Chapter 2:
Lecture #3
Objectives:
Chemistry Comes Alive
1. Describe matter and the states in which it exists.
2. Define chemical element and list the four elements that form the bulk of body
matter.
3. Describe the composition of an atom.
4. Distinguish between a compound and a mixture; compare solutions, colloids,
and suspensions.
5. Differentiate between ionic and covalent bonds. Contrast these bonds with
hydrogen bonds.
6. Compare and contrast polar and nonpolar compounds.
7. Describe synthesis, decomposition, and exchange reactions; describe factors
that affect chemical reaction rates.
Matter: made of atoms, all things made of matter. Forms or states of matter: solid, liquid, gas
Element and four elements of living things: Carbon, Hydrogen, Oxygen, Nitrogen
(CHON). Elements are the smallest unit of matter, made of the same type of atoms
Trace elements: Mg, K, Na, Ca, S, P, etc (abt. 25)
Atom: smallest unit of an element, composed of a nucleus (protons, neutrons), and an electron
cloud (electrons)
Solutions (mixtures):



Homogeneous mixture w/ solute (usually solid) and solvent (liquid)
Most nutrients, wastes, pH, etc, in solution in plasma of blood or extracellular fluid
Heterogeneous mixture: colloids (cytoplasm) and suspensions (blood)
Bonding
I. Ionic: atoms donate electrons to create ions that are then attracted to one another to form
molecules (NaCl or sodium chloride).
II. Covalent: atoms share electron between atoms to form molecules
A. Polar: unequal sharing of electrons that creates positively and negatively charged
ends to a molecule. Water is a common polar compound, also phosphates in cell
membrane
B. Nonpolar: evenly shared electrons; CO2, hydrocarbons in cell membrane.
C. Hydrogen: hydrogen atoms are attracted to the negative end of another polar
covalent molecule; “rungs” of DNA molecule.
Chemical Reactions
I. Synthesis: A + B  AB. An anabolic reaction found in rapidly growing tissues.
II. Decomposition: AB  A + B. A catabolic reaction, ex., glycogen to glucose.
III. Exchange: AB + C  AC + B, AB + CD  AC + BD
Oxidation-reduction reactions
Cellular respiration and photosynthesis:
IV. Factors influencing rates of reactions: temperature, particle size, concentration,
catalysts/enzymes present.
Lecture #4 & 5
Chapter 2 continued
Objectives: 1. Describe the bonding characteristics of carbon found in organic compounds.
2. Explain the importance of water and salts to body homeostasis.
3. Define acid and base, and explain the concept of pH.
4. Explain the role of dehydration synthesis and hydrolysis in the formation and
breakdown of organic molecules.
5. Describe and compare the building blocks, general structures, and biological
functions of carbohydrates, lipids, proteins, and nucleic acids.
6. Describe the four levels of protein structures.
7. Describe the general mechanism of enzyme activity.
8. Explain the role of ATP in cell metabolism.
Biochemistry: study of chemicals necessary for and present in living things.
Organic Compounds: made of carbon, diverse compounds because:
1.
2.
3.
4.
Carbon
Carbon
Carbon
Carbon
can
can
can
can
bond
bond
bond
bond
to up to 4 different things at once
in long chains, branching chains, or rings
to functional groups (OH, SH, phenol, etc)
with double and triple bonds.
Inorganic Compounds
I. Water: has properties due to its polar covalent bond
A. High Heat Capacity: allows subtle changes in temperature
B. High Heat of Vaporization: allows evaporative cooling (sweating)
C. Polar solvent properties: acts as a transport medium for substances in the body
(wastes, nutrients, gases), especially those that are also polar.
D. Reactivity: involved in chemical reactions; ex. Water added in hydrolysis for
digestion
E. Cushioning: protects organs (brain, fetus) from physical trauma
II. Salts: required for nerve impulse transmission (NaCl), harden bones and teeth (Ca),
transport oxygen (Fe).
Acids and Bases
I. Acids: release H+ in water, ex. carbonic acid, acetic acid, HCl
II. Bases: release OH- in water or take up H+, ex. bicarbonate, ammonia, proteins, phosphates
III. pH and neutralization: concentration of H+ or OH- in solution. 0-14 is pH scale, 7 is
neutral. 0-6.9 is acidic, 7.1-14 is basic
IV. Buffers: resist large and abrupt swings of pH in the body. Bicarbonate, phosphate, proteins
are the main three.
Dehydration Synthesis: removal of a molecule of water from two molecules will allow them
to covalently bond with one another. Ex. formation of organic molecules (polymers) from
monomers
Hydrolysis: the addition of water between two molecules breaks them apart. Ex. the splitting of
polymers into monomers
Organic Compounds
I. Carbohydrates
A. Monosaccharides: glucose, ribose in DNA and RNA
B. Disaccharides: maltose and sucrose
C. Polysaccharides: starch (glycogen) and cellulose
D. Functions: short term energy storage, structural molecules, used for immediate
energy
II. Lipids: monomers are glycerol and fatty acids (saturated and unsaturated)
A. Neutral fats: triglycerides in adipose cells
B. Phospholipids: phosphate, glycerol, and two fatty acids in cell membrane
C. Steroids: cholesterol and sex hormones
D. Functions: longterm energy storage in adipose tissue, forms sex hormones, found
in cell membrane
III. Nucleic Acids: polymers are DNA and RNA
A. Nucleotides: monomers of a sugar, phosphate, and nitrogenous base of either
adenine, guanine, cytosine, or thymine
B. Functions: hereditary information, blueprint for proteins
IV. Proteins
A. Amino acids: monomers of proteins, come in 20 different types with a common
basic structure:
R

NH2  C  COOH

H
B. Functions: enzymes, receptors, buffers, structure, transport, defense
C. Four levels of protein structure
i. Primary: polypeptide chain of amino acids
ii. Secondary: alpha helix or beta pleated sheet
iii. Tertiary: “scribble” shape due to various bonds between R groups
iv. Quaternary: two or more proteins, fibrous or globular
D. Denaturation: breakage of bonds in protein, results in loss of function. High temperature
and low pH (acidity) often denature proteins.
E. Enzyme Activity: shape of protein determines its activity. An enzyme’s role is to lower the
energy required for a reaction to occur and thereby occur more quickly and more likely.
ATP: energy molecule in shape of adenine nucleotide with 3 phosphate groups. Made by cell
during glycolysis and aerobic respiration from glucose. Necessary for most cellular and system
functions.