All cells must transcribe rRNA in order to construct a functioning ribosome. Scientists have isolated and identified rRNA  genes that contribute to ribosomal structure for both prokaryotes and eukaryotes. Figure 1 compares the transcription and processing of prokaryotic and eukaryotic  rRNA.

Figure 1. Comparison of rRNA processing in prokaryotes and eukaryotes

Which of the following statements provides the best explanation of the processes illustrated in Figure 1 ?

• Introns are removed from the pre-rRNA, and the mature rRNA molecules are joined and then translated to produce the protein portion of the ribosome.

  A

• Introns are removed from the pre-rRNA, and each mature rRNA molecule is translated to produce the proteins that make up the ribosomal subunits.

  B

• Sections of the pre-rRNA are removed, and the mature rRNA molecules are available to combine with proteins to form the ribosomal subunits.

  C

• Sections of the pre-rRNA are removed, and the mature rRNA molecules are available to bring different amino acids to the ribosome.

1. Cystinuria is a disease characterized by the abnormal production of painful kidney stones. The stone formation does not appear to be related to patient dehydration. These stones are produced because certain amino acids tend to build up and crystallize outside the transport cells. Can your group think of any reason why a cell might fail to reabsorb organic molecules?
2. Epulos, a bacterium growing in the gut of tropical surgeonfish can reach the size of 500 micrometers. How does this compare to other bacteria and what problems does this present the Epulos? What are some ways that a cell this size could alter its structure to survive?
3. Many biologists speculate that the first major steps in the evolution of a eukaryotic cell from a prokaryotic ancestor would be the loss of a cell wall and the development of an extensive cytoskeleton. Why do you suppose these steps are so important? Specifically discuss what these steps allowed a eukaryotic ancestor.

Imagine that you are part of a research team that specializes in diagnosing disorders associated with malfunctioning cellular organelles and structures.Medical doctors consult your group to help diagnose particularly difficult cases.  Read the patient history, physical examination and lab results to provide a cellular explanation for the case below. In the answer box type the tell the malfunctioning organelle (4 points) AND Rationale for Diagnosis (6 points) (explanation of how history, physical examination and laboratory results suggest diagnosis). Be sure to give all details as rationale counts majority of points.

Patient History:    

• 2-day old male, Low birth-weight (4pds. 5 ounces), Difficulty suckling/swallowing, Seizures, Gastrointestinal bleeding

Physical Examination

• Enlarged liver, Low muscle tone/inability to move, Glaucoma, Facial deformities, Impaired hearing
• Jaundiced skin

Laboratory Results

• High levels of hydrogen peroxide in cells
• High levels of fats and amino acids in cells

why are unsaturated fatty acids the “good” fats to have in your diet? What is the importance of unsaturated omega-3 fatty acids and unsaturated omega-6 fatty acids in your diet? What percentage of your total fat intake should be unsaturated fatty acids? What kinds of foods contain a significant amount of unsaturated fatty acids? And is it possibly to consume too many unsaturated fatty acids in your diet, and if so what are some effects that the increased amounts of unsaturated fatty acids would have on your body, likes diseases or health conditions?

18. Circle the fatty acid in each pair that has the higher melting temperature.
(a) 18:1∆9 vs 18:2∆9,12
(b) 18:0 vs 18:1∆9
(c) 18:0 vs 16:0
19. Categorize each of the following as an aldose, a ketose, or neither.
H H H H H
HOH OHOH HOHO
O HOH HOH HOH HOH HOH HOH HOHO HH
H H H H H
(a) (b) (c) (d) (e)


20. What is the most significant chemical difference between triacylglycerols and glycerophospholipids that leads to their different functions?  


21. What is the effect of a double bond on the fatty acid structure?  



22. (a) When relatively high concentrations of fatty acids are suspended in water, they form structures known as ________. (b) When relatively high concentrations of membrane phospholipids are dissolved in water, they form structures known as ________. (c) Why are the structures listed in your answers to (a) and (b) above energetically favored?  


23. What is the role of cholesterol in terms of membrane fluidity?


24. There are two reactions in glycolysis which involve the isomerization of an aldose to a ketose or vice-versa. What enzymes catalyze those two reactions?


25. The simple sugar that is used as the reference for naming D and L states of sugars is:



26. Draw D-glucose and a C-3 epimer of D-glucose.






27. Draw the cyclic forms of D-glucose and indicate the anomeric carbon with a *. Name the forms.




28. Describe the structure of starch. Include the identity of its subunits and the details of the bonds between them.




29. Why can humans not use cellulose as a nutrient?




30. Circle the following fatty acid that would have the lowest melting point. Put a square box around the fatty acid that is unlikely to be a natural product. Lastly, Name the fatty acid that you have not Circled or Boxed.

31. In cells, fatty acids are stored as triacylglycerols for energy reserves. Draw the molecule that fatty acids react with to form these energy storage molecules.

Upon presentation: An 18-month-old female arrives by ambulance at the emergency department. The paramedics report that there was no known history of any recent trauma, and no known fever, vomiting, or other unusual behavior. There were no known ingestions or medications in the household. There was no evidence of trauma. Interview and History: At 9 PM the previous night, Ella was described by her mother as appearing more quiet than usual. They had spent the day traveling from the grandmother's house and Ella had been carsick so had not eaten very much during the day. When they got home, Ella had some water and went to bed. Ella slept longer than usual and was found unresponsive by her mother at 9 AM. At this time her mother called 911. Follow-up tests: 1) Blood glucose: 23 mg/dL (normal range 90 – 125 mg/dL) 2) Repeat blood glucose: 50 mg/dL following administration of glucagon 3) Urinary acids: Markedly elevated levels of glutaric, ethylmalonic, and dicarboxylic acids; ketones absent 4) Serum free fatty acids: 0.84mmol/L (normal range: 0.00-0.72 mmol/L) Treatment: She was transferred to the pediatric intensive care unit and remained comatose for 16 hours. Blood glucose levels remained stable with a continuous infusion of dextrose. Inpatient treatment consisted primarily of glucose supplementation and supportive care. Questions: In this individual, at the time of presentation, what is the relative ratios of the following hormones: insulin epinephrine glucagon cortisol Based on the data presented above. This individual most likely has a primary deficiency in which of the following pathways. Please describe why you choose a specific pathway and why you DID NOT choose other pathways. a. Glycogenolysis b. Gluconeogenesis c. Lipolysis d. Glycogen synthesis e. Glycolysis f. Ketogenesis g. β-oxidation h. Protein catabolism Based on your choice above, would the use of carnitine supplementation be of any benefit to your patient? (Review the role of carnitine!)

Compare the ATP yield of three glucose molecules that enter glycolysis and are converted to pyruvate with that of three glucose molecules that proceed through the pentose phosphate pathway such that their carbon skeletons (as two F6P and one GAP) reenter glycolysis and are metabolized to pyruvate. Indicate the steps where ATP was used or produced and the overall ATP totals.

Compare the ATP yield of three glucose molecules that enter glycolysis and are converted to pyruvate with that of three glucose molecules that proceed through the pentose phosphate pathway such that their carbon skeletons (as two F6P and one GAP) reenter glycolysis and are metabolized to pyruvate. Indicate the steps where ATP was used or produced and the overall ATP totals.

1. During cellular respiration, glucose is ______________.

Question 2

During cellular respiration, oxygen is ­­­­­­­­­­­­­­_______________.

Question 3

________________ is the breakdown of glucose into two molecules of pyruvate.

The _______________ is a series of carriers on the cristae of the mitochondria and extracts energy from NADH and FADH2 to produce molecules of ATP.

Question 5

The _______________ occurs in the matrix of the mitochondria and produces NADH and FADH2.