Download BIO 200 Chemistry - Imperial Valley College

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prepared by Vince Austin,
Bluegrass Technical
and Community College
CHAPTER
Elaine N. Marieb
Katja Hoehn
Human
Anatomy
& Physiology
SEVENTH EDITION
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
2
PART B
Chemistry
Comes Alive
Biochemistry

Organic compounds


Contain carbon, are covalently bonded, and are
often large
Inorganic compounds

Do not contain carbon

Water, salts, and many acids and bases
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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
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Properties of Water


Reactivity – important part in hydrolysis and
dehydration synthesis reactions
Cushioning – resilient cushion around certain body
organs
Characteristics of water polarity
1.
2.
3.
Liquid – remains liquid in our bodies
Universal solvent – helps facilitate chemical reactions
in/out of our bodies
Cohesive properties – helps water-base solutions fill
blood vessels
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Salts

Inorganic compounds

Contain cations other than H+ and anions other
than OH–

Are electrolytes; they conduct electrical currents
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Water and Living Things
Characteristics of water polarity
4.
5.
6.
Ability to change temperature slowly –
prevents drastic changes
Vaporization – keeping body temperature from
overheating
Ability to freeze – becomes less dense and in
weight.
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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
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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
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The pH scale
Acidic:
pH 0–6.99
Neutral:
pH 7.00
Basic:
pH 7.01–14
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Buffers

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
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Buffers

Bicarbonate ions

Stabilize pH within normal limits

Take up excess H or OH molecules to resist pH
changes

Bufferin, shampoos, deodorants
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ORGANIC MOLECULES
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Organic Compounds

Molecules unique to living systems contain carbon
and hence are organic compounds

They include:

Carbohydrates

Lipids

Proteins

Nucleic Acids
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
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)
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Carbohydrates

Functions

Principal energy source for cells

First function for short term energy storage

Structural components in some cells

Cell to cell recognition- surface antigens
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Carbohydrates

Contain carbon, hydrogen, and oxygen

Their major function is to supply a source of
cellular food

Examples:

Monosaccharides or simple sugars
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Figure 2.14a
Carbohydrates

Disaccharides or double sugars
PLAY
Disaccharides
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Figure 2.14b
Carbohydrates

Polysaccharides or polymers of simple sugars
PLAY
Polysaccharides
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Figure 2.14c
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
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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
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Lipids

General characteristics

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
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Neutral Fats (Triglycerides)

Composed of three fatty acids bonded to a glycerol
molecule
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Figure 2.15a
Other Lipids

Phospholipids – modified triglycerides with two
fatty acid groups and a phosphorus group
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Figure 2.15b
Lipids
Emulsification
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
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Other Lipids


Steroids – flat molecules with four interlocking
hydrocarbon rings
Eicosanoids – 20-carbon fatty acids found in cell
membranes
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Figure 2.15c
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
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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
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Amino Acids

Building blocks of protein, containing an amino group and
a carboxyl group

Amino group (NH2)) and Carboxyl groups COOH
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Protein
Macromolecules composed of combinations of 20
types of amino acids bound together with peptide
bonds
Peptide bond
H
H
R
O
N
C
C
H
+
OH
Amino acid
H
H
R
O
N
C
C
H
Dehydration H O
2
synthesis
OH
H
Hydrolysis
Amino acid
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H2O
H
R
O
H
R
O
N
C
C
N
C
C
H
H
OH
Dipeptide
Figure 2.17
Structural Levels of Proteins

Primary – amino acid sequence

Secondary – alpha helices or beta pleated sheets
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Structural Levels of Proteins


Tertiary –
superimposed folding
of secondary structures
Quaternary –
polypeptide chains
linked together in a
specific manner
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Structural Levels of Proteins
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Figure 2.18b,d,e
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
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Functions of Protein:

Keratin – builds hair, nails and collagen

Hormones – cellular metabolism




Actin & myosin – 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
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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
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Figure 2.19a
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
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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
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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
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Structure of DNA
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Figure 2.22b
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
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Adenosine Triphosphate (ATP)

Source of immediately usable energy for the cell

Adenine - containing RNA nucleotide with three
phosphate groups
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