Exam 3 Cumulative Practice Questions

A. Source of the extra chromosome in trisomy 21 is ~90% maternal, due to meiotic non-disjunction.

A 40-year-old woman gave birth to a child whose karyogram is displayed below. There is no other family history suggestive of chromosome abnormalities. Which of the following is the most likely source of the extra chromosome? origin non-disjunction during A) maternal meiosis B) maternal mitosis C) paternal meiosis D) paternal mitosis

D. The cDNA clones are made from mRNA molecules (reverse transcription). Thus, cDNA only has sequences that would be on a fully processed mRNA—such as A. exons, B. translation start codon, C. polyadenylation signal, and E. the 3' untranslated region. It would not contain promoter sequences (answer D). Promoter sequences are located on the DNA template molecule upstream of the start site of transcription. The promoter guides the binding of RNA polymerase II, but the promoter region itself is not transcribed.

A full-length cDNA clone will contain sequences corresponding to each of the following EXCEPT: a. exons b. translation start codon c. polyadenylation signal d. promoter e. 3' untranslated region

E.

A newborn male with dysmorphic features is identified as having an insertion of a piece of chromosome 8 into chromosome 10. Which of the following is the correct ISCN nomenclature for this karyotype? A) 46,XY,ins(8;10)(p21;p21) B) 46,XY,der(10)(8;10)(p21;p23) C) 46,XY,der(8)(10;8)(p21;p23) D) 46,XY,der(8)(8;10)(p21;p23) E) 46,XY,ins(10;8)(p21;p23p26)

A. High at two months, then lower at two years Rationale: The adaptive immune response typically contracts in the weeks to months following infection. T cell and B cell numbers (after initially rising during the primary infection) will begin to decline, as will antibody levels in the blood. After re-infection, memory cells that remain will quickly expand, and these cell numbers (and antibody levels) will dramatically rise again to even higher levels than seen during the primary infection.

A patient is infected with an infectious disease. If we were to look for antibodies two months later, and also two years later, what would be the most likely relative antibody titers? A. High at two months, then lower at two years B. High at two months, and similarly high at two years C. Low at two months, then higher at two years D. Low at two months, and similarly low at two years

A.

A two-year-old child of a migrant farm worker presents with acute abdominal colic (pain) and some signs of growth retardation. A blood smear shows a moderate but distinct increase in reticulocyte count. The smear also contains cells showing coarse basophilic stippling ("ringed sideroblast"). You request urine samples to look for elevated δ-aminolevulinic acid. You also order an X-ray examination of the patient's long bones to look for deposits at the epiphyses. Which of the above enzymes do you suspect to be inhibited? A. porphobilinogen synthase (δ-aminolevulinic acid dehydratase) B. diphosphoglycerate mutase C. δ-aminolevulinic acid (ALA) synthase D. lysyl hydroxylase E. glucose 6-phosphate dehydrogenase

E.

After collection from a patient, blood would clot when deposited into a laboratory test tube. Which of the following, when added to blood, would allow you to isolate plasma instead of serum? A. dermatan sulfate B. keratin sulfate C. chondroitin sulfate D. hyaluronic acid E. heparin

C.

All of the following CBC (complete blood count) would results suggest anemia EXCEPT: A. low hematocrit (HCT) B. low RBC count (RBC) C. low Reticulocyte (Retic, % of RBC) D. low plasma hemoglobin (HGB) E. low corpuscular hemoglobin (MCH)

B.

An ink spot obscured the hematocrit data in the lab report. No matter. You have a pretty good idea what the hematocrit might be. Which of the following possibilities would be the most reasonable guess? A. 0 % B. 28 % C. 42 % D. 71% E. 100%

E.

Anti-malarial therapy with primaquine caused an acute hemolytic episode, with highly elevated serum non-conjugated bilirubin. Which of the above enzymes do you suspect to be deficient? A. porphobilinogen synthase (δ-aminolevulinic acid dehydratase) B. diphosphoglycerate mutase C. δ-aminolevulinic acid (ALA) synthase D. lysyl hydroxylase E. glucose 6-phosphate dehydrogenase

B.

Change in the amino acid sequence of the ß chain of hemoglobin: A. hemochromatosis or jaundice B. sickle cell disease C. hypochromic anemia or α-thalassemia D. megaloblastic anemia or sideroblastic anemia E. hemolytic anemia or megaloblastic anemia

D. Robertsonian translocations involve fusion of two acrocentric chromosomes at the centromere; should be detectable by karyotyping (at the light microscopy level). The others depend on the size of alteration(s).

