1. 3.3 Molecules of Life

2. Objectives
Define monosaccharide, disaccharide, and polysaccharide, and discuss their significance to organisms
Relate the sequence of amino acids to the structure of proteins
Relate the structure of lipids to their functions
List two essential functions of nucleic acids

3. Carbohydrates
organic compounds in a ratio of 2 hydrogen atoms to one oxygen atom; the # of carbon atoms varies

4. Obj 8: Define monosaccharide, disaccharide, and polysaccharide, and discuss their significance to organisms
Monosaccharide
a monomer of a carbohydrate
simple sugars made mostly by green plants
have one carbon ring
used for energy

5. Ex. glucose, fructose, galactose, and dextrose these examples are isomers to each other
all have same molecular formula – C6H12O6
have different structural formulas – diff. shape

6. Disaccharide
complex sugars
two carbon rings
formed by combining of 2 monosaccharides in a condensation reaction

7. Ex.
glucose + galactose = lactose (milk sugar) + H2O
glucose + glucose = maltose (malt sugar) + H2O
glucose + fructose = sucrose (table sugar) + H2O
“-ose” ending tells you it’s a sugar

8. Polysaccharide
composed of three or more monosaccharides
Ex.
1. glycogen (animal starch)
hundreds of glucose monomers strung together in highly branched chains
2. cellulose (plant starch)
thousands of glucose monomers linked in long, straight chains
So monomer is glucose

9. Obj 9: Relate the sequence of amino acids to the structure of proteins
Amino Acids - the building blocks of proteins
there are 20
basic structure is:
a central carbon atom bonded to
1. a single hydrogen atom,
2. a carboxyl group (-COOH),
3. an amino group (-NH2), and
4. a functional group (called the R group)

13. differences in a.a.’s found in their R groups
diff R groups of a.a.’s give proteins their shape – diff shapes have different functions
(structure related to function)
2 a.a.’s bond to form a dipeptide
covalent bond is called a peptide bond
is a condensation reaction
long strands of a.a.’s called polypeptides

14. Protein - an organic macromolecule
– composed of long strands of polypeptides
sequence or order, #, and kind of amino acids will determine the structure (what protein is produced)
- temperature can affect the structure (shape), and so function

16. enzymes - special proteins that act as catalysts in reactions
rxns depend on physical fit btwn enzyme and substrate (reactant being catalyzed) – called a lock-and-key model
can be affected (& so fail to work) w/ temp or pH change

17. Obj 10: Relate the structure of lipids to their functions
(fats) - large, nonpolar molecules
do not dissolve in water
have large #’s of carbon-hydrogen bonds
store energy efficiently

19. Fatty Acids
unbranched carbon chains (12 to 28 carbons)
- have a carboxyl group (-COOH) at one end
carboxyl end is polar, so hydrophilic, “water-loving”
other hydrocarbon end is nonpolar, so tends not to react w/ water – termed hydrophobic or “water-fearing”
- make up most lipids

20. 1) saturated (“full”) each carbon has 4 bonds all single bonds
2 types:
1) saturated (“full”)
each carbon has 4 bonds
all single bonds
2) unsaturated
less than 4 bonds
some double bonds

21. 4 types of lipids – 1st 3 contain fatty acids and an alcohol
triglycerides – structure: 3 f.a.’s & 1 alcohol (glycerol)
function: Saturated vs. Unsaturated
saturated have high melting points, and tend to be room temp.
ex. margarine, lard

22. unsaturated - liquid @ room temp - found in plant seeds and fruits
energy source for sprouting plants
2. phospholipids – structure: 2 f.a.’s joined by glycerol
function:
form 2 layers of cell membrane
waterproof barrier for cell
insulation

25. 3. waxes – structure: 1 long f.a. chain joined to a long alcohol chain
function:
highly waterproof
protective coating in plants & animals
ex. earwax vs. microorganisms

26. 4. steroids – structure: composed of 4 fused carbon rings w/
various functional groups
function:
needed for normal nerve cell function
ex. cholesterol
male development (testosterone)

27. Obj 11: List two essential functions of nucleic acids
DNA (deoxyribonucleic acid) – stores genetic information
ribonucleic acid (RNA) – transfers info. for building proteins
Both DNA & RNA are polymers composed of repeating monomers called nucleotides

28. 4 monomers: adenosine, thymine, guanine, cytosine
Have 3 components (parts)
a 5-carbon sugar (deoxyribose)
a phosphate group
a ring-shaped nitrogenous base
4 monomers: adenosine, thymine, guanine, cytosine