energy the capacity to do work (put matter into motion) types of energy kinetic – energy in...
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Energy
The capacity to do work (put matter into motion)
Types of energy
Kinetic – energy in action
Potential – energy of position; stored (inactive) energy (eg. glycogen)
Forms of Energy
Chemical – stored in the bonds of chemical substances
Electrical – results from the movement of charged particles
Mechanical – directly involved in moving matter
Radiant or electromagnetic – energy traveling in waves (i.e., visible light, ultraviolet light, and X rays)
Major Elements of the Human Body
Oxygen (O)
Carbon (C)
Hydrogen (H)
Nitrogen (N)
Lesser and Trace Elements of the Human Body
Lesser elements make up 3.9% of the body and include:
Calcium (Ca), phosphorus (P), potassium (K), sulfur (S), sodium (Na), chlorine (Cl), magnesium (Mg), iodine (I), and iron (Fe)
Trace elements make up less than 0.01% of the body
They are required in minute amounts, and are found as part of enzymes
Figure 2.8
Comparison of Ionic, Polar Covalent, and Nonpolar Covalent Bonds
Ionic Bonds
Ions are charged atoms resulting from the gain or loss of electrons
Anions have gained one or more electrons
Cations have lost one or more electrons
Ionic bonds form between atoms by the transfer of one or more electrons
Ionic compounds form crystals instead of individual molecules
Example: NaCl (sodium chloride)
Formation of an Ionic Bond
Figure 2.5a
Formation of an Ionic Bond
Figure 2.5b
Covalent Bonds
Covalent bonds are formed by the sharing of two or more electrons
Electron sharing produces molecules
Single Covalent Bonds
Figure 2.6a
Double Covalent Bonds
Figure 2.6b
Triple Covalent Bonds
Figure 2.6c
Polar and Nonpolar Molecules
Electrons shared equally between atoms produce nonpolar molecules
Unequal sharing of electrons produces polar molecules
Hydrogen Bonds
Too weak to bind atoms together
Common in dipoles such as water
Responsible for surface tension in water
Important as intramolecular bonds, giving the molecule a three-dimensional shape
Hydrogen Bonds
Figure 2.9
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
Salts
Inorganic compounds
Contain cations other than H+ and anions other than OH–
Are electrolytes; they conduct electrical currents
Organic Compounds
Molecules unique to living systems contain carbon and hence are organic compounds
They include:
Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbohydrates
Figure 2.13a
Contain carbon, hydrogen, and oxygen
Their major function is to supply a source of cellular food
Examples:
Monosaccharides or simple sugars
Carbohydrates
Figure 2.13b
Disaccharides or double sugars
Carbohydrates
Figure 2.13c
Polysaccharides or polymers of simple sugars
Representative Lipids Found in the Body
Neutral fats (triglycerides)– 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
Fat-soluble vitamins – vitamins A, E, and K
Eicosanoids – prostaglandins, leukotriens, and thromboxanes
Lipoproteins – transport fatty acids and cholesterol in the bloodstream
Neutral Fats (Triglycerides)
Figure 2.14a
Composed of three fatty acids bonded to a glycerol molecule
Other Lipids
Figure 2.14b
Phospholipids – modified triglycerides with two fatty acid groups and a phosphorus group
Other Lipids
Figure 2.14c
Steroids – flat molecules with four interlocking hydrocarbon rings
Amino Acids
Building blocks of protein, containing an amino group and a carboxyl group
Amino acid structure
Amino Acids
Figure 2.15d, e
Protein
Figure 2.16
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Structural Levels of Proteins
Primary – amino acid sequence
Secondary – alpha helices
or beta pleated sheets
(H - H bonds)
Structural Levels of Proteins
Tertiary – superimposed folding of secondary structures (S-S bonds)
Quaternary – polypeptide chains linked together in a specific manner (covalent bonds)
Structural Levels of Proteins
Figure 2.17d, e
S -- S bondscovalent bonds
Fibrous and Globular Proteins
Fibrous proteins
Extended and strandlike proteins
Examples: keratin, elastin, collagen, and certain contractile fibers
Globular proteins
Compact, spherical proteins with tertiary and quaternary structures
Examples: antibodies, some hormones, and enzymes