Biochemistry Question Set 2

A 43-year-old female presents to the office for fatigue. Although she had it for several months, over the past few weeks, her fatigue has been worsening. She has no other symptoms. She denies any changes in her bowel habit or blood in her stool. There has been no change in her mood or difficulty with her sleep. She was recently fired from her job as she was found to come to work drunk several times. She says that she can quit everything but not alcohol. Her diet is poor. The physical exam reveals a malnourished lady with moderate conjunctival pallor. Pertinent lab results are Hemoglobin 10 g/dL, with a Mean Corpuscular Volume (MCV) of 108 fl. Elevated Level of which of the following will most likely to be found in this patient?

A 35-year-old male presents with a skin rash of two days. The rash appeared suddenly and has progressively gotten worse. It started off as an erythematous lesion on the back of his hands and over his nose. The lesions over his hands have become bullous and tensed. He has never experienced similar symptoms before. He just got back from a canoeing trip during a very hot and sunny weekend. Physical exam is significant for erythematous, vesicular lesions over the nap of the neck and bridge of the nose as well as tense bullae over the dorsum of both hands. The attending physician suspects a defect in the synthesis of heme and orders some blood tests. Which of the following precursors will most likely be elevated in this patient?

A 6-year-old boy is brought to the office by his mother for abdominal pain and constipation. She reports that his appetite has been reduced and that he has not had a bowel movement in two days. Prior to this, he had a regular bowel movement once a day. She also reports that he has appeared to be more tired than usual. He is not as active as he usually is. The family recently moved into a house built in the 1940s and have just begun renovations. Physical exam is only significant for moderate conjunctival pallor. A peripheral blood smear shows red blood cells with basophilic stippling. What is the most likely mechanism causing this patient’s symptoms?

A 36-year-old nursing home worker presents to the clinic with the complaints of breathlessness, cough, and night sweats for the past two months. She further expresses her concerns about the possibility having tuberculosis as one of the patients under her care is being treated for tuberculosis. A PPD skin test is done and it reads 11mm on day 3. Chest X-ray shows signs of a cavitary lesion in the right upper lobe. Standard anti-tuberculosis medication regimen is started. At a follow-up appointment 3 months later, the patient presents with fatigue. She has also been experiencing occasional dizziness, weakness, and numbness in her feet. Physical exam is positive for conjunctival pallor. Lab work is significant for Hemoglobin level of 10 gm/dL and Mean Corpuscular Volume of 68 fl. What is the most likely cause of her current symptoms?

A 43-year-old Caucasian male presents with the complaint of pain in the small joints of his left hands. The pain is intermittent and cramping in nature in his second and third metacarpal phalangeal (MCP) joints that has progressively worsened over the past few weeks. He also reports that he has been feeling thirsty more often as well as urinating more frequently over the past few weeks. He does not describe any pain during micturition. His stools are pale in color. He also reports that his skin appears to be darker than usual even though he has not been outdoors much over the past few weeks. Physical exam is significant for tenderness in the second and third MCPs of both hands, and right upper quadrant tenderness. Lab results show: Aspartate Aminotransferase (AST): 450 U/L Alanine Aminotransferase: 350 U/L Serum Ferritin: 460 ng/ml. Deficiency of which of the following is the most likely cause of her symptoms?

A 25-year-old Caucasian male presents to the office with the complaint of yellow discolouration of his skin. He reports that the discolouration appeared gradually over the past 5 days. He does not have any other complaints. He has never had similar symptoms before. Past medical history is only significant for a recent flu that was so bad that he was on a leave from work for a week. The physical exam is significant for yellow sclera and slight yellowish discolouration of the skin over the face and neck. Liver function tests reveal Total bilirubin level: 2 mg/dl Direct bilirubin level: 0.4 mg/dl Aspartate Aminotransferase: 25 U/L Alanine Aminotransferase: 15 U/L What is the most likely pathology in giving rise to this patient's condition?

