Input/Circle correct answer where applicable.

a) The main class of enzymes that digest proteins are known as_______________. Endopeptidases causes bonds to break in the middle/end of peptides. Exopeptidases are important for cleaving off the terminal amino acids. For C-terminal amino acids _________-peptidases will be used while _________ -peptidases will cleave N-terminal amino acids. Examples of such enzymes are pepsin, which requires an alkaline/acidic environment in the _______________ in order to be functional, and _______________, found in pancreatic secretions, which requires an _______________ environment.

b) Ghrelin is an (orexigenic/anorexigenic) hormone. Its levels in the blood are (increased/decreased) during times of fasting or hypoglycemia and (increased/decreased) when blood glucose and amino acid levels are high. Ghrelin acts at the level of the stomach to (increase/decrease) gastric acid release and motility. With regards to its functions on food intake, the hormone that works as part of the “antagonistic pair” with ghrelin is _________.

c) Carbohydrate digestion mainly occurs in the ______________ and _______________ whereas protein/peptide digestion mainly occurs in the ______________ and ______________.

1. Most carbohydrates contain carbon, hydrogen and oxygen in the ratio of ____________.
2. Starch and glycogen are composed of subunits of _____________________
3. Proteins are composed of ________ common amino acids linked together by _____________ bonds.
4. ________________ are the building blocks of nucleic acids.
5. The types of nucleic acids important in the storage of hereditary information are ____________ and _____________.
6. The monosaccharide common to sucrose, starch, glycogen and cellulose is:
7. Glucose and galactose are
8. Carbohydrates and fats are used by living organisms mainly as
9. A fat molecule is formed by the reaction of three fatty acid molecules with one molecule of
10. Fats contain about ____ energy as carbohydrates
11. The two chains of DNA are held together by _____ bonds.
12. Cows can digest cellulose in grasses, but people cannot. A cow’s four-chambered stomach holds populations of microbes that are not normal residents of the human stomach. What kind of metabolic reactions do you think the microbes carry out in the stomach of the cows? What do you think might happen to a cow being treated with an antibiotic that kills the microbes?

To calculate the isoelectric point of amino acids having other ionizable functional groups, we must also take into account the

pK_a

of the additional functional group in the side chain.

Indicate which

pK_a

values must be used to calculate the pI of the following amino acids: [1] aspartic acid; [2] arginine; [3] lysine. Be sure to answer all parts.

Now you will translate the amino acid sequence for the given tRNA strand. Remember that codons are 3 base pairs long.

1. AUG CAC UGU CCU UUC GCU GAC

2. GAG AUC UGG UUG GAA UCG

The following are pieces of mRNA. Give the DNA strand from which it was transcribed.

3. mRNA: G A G A U C U G G U U G G A A U C G

DNA   :

Using the following piece of DNA, give the mRNA molecule, and the amino acid sequence for which it codes.

DNA                 : A T A T A A A C G A G G A A A T T C C G G G C G

mRNA              :

tRNA                :

Amino acids    :

Use the mRNA sequence to find the DNA sequence and the amino acid sequence, the tRNA sequence and the aminoacids.

DNA                 :

mRNA              : A U G C C U A C A U G U G G U G U A A C C U U A

tRNA                :

Amino acids    :

Complete the table below showing the sequences of DNA, mRNA codons, tRNA anticodons and the amino acids. Remember the genetic code is based on mRNA codons.

MACROMOLECULES:

Standard components and functional groups of amino acids and description.

Which of the following amino acids pairs would form the described hydrogen bond at pH 7? Explain your answer?

A. His Asp

B. Tyr His

C. Ser Arg

D. Glu Thr

A certain protein has a molecular weight of 250 kD. What is the approximate number of amino acids residues?

A. 2

B. 750

C. 1200

D. 2300

E. 27500

Draw by hand a 3 pass transmembrane protein of your own creation (not a known one) through a plasma membrane. In your drawing clearly draw and label: The plasma membrane and the extracellular and cytosolic side The C and N terminus All the regions where you expect to find higher proportions of polar amino acids All the regions where you expect to find higher proportions of nonpolar amino acids.

a) The presence of natural amino acids with enantiomeric excess from the meteorite is still a subject of debate. Discuss why this is - what are the experimental issues with stating that alanine found on the Murchison meteorite has an excess of one (L) enantiomer? How might "false positives" be observed in the analysis of these meteorite samples?

b) An argument put forward to corroborate the meteorite theory is the presence of unnatural α-alkyl amino acids such as isovaline, which was observed to exist in the meteorite with a slight enhancement of the L isomer. Discuss why the observation of unnatural amino acids such as these is less susceptible to false positives than the presence of alanine above.

c) Assume that there was an excess of (L)-isovaline on the Murchison meteorite. Discuss the plausibility of (L)-isovaline conferring chirality on species such as 1, based on your reading of Noorduin, et al.

Glycolysis

a) occurs in the liver during arduous exercise

b) has a net energy gain

c) provides a storage form of glucose

d) costs 4 ATP + 2 GTP per glucose synthesized

Stage 1 of glycolysis includes steps 1-3. These reaction types include

a) isomerization, phosphorylation

b) isomerization, dehydrogenation

c) cleavage, dehydrogenation

d) dehydration, phosphorylation

Which step of glycolysis generates ATP?

a) Step 4, cleavage of F-1,6-BP (fructose-1,6-bisphosphate) to DHAP

(dihydroxyacetonephosphate) plus GAP (glyceraldehyde-3-phosphate)

b) Step 5, isomerization of DHAP to GAP

c) Step 6, oxidation of GAP to 1,3-bisphosphoglycerate

d) Step 10, conversion of PEP (phosphenolpyruvate) to pyruvate

Resting muscle tightly regulates the enzyme PFK (phosphofructokinase)

a) because it catalyzes the only step in glycolysis with a significant energy release

b) through feedback inhibition by ATP

c) through feedback stimulation by NADH

d) independently of its enzyme activity