extended and thread-like. Water insoluble, have secondary structure

Ex) collagen, keratin, elastin

Globular proteins (functional proteins) are spherical and compact. Water soluble with tertiary structure.

Ex) enzymes, hemoglobin, and antibodies

Antibodies-proteins important in the immune response

Hormones-chemical messengers carried in the blood that stimulate target cells.

Transport proteins-carry materials in the blood (hemoglobin) and across cell membranes

Catalysts (Enzymes)-act as biological catalysts, to regulate and accelerate the rate of biochemical reactions without being used up in the process.

When enzymes and other proteins are exposed to conditions outside the optimum temperature and pH range, their three dimensional shape changes (denaturation).

Since enzymes are shape-specific, any changes prevent them from carrying out their function.

Nucleic acids are composed of C,H,O, N, and P. The structural unit of nucleic acids are nucleotides.

A nucleotide consists of a nitrogen containing base, a five carbon sugar, and a phosphate group.

DNA contains deoxyribose, is double stranded, and contains the bases adenine, thymine, adenine, and guanine. Base pairing: A—T and G—C

DNA stores genetic information

RNA is single stranded, contains ribose, the base uracil instead of thymine

RNA helps carry out its instructions.

Although glucose is the most important cellular fuel, its energy cannot be used directly by cells.

Glucose catabolism is coupled with ATP synthesis, with energy being stored in the bonds of ATP.

ATP is the universal energy compound of body cells.

How ATP Drives Cellular WorkHow ATP Drives Cellular Work

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• ATP has 3 phosphates attached (P)

• Removal of a P releases energy from the bond, leaving ADP

• Removal of another P releases less energy, leaving AMP