Transcription and Translation

1. Double strand of DNA:

5’-ATGTACCAGCATTCTCGATACCCT-3’

3’-TACATGGTCGTAAGAGCTATGGGA-5’

mRNA strand made from the DNA: 5’-AUGUACCAGCAUUCUCGAUACCCU-3’

a) Which strand of the DNA is the template for mRNA synthesis? Select the correct answer: i. 5’ – 3’ ii. 3’ – 5’ (0.5 points)

b) Draw an arrow on the DNA above, to show the direction of transcription i.e. in which order the nucleotides were added to create mRNA. (0.5 points)

c) What is the peptide sequence of this piece of mRNA? There is a codon table at the end of this assignment you might find useful! And don’t forget the start codon. (1 point) 2. Template Strand of DNA: 5’-AATGTCACGAGATGAGTTCAT-3’

a) Write out the mRNA sequence made from this piece of DNA, making sure you list the 5’ end first. Remember, nucleic acids are created in the 5’-3’ direction. (1 point)

b) What is the peptide sequence of this piece of mRNA? (1 point) 2

3. Template Strand of DNA: 5’-CGATTGGCCACGCATGACTAA-3’

a) Write out the mRNA sequence made from this piece of DNA, making sure you list the 5’ end first. Remember, nucleic acids are created in the 5’-3’ direction. (1 point)

b) What is the peptide sequence of this piece of mRNA? (1 point)

4. Non-Template (coding) strand of DNA: 3’-CCAATATACGGTCTATGCGGT-5’

a) Write out the mRNA sequence, making sure you list the 5’ end first. Remember, nucleic acids are created in the 5’-3’ direction. (1 point)

b) What is the peptide sequence of this piece of mRNA? Hint: what was my advice in the lecture video in this situation. (1 point) /8 3

1. Myristoyl-CoA is a saturated fatty acid with 14 carbons attached to coenzyme A. How many molecules of ATP would be generated from the complete oxidation of a single molecule of myristoyl-CoA? Important notes: Recall that the investment of 2 ATP is required to generate Myristoyl-CoA from myristate. Do not include these 2 ATP in your calculations of ATP yield. Assume that each molecule of NADH corresponds to 2.5 ATP synthesized, and each molecule of FADH₂ leads to 1.5 ATP synthesized.

2. What are TWO major differences between glucokinase (expressed in the liver) and hexokinase (expressed in most other tissues)?

a. Glucokinase has a lower affinity for glucose than hexokinase.

b. Glucokinase has a higher affinity for glucose than hexokinase.

c. Glucokinase is allosterically activated by glucose, hexokinase is not.

d. Glucokinase is allosterically inhibited by glucose, hexokinase is not.

e. Hexokinase is allosterically inhibited by glucose 6-phosphate, glucokinase is not.

3. To which anabolic pathway in the liver do fatty acids NOT contribute?

a. They are incorporated into liver fat droplets and could cause fatty liver disease.

b. They are exported into the bloodstream as fatty acids bound to serum albumin.

c. They are incorporated into lipoproteins and exported into the bloodstream.

d. They contribute to synthesizing new glucose via gluconeogenesis.

4. What is an important piece of evidence suggesting that fermentation is an important source of energy during high-intensity exercise?

a. Gluconeogenesis is activated in the liver

b. Phosphocreatine levels drop in the muscle

c. ATP levels drop in the muscle

d. pH levels drop in the blood

5. Which of the pathways below is NOT a major source of energy for a 1,000m foot race?

a. ATP from oxidative phosphorylation of fatty acids

b. ATP from oxidative phosphorylation of glycogen

c. ATP from lactate fermentation in the muscle

d. ATP regenerated from phosphocreatine

AMP is synthesized in a two-step reaction sequence involving inosinic acid, ATP and glutamine.

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Question 801 pts

During starvation when gluconeogenesis increases to maintain the levels of blood glucose, the metabolism of glutamate to glucose-6-phosphate is enhanced.

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Question 811 pts

Measurement of blood ammonia level is a sensitive test of kidney function.

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Question 821 pts

The increase of glycogenolysis in muscle produced by epinephrine may be attributed to the conversion of phosphorylase b to phosphorylase a.

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Question 831 pts

Glucagon targets primarily on liver to increase glycogen degradation.

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Question 841 pts

The formation of glucose 6-phosphate renders the entry of glucose into most cells almost irreversible (i.e. staying intracellular).

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Question 851 pts

Before fatty acids can be oxidized, they must be activated for reactions. This activation process is catalyzed by acyl carrier protein.

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Question 861 pts

In the oxidation of fatty acids, transportation of activated fatty acids into mitochondria requires the reaction with carnitine.

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Question 871 pts

The breakdown of the fatty acid CH3CH2CH2CH2CH2CH2CH2CH2COOH via the β-oxidation pathway would yield three moles acetyl units and one mole propionyl unit.

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Question 881 pts

In the biosynthesis of fatty acid, the acyl group carrier for the biosynthetic reaction is acyl carrier protein.

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Enalaprilat is a competitive inhibitor of the angiotensin-converting enzyme (ACEACE), which cleaves the blood-pressure regulating peptide angiotensin I. ACEACE has a KM=52KM=52 μMμM for angiotensin I, which is present in plasma at a concentration of 78 μMμM. When enalaprilat is present at 2.8 nMnM, the activity of ACE in plasma is 13 %% of its uninhibited activity. What is the value of KIKI for enalaprilat?

A 4-month old baby is admitted to the hospital with a fever of 104o F (compared to a normal temperature of 98.6o F) and a decreased blood pH. Why is it critical to reduce this fever as quickly as possible and restore normal pH? Discuss the role and sensitivity of proteins in (1) normal body chemical processes and (2) how enzyme activity is directly affected by changes in pH or temperature.

1. ______ _____ is the messenger that regulates blood pressure by causing arterial smooth muscle relaxation.
2. ______ nucleotides are common second messengers in animal cells.
3. Cells can regulate precisely where signaling occurs within the cell (e.g., in the yeast mating pathway) by association of the signal pathway proteins with a ________ ________.
4. In smooth muscle cells, acetylcholine stimulates activation of the enzyme ____________ __, which cleaves ____ to form the second messengers ___ and ___.

4. a. we learned about 4 different types of membrane cell receptors. describe these different types and give a spesific example for each of them.

b. a certain patient as a mutation that nutrelizes the enzyme that is incharge of Myristoylation of proteins. which of the types of receptors that you descibed in question a will be affected by this mutation? what will be the effect? what is the role of Myristoylation? give as much details as possible.

ATCase perfrorms the first step in CTP synthesis using aspartate as a substrate. It is a wonderful example of allosterism:

a) Describe the quartenary structure of ATCase. To get you started remember that the enzyme consists of two different subunits, of which there are 6 of each for a total of 12 subunits.

b) What are the functions of the two different subunits?

c) what are the allosteric effectors and what is their role in the KM of ATCase?

Question 2-17

You want to maintain a pH = 7.0 for an enzyme-catalyzed reaction that will produce hydrogen ions along with the desired product. At equal concentrations, which weak acid, if any, will serve as the better buffer for the reaction: Acid A, with pKa = 6.5 or Acid B, with pKa = 7.5?

a. Acid A

b. Water is as good as either of the acid available

c. Acid B