A 6-year-old boy is brought to the office by his mother. She reports that her boy is well but has some concerns with regards to his overall health. She says that he is shorter and physically, seems less developed compared to his older brother and sister at his age. He recently started school and the mother reports that the boy’s teachers have some concerns regarding his learning capability not being at the level of his peers. His height and weight are in the 10th and 15th percentile, respectively. Lab results reveal: Hemoglobin: 10 gm/dl Mean Corpuscular Volume: 110 fl Multi-segmented neutrophils are seen on peripheral blood smear. Urinary Orotic acid levels are found to be high. What is the most likely cause of this patient’s condition?

A 50-year-old male presents to the office with the complaint of pain in his left great toe. The pain started 2 days ago and has been progressively getting worse to the point that it is difficult to walk even a few steps. He adds that his left big toe is swollen and hot to the touch. He has never had similar symptoms in the past. He normally drinks 2-3 cans of beer every night but recently had binge three nights ago. Physical examination is notable for an overweight gentleman (BMI of 35) in moderate pain, with an erythematous, swollen, and exquisitely tender left great toe. Lab results reveal a uric acid level of 9 mg/dl. A complete blood count shows: Hemoglobin %: 12 gm Hematocrit: 45 % Mean Corpuscular Volume (MCV): 90 fl Platelets: 160,000/ mm^3 Leukocytes: 8000/ mm^3 Segmented Neutrophils: 65 % Lymphocytes: 25% Eosinophils: 3 % Monocytes: 7 % Red Blood Cells: 5.6 million/ mm^3 Synovial fluid analysis shows: Cell count: 15000 cells/ mm^3 (80 % Neutrophils) Crystals: Negatively birefringent crystals present Culture: Pending Gram Stain: No organism seen Which of the following is the mechanism of action of the drug that will most probably be used in the long term management of this patient?

An 8-month-old boy is brought to the office by his mother for recurrent infections. Over the past two months, the boy has had multiple visits to the urgent care clinic for respiratory, ear and skin infections. His mother is concerned about the health of her child. Currently, the child has a runny nose for the last two days. There is no fever but the mother adds that the boy is not eating very well. His mother denies any history of infection during her pregnancy and was tested negative for HIV. Vital signs reveal a temperature of 98 F, a pulse of 90/min and respiratory rate of 14/min. On physical exam, there are decreased lung sounds in the left lower lobe. A Chest X-ray fails to show any lung pathology along with an absent thymic shadow. There is no history of similar symptoms in the family of both parents. What is the most likely cause of this patient’s condition?

A 41 year old male presents to the office with pain in his right big toe. The pain started yesterday and has been progressively getting worse to the point it is difficult to walk. He describes his right big toe as being swollen and hot to the touch. He has never had symptoms like this before. He drinks 3 beers per night. Medical history is otherwise only significant for chronic kidney disease. Physical exam is notable for an overweight gentleman in moderate pain, with an erythematous, swollen, and tender right toe. A joint fluid analysis in this patient is most likely to show what?

A 6 year-old boy presents to the office with his mother to discuss his weight. The mother reports that her child’s appetite has been progressively more insatiable over the past year. As a result he has gained a lot of weight. His diet is balanced and healthy but he is not very active. She also reports that he has been having more temper tantrums at home lately. He attends a special education program at school. As an infant the child had feeding difficulties, weak muscle tone, and delayed development. Physical exam is notable for a short, obese child with a narrow forehead, and almond-shaped eyes. Which of the following genetic abnormalities is the most likely to have caused this condition?

A 5 year-old boy brought to the office by his mother for a regular check-up. During this visit he appears happy, active, smiling and laughing alot. This child was born with a genetic disorder that left him with severe intellectual disability, inability to speak with a history of recurrent seizures. The mother denies any recent seizures but mentions he continues to have trouble maintaining his balance when he walks and has sleeping difficulties. On physical exam, the boy has a small head compared to his body, laughs throughout the exam and is maks flapping hand gestures. The mother wants to know what other medical concerns she needs to watch for her as her son grows up. What is most likely to develop in this patient as he gets older?

