Pre-Test Flashcards
A 14-month-old boy presents with a fever of 102°F. The child has a longstanding history of recurrent lower respiratory tract infections includ- ing bronchitis and pneumonia. Chronic diarrhea is a longstanding prob- lem. His mother reports that she had numerous upper respiratory infections and chronic diarrhea as a young child. A complete blood count, lung function tests, and urinalysis values are all within normal range. Serum immunoglobulin levels are normal for IgG and IgM, but IgA was 25 mg/dL (normal = 40–60 mg/dL). There are numerous neutrophils and other white cells in the stool sample and the stool is cultured for specific bacteria. IgA coats pathogens facilitating repulsion of the negative charge on the cell membrane. That negative charge on the cell membrane is pri- marily caused by which of the following?
a. Free saccharide groups
b. Glycoprotein
c. Cholesterol
d. Peripheral membrane protein
e. Integrins
b. Glycoprotein
Band 3 protein exists as a 95-kDa multipass membrane protein that functions as the primary anion exchanger in erythrocytes. Within the red blood cell (RBC) membrane, band 3 binds to spectrin dimers and tetramers indirectly through ankyrin. The spectrin tetramers are bound together by actin and band 4.1 protein, which also binds to band 3 and glycophorin. Null mutations in band 3 occur in the human population. Which of the fol- lowing is most likely to decrease in the absence of band 3 protein?
a. Osmotic fragility
b. Destruction of RBCs in the spleen
c. Bile production
d. Erythroid production in the bone marrow
e. Blood pH
e. Blood pH
A 56-year-old man who drinks a six-pack of beer a day, with higher alcoholic intake on weekends, holidays, and “special days,” presents to the internal medicine clinic. He has an abnormal plasma lipoprotein profile. It is known that erythrocyte fluidity is altered in liver disease. Which of the following would increase membrane fluidity in the hepatocytes of this patient’s liver?
a. Restriction of rotational movement of proteins and lipids in the membrane
b. Transbilayer movement of phospholipids in the plasma membrane
c. Increased cholesterol/phospholipids ratio in the plasma membrane
d. Binding of integral membrane proteins with cytoskeletal elements
e. Binding of an antibody to a cell-surface receptor
e. Binding of an antibody to a cell-surface receptor
A 44-year-old African-American woman calls 911. When the MedAct unit arrives they find a patient with acute shortness of breath and audible wheezing. A physical exam reveals: pulse 115 (normal 60–100), RR 42 (normal 15–20) with signs of accessory muscle use. She is coughing up mucus. Auscultation reveals decreased breath sounds with wheezing on inspiration and expiration. The patient has taken her prescribed medica- tions with no relief of symptoms prior to her 911 call. Her current medica- tion is albuterol, a moderately selective β2-receptor agonist. Which of the following is true regarding those receptors:
a. They possess a single hydrophobic transmembrane segment in the form of an α-helix.
b. They can activate plasma membrane–bound enzymes or ion channels
c. They possess an intracellular ligand-binding domain
d. They possess intrinsic enzyme activity
e. They are arranged so that both the amino- and the carboxy-terminals are
located intracellularly
b. They can activate plasma membrane–bound enzymes or ion channels
Which of the following is the function of the large subunit of the ribosome?
a. Bind messenger RNA (mRNA)
b. Bind transfer RNA (tRNA)
c. Catalyze peptide bond formation
d. Link adjacent ribosomes in a polyribosome
e. Initiate protein synthesis
c. Catalyze peptide bond formation
Theprimaryfunctionofintermediatefilamentsiswhichofthefollowing?
a. Generate movement
b. Provide mechanical stability
c. Carry out nucleation of microtubules
d. Stabilize microtubules against disassembly
e. Transport organelles within the cell
b. Provide mechanical stability
Which of the following mechanisms is used to establish the mito- chondrial electrochemical gradient?
a. The action of ATP synthase
b. Transfer of electrons from NADH to O2 in the intermembrane space
c. Pumping of protons into the mitochondrial matrix by respiratory chain activity
d. Proton-translocating activity in the inner membrane
e. Transport of ATP out of the matrix compartment by a specific transporter
d. Proton-translocating activity in the inner membrane
A boy is born with epicanthal folds, a high forehead, hypoplastic supra- orbital ridges, and upslanting palpebral fissures. He shows growth retarda- tion following birth, he feels like a rag doll when held, and he exhibits neonatal seizures. He also has a ventricular septal defect, glaucoma, cataracts, elevated iron and copper levels in his blood, and hepatomegaly. A liver biopsy is prepared for electron microscopy and shows the presence of empty peroxisomes. The pathologist describes them as peroxisome “ghosts.” Which of the following cellular activities should be decreased in the hepatocytes from this patient?
a. Energy production
b. Plasmalogen synthesis
c. Exocytosis
d. Detoxification by the smooth endoplasmic reticulum
e. Lysosomal enzyme synthesis
b. Plasmalogen synthesis
nhibition of actin assembly by cytochalasins would interfere primarily with which of the following?
a. Separation of chromosomes in anaphase of the cell cycle
b. Vesicular transport between the Golgi apparatus and cell membrane
c. Ciliary movement
d. Phagocytic activity by macrophages
e. The structure of centrioles
d. Phagocytic activity by macrophages
Chloroquine is a weak base that neutralizes acidic organelles. In a pan- creatic beta cell, which of the following would be a direct effect of chloro- quine treatment?
a. Increased proinsulin content in secretory vesicles
b. Increased release of C peptide
c. Increased number of amylase-containing secretory vesicles
d. Reduced translation of glucagon mRNA
e. Increased stability of insulin mRNA
a. Increased proinsulin content in secretory vesicles
