Lipids
Glycerol
CH2---OH
I
CH----OH
I
CH2---OH
Carboxylic acids attach to glycerol to form triacylglycerols (fatty acids).
So, 3 CH3-CH2-CH2-C-OH (butanoic acid) molecules can
II
O
link to the glycerol to form a “simple triacylglycerol.” To make this formation
happen on paper, I strike out the H’s from the OH’s on the glycerol molecule and
strike out the OH from the butanoic acid molecule. Then I flip around the
butanoic acid molecule so that the CH3 is on the right side and the C with the
double-bonded O is on the left. Then you have
O
II
+ C-CH2-CH2-CH3
CH2---O
I
CH----O + O=C-CH2-CH2-CH3 (I had to put the O to the left of the C for lack of room)
I
CH2---O
+ C-CH2-CH2-CH3
II
O
Then connect the 2 structures together and you get the structure,
CH2——CH——CH2
I
I
I
O
O
O
I
I
I
O =C O=C
C=O
I
I
I
(CH2)2 (CH2)2 (CH2)2
I
I
I
CH3
CH3 CH3
Carbohydrates
The main area of the carbohydrates that Mr. Griffin stressed for the purpose of
the latest quiz as well as the exam was the nomenclature.
There are three components to a formal name of a carbohydrate. The first
component of the name indicates whether there is a ketone group or an aldehyde
group attached to it. If there is a ketone group attached then the name will begin
with the prefix “keto” and if there is an aldehyde group attached to it then the
name will begin with the prefix “aldo.” The second component indicates the
number of carbon atoms in the carbohydrate. So if a name began with “ketohex”
then you can discern that there are 6 carbon atoms and that there is a ketone
group attached. The last component of a formal carbohydrate name is always the
suffix “ose” indicating that it is a sugar.
Proteins
The formula for the amino acids that form peptide proteins is
NH2—CH—COOH
I
R
The three amino acids that Mr. Griffin taught us about for the purpose of the last
quiz as well as the exam were Glycine, Alanine, and Phenylalanine.
For Glycine (gly), R = H
For Alanine (ala), R = CH3
For Phenylalanine (Phe), R = CH2—
These three amino acids can be linked together in any possible order. When
linking amino acids together, strike out the OH off the end of each amino acid
molecule except for the last molecule in the link. Also, reduce NH2 to NH for each
amino acid link except the first one in the link.
When linking peptide fragments (such as phe.pro.try, ala.phe, try.ala, etc)
together, simply look for similarities on the ends of the fragments and link them
together. Example: “A peptide contains cys, gly, his2, leu2, and ser. Partial
hydrolysis gives cys.gly.ser, his.leu.cys, and ser.his.leu. Connect these together to
form a peptide sequence.”
Answer: his.leu.cys.gly.ser.his.leu. (note that while connecting two ends that
have the same amino acid only one of the ends is included in the final answer.
Example: connect ala.cys with cys.try. Answer is ala.cys.try instead of
ala.cys.cys.try.)