Chromosomal abnormalities reliably detected by karyotyping (light microscopy level) include: A) Interstitial deletion B) Paracentric inversion C) Reciprocal translocation D) Robertsonian translocation E) Subtelomeric deletion

B.

Congenital hemolytic anemia in which deoxygenated hemoglobin molecules form fibrous precipitates: A. HbM B. HbS C. HbCO D. HbF E. HbA

A.

Congenital hemolytic anemia in which hemin (Fe3+ form of heme) rather than heme (Fe2+ form) is bound by hemoglobin polypeptides, which aggregate and precipitate in Heinz Bodies: A. HbM B. HbS C. HbCO D. HbF E. HbA

B.

Defect (little or no activity, relative to normal) in heme production characterized by the presence of erythrocyte precursors that contain visible ferritin granules: A. megaloblastic anemia B. sideroblastic anemia C. hypochromic anemia D. α-thalassemia E. sickle cell disease

D.

Defect in the control of iron absorption, resulting in the deposition of excess iron on certain tissues: A. megaloblastic anemia B. hypochromic anemia C. sickle cell disease D. hemochromatosis E. methemoglobinemia

C.

Deficiency in the erythrocyte isozyme of glucose 6-phosphate dehydrogenase: A. sideroblastic anemia and hemoglobin M B. megaloblastic anemia and hemochromatosis C. hemolytic anemia and jaundice D. hypochromic anemia and iron deficiency E. thalassemia- and sickle cell disease

B - H - A - G - C - F - D - E Rationale: Phagocytes first detect pathogens by TLRs, which induces MyD88 activation and the subsequent activation of NF-kB signaling. This leads to transcription of genes encoding IL-1, Il-6, IL-8 and TNF-alpha, which promotes inflammation and neutrophil recruitment. Neutrophils begin to phagocytose materials and kill themselves, leading to pus production. Other APCs, like dendritic cells, process antigen and activate the adaptive response, leading to antibody production. After resolution of the infection, remaining residual effector lymphocytes will die by apoptosis.

During an initial infection with a microbe, place the following immunological events in the most appropriate chronological order. A. NF-kB is activated B. Toll-like receptor binds to peptidoglycan C. Neutrophils are recruited to the infection D. Antibodies are produced E. Lymphocytes die by apoptosis F. Pus is produced G. IL-1, IL-6 and TNF-alpha are produced H. MyD88 is recruited to TLRs and activates signaling

D.

During erythropoiesis, at what stage are the cells first committed to form red blood cells? A. mature cells B. multipotential hematopoietic stem cells C. precursor cells D. progenitor cells E. pluripotent hematopoietic stem cells

D.

During the American Revolutionary War, King George III of England was thought to have suffered from acute intermittent porphyria, with bouts of abdominal pain and dementia. A urine sample from King George would most likely contain , revealing high levels of accumulation of this substance in his body. A. bilirubin B. hematin C. hemosiderin D. porphobilinogen E. transferrin

C.

Enzyme responsible for the net production of ATP during glycolysis in erythrocytes: A. hexokinase B. ferrochelatase C. pyruvate kinase D. glutathione reductase E. glucose 6-phosphate dehydrogenase

C.

Enzyme that initiates the heme biosynthesis pathway and whose activity is regulated by its end product. A. porphobilinogen synthase (δ-aminolevulinic acid dehydratase) B. diphosphoglycerate mutase C. δ-aminolevulinic acid (ALA) synthase D. lysyl hydroxylase E. glucose 6-phosphate dehydrogenase

B. Western blotting provides information on both the size of the polypeptide chain as well as its level.

Hereditary hemochromatosis (an autosomal recessive disease) can be caused by any of eleven different mutations in the HFE gene. A nonsense mutation in the HFE gene might result in changes to both the size and the abundance of the protein encoded by that gene. Which of the following methods would best reveal these changes to the protein? A. Southern blot B. Western blot C. Allele-specific oligonucleotide hybridization D. Microarray analysis

B.

In a peripheral blood smear taken from a patient, the red blood cells appear to vary in size. What is the correct term for this? A. poikilocytosis B. anisocytosis C. spherocytosis D. hypochromic E. macrocytic

A.

In panel III of the color micrographs, which letter (A - E) represents a cell whose derivative is critical in the formation of the hemostatic plug?

A.

In panel IV, which letter (A - E) represents a precursor cell that will differentiate into a blood cell that transports oxygen?

A. CD3 - 2) All T cells B. CD4 - 1) Helper T cells C. CD8 - 3) Cytotoxic T cells D. CD14 - 5) Macrophages E. CD16 - 6) Natural killer cells F. CD18 - 7) Neutrophils F. CD19 - 4) B cells

In the attached image, match the CD cell surface marker with the most likely leukocyte expressing each marker.

