Download Ch 2 - Biochemistry

Ch 2 - Chemistry Comes Alive
BASIC CHEMISTRY
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MATTER - Solid, liquid, gaseous states – all found in the human body
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ENERGY
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Less tangible, (not mass, fills no space)
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Def: the capacity to do work; or put matter into motion.
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The greater the work done, the more energy used.
Type of Energy:
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Kinetic - Energy in action/motion
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Potential
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Stored energy; inactive energy.
When potential energy is released it becomes kinetic energy
Forms of Energy
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Chemical energy - ATP (Adenosine triphospate)
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ATP is needed for cellular metabolism in the human body
Electrical energy
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Results from charged particles (ions).
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Nerve impulses in the nervous system are electrical currents that transmit messages
from one part of the body to another.
Mechanical energy
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Directly involved in moving matter. Like riding a bike or the Stomach’s
mechanical digestion
Radiant energy – electromagnetic - Energy that travels through waves
MOLECULES
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Atoms combined with other atoms
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Compound molecules – 2 or more different6 kinds of atoms bind.
Mixtures: solutions, colloids, suspension
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Solution – homogenous mixture of compounds
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Solvent – substance present in greatest amount.
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Solute - the substance present in smallest amount
Colloids – emulsions; a heterogeneous mixture
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Solute particles are larger than those in a solution
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Particles do not settle out.
Ex: Cytosol
Suspensions – heterogeneous mixtures with large visible solutes
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Solute particles settle out.
Ex: blood & plasma
Chemical Bonds
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Ionic Bonds – form by transferring one or more electrons from one atom to the other.
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Changes the balance of + (cation) or - (anion) charges to form an ion
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Covalent bonds – share the outer electron with the bonded atoms
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Hydrogen bonds – attractions rather than bonds, weakest bond.
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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:
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High heat capacity – absorbs and releases large amounts of heat before changing temperature
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High heat of vaporization – changing from a liquid to a gas requires large amounts of heat
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Polar solvent properties – dissolves ionic substances, forms hydration layers around large
charged molecules, and serves as the body’s major transport medium
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Reactivity – important part in hydrolysis and dehydration synthesis reactions
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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
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Contain cations other than H+ and anions other than OH–
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Are electrolytes; they conduct electrical currents
Water and Living Things:
Characteristics of water polarity
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Ability to change temperature slowly – prevents drastic changes
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Vaporization – keeping body temperature from overheating
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Ability to freeze – becomes less dense and in weight.
Acid – Base
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Water breaks up (dissociates) equal number of hydrogen (H) and hydroxide (OH) ions
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Acid solutions – release H
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Tomato juice, coffee, vinegar
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Sharp, sour taste associated with indigestion
Basic solutions – release OH and gain H
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MOM, ammonia, household cleaners & detergents
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Bitter taste, become slippery when wet
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Acid-Base Concentration (pH)
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Necessary to maintain homeostasis
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Acidic solutions have higher H+ concentration and therefore a lower pH
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Alkaline solutions have lower H+ concentration and therefore a higher pH
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Neutral solutions have equal H+ and OH– concentrations
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The pH scale
Buffers:
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Are systems that resist abrupt and large swings in the pH of body fluids
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Carbonic acid-bicarbonate system
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Carbonic acid dissociates, reversibly releasing bicarbonate ions and protons
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The chemical equilibrium between carbonic acid and bicarbonate resists pH changes in
the blood
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They combine with Hydrogen (H) ions or hydroxide ions (OH) to resist pH changes
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Bicarbonate ions
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Stabilize pH within normal limits
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Take up excess H or OH molecules to resist pH changes
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Ex: Bufferin, shampoos, deodorants
ORGANIC MOLECULES
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Organic Compounds
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Molecules unique to living systems contain carbon and hence are organic compounds
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They include: Carbohydrates; Lipids; Proteins and Nucleic Acids
Organic molecule Structure:
The molecules of life always:
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Are important to living organisms
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Always contain carbon and hydrogen
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Macromolecules – a large molecule structure containing many molecules joined
together (polymers)
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Simple organic molecule - subunit of a polymer (monomers)
Carbohydrates: functions of carbohydrates
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Principal energy source for cells
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First function for short term energy storage
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Structural components in some cells
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Cell to cell recognition- surface antigens
Carbohydrates - Contain carbon, hydrogen, and oxygen
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Their major function is to supply a source of cellular food
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Examples: Monosaccharides or simple sugars; Disaccharides or double sugars;
Polysaccharides or polymers of simple sugars
Organic molecules
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Synthesis and degradation reactions in macromolecules
`Dehydration synthesis
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Links monomers together to form a polymer
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2 hydrogens and an oxygen removed in the reaction and unite to form water
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Water is also always a byproduct
Hydrolysis
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Polymer is broken down to monomers
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Water is required to replace 2 hydrogens and the oxygen
Lipids
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Contain C, H, and O, but the proportion of oxygen in lipids is less than in carbohydrates
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Examples:
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Neutral fats or triglycerides
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Phospholipids
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Steroids
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Eicosanoids
General characteristics of lipids are extremely diverse group of organic molecules:
fats, oils, steroids, waxes, phospholipids
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Common characteristic - nonpolar molecules which are insoluble in water
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Contain more calories of energy per gram so are ideal energy storage molecules
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Also function as structural components, insulation, cushioning of organs, and hormones
Neutral Fats (Triglycerides)
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Composed of three fatty acids bonded to a glycerol molecule
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Other Lipids include: Phospholipids – modified triglycerides with two fatty acid groups and a
phosphorus group
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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:
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Steroids – flat molecules with four interlocking hydrocarbon rings
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Eicosanoids – 20-carbon fatty acids found in cell membranes
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Representative Lipids Found in the Body
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Neutral fats – found in subcutaneous tissue and around organs
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Phospholipids – chief component of cell membranes
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Steroids – cholesterol, bile salts, vitamin D, sex hormones, and adrenal cortical hormones
Representative Lipids Found in the Body
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Fat-soluble vitamins – vitamins A, E, and K
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Eicosanoids – prostaglandins, leukotrienes, and thromboxanes
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Lipoproteins – transport fatty acids and cholesterol in the bloodstream
Amino Acids
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Building blocks of protein, containing an amino group and a carboxyl group
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Amino group (NH2)) and Carboxyl groups COOH
Protein - are Macromolecules composed of combinations of 20 types of amino acids bound together
with peptide bonds
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Structural Levels of Proteins
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Primary – amino acid sequence
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Secondary – alpha helices or beta pleated sheets
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Tertiary – superimposed folding of secondary structures
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Quaternary – polypeptide chains linked together in a specific manner
The Structural Levels of Proteins are:
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Fibrous and Globular Proteins
Fibrous proteins
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Extended and strand-like proteins
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Examples: keratin, elastin, collagen, and certain contractile fibers
Globular proteins
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Compact, spherical proteins with tertiary and quaternary structures
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Examples: antibodies, hormones, and enzymes
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Functions of Protein:
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Keratin – builds hair, nails and collagen
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Hormones – cellular metabolism
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Actin & myosin – movement of cells and muscular contractility
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Hemoglobin – transports oxygen in blood
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Antibodies – bind foreign subtances to prevent the destruction of cells
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Enzymes – speed up chemical reactions in the body
Protein Denuaturation
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The final shape of a protein molecule is often critical to its function
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Extreme exposure of heat and pH can change the shape of the protein molecule.
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Denaturation = irreversible change in shape
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Reversible unfolding of proteins due to drops in pH and/or increased temperature
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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
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Most are globular proteins that act as biological catalysts
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Holoenzymes consist of an apoenzyme (protein) and a cofactor (usually an ion)
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Enzymes are chemically specific
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Frequently named for the type of reaction they catalyze
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Enzyme names usually end in -ase
Nucleic Acids
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Composed of carbon, oxygen, hydrogen, nitrogen, and phosphorus
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Their structural unit, the nucleotide, is composed of N-containing base, a pentose sugar, and a
phosphate group
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Five nitrogen bases contribute to nucleotide structure – adenine (A), guanine (G), cytosine (C),
thymine (T), and uracil (U)
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Two major classes – DNA and RNA
Deoxyribonucleic Acid (DNA)
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Double-stranded helical molecule found in the nucleus of the cell
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Replicates itself before the cell divides, ensuring genetic continuity
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Provides instructions for protein synthesis
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Structure of DNA
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Ribonucleic Acid (RNA)
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Single-stranded molecule found in both the nucleus and the cytoplasm of a cell
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Uses the nitrogenous base uracil instead of thymine
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Three varieties of RNA: messenger RNA, transfer RNA, and ribosomal RNA
Adenosine Triphosphate (ATP)
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Source of immediately usable energy for the cell
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Adenine - containing RNA nucleotide with three phosphate groups