Transcript Chapter 3-Biochemistry

Chapter 3: Bio-Chemistry
3-1 Water
3-2 Carbon Compounds
3-3 Molecules of Life
3-1 Water
I. Polarity (i.e., polar molecule)
• TWO opposing regions of slight ELECTRICAL charge:
(1) A Positive end (+)
(2) A Negative end (-)
(1) Polar (e.g., water molecule)
• With (+) charge, O atom PULLS on shared e- with GREATER force than
(+) of H atoms.
II. Hydrogen Bonding
• Weak force between O atoms and H atoms of adjacent water molecules.
(A) Cohesion and Adhesion: Two Properties of Water
• COHESIVE force are STRONG enough to cause water to have a thin
“SKIN” on its surface.
NOTE: ADHESION is force between UNLIKE substances
(Ex: Water holding TWO glass microscope slides together)
•
Critical Thinking
(1) The SURFACE TENSION of water at room temperature is so great
that you can actually “float” a small needle on the surface of water. (The
needle doesn’t truly float—it is denser than water. It is held in place by
the force of hydrogen bonding between water molecules lying below and
around the needle.) If the water were HEATED, WHAT would LIKELY
happen to the needle and WHY?
(1) Capillarity (result of BOTH cohesion AND adhesion of water)
• Property of water to be PULLED UP a straw OR a stem of a plant.
Critical Thinking
(2) Most automobiles have water-cooled engines. What must be true about
a SOLUTION that can replace water in the cooling system, such as
ANTIFREEZE?
Critical Thinking
(3) Cells contain mostly WATER. What might happen to the stability of an
organism’s INTERNAL TEMPERATURE with respect to environmental
temperature changes if cells contained mostly OIL, which does NOT have
extensive hydrogen bonding?
(B) Temperature Modification (Crucial to LIFE)
• Water MUST gain or lose a HUGE amount of THERMAL energy for its
temperature to SLIGHTLY change.
Advantage?
• A body that does not overheat easily (70% water)
• A stable environment for aquatic ecosystems, freshwater and marine.
3-2 Carbon Compounds
I. Organic (vs. Inorganic) Compounds
• Carbon (organic) COVALENTLY bonded to C, H, O, and N atoms.
II. Carbon Bonding (single, double, AND triple bonds are POSSIBLE!!)
• 4 e- in OUTER energy level (valence),  carbon would PREFER 4 BONDS.
III. Functional Groups (e.g., hydroxyl group = polarity)
• A GROUP off a CARBON ATOM that influences the molecule.
(1) Alcohol (C-0H)
• -OH group brings POLARITY to alcohols (i.e., ethanol, glycerol).
III. Large Carbon Molecules (Monomer + Monomer  Polymer)
• POLYMERS are built from MONOMERS during chemical reactions.
(1) Condensation Reaction (a.k.a “Dehydration Synthesis”)
• LINKS monomers TOGETHER to form POLYMERS releasing a WATER.
(2) Hydrolysis (i.e., “to BREAK with WATER”)
• BREAKS DOWN polymers to MONOMERS requiring a WATER molecule.
(i.e., the REVERSAL of condensation reaction)
(A) Energy Currency
• NRG in a compound known as ATP used to run reactions
(a HIGH energy-yielding compound).
(1) Adenosine triphosphate (ATP)
• HYDROLYSIS of ATP  (ADP) and (Pi) + 7kcal of NRG.
3-3 Molecules of Life
I. Carbohydrates (3 CLASSES)
• NRG yielding and structural molecules (sugars, starch, cellulose)
(A) Monosaccharides (i.e., simple sugars)
• MONOMER of starch OR glycogen (e.g., glucose, fructose, and galactose)
NOTE: The RATIO of C to H to O is 1:2:1. Formula is written as (CH2O)n.
(1) Isomers (of monosaccharides)
• Each monosaccharide has SAME molecular FORMULA, C6H12O6, BUT they
are STRUCTURED (appear) differently…
Isomers include…
Glucose
Fructose
Galactose
(B) Disaccharides (2-sugar unit) and Polysaccharides (many sugar unit)
• Glycogen (animal storage), Starch (plant storage), Cellulose (plant
STRUCTURAL component)
• CELLULOSE provides strength to PLANT cells, BUT have their glucose
monomers CROSS-LINKED with H-bonds, and are UNABLE to be broken
(via HYDROLYSIS) in humans due to a LACK of an ENZYME.
II. Proteins (tissue development, enzymes, NOT NRG)
• Built by AMINO ACIDS (monomer of protein), made of N, C, H, and O.