A. C3 -- 2. Inactive zymogen in blood, requires cleavage B. C3a -- 1. Anaphylatoxin, induces inflammation C. C3b -- 4. Binds to bacterial surfaces, opsonization D. C9 -- 3. Part of the membrane attack complex

In the attached image, match the following complement pathway proteins with the most appropriate function.

A. Alternative pathway -- 3. C3b binds to the bacterial surface B. Classical pathway -- 1. Antibody binds to the bacterial surface C. Lectin pathway -- 2. MBL binds to the bacterial surface

In the attached image, match the following complement pathways with the most likely initial stimulus event.

A. Interleukin-2 -- 2. Activation and growth of T cells B. Interferon-alpha and beta -- 3. Induction of anti-viral defenses C. G-CSF -- 7. Induction of neutrophil hematopoiesis D. Interferon-gamma -- 5. Macrophage activation E. Interleukin-1 -- 4. Induction of inflammation F. Interleukin-6 -- 4. Induction of inflammation G. Tumor necrosis factor-alpha -- 4. Induction of inflammation I. Interleukin-8 (CXCL8) -- 1. Neutrophil attraction/recruitment J. Interleukin-10 -- 6. Inhibition of inflammation K. Transforming growth factor-beta -- 6. Inhibition of inflammation

In the attached image, match the following cytokines with the most likely primary function (some are redundant).

A. Bone marrow: 3. T cell hematopoiesis, 5. B cell hematopoiesis , 6. B cell maturation B. Spleen: 2. Filters blood for antigen, lymphocyte activation C. Lymph Node: 4. Filters local lymph fluid for antigen, lymphocyte activation D. Thymus: 1. T cell maturation

In the attached image, match the following immune system organs with the most appropriate function (some may have more than one function).

A. Natural passive immunity -- 5. Transfer of antibodies to infant via breast milk B. Natural active immunity -- 3. Infection leading to immunity C. Artificial passive immunity -- 4. Injection of antibodies against a disease D. Artificial active immunity -- 7. Vaccination leading to immunity E. Autoimmunity -- 1. Antibodies target self-tissues F. Primary immune deficiency -- 2. Genetic deficiency in the immune response G. Secondary immune deficiency -- 6. A defect in the immune response due to a drug

In the attached image, match the following immunological terms with the most appropriate definition or scenario.

A. Sporadic congenital neutropenia -- 1. Poor development of neutrophils B. Chronic granulomatous disease -- 5. No reactive oxygen production by phagocytes C. Leukocyte adhesion deficiency -- 4. Poor extravasation of neutrophils D Chediak-Higashi disease -- 2. Poor lysosomal trafficking in all cells E. C3 deficiency -- 3. No complement produced by liver cells

In the attached image, match the following innate immunodeficiencies with the most likely cell type affected and the defect that results.

A. Cytotoxic T lymphocytes -- 2. Killing of infected cells B. B lymphocytes -- 1. Secretion of IgM, IgG C. Macrophages -- 4. Phagocytosis of bacteria D. Mast cells -- 3. Release of histamines E. Eosinophils -- 5. Control of parasitic infections F. NK cells -- 2. Killing of infected cells

In the attached image, match the following leukocytes with the most likely cellular function (some may be redundant).

A. Complement C3b -- 2. Bacterial membranes B. IgG -- 5. Antigen C. NF-kB -- 3. DNA promoter regions D. TLR2 -- 6. Peptidoglycan E. TLR3 -- 4. Double-stranded RNA F. TLR4 -- 1. Lipopolysaccharide

In the attached image, match the following proteins with the ligand they most likely bind to.

A. CD8 -- 5. Viruses B. NF-kB -- 1. All viruses and bacteria C. Major basic protein -- 4. Helminths D. TLR2 -- 3. Gram-positive bacteria E. TLR4 -- 2. Gram-negative bacteria

In the attached image, mutations in the following proteins would most likely lead to an infection with which of the following classes of microbes (matching question)?

C.

Iron is transported in the blood predominantly as: A. Fe+3 -Iron Responsive Protein complex B. free ferrous (Fe+2 ) ion C. transferrin-Fe+3 complex D. ferritin-Fe+3 complex E. hemosiderin-Fe+3 complex

E.

Methemoglobin (MetHb) production: A. is unimportant in that oxygen transport is not affected B. occurs chiefly in thalassemias C. results from the reduction of iron of heme units D. requires the presence of glutathione E. occurs as a continuous, normal side-reaction in erythrocytes

A.

