Isomerism/Chirality
Functional Groups
Monomers/Polymers
Lipids & Carbohydrates
Proteins
100
What are structural isomers? Come up with a pair.
Structural isomers have the same formula, but a different arrangement (connectivity) of atoms.
Draw pair on the board.
100
Which functional group is found in alcohols and carbohydrates? (hint: can form hydrogen bonds)
-OH (hydroxyl group)
100
What are monomers and polymers? How do monomers link (ionically/covalently) to form polymers? What is the relationship between the two?
Monomers = small repeating units that combine to form polymer
Polymer = chain of covalently-linked monomers
Monomers are the building blocks of polymers and are unique to each type of macromolecule
100
What makes a molecule polar? Describe with an example
Net dipole
water
amino
etc
100
What is the structure of an amino acid? Are all amino acids chiral?
amino acids have a carbon bonded to
1- carboxyl
2- amine
3- H
4- R group (side chain)
200
Define enantiomers. How is the concept of chirality relevant here?
Give an example of a chiral compound.
Enantiomers are non-superimposable mirror images (hands). A chiral center is a carbon that has 4 distinct things (atom/R group) attached.
An achiral compound does not have an enantiomer.
chiral = asymmetric
200
What is a carbonyl group and in which 2 forms can it show up within a molecule (sugars)? What is a way to remember the difference?
Draw ketone/aldehyde on the board
aldoses/ketoses in sugars
200
What is dehydration synthesis? If 177 monomers are linked by this process to form a polymer chain, how many water molecules are removed?
Dehydration synthesis = removal of water to MAKE (synthesize) polymer
176
200
Is cellulose a polymer of alpha or beta glucose? Can it be digested by the human body? Why or why not?
beta
no, because we lack the pertinent receptors
cellulose = structural polysaccharide (think plant cell walls)
200
What are the 3 categories of amino acids?
Polar, nonpolar, and polar-charged
300
How many chiral centers are there in the above molecule? Explain and identify each one.
There are 8 chiral/stereocenters in this molecule.
300
What is a carboxyl group and how does it contribute to increasing/decreasing the acidity of a solution?
In which monomers/macromolecule polymers are carboxyl groups found?
Draw carboxylic acid. Proton dissociates into solution, increases [H+], thus increasing acidity (decreases pH)!
Found in amino acids, lipids
300
Define hydrolysis. If a molecule with 23 monomer units is to be broken down completely, how many water molecules are needed?
Hydrolysis ADDS water to a molecule to break (lysis) a bond.
opposite of dehydration synthesis
22
300
How are saturated fats different than unsaturated fats?
If you hydrogenate unsaturated fats (ex-partially hydrogenated palm oil), what is the result? Why would this be done (food-wise)? Does consumption have an effect on human health?
saturated - no double bonds, tightly packed, SOLID at room temp (animal fats)
unsaturated - some CIS double bonds, pack less tightly, and are thus LIQUID at room temp (plant oils- plants store oils in seeds, fish)
In hydrogenation, double bonds are isomerized, mix of cis and trans results.
trans are unhealthy (same as saturated fat argument plus poorly-understood reasons)
300
In the linkage of amino acids to form a polypeptide, how is the removed water molecule generated?
Hint: from which ends of the amino acid do the H and OH come off of?
The H comes off of the amine group end, while the OH comes off of the carboxyl group end
400
What are cis-trans isomers? Draw a pair.
Cis-trans isomers have a cis/trans relationships of attached substituents that cannot be equated by rotation (double bond present)
400
Which functional group is hydrophobic and why?
methyl group (nonpolar); does not dissolve in water
important for DNA
400
What are the monomers of carbohydrates?
Of proteins?
Of lipids?
Of nucleic acids?
CARBS = saccharides (simple sugars, mono- & di-)
Proteins = amino acids (polymer = polypeptide)
*Lipids = glycerol + fatty acids ("special case"; not really considered monomers; ester linkages)
Nucleic acids = nucleotides
400
Explain and draw the structure of a phospholipid bilayer in water.
hydrophilic heads, hydrophobic (nonpolar) tails (on the inside of bilayer, so they don't come in contact with polar water)
hydrophilic head = 1 choline (basic compound), 1 phosphate (f.g.), 1 glycerol (connects to fatty acids with ester linkage)
hydrophobic tail = 2 fatty acid chains
400
What is the primary structure of a protein?
secondary? tertiary? quaternary?
primary - polypeptide sequence
secondary - hydrogen bonding to fold protein into alpha-helix/beta-pleated sheet
tertiary - hydrophobic/van der Waals interactions, ionic bonds, disulfide bridges, hydrogen bonds all present
quaternary- multiple polypeptides undergo further folding, can act as functional units (ex=hemoglobin)
500
Is this molecule chiral?
No, it is achiral overall (meso) although it contains 2 chiral centers.
500
How does an amine group (-NH2) change the pH of a solution?
Amine group takes up a proton from solution to become NH3+ ; thus decreasing [H+] of the solution and increasing the pH (more basic).
500
Which is the most diverse of the macromolecules? Why is it given this classification?
PROTEINS
have NUMEROUS functions
enzymatic, structural, hormonal, storage, transport, defensive, receptor, contractile & motor
500
A steroid is classified as which type of biological macromolecule?
lipid
structural (cholesterol) or hormone (testosterone)
500
How can a protein become denatured? Is this process reversible?
Inadequate pH (too acidic, too basic), excess heat, exposure to oxidizing/reducing agents (disruption of bonds in secondary and/or tertiary structure)
Renaturation can occur, but is difficult and not always a possibility
(ex= frying an egg; even after it cools, it does not return to its 'raw' form - irreversible denaturation)