A 4 year-old boy presents with his mother to the office for a routine exam. He doesn't have any complaints at this visit. The boy has a history of being born with an opening in the side of his abdomen that required surgical repair. During infancy and into early childhood he struggled to breathe and eat due to an enlarged tongue. Over the past couple years he experienced accelerated but uneven growth of his body. Pertinent physical exam findings include hemihypertrophy of the right side, along with an enlarged tongue. This patient is at increased risk of developing which of the following?

Researchers are investigating the allele frequency of CFTR gene in a population of 1000 individuals. The mode of inheritance for this gene is autosomal recessive. They find that 80 % of the alleles were dominant. What is the genotype frequency for the recessive trait in this population?

A 16-year-old female presents to the office accompanied by her mother. The mother expresses concerns about her daughter’s health because she has not yet had a period. The daughter confirms this and upon further questioning denies any significant weight loss, changes in mood or changes in her appetite. She denies being sexually active. She is a good student who works hard and enjoys competing in sports. On physical exam, the patient is short in stature with her height in the 33rd percentile, has an excessive skin in the neck and has a broad chest with widely spaced nipples. A pregnancy test done at the office is negative. Which of the following genetic abnormalities is the most likely cause of this patient’s condition?

A 3-year-old boy is brought to the clinic by his mother as he appears to be fatigued all the time. She also mentions that he struggles to get out of his seat after eating his meals and spends more time sitting in just one place.Now when he walks she notices that he waddles more than he used to. He was much more active at his previous well-child visit. Gross motor skills have delayed to appear since his last visit. Vaccinations are up to date. There is a family history of a maternal uncle with similar symptoms that started in early childhood. On examination, the child has thick calves and uses his hands to support himself as he stands up from a sitting position. Reflexes are decreased bilaterally. Lab studies show elevated Creatinine Phosphokinase(CPK) and Lactate Dehydrogenase(LDH). Which of the following genetic abnormalities is most likely responsible for this patient’s condition?

Researchers are studying the inheritance pattern of 2 genes, Gene A and Gene B. It is believed that both of these genes are found on the same chromosome. Assuming crossover occurs, what is the expected recombination frequency if genotype AaBb is crossed with genotype aabb?

A 50 year old female presents to the clinic with joint pain of 7 months duration. She reports having intermittently swollen, hot and tender knee joints bilaterally. She adds that when she wakes up in the morning her knees are stiff and do not loosen up until an hour later. The pain tends to improve with movement. Physical exam is significant for warm, erythematous, swollen, tender knee joints bilaterally. Lab results are positive for rheumatoid factor and Anti-Cyclic Citrullinated Peptide (CCP) antibodies. Plain Xrays of the knee joints show periarticular osteopenia and bony erosions. She was started on the first line drug for her condition to which she responded very well. Which of the following is the mechanism of action for the drug that was most likely used in this patient?

A 9-month-old boy is brought to the pediatrician because he can not sit on his own without support and has involuntary movements.He was born normally at full term with no significant perinatal event. There is no history of consanguinity among parents. On physical examination, it was noticed that he is a stunted infant with generalized hypotonia with severe generalized dystonic movements. The mother says that she has noticed presence of orange sand in his diapers many times. Laboratory evaluation revealed elevated uric acid levels in both blood and urine. Hypoxanthine-guanine phosphoribosyl transferase is found to be deficient in his blood samples. He was prescribed an appropriate medication and sent home. The most likely mechanism of this drug is inhibition of which of the following enzymes in addition to xanthine oxidase?

An 8-year-old boy developed nausea, abdominal pain, and watery diarrhea 6 hours after consuming mushroom soup in a Chinese restaurant. The boy is rushed to the emergency department. He is severely dehydrated and his blood pressure is 60/40 mmHg. He is managed with intravenous fluids and other supportive treatment. The manager of the restaurant was contacted and samples of mushrooms were sent to the lab for analysis. The lab reports confirmed that the mushrooms contained some kind of toxin. Which of the following enzymes is most likely inhibited by this toxin?