Methemoglobin aggregates and Heinz body accumulation: A. hemoglobin M and hemolytic anemia B. megaloblastic anemia or hemochromatosis C. sideroblastic anemia and jaundice D. hypochromic, microcytic anemia E. α-thalassemia or sickle cell disease

In forming the ring chromosome, parts of the p-arm and q-arm of chromosome are lost and the ends are joined to form a ring. So, the child with 46,XY, r(15) is monosomy for parts of the p- and q-arms of chromosome 15 and most likely would exhibit a phenotype different from normal. The second child, with 47,XY, +r(15) has an extra chromosome 15 in a ring. Therefore, he would be trisomy in certain parts of chromosome 15. So, the two children will most likely have different phenotypes.

One child has a 46,XY, r(15) karyotype; a second child has a 47,XY, +r(15) karyotype. Would these children have different phenotypes? Why or why not?

C.

Panel II is a color micrograph of blood cells found in normal peripheral blood. Which of the following correctly applies to the cell at the tip of the pointer? A. This cell is the least common type of white blood cell in normal blood. B. This cell is the precursor to the mast cell of connective tissue. C. This cell is derived from the myeloid lineage of colony forming unit (CFU). D. The differentiation of this cell is stimulated by erythropoietin. E. The immature form of this cell has distinctive basophilic granules in the cytoplasm.

1 -- B. Recognition of antigen by receptors 2 -- A. Proliferation of lymphocytes 3 -- D. Differentiation of lymphocytes 4 -- C. Death of effector lymphocytes

Place the following adaptive immune events in the most likely chronological order. A. Proliferation of lymphocytes B. Recognition of antigen by receptors C. Death of effector lymphocytes D. Differentiation of lymphocytes

C. It is important to remember that hereditary hemochromatosis is an autosomal recessive disease. Patient 1 has the H63D mutation but is heterozygous here; therefore, most likely NOT affected. Patient 4 yielded hybridization with all four normal probes. Thus, patients 1 and 4 represent the pair in the question. Patient 2 appears homozygous with the S65C and will most likely be affected. Patient 3 has mutations at H63D and V53M and will most likely be affected unless both mutations happen to be on the same copy, leaving one copy of normal gene.

The ASO panel (attached) shows results of tests performed on four patients (1 through 4) for the four most common mutant alleles of the HFE gene. Which pair of patients are most likely not affected by the disease? (n = normal; m = mutant; black dot = hybridization). A. Patients 1 and 2 B. Patients 1 and 3 C. Patients 1 and 4 D. Patients 2 and 3 E. Patients 2 and 4

B.

The blood smear from this patient shows erythroblasts with dark granules, amongst erythrocytes. This is exemplified in Panel I of color micrographs on the preceding page (see cells at tips of arrows). The dark granules are most likely to contain: A. calcium phosphate crystals B. aggregated ribosomal RNA C. transferrin iron D. heparin granules E. heme iron

C.

The clinical presentation and the lab results suggest that the 55-year-old female patient LG suffers from Blank X due to impaired DNA and RNA synthesis in red blood cell precursors. What goes into Blank X ? A. β-thalassemia B. methemoglobinemia C. megaloblastic anemia D. glucose 6-phoshpate dehydrogenase deficiency E. sickle cell anemia

D. The inheritance pattern of CF is autosomal recessive; this means that for any unaffected carrier, the mutant allele must also have a corresponding normal counterpart. Thus, the DNA of the father, a carrier for the Δ508 mutation, hybridizes to both the N (normal) and M (mutant) probes at Δ508— this corresponds to the ASO blot for patient 2. Similarly, the DNA of the mother, a carrier for the G551D mutation, hybridizes to both the N and M probes at G551D—this corresponds to the ASO blot for patient 4. The key now is to pick the ASO blot results for the affected son. Remembering now that the father (carrier of Δ508) is normal at G551D and the mother (carrier of G551D) is normal at Δ508, the son must have positive ASO blots for the N probe, as well as for the M probes, at these positions—this corresponds to the ASO blot of patient 3. So, the son is affected because he has two bad copies of the CF gene: one bad copy from the father mutated at Δ508 but normal at G551D and another bad copy from the mother mutated at G551D but normal at Δ508. Thus the son is a "compound heterozygote" as indicated by patient #3 in the ASO blot.

