Chapter 1: An Introduction to Biology
Principles of Life: Distinguish living things from non-living things
1. Cells are the simplest units of life/organization. Organisms maintain internal order
(homeostasis) different from the environment. Cell theory: all organisms are composed of cells;
cells are the smallest units of life; new cells form via cell diffusion from old cells
2. Living organisms use energy: they must acquire energy from environment to maintain eternal
3. Interaction with environment: respond to environmental changes
4. Homeostasis: the degree varies from organism to organism but all regulate cellular metabolism
5. Growth/development/reproduction: series of changes in state of cells, tissue or organism
eventually resulting in organisms with defined set of characteristics; all have finite lifespan –
6. DNA (genetic material): transmitted from parent to offspring via reproduction. Used
dynamically to fit needs of organization
7. Evolution: heritable change in DNA for population of organisms
8. Related by Evolutionary History: all organisms on Earth share a common ancestry
9. Structure determines function: follow rules of chemistry and physics plus shape plays a
function of biology
Levels of Organization
1. Atom: smallest component of an element with all chemical properties
2. Molecules and macromolecules: atoms bond to form molecules, molecules then form
macromolecules. This includes carbohydrates, proteins, DNA, RNA etc
3. Cells: associate with one another to from organelles which are enclosed by a cell membrane
4. Tissues: many cells of the same type associate with each other (ex. muscle tissue)
5. Organs: composed of two or more types of tissue
6. Organ systems: work together to accomplish larger functions
7. Organism: distinct unit of life
8. Species: related group (genetics); distinct form + set of attributes
9. Population: organisms of same species occupying a continuous space
10. Community: assemblage of populations of different species
11. Ecosystem: interactions of community with physical non-living environment
12. Biosphere: all of living earth: air, water, land Evolution
In evolution, structure is often modified for new purpose. Two types of changes through evolution:
vertical descent with mutation and horizontal gene transfer.
Vertical descent: changes in a series of changes through series of ancestors (lineage). Called vertical
descent because of how it’s usually depicted. Become a species by mutation (inheritable change in genetic
material). Increase chance of survival or reproduction. Natural selection: neutral changes occur too.
Horizontal gene transfer: genetic exchanges occurring between different species, especially bacteria.
Sub discipline of biology in attempt to determine relatedness. Three main domains: Bacteria, Archaea,
Bacteria and Archaea are prokaryotic microorganisms that still show differences in lipid organization,
packaging of heretic material, regulation of production of mRNA. Eukarya are eukaryotic with larger
cells with genetic material with membrane. Eight different subgroups.
Binomial nomenclature: used to provide each species with unique scientific name (in latin).
Order: Domain Kingdom Phylum Class Order Family Genus Species
The genetic material of an organism, compiled of collection of DNA. This acts as stable information unit
+encodes information of organism function. It stores encoded info to make located + modify all
organisms proteins proteome: collection of proteins being made in a cell under particular conditions.
Also, provides continuity from generation to generation (via reproduction). Helps evolutionary change via
mutation. Used for genomic analysis in research. Reading of blueprint is influenced by the environment;
RNAs read genome differently.
Biology as a science
Follows a scientific method via predictions that can be experimentally/observationally tested. Discovery
based science is collection and analysis without need for preconceived hypothesis. This includes
hypothesis (proposed explanation for a natural phenomenon), theory (based explanation of some aspect of
natural world). Hypothesis testing is the scientific method, observations hypothesis, experimentation,
data, acceptance/rejection Chapter 2: The Chemical Basis of Life I; Atoms, Molecules and Water
Energy shells are where orbitals (area of where probability is high in finding electrons are found).
Orbitals can only have two electrons. First level is 2s. Second level is 2s + 2p which is 6 electrons.
Energy shells closest to the nucleus have the lowest energy and they fill up first. In orbitals with one or
more than one section, each compartment fills up evenly. Valence electrons are located in outmost energy
cell and are available to combine with other atoms.
Cations: ions with new positive charge. Anions: ions with net negative charge. Free radical: molecule
containing single unpaired electron in outer shell, and this can be harmful. Brownian motion: heat
energy causes atoms to vibrate and move. Catalysts: substance that speeds up chemical reaction without
itself being affected. For example, a biomolecule catalyst such as RNA or protein. A feature of chemical
reactions in living things occur in water environments. Molecular flexibility is of great importance, as is
Van der Waals: chemical forces that occur intermolecularity between different regions of large
molecules. Electrostatic interactions between molecules of opposite charges. The strength is determined
by degree of charges and distance between molecules. Weaker than covalent and ionic.
Ion-dipole: occur between ions + dipoles, for example ionic molecules in water (most important type)
Dipole-dipole: there are many different types, with the most important one being hydrogen of one polar
molecule and oxygen, nitrogen or fluorine. Hydrogen bonds: stronger than other dipole-dipole because all
three relevant atoms and H-O and H-N bonds are very polar. H is very positive and other are very
negative. Single H bond is weak bu makes a huge difference. For example, it makes DNA stable. The
closer the molecules are, the stronger the van der waal force is
Heat of vaporization: heat required to bring 1 mole of any substance to boiling point under standard
Heat of fusion: when substance goes from liquid to slid (fusion) = amount of energy released.
Specific heat: amount of heat required per unit of mass to raise mass one degree Celsius. Water has a
high specific heat because of hydrogen bonds.
Solutes are substances dissolved in solvent to form a solution. Concentration is the amount of solid
dissolved in unit volume of solution. Colligative properties depend strictly on concentration of dissolved
solute particles. Anti-freeze found in some organisms.
Micelles: what long amphipathic molecules from spheres can form when mixed with water. Hydrophilic
have polar regions on surface, hydrophobic regions are non-polar parts that face the center. Chapter 3: Chemical Basis of Life II; Organic Molecules
Hydrocarbons: mainly hydrogen and carbon. Hydrophobic because H-C bonds are non-polar and
insoluble. But when C makes polar covalent bonds with oxygen or nitrogen, it is polar and soluble. They
can then serve different functions. Bonds are stable at different temperatures associated with life. Short
bonds because small molecules.
Groups of atoms with special chemical features that contribute to molecular properties. Isomers: two
structures with identical molecular formula but different structures and characteristics. Structural
isomers: same atoms in different bonding relationships. Stereoisomers: identical bonding relationships
but different spatial positioning. Geometric isomers (another stereoisomer): cis and trans bonding.
Erantiomers (stereoisomer): mirror images, identical properties but different orientation = different
Condensation reaction: Two or more molecules combine (lose water molecule)
Dehydration reaction: types of water condensation, catalyzed by enzymes (opposite of hydrolysis)
Triglycerides/triacylglycerol: glycerol bonded to three fatty acids (C and H with carboxyl at end). Ester
bond found between the glycerol carboxyl group of fatty acid (covalent). Essential fatty acids: needed for
good health, organisms (eg. humans) who cannot be made in the body but must be obtained Most
unsaturated fats have H in cis position, trans fats are trans positions. Unsaturated or trans are more solid.
Hydrolysis of triglycerides release fatty acids from glycerol (fatty acid metabolised).
The energy for the C-H bond is greater than C-OH bond. 1g of fats = 2x energy as 1g carbohydrates.
In phospholipids, third hydroxyl is linked to phosphate group instead of fatty acid. Steroids have four
fused carbon rings where steroids with hydroxyl groups = sterols. Not water soluble.
Factors that determine protein structures
1. Hydrogen bonds: strong force that promotes protein folding and stability (second, third, fourth
2. Ionic/polar: some amino acid chains = positive/negative which promotes folding stability
(second, third, fourth degree)
3. Hydrophobic effect: non-polar avoid water and are the centre of the protein (third, fourth degree)
4. Van der waals force