A 28-year-old man comes to the office with facial swelling and blood in urine for last 3 days. Upon detailed inquiry, he says that he has been experiencing weakness, malaise, and low-grade fever for the past 3 months. On physical examination, blood pressure is 160/96 mm Hg and you observe bilateral periorbital edema. Lab reports show leukocytosis, elevated blood urea nitrogen, and elevated serum creatinine. Urinalysis shows gross hematuria, proteinuria, and red blood cell casts. You suspect that this patient has Goodpasture's disease and decide to do some additional tests to confirm the diagnosis. Antibodies to which of the following would most likely be present in this patient if your suspicion is correct?

While studying vesicular trafficking in mammalian epithelial cells, a scientist identified a specific protein that was responsible for contorting the plasma membrane to capture extracellular materials and forming endosomes. This protein also helps transport those endosomes from the trans-Golgi network to lysosomes. Which of the following is the protein has the scientist identified?

An adopted 7-year-old boy is brought to a pediatrician with history of progressive muscular weakness, intellectual impairment, and speech problems. The adoptive parents informed that the boy was normal at birth, but as he grew older, muscular weakness increased. Physical examination revealed wasting of muscles of dorsal forearm and of anterior compartment of lower legs. Thenar and hypothenar eminences were also flattened. However, tendon stretch reflexes were preserved. His face had a typical appearance with thin cheeks, and concave temporal muscles. When he was asked to make a tight fist and to open the hands quickly, he could not open them immediately, and relaxation of the contracted muscles was very slow. The pediatrician suspected a genetic muscular dystrophy. Expansion of which of the following trinucleotide repeats is associated with the most possible muscular dystrophy the boy is suffering from?

A 19-year-old adolescent female with a known case of malabsorption syndrome presents with a painful red tongue, red eyes, cracked lips (especially at the corners of her mouth) after moving away from home for college 4 months ago. She also complains of photophobia and spontaneous lacrimation and itchy dermatitis. She reports that she hasn't been maintaining her diet or taking her vitamins regularly due to her busy schedule, but does somehow remember to take her . On general examination, she has a malnourished appearance with significant pallor and corneal vascularization. Which of the following tests will be most helpful to support diagnosis of a specific vitamin deficiency in the patient?

A 22-year-old medical student decides to fast for 24 hours after reading about possible benefits of fasting on health. She read that the blood glucose levels are maintained by metabolic processes such as hepatic glycogenolysis and hepatic gluconeogenesis during initial 3 days of fasting. During the day, she did not have hypoglycemia. Which of the following most likely stimulates the reaction which maintained her blood glucose during this period after all her stored glucose is broken down and used up?

A 62-year-old homeless man presents in Emergency Department with shortness of breath on exertion and fatigability. He has history of chronic alcoholism. Physical examination reveals BP 100/60, T 98.4 F, RR 18, Pulse 98. There is bilateral pedal edema and decreased sensation over both feet. Basal crackles and ronchi are heard on chest auscultation bilaterally. There is no murmur. Chest X-Ray PA view shows cardio-thoracic ratio of 0.7. The deficiency of which of the following nutrients is most likely responsible for the patient’s condition?

A 45-year-old male presents to your clinic with lethargy, muscle aches and rough dry skin. He is underweight and has very particular eating habits. Physical examination reveals swollen bleeding gums, cracked lips, petechiae, perifollicular hemorrhage, and corkscrew hairs. You suspect a nutritional deficiency. Which of the following is the key function of the deficient nutrient?

A group of researchers are studying the molecules and DNA segments that are critical for key cellular processes in eukaryotic cells. They have identified a region that is located about 28 bases upstream to the coding 5’-DNA segment. It promotes the initiation of transcription by binding with transcription factors. Which of the following region the researchers have identified?

A 2-year-old boy presented with high grade fever, muscle aches, headache, and lethargy. He attends day care and other children are also having similar complaints. A double-stranded DNA virus is isolated from the respiratory secretions of the patient that contained 20% of guanine in its genome. What is the percentage of Thymine in this viral genome?

A 15-year-old male presents with sudden onset of right sided weakness of arm, face and difficulty in speaking. His comprehension is intact. Patient has no history of chest pain, hypertension, or diabetes mellitus. Physical exam reveals facial droop and positive Babinski’s reflex on the right. Patient is thin, with long arms, slender fingers, and dislocated lens on eye examination. Brain CT scan shows absence of hemorrhage. Laboratory investigations reveal increased concentrations of a metabolic intermediate product in serum and urine. Which of the following enzymes are deficient in this patient?

A 54-year-old female presents with increasing shortness of breath on exertion for the past few months. She also complains of fatigue but denies swelling of her feet, difficulty breathing at night or while lying down on the bed. Physical exam is normal except for mild conjunctival pallor. There are no neurological deficits. A peripheral smear shows macrocytosis and hypersegmented granulocytes. You suspect a nutritional anemia and decide to do some more tests. An increase in which of the following substances will clear your suspicion?

A 6-year-old African American boy presents with severe pain and swelling of both his hands and wrists. He has had diarrhea for the last two days and looks dehydrated. He had two similar episodes of severe pain in the past. Physical exam reveals pallor, jaundice, dry mucous membranes and sunken eyes. There is no visceromegaly. Regarding the genetics of this patient, which of the following mutations is most consistent with this patient’s clinical condition?

A 34-year-old lady comes to the office with the complaints of weight gain despite her efforts to lose weight. She also has constipation and says that she feels she has no energy. She likes warm weather these days. Her BP is 140/85 mmHg, pulse is 60/min, temperature is 98F and respirations are 22/min. Her ankle reflex has a delayed relaxation phase. You suspect a hormone deficiency disorder and send blood for lab investigation. The lab report confirms your suspicion and you prescribe her a synthetic hormone. How does this synthetic hormone act to produce its cellular effects?

A 17-year-old girl presents with episodic shortness of breath. She has a family history of eczema. Physical exam reveals BP 100/70 mmHg, Pulse 110, RR 28, Temp 98.6F (37C). There are bilateral wheezes on chest auscultation. Pulmonary function tests reveal decreased FEV1/FVC which is reversed by the Beta 2 Adrenergic receptor agonist inhalation. Which of the following chemical mediator is responsible for this patient's condition?

A nutritionist is studying the effects of different diets on body metabolism and muscle growth. He noticed that some diets are not producing the expected muscle growth. After some research, he came to conclusion that these diets are lacking which one of the following amino acids?

A 7-year-old Muslim boy presents to the Emergency Room with left-sided knee pain, which has progressively increased in severity over the past two days. It started when he was playing football but he does not recall any injury. His parents inform you that he bled excessively during circumcision. His maternal uncle has similar problem. Physical exam reveals swollen left knee. Both knees look deformed. His lab investigations reveal: Hemoglobin: 11.8 g/dL WBC count: 7,000/mL Platelets: 250,000/mL INR: 1.1 APTT: 62 sec (Ref: 30 – 40 seconds) Bleeding time: 3 min (Ref: 1 – 9 minutes) Which of the following disorders have the same mode of inheritance as this patient’sdisease?

A 45-year-old male presents to the Emergency Department with hematemesis and melena, which is actively managed. He has been previously diagnosed with liver cirrhosis. An esophagogastroduodenoscopy (EGD) has been planned and patient has been asked to observe an overnight fast. The patient had dinner at 7 pm and endoscopy was performed at 1 pm the next day. At the time of endoscopy, some pathways were generating glucose to maintain serum glucose levels. Which of the following enzymes catalyze the irreversible biochemical reaction of this process?

A 31-year-old male is brought to the ER by his wife due to patient’s gradually increasing eccentric behavior and involuntary movements, especially of arms and hands. The patient also has difficulty remembering things. Patient’s father had similar symptoms before he died but those symptoms started at the age of 40. Physical exam reveals involuntary writhing movement of hands, impaired gait, slow eye movements, and rigidity. You have explained patient’s wife that patient has an inherited disorder in which the symptoms occur progressively at an earlier age than the parent and often in increased severity in future generations. Which of the following is the most likely diagnosis of this patient?