The family being tested concerns a father, who tests positive for being a carrier of the ΔF508 mutation and the mother, who tests positive for being a carrier for the G551D mutation. They have a son who is affected with cystic fibrosis. Which of the patients shown above in the ASO blot represent the ASO test outcomes for the father, the mother, and the son RESPECTIVELY (assume no recombinations)? A) patient 2, patient 4, and patient 1 B) patient 3, patient 4, and patient 1 C) patient 4, patient 2, and patient 3 D) patient 2, patient 4, and patient 3 E) patient 4, patient 2, and patient 1

B.

The history and the laboratory data presented above leads the physicians to a tentative diagnosis in this case. Which of the following tests would be most useful in confirming this diagnosis? A. assay for serum iron, total iron binding capacity, and percent saturation B. determination of blood lead level C. assay for Heinz body formation D. determination of blood level of NADPH E. determination of blood calcium level

B. Normal human male (G-banding; 300 bands)

The karyotype most appropriate for the karyogram attached is: A) 45, X B) 46, XY C) 46, XX D) 47, XXY E) 47, XXX

A.

The lab report failed to distinguish conjugated versus non-conjugated bilirubin. Oh well. Which of the following possibilities would be the most reasonable guess? NOTE: In this answer table, up and down arrows denote the degree of increase or decrease compared to normal. ↔ denotes no significant departure from normal.

C.

The patient's reticulocyte count is highly elevated. Of the cells shown in the Panel of the color micrographs (see next page), which cell represents the most immediate precursor to the reticulocyte? A. cell 2 B. cell 3 C. cell 5 D. cell 6 E. cell 7

D. Since this is an autosomal recessive disease, the parents of II-2 are obligate carriers. Comparison of the VNTR patterns of I-1 and I-2 with that of the affected, II-2, indicates that the VNTR alleles a and d are most likely not associated with the recessive disease allele and therefore, II-3 is most likely NOT a carrier.

The pedigree attached depicts an autosomal recessive disease in a family. All affected individuals are shown. Below the pedigree are Southern blot results for a closely linked polymorphic VNTR with four alleles (a through d - each blot result is located directly below the tested individual). Which individual in this family is most likely NOT a carrier of the recessive disease allele? a. I-1 b. I-2 c. II-1 d. II-3 e. II-4

A.

The regulated step in heme biosynthesis is catalyzed by: A. δ-amino levulinic acid synthase B. ferrochelatase C. glutathione peroxidase D. porphobilinogen synthase E. superoxide dismutase

A. Scanning the DNA sequence from 5' to 3', you will see that the recognition sequence only appears once (starting with the fourth basepair from the left end). The restriction enzyme will not recognize the sequence going 3' to 5'.

The restriction enzyme EcoRI recognizes the DNA sequence 5'-GAATTC-3'. The enzyme is incubated with the following DNA sequence: 5'-TACGAATTCGGCTTAAGAGCGCTTAAGGATCCGAT-3' 3'-ATGCTTAAGCCGAATTCTCGCGAATTCCTAGGCTA-5' How many times will this sequence of DNA be cleaved? a. only once b. twice c. three times d. four times e. five times

D. A key feature of this technology is the fluorescently tagged nucleotides. They are nucleotides that have been modified by adding a fluorescent tag at the 3' position. The tag not only allows the monitoring of which nucleotide was incorporated but also blocks the 3' position so that no more nucleotides are allowed to be added.

The sequencing by synthesis phase of Illumina sequencing requires which of the following? A) dNTPs B) ddNTPs C) DNA ligase D) Fluorescently tagged dNTPs E) Restriction endonucleases

D.

The substitution of valine (Val) for glutamic acid (Glu) in the sixth position of the β-chain of hemoglobin produces sickle cell anemia in the homozygote because: A. the cooperative binding of oxygen is lost B. the apoprotein can no longer protect the heme from becoming oxidized C. the Val-6 mutant hemoglobin tends to retain oxygen when the oxygen concentration is low. D. the Val-6 mutant alters red blood cell morphology upon deoxygenation E. the erythrocyte is unable to sequester a high enough concentration of the Val-6 mutant hemoglobin.

C. Western blots use Antibodies to bind to specific proteins. All of the others use denaturation and hybridization of nucleic acids at some point in their use.

This assay does not involve the denaturation and hybridization of nucleic acids.

D. VNTR analysis involves PCR amplification of DNA that contains repeated sequences of DNA varying in length from 2 to 6 nucleotides, with each allele having varying numbers of repeated units. The other assays generally don't use variation in the number of repeat units as part of the assay.

This assay involves the characterization of alleles based on differences in the number of tandemly repeated units.

B. In Northern blot analysis, RNA is run on a gel and a nucleic acid probe is used to detect a specific mRNA transcript. None of the other assays use RNA.

