D’YOUVILLE COLLEGE
BIOLOGY 102 - INTRODUCTORY BIOLOGY II
LECTURE # 1 SIMPLE CHEMISTRY
1.
Characteristics of Living Things: (chapter 1)
• hierarchy of structure: high level of order of living things characterized by
layers of increasing complexity; the smallest component layer that is capable of
independent life is the cell (unit of life), which is itself composed of smaller layers (fig.
1 – 4 & ppt. 1)
- layers include: atoms, ions & molecules, organelles, cells, tissues, organs,
organ systems & the organism
- each layer consists of lower layers & is incorporated into higher layers; a
given layer exhibits properties that exceed the properties of its constituents (emergent
properties); these derive from orderliness and interactions involving the constituents
(fig. 2. – 3 & ppt. 2)
• properties of living things (fig. 1 – 3): physicochemical systems with high level
of order, capable of growth, differentiation & reproduction; capable of acquiring
energy from environment to maintain order (fig. 1 – 5); capable of sensing and
responding to environment; possession of many regulatory capabilities (fig. 1 – 13) (homeostasis) and adaptation to changing environmental circumstances
2.
Atoms (fig. 2 – 5 & ppt. 3):
• elementary particles: protons (positively charged), neutrons (neutral) &
electrons (negatively charged); protons and neutrons have a mass approx. = 1; electrons
have virtually no mass
• nucleus of an atom contains the protons and (usually) neutrons
• elements: materials made up exclusively of same type of atoms (table 2 – 1 &
ppt. 4)
Biology 102 - Spring ‘13
page 2
• atomic number: # of protons in nucleus; defines the element (fig. 2 – 9 & ppt. 5)
• mass number: # of protons and neutrons
Biology 102 - Spring ‘13
page 3
- isotopes – atoms of same atomic # but different mass #, e.g., 12C & 14C
- unstable isotopes – isotopes that undergo nuclear decay over time through
loss of elementary particles + energy; these are radioactive – useful in scientific studies
(fig. 2 – 6)
• orbitals (figs. 2 – 8, 2 – 10, ppts. 6 & 7): discrete energy levels that are occupied
by electrons; orbitals make up shells with a characteristic maximum # of electrons: K =
2; L = 8; M = 8 (fig. 2 – 9 & ppt. 5)
• stable configuration: maximal # of electrons in outer shell; virtually all of
chemical reactions involve behavior of atoms seeking to achieve this stability
3.
Ions & Molecules:
• valence: # of electrons to lose (positive valences), gain (negative valences), or
share to satisfy stable configuration (formation of bonds)
• molecules: electron pairs shared (covalent bonds – figs. 2 – 11, 2 – 12 & ppt. 8);
double bonds (two electron pairs shared) and triple bonds also exist
- compounds – atoms combine to form compounds by covalent bonding;
orbitals confer specific shapes (important for biological functions) upon molecules (fig.
2 – 17, ppts. 9 & 10) – particularly important for organic chemicals (fig. 2 – 18 & ppt. 11)
Biology 102 - Spring ‘13
page 4
- polar molecules – molecules with bonds involving unequal sharing of
electron pair; confers positive and negative ‘poles’ upon molecule (fig. 2 – 13 & ppt. 12)
- hydrogen bonds – weak bonds between positive regions of one molecule
and negative regions of another involving hydrogen atom of one molecule attracted,
(but not lost) to another (figs. 2 – 16, 3 – 2 & ppts. 13 & 14)
• ions: positive ions (= cations) have lost one or more electrons; negative ions (=
anions) have gained one or more electrons
- attraction of cations to anions constitutes ionic bond (figs. 2 – 3, 2 – 14, 2 - 15 &
ppts. 15, 16 & 17)