Biochemistry

1
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

2
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 bodys major
  transport medium

3
Properties of Water

• Reactivity is an important part of hydrolysis
  and dehydration synthesis reactions
• Cushioning resilient cushion around certain
  body organs

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InterActive Physiology Fluid, Electrolyte, and
Acid/Base Balance Introduction to Body Fluids
4
Salts

• Inorganic compounds
• Contain cations other than H and anions other
  than OH
• Are electrolytes they conduct electrical currents

5
Acids and Bases

• Acids release H and are therefore proton donors
• HCl ? H Cl
• Bases release OH and are proton acceptors
• NaOH ? Na OH

6
Acid-Base Concentration (pH)

• 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

7
Acid-Base Concentration (pH)

• Acidic pH 06.99
• Basic pH 7.0114
• Neutral pH 7.00

Figure 2.13
8
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

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InterActive Physiology Fluid, Electrolyte, and
Acid/Base Balance Acid/Base Homeostasis
9
Organic Compounds

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

10
Carbohydrates

• Contain carbon, hydrogen, and oxygen
• Their major function is to supply a source of
  cellular food
• Examples
• Monosaccharides or simple sugars

Figure 2.14a
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Carbohydrates

• Disaccharides or double sugars

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Disaccharides
Figure 2.14b
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Carbohydrates

• Polysaccharides or polymers of simple sugars

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Polysaccharides
Figure 2.14c
13
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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Fats
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Neutral Fats (Triglycerides)

• Composed of three fatty acids bonded to a
  glycerol molecule

Figure 2.15a
15
Other Lipids

• Phospholipids modified triglycerides with two
  fatty acid groups and a phosphorus group

Figure 2.15b
16
Other Lipids

• Steroids flat molecules with four interlocking
  hydrocarbon rings
• Eicosanoids 20-carbon fatty acids found in cell
  membranes

Figure 2.15c
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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
• Carboxyl groups COOH

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Amino Acids
Figure 2.16ac
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Amino Acids
Figure 2.16d, e
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Protein

• Macromolecules composed of combinations of 20
  types of amino acids bound together with peptide
  bonds

Figure 2.17
23
Protein

• Macromolecules composed of combinations of 20
  types of amino acids bound together with peptide
  bonds

Figure 2.17
24
Protein

• Macromolecules composed of combinations of 20
  types of amino acids bound together with peptide
  bonds

Figure 2.17
25
Protein

• Macromolecules composed of combinations of 20
  types of amino acids bound together with peptide
  bonds

Figure 2.17
26
Protein

• Macromolecules composed of combinations of 20
  types of amino acids bound together with peptide
  bonds

Figure 2.17
27
Protein

• Macromolecules composed of combinations of 20
  types of amino acids bound together with peptide
  bonds

Figure 2.17
28
Protein

• Macromolecules composed of combinations of 20
  types of amino acids bound together with peptide
  bonds

Figure 2.17
29
Protein

• Macromolecules composed of combinations of 20
  types of amino acids bound together with peptide
  bonds

Figure 2.17
30
Protein

• Macromolecules composed of combinations of 20
  types of amino acids bound together with peptide
  bonds

Figure 2.17
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Structural Levels of Proteins

• Primary amino acid sequence
• Secondary alpha helices or beta pleated sheets

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Chemistry of Life Introduction to Protein
Structure
PLAY
Chemistry of Life Proteins Primary Structure
PLAY
Chemistry of Life Proteins Secondary Structure
32
Structural Levels of Proteins

• Tertiary superimposed folding of secondary
  structures
• Quaternary polypeptide chains linked together
  in a specific manner

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Chemistry of Life Proteins Tertiary Structure
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Chemistry of Life Proteins Quaternary Structure
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Structural Levels of Proteins
Figure 2.18ac
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Structural Levels of Proteins
Figure 2.18b,d,e
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Fibrous and Globular Proteins

• Fibrous proteins
• Extended and strand-like proteins
• Examples keratin, elastin, collagen, and certain
  contractile fibers

36
Fibrous and Globular Proteins

• Globular proteins
• Compact, spherical proteins with tertiary and
  quaternary structures
• Examples antibodies, hormones, and enzymes

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Protein Denuaturation

• Reversible unfolding of proteins due to drops in
  pH and/or increased temperature

Figure 2.19a
38
Protein Denuaturation

• Irreversibly denatured proteins cannot refold and
  are formed by extreme pH or temperature changes

Figure 2.19b
39
Molecular Chaperones (Chaperonins)

• Help other proteins to achieve their functional
  three-dimensional shape
• Maintain folding integrity
• Assist in translocation of proteins across
  membranes
• Promote the breakdown of damaged or denatured
  proteins

40
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

41
Characteristics of Enzymes

• Frequently named for the type of reaction they
  catalyze
• Enzyme names usually end in -ase
• Lower activation energy

42
Characteristics of Enzymes
Figure 2.20
43
Mechanism of Enzyme Action

• Enzyme binds with substrate
• Product is formed at a lower activation energy
• Product is released

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How Enzymes Work
44
Figure 2.21
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Figure 2.21
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Figure 2.21
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Figure 2.21
48
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

49
Nucleic Acids

• Five nitrogen bases contribute to nucleotide
  structure adenine (A), guanine (G), cytosine
  (C), thymine (T), and uracil (U)
• Two major classes DNA and RNA

50
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
Figure 2.22a
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Structure of DNA
Figure 2.22b
53
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

54
Adenosine Triphosphate (ATP)

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

55
Adenosine Triphosphate (ATP)
Figure 2.23
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Figure 2.24
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Figure 2.24
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Figure 2.24
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Figure 2.24
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Figure 2.24
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Figure 2.24
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Figure 2.24
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Figure 2.24