Exam 3, October 17, 2007
(100 points; 2 points/question)
Complete scantron for all answers.
You may keep this for your records.
Much of the requirement for leucine could be met by feeding its respective ketoacid because what
animals really require is the amino acid’s carbon skeleton.
Without exception, proteins must be broken down to amino acids, di-, and tri-peptides to be absorbed
Wheat is low in lysine, but peanut butter has quite a bit of lysine.
So if you ate wheat bread with
peanut butter for lunch, the amino acid balance would be relatively good.
Sometimes young animals require a specific AA in their diets, but once they are older they can
synthesize adequate amounts so that it is no longer “essential”.
Raw soybeans should never be fed to any mammal because they contain an enzyme that inhibits the
digestion of protein.
If starch intake of a cow is increased, microbial protein yield will likely increase unless rumen pH
drops considerably from the increase in fermentation acids.
The AA balance of alfalfa is of little concern for a dairy cow because cows simply do not get that
much Rumen-Undegraded Protein from alfalfa.
The N recycling that occurs in a ruminant is useful to a high producing dairy cow fed a 19% CP diet.
Rumen microbial protein has a higher biological value than the protein of cereal grains.
In general, the amount of water an animal drinks is not affected by the % moisture in its diet.
Matching 11-14 (use each answer only once, one answer will not be used)
Sulfur-containing AA, not used as a building block to make protein but essential for cats
Sulfur-containing AA, methyl-donor, often first-limiting for birds
Basic AA, generally considered essential, first-limiting AA of cereal grains
Branched-chain AA, essential, may regulate protein metabolism, corn has lots of it.
e. none of these
Matching 15-18 (use each answer only once, one answer will not be used)
Similar in structure to phenylalanine and decreases the need for phe in the diet
Part of the urea cycle; not used as a building block to make protein
Part of the urea cycle; generally considered essential, but adult mammals can make their own
Large neutral AA, precursor for making serotonin
e. none of these
Multiple Choice (only one best answer per question)
Which of the following consists only of the ten AA that are generally considered essential?
a. lys, leu, tyr