•Examples include…
Collagen
Fibrinogen
Lactase
Hemoglobin
(A) Amino Acids (20 different types; building blocks of proteins)
•All begin with a CENTRAL carbon covalently bonded to 4 other atoms.
(1) A H atom at 1st site.
(2) A carboxyl group (-COOH) at 2nd site
(3) An amino group (-NH2) at 3rd site
(4) A functional group (-”R”) at 4th site (** SHAPE and FUNCTION **)
(B) Dipeptides and Polypeptides
• Adjacent amino acids form a COVALENT bond  PEPTIDE bond.
(1) Peptide Bond
• Strong bond between N-H of 2 AMINO ACIDS in a PEPTIDE chain.
NOTE: A protein’s STRUCTURE and SHAPE are linked to FUNCTION.
This will be influenced by TWO PHYSICAL conditions:
(1) Temperature
(2) pH
(C) Enzyme (weakens BONDS, lowers ACTIVATION NRG)
• A protein that acts as a CATALYST during chemical rxns.
(1) Substrate (i.e., reactant)
• Bonds and is catalyzed by an enzyme (broken up OR pulled together).
Critical Thinking
(4) HIGH temperatures can WEAKEN bonds between different parts of a
protein molecule, thus changing its SHAPE. How might this SHAPE change
alter the EFFECTIVENESS of an enzyme?
III. Lipids (3 CLASSES)
• NON-polar (do NOT dissolve in water) AND stores MORE NRG than
carbs due to NUMEROUS C-H bonds (carbs LESS NRG  C-O bonds)
(A) Fatty Acids (BUILDING BLOCKS of most LIPIDS)
• Unbranched C chain with TWO ends of DIFFERENT properties:
(1) Hydrophilic
• CARBOXYL end of chain, polar, and “water-LOVING”
(2) Hydrophobic
• HYDROCARBON end of chain, non-polar, and “water-FEARING”
(B) Complex Lipids
• Include 3 classes:
(1) Triglycerides
(2) Phospholipids
(3) Waxes
(1) Triglyceride (e.g., saturated (animal) and unsaturated (plant) fats
• 3 fatty acids joined to a GLYCEROL molecule.
Critical Thinking
(5) Triglycerides in ANIMALS’ bodies are usually SOLID FATS, and those
in PLANTS are usually OILS. However, many animal species living in the
Arctic and Antarctic have a GREATER number of triglycerides that are
OILS than do other animals. What advantage might the storage of body
fat as OIL INSTEAD of SOLID FAT be to animals that inhabit freezing
climates?
(2) Phospholipids
• TWO fatty acids joined by a glycerol
(in CELL MEMBRANE, we call this the “LIPID BILAYER.”
(3) Wax (i.e., ear wax, plant cuticle)
• STRUCTURAL lipid; long fatty-acid joined to an ALCOHOL.
(WATERPROOF)
(C) Steroids
• Made using 4 carbon RINGS with various groups attached.
• Ex: Sex HORMONES (testosterone and estrogen), CHOLESTEROL, a key
for nerve transduction AND cell membrane stability.
IV. Nucleic Acids (2 CLASSES, DNA and RNA)
• Encrypt HEREDITARY data for cells.
(e.g., Sequence of bases READ like a CODE and is UNIQUE).
(1) Deoxyribonucleic Acid (DNA)
• BLUEPRINT for cellular activity; NEVER leaves nucleus of cell.
(2) Ribonucleic Acid (RNA)
• 3 types of RNA; work with DNA to allow a cell to make its PROTEINS.
(1) Nucleotide (monomer for DNA and RNA, 4 types of nucleotides)
• Made of 3 PARTS:
(1) Sugar  deoxyribose (DNA) OR ribose (RNA)
(2) Phosphate Group (PO4)
(3) Nitrogenous Base (A, T, C, G) (U in RNA)
Extra Slides AND Answers for Critical Thinking Questions
(1) Solutions that can replace water as a coolant in automobiles must have
the ability to absorb large quantities of heat.
(2) An organism’s internal temperature would likely change more abruptly
and drastically in response to environmental temperature changes.
(3) Heating the water would cause the water molecules to move about and
the hydrogen bonds to break, thus allowing the needle to eventually fall
through the surface of the water.
(4) Changing the shape of an enzyme may affect its ability to function
because the enzyme may no longer physically interact appropriately with its
substrate.
(5) Oil solidifies at a lower temperature than fat does; storing body fat as
oil is helpful in freezing climates because oil is less likely to solidify in
these climates than is fat.