Basic chemistry – information from periodic table, isotopes, proteins, neutrons, ions, electrons, atomic
mass, atomic number, ionic bonds, covalent bonds, hydrogen bonds, Van der Waals (shifting attraction
between large molecules because they have areas of momentary polarity).
Water – hydrogen bonds – explain what is a hydrogen bond? What is polarity and why? What kinds of
things does hydrogen bonding allow water to do?
Why is a water molecule polar? Covalent bonds connect atoms in a molecule. But not all atoms are
created equally!!! Hydrogen is the puniest of all atoms and only has one proton in its tiny, insignificant
excuse for a nucleus…..therefore it will NEVER be stronger than any other atom it binds to!!! Oxygen,
nitrogen, phosphorus are particularly bullish! They are close to the noble gases – so only need a few
electrons to achieve perfection – ha, ha!!! So when puny hydrogen bonds with oxygen, nitrogen or
phosphorus it will always, always, always lose the tug-of-war for complete and total control of the
electrons and will always be a little positive (like a ray of sunshine). Because water is also asymmetrical,
it has a positive end and a negative end.
So, neighboring water molecules can orient themselves to maximize the attractions between negative
and positive sections (remember opposites attract). Water molecules stick together –cohesion!! This
allows them to flow. At the surface of the water, there is extra cohesion because water molecules don’t
want to leave their polar buddies for the cold unfeeling world of nonpolar air.
Yada, yada, yada….
Don’t forget basics of early Earth –
4-5 BYA – Earth formed – swirling mass of hot molten particles
1. Evidence to suggest that organic molecules could form abiotically or be brought in by meteor
2. Eventually these organic molecules would get trapped in some sort of container and could
replicate.
3. Simple prokaryotes formed
4. Photosynthesis eventually evolved and as a by-product released oxygen
5. Allowed more evolution – all occurred under the pressure of natural selection – organisms
change to be most reproductively successful.
6. MOST SIGNIFICANT EVIDENCE OF LIFE IN ANY SETTING IS THE PRESENCE OF NUCLEIC ACIDS.
Four main categories of organic molecules (for Moryn) –
1. Carbohydrates – general formula of C:2H:O – For some organisms these are structural – i.e. cell
walls in plants, fungi, bacteria, and the exoskeleton of insects. For others these are energy
storage – The bonds of carbon with other carbons and hydrogen or other atoms can store
energy because it takes energy to make them and when you break them, you release them.
2. Lipids – all share characteristic of being nonpolar – lipids can be energy storage, components of
cell membranes (phospholipids), insulation and padding (fat), steroids (hormones), cholesterol.
3. Proteins – chains of amino acids – these are the workers of the organism – the enzymes which
regulate nearly all chemical reactions (metabolism). Also strong structural components –
cytoskeleton, tendons, ligaments. Also can identify cells. Hold things together, pass messages,
make signals. Amino acids are the monomers of protein.
4. Nucleic acids – This is where it gets REAL!!!! This is what I’m talking about! DNA, RNA – genetic
material – everything that makes you, you!!! Nucleic acids are long chains of nucleotides. Sole
purpose of nucleic acids is to carry and communicate codes to make proteins. Nucleotides are
the monomers of nucleic acids.
Monomers are single units that are bound together to make polymers. The monomers of a complex
carbohydrates are simple sugars – they are “put” together in a process called condensation reaction (or
dehydration synthesis) where a water molecule is removed to make bond between the units. The
opposite is hydrolysis – where a water molecule is added to a polymer to break the monomers apart.
Laws of thermodynamics – energy in living systems can be passed from one organism to another but
there always a little loss (as heat which dissipates into atmosphere). What this means is that the bottom
of the ecological energy pyramid is made of producers (organisms that trap inorganic energy into
organic molecules) – so the biomass of the photosynthetic organisms will always be larger than that of
the organisms that consume them.
Carbon – can form 4 bonds so can make all kinds of 3-D molecules!!! Branches, chains, and rings. It can
form high energy bonds (bonds that when broken will release energy back out – think of
photosynthesis). It can form double, triple, single bonds which add to diversity. A basic carbon skeleton
can be modified by “hanging” different functional groups on it.
Hierarchy of life – molecule, organelles, cells, tissue, organs, organisms, populations, community,
ecosystem, biosphere.