Ch 2 - Chemistry Comes Alive

BASIC CHEMISTRY

  • MATTER - Solid, liquid, gaseous states – all found in the human body
  • ENERGY
  • Less tangible, (not mass, fills no space)
  • Def: the capacity to do work; or put matter into motion.
  • The greater the work done, the more energy used.

Type of Energy:

  • Kinetic - Energy in action/motion
  • Potential
  • Stored energy; inactive energy.
  • When potential energy is released it becomes kinetic energy

Forms of Energy

  • Chemical energy - ATP (Adenosine triphospate)
  • ATP is needed for cellular metabolism in the human body
  • Electrical energy
  • Results from charged particles (ions).
  • Nerve impulses in the nervous system are electrical currents that transmit messages from one part of the body to another.
  • Mechanical energy
  • Directly involved in moving matter. Like riding a bike or the Stomach’s mechanical digestion
  • Radiant energy – electromagnetic - Energy that travels through waves

MOLECULES

  • Atoms combined with other atoms
  • Compound molecules – 2 or more different6 kinds of atoms bind.

Mixtures: solutions, colloids, suspension

  • Solution – homogenous mixture of compounds
  • Solvent – substance present in greatest amount.
  • Solute - the substance present in smallest amount

Colloids – emulsions; a heterogeneous mixture

  • Solute particles are larger than those in a solution
  • Particles do not settle out. Ex: Cytosol

Suspensions – heterogeneous mixtures with large visible solutes

  • Solute particles settle out. Ex: blood & plasma

Chemical Bonds

  • Ionic Bonds – form by transferring one or more electrons from one atom to the other.
  • Changes the balance of + (cation) or - (anion) charges to form an ion
  • Covalent bonds – share the outer electron with the bonded atoms
  • Hydrogen bonds – attractions rather than bonds, weakest bond.
  • Forms when a H atom (already linked with another atom; N, O2) is attracted by another electron-hungry atom and bridges between Ex: water molecules

Organic compounds - Contain carbon, are covalently bonded, and are often large

Inorganic compounds- Do not contain carbon. Ex: water, salts, and many acids and bases

Properties of Water:

  • High heat capacity – absorbs and releases large amounts of heat before changing temperature
  • High heat of vaporization – changing from a liquid to a gas requires large amounts of heat
  • Polar solvent properties – dissolves ionic substances, forms hydration layers around large charged molecules, and serves as the body’s major transport medium
  • Reactivity – important part in hydrolysis and dehydration synthesis reactions
  • Cushioning – resilient cushion around certain body organs

Characteristics of water polarity

  1. Liquid – remains liquid in our bodies
  2. Universal solvent – helps facilitate chemical reactions in/out of our bodies
  3. Cohesive properties – helps water-base solutions fill blood vessels

Salts: Inorganic compounds

  • Contain cations other than H+ and anions other than OH–
  • Are electrolytes; they conduct electrical currents

Water and Living Things: Characteristics of water polarity

  • Ability to change temperatureslowly– prevents drastic changes
  • Vaporization – keeping body temperature from overheating
  • Ability to freeze – becomes less dense and in weight.

Acid – Base

  • Water breaks up (dissociates) equal number of hydrogen (H) and hydroxide (OH) ions
  • Acid solutions – release H
  • Tomato juice, coffee, vinegar
  • Sharp, sour taste associated with indigestion
  • Basic solutions – release OH and gain H
  • MOM, ammonia, household cleaners & detergents
  • Bitter taste, become slippery when wet
  • Acid-Base Concentration (pH)
  • Necessary to maintain homeostasis
  • Acidic solutions have higher H+concentration and therefore a lower pH
  • Alkaline solutions have lower H+ concentration and therefore a higher pH
  • Neutral solutions have equal H+ and OH– concentrations
  • The pH scale

Buffers:

  • Are systems that resist abrupt and large swings in the pH of body fluids
  • Carbonic acid-bicarbonate system
  • Carbonic acid dissociates, reversibly releasing bicarbonate ions and protons
  • The chemical equilibrium between carbonic acid and bicarbonate resists pH changes in the blood
  • They combine with Hydrogen (H) ions or hydroxide ions (OH) to resist pH changes
  • Bicarbonate ions
  • Stabilize pH within normal limits
  • Take up excess H or OH molecules to resist pH changes
  • Ex: Bufferin, shampoos, deodorants

ORGANIC MOLECULES

  • Organic Compounds
  • Molecules unique to living systems contain carbon and hence are organic compounds
  • They include: Carbohydrates; Lipids; Proteins and Nucleic Acids

Organic molecule Structure: The molecules of life always:

  • Are important to living organisms
  • Always contain carbon and hydrogen
  • Macromolecules – a large molecule structure containing many molecules joined together (polymers)
  • Simple organic molecule - subunit of a polymer (monomers)

Carbohydrates: functions of carbohydrates

  • Principal energy source for cells
  • First function for short term energy storage
  • Structural components in some cells
  • Cell to cell recognition- surface antigens

Carbohydrates - Contain carbon, hydrogen, and oxygen

  • Their major function is to supply a source of cellular food
  • Examples: Monosaccharides or simple sugars; Disaccharides or double sugars; Polysaccharides or polymers of simple sugars

Organic molecules

  • Synthesis and degradation reactions in macromolecules
  • `Dehydration synthesis
  • Links monomers together to form a polymer
  • 2 hydrogens and an oxygen removed in the reaction and unite to form water
  • Water is also always a byproduct
  • Hydrolysis
  • Polymer is broken down to monomers
  • Water is required to replace 2 hydrogens and the oxygen

Lipids

  • Contain C, H, and O, but the proportion of oxygen in lipids is less than in carbohydrates
  • Examples:
  • Neutral fats or triglycerides
  • Phospholipids
  • Steroids
  • Eicosanoids
  • General characteristics of lipids are extremely diverse group of organic molecules:

fats, oils, steroids, waxes, phospholipids

  • Common characteristic - nonpolar molecules which are insoluble in water
  • Contain more calories of energy per gram so are ideal energy storage molecules
  • Also function as structural components, insulation, cushioning of organs, and hormones
  • Neutral Fats (Triglycerides)
  • Composed of three fatty acids bonded to a glycerol molecule
  • Other Lipids include: Phospholipids – modified triglycerides with two fatty acid groups and a phosphorus group
  • Lipids are broken down by Emulsification. Bile is an emulsifier

Fats are nonpolar; they do not dissolve in water and tend to form “globules” (oil and vinegar dressing)

Emulsifier breaks down the globules of fat into smaller droplets

Emulsifiers have a nonpolar end which attaches to the fat, and a polar end which interacts with water molecules so that the droplets can disperse

Other Lipids:

  • Steroids – flat molecules with four interlocking hydrocarbon rings
  • Eicosanoids – 20-carbon fatty acids found in cell membranes
  • Representative Lipids Found in the Body
  • Neutral fats – found in subcutaneous tissue and around organs
  • Phospholipids – chief component of cell membranes
  • Steroids – cholesterol, bile salts, vitamin D, sex hormones, and adrenal cortical hormones

Representative Lipids Found in the Body

  • Fat-soluble vitamins – vitamins A, E, and K
  • Eicosanoids – prostaglandins, leukotrienes, and thromboxanes
  • Lipoproteins – transport fatty acids and cholesterol in the bloodstream

Amino Acids

  • Building blocks of protein, containing an amino group and a carboxyl group
  • Amino group (NH2)) and Carboxyl groups COOH

Protein- are Macromolecules composed of combinations of 20 types of amino acids bound together with peptidebonds

  • Structural Levels of Proteins
  • Primary – amino acid sequence
  • Secondary – alpha helices or beta pleated sheets
  • Tertiary – superimposed folding of secondary structures
  • Quaternary – polypeptide chains linked together in a specific manner

The Structural Levels of Proteins are: Fibrous and Globular Proteins

  • Fibrous proteins
  • Extended and strand-like proteins
  • Examples: keratin, elastin, collagen, and certain contractile fibers
  • Globular proteins
  • Compact, spherical proteins with tertiary and quaternary structures
  • Examples: antibodies, hormones, and enzymes
  • Functions of Protein:
  • Keratin – builds hair, nails and collagen
  • Hormones – cellular metabolism
  • Actinmyosin – movement of cells and muscular contractility
  • Hemoglobin – transports oxygen in blood
  • Antibodies – bind foreign subtances to prevent the destruction of cells
  • Enzymes – speed up chemical reactions in the body

Protein Denuaturation

  • The final shape of a protein molecule is often critical to its function
  • Extreme exposure of heat and pH can change the shape of the protein molecule.
  • Denaturation = irreversible change in shape
  • Reversible unfolding of proteins due to drops in pH and/or increased temperature
  • Irreversibly denatured proteins cannot refold and are formed by extreme pH or temperature change
  • Once protein loses its normal shape it become dysfunctional

Characteristics of Enzymes

  • Most are globular proteins that act as biological catalysts
  • Holoenzymes consist of an apoenzyme (protein) and a cofactor (usually an ion)
  • Enzymes are chemically specific
  • Frequently named for the type of reaction they catalyze
  • Enzyme names usually end in -ase

Nucleic Acids

  • Composed of carbon, oxygen, hydrogen, nitrogen, and phosphorus
  • Their structural unit, the nucleotide, is composed of N-containing base, a pentose sugar, and a phosphate group
  • Five nitrogen bases contribute to nucleotide structure – adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U)
  • Two major classes – DNA and RNA

Deoxyribonucleic Acid (DNA)

  • Double-stranded helical molecule found in the nucleus of the cell
  • Replicates itself before the cell divides, ensuring genetic continuity
  • Provides instructions for protein synthesis
  • Structure of DNA
  • Ribonucleic Acid (RNA)
  • Single-stranded molecule found in both the nucleus and the cytoplasm of a cell
  • Uses the nitrogenous base uracil instead of thymine
  • Three varieties of RNA: messenger RNA, transfer RNA, and ribosomal RNA

Adenosine Triphosphate (ATP)

  • Source of immediately usable energy for the cell
  • Adenine - containing RNA nucleotide with three phosphate groups