This assay would be used to determine the size of an mRNA transcript.

E.

What is the most likely cause of the patient's sensation of severe pain? A. viral hepatitis B. bile duct obstruction C. neonatal jaundice D. high concentration of glucose in the urine E. vaso-occlusion and oxygen deprivation in the tissues

D.

What is the most likely molecular/genetic basis for the patient's problems? A. glucose 6-phosphate dehydrogenase deficiency B. hemoglobin M C. hemophilia A D. sickle cell disease E. β-thalassemia

Antibodies (Immunoglobulins, such as IgG); memory B lymphocytes or memory T lymphocytes can also be detected, although this is more technically challenging

What molecules or cells, if detected in peripheral blood samples, would prove the presence of pre-existing immunity against a pathogen?

B.

Which of the cells labeled in Panel III is the immature form of the granulocyte known as the "band or "stab" cell?

A. B lymphocyte B. Cytotoxic T lymphocyte D. Helper T lymphocyte

Which of the following are cells of the adaptive immune response (choose all that apply)? A. B lymphocyte B. Cytotoxic T lymphocyte C. Eosinophil D. Helper T lymphocyte E. Macrophage F. Natural killer cell G. Neutrophil

A. Normally presents intracellular antigens, and C. Involves TAP to help transport peptides into the ER

Which of the following are features of MHC I, but not MHC II (choose all that apply)? A. Normally presents intracellular antigens B. Can directly induce antibody production by B lymphocytes C. Involves TAP to help transport peptides into the ER D. Is expressed by macrophages only after TLR4 engagement E. Is used to activate CD4+ T cells F. Utilizes CLIP to facilitate MHC complex assembly

B. It is stronger than a primary response Rationale: Memory T and B cells are much quicker to activate during a re-infection, and proliferate to higher levels than in a primary infection and response.

Which of the following best describe a secondary adaptive immune response? A. It occurs only in adults B. It is stronger than a primary response C. It occurs slower than primary response D. It is weaker than primary response E. It occurs immediately after a primary response

D. Immunity is active Rationale: Vaccination induces active immunity in a patient, but is considered artificial.

Which of the following best describe the immunity generated by vaccines in a patient? A. Immunity is temporary B. Immunity is natural C. Immunity lacks memory D. Immunity is active

B. Dendritic cells, D. Macrophages and F. Neutrophils

Which of the following cell types are normally phagocytic within the immune system (choose all that apply)? A. Cytotoxic T lymphocytes B. Dendritic cells C. Helper T lymphocytes D. Macrophages E. Mast cells F. Neutrophils

B. The primers hybridize to the two template strands, from which a heat stable polymerase (Taq polymerase) copies the sequence(s) of interest.

Which of the following components are needed to carry out the polymerase chain reaction? a. primase b. single-stranded primers flanking the sequence of interest c. an origin of replication within the sequence of interest d. a radiolabeled or fluorescent probe that will hybridize to the amplified fragment e. DNA ligase

E.

Which of the following correctly describes a normal sequence of differentiation for the cells shown in the top panel? A. cell 3 ➔ cell 5 B. cell 6 ➔ cell 5 C. cell 2 ➔ cell 1 D. cell 5 ➔ cell 4 E. cell 2 ➔ cell 6

C. MHC I and D. MHC II

Which of the following dendritic cell proteins most likely contain antigen for presentation to T cells? A. CD4 B. CD8 C. MHC I D. MHC II

B.

Which of the following factors is most responsible for driving the differentiation pathway from progenitor cells to reticulocytes? A. colony stimulatory factor B. erythropoietin C. ferritin D. transferrin E. thrombopoietin

A. The carrier of a Robertsonian translocation, a balanced reciprocal translocation, or a pericentric inversion can produce offspring, each with risk of an abnormal phenotype. Isochromosomes are not usually viable for most autosomes and so high risk (but 46,X,i(Xq) has been observed). A carrier of paracentric inversion never produces viable offspring (the affected chromosome homologs get all tangled up during meiosis) and therefore has the LOWEST risk of producing an offspring with abnormal phenotype.

Which of the following individuals has the LOWEST risk of having live born offspring with an abnormal phenotype? A) A carrier of a paracentric inversion B) A carrier of a Robertsonian translocation C) A carrier of a balanced reciprocal translocation D) A carrier of a pericentric inversion E) A carrier of an isochromosome

D. A repressor binding site (operator) is not an essential component of vectors. Operator sequences are necessary for regulation of bacterial gene expression. Answers A, B and C indicate essential elements of a cloning vector. The purpose of vectors is to carry along "foreign" DNA to be replicated in a host organism. Whether or not that foreign DNA should be expressed for a variety of purposes is a separate question.

Which of the following is NOT an essential feature of a cloning vector? a. origin of replication b. selectable marker c. single site for at least one restriction enzyme d. repressor binding site (operator)

B. Although genetic factors (and environmental factors as well) contribute to the likelihood of developing bipolar disorder, the condition has not been associated with chromosomal anomalies. The other foils (A, C, and D) all suggest that a chromosome analysis might be informative.

Which of the following is NOT an indication for chromosome analysis? A) Previous child with a heritable chromosome abnormality B) Both parents have bipolar affective disorder (manic depression) C) Child has microcephaly with developmental delay D) Child with multiple cogenital anomalies E) All of the above

B. Basically the conventions of nomenclature. (C) Balanced reciprocal translocations can occur between chromosomes 2 and 8, neither of which are acrocentric. (D) Balanced reciprocal translocations can indeed yield viable gametes and balanced carriers can have normal offsprings. See analysis and challenge for Question 13 of this Problem Set. (E) Balanced reciprocal translocations do not yield mirror image chromosomes. Mirror image chromosomes arise as isochromosomes, formed by improper division of the two sister chromatids at the centromere.

Which of the following is TRUE regarding balanced reciprocal translocations? A) The karyotype always lists the highest chromosomal number first. B) The karyotype always lists the sex chromosome or chromosome with the lowest number first. C) A balanced reciprocal translocation almost always involves the acrocentric chromosomes. D) Balanced reciprocal translocations almost always result in non-viable gametes. E) Balanced reciprocal translocations result in the formation of mirror image chromosomes.

D. Paracentric inversions never produce viable offspring. Many non-disjunctions during meiosis (e.g. resulting in trisomy 21 Down syndrome) do not involve inversions. Recombination events during meiosis I involve homologous sequences on non-sister chromatids of the same chromosome (e.g. chromosome 6) while translocations involve sequences (segments) of different chromosomes (e.g. chromosome 8 and chromosome 10). A parent with a balanced structural rearrangement (e.g. see page 335-336 on balanced reciprocal translocation or page 342 on pericentric inversion) can have unbalanced offspring with more than one type of abnormal genotype (not just partial monosomy but partial trisomy as well).

Which of the following is TRUE regarding structural chromosome alterations? A) Carriers of a paracentric inversion primarily face the prospect of giving birth to a chromosomally unbalanced offspring. B) Inversions are primarily responsible for non-disjunction events during meiosis. C) A chromosomally unbalanced offspring derived from a parent carrying a balanced translocation is caused by recombination events between different chromosomes during meiosis. D) Children with a deletion of part of a chromosome (partial monosomy) may also have siblings that have a duplication of a part of a chromosome (partial trisomy) as well.

D. Ability to undergo DNA mutation and recombination Rationale: The adaptive response is able to mutate and recombine the genes encoding antibodies and T cell receptors, which create millions of types of receptors in a given individual with specificity to bind to millions of different antigens.

Which of the following is a feature of cells of the adaptive response, but not the innate response? A. Ability to eliminate bacteria B. Ability to eliminate viruses C. Ability to induce cytokine release D. Ability to undergo DNA mutation and recombination E. Ability to phagocytose materials

C. The idiogram displays pairs of homologous chromosomes with sister chromatids attached at the centromeres. First, get the sex right; this is clearly XY. Scan the chromosomes and notice that there is a piece of the p arm of chromosome 5 missing. No other translocation or rearrangement seems apparent. Therefore, deletion in 5p.

Which of the following is the correct karyotype description for this idiogram? A) 46,XX,der(5)(p12) B) 46,XX,del(5p) C) 46,XY,del(5p) D) 46,XY,del(5q) E) 46,XY,der(5q)

E. Triploid means three of each of the 23 chromosomes. All the other scenarios would result in aneuploidy.

Which of the following is the most common cause of triploidy? A) Nondisjunction in maternal meiosis I B) Nondisjunction in maternal meiosis II C) Fertilization of a normal egg by an aneuploidy sperm D) Fertilization of an aneuploidy egg by a normal sperm E) Fertilization of a normal egg by two normal sperms

A.

Which of the following is the most likely reason that the medication for patient LG was administered by "shots?" A. Patient LG had a genetic condition that impaired drug absorption. B. The drug has a foul odor and LG did not like the smell. C. Patient LG could not stand the taste of the drug. D. The drug was volatile and produced a gas in the patient's GI tract. E. Patient LG could not stand the sight of the drug.

E. Definition of aneuploidy --- not a multiple of the haploid number of chromosomes.

Which of the following karyotypes is an example of aneuploidy? A) 46,XX B) 23,X C) 69,XXX D) 92,XXYY E) 48,XX,+21,+22

E.

Which of the following laboratory results in the attached image is most likely for a patient suffering from hemochromotosis?

C. Protein degradation via the proteasome

Which of the following mechanisms occurs within dendritic cells during preparation of intracellular proteins for antigen presentation? A. Protein cleavage via lysozyme B. Protein hydrolysis via acid vesicles C. Protein degradation via the proteasome D. Protein modification via acetylation E. Protein modification via glycosylation

B. CD4

Which of the following molecules interacts with MHC II to induce lymphocyte activation? A. CD3 B. CD4 C. CD8 D. CD19 E. CD28

D. In forming a ring chromosome, there is loss of genetic material from the ends of both p-arm and q-arm; therefore, unbalanced and the individual most likely will exhibit some phenotype. Make sure you understand that the other foils all represent balanced chromosomal rearrangements and for individuals carrying such balanced rearrangements, most likely no phenotype (but with consequences for offspring).

Which of the following most likely represents an UNBALANCED chromosomal alteration? A) Paracentric inversion on chromosome 1 B) Pericentric inversion on chromosome 2 C) Reciprocal translocation between chromosomes 4 and 20 D) Ring chromosome 15

E. Filter paper is used in Southern, Northern and Western blots - but not in standard PCR reactions.

Which of the following operations is NOT a necessary step in the polymerase chain reaction? a. denaturing the template DNA b. annealing primers to template DNA c. extending primers using DNA polymerase d. designing primers specific for each end of the fragment to be amplified e. blotting reaction products onto a filter paper

A. Nearly all cells of an individual contain the same genomic DNA information. Thus genomic clone libraries from muscle and liver would contain identical information. However, various tissues do not express the same genes. As a result, their pools of mRNA will be different depending on what genes are being expressed. Therefore, cDNA libraries made from these pools of mRNA in various tissues will be different to each other and different from the genomic DNA.

Which of the following pairs of recombinant DNA libraries would contain identical information? a. genomic clone library from muscle and genomic clone library from liver b. cDNA library from muscle and cDNA library from liver c. genomic DNA library from muscle and cDNA library from muscle d. expression library from liver and genomic library from liver

E. Information in a cDNA clone is derived from mRNA. Signals regulating transcription (promoter, enhancer, silencer) are at the level of genomic DNA and would not even show up in a RNA transcript. The 5'-splicing consensus sequence would have been used to process the primary transcript (hnRNA) to the mature mRNA and therefore, it will not show up in a cDNA sequence.

Which of the following regulatory signals would most likely be found within a cDNA clone of the HFE gene? A. transcriptional promoter B. enhancer C. silencer D. 5' splicing consensus E. polyadenylation signal

D.

Which of the following statements about iron homeostasis is correct? A. Iron overload cannot occur, because very efficient excretory mechanisms are available. B. Cells cannot regulate their uptake of iron in the face of changing iron content. C. Transferrin decreases in iron deficiency, which facilitates the storage of iron. D. Iron homeostasis is maintained, in part, by iron regulatory proteins binding to iron- responsive elements on certain mRNA molecules. E. In iron depletion, serum ferritin levels rise rapidly as iron is released from storage.

B. The karyotype for mom, Tess, is most likely 46,XX,t(1,5)(breakpoints). This eliminates foils with "parents with completely normal chromosomes" and with karyotype 46,XY,t(1,5). Daughter Irene did not inherit a balanced translocation; she inherited only one derivative chromosome and therefore, is unbalanced with respect to chromosomal content. Remember the general punch line: a carrier of a balanced translocation may have: (a) normal offspring; or (b) offspring with inherited balanced translocation; or (c) offspring with unbalanced chromosome complement. Draw the schematic how (D) might have occurred for the mating of Mark and Tess.

Which of the following statements best describes the schematic diagram attached? A) Parents with completely normal chromosomes yielded a phenotypically normal offspring. B) One normal parent mated with a parent with a balanced translocation (46,XX,t(1,5)) yielded an offspring with unbalanced chromosomal content. C) One normal parent mated with a parent with a balanced translocation (46,XY,t(1,5) yielded an offspring with unbalanced chromosomal content. D) Parents with balanced chromosomal content yielded an offspring with an inherited balanced translocation. E) Parents with completely normal chromosomes yielded an offspring with an inherited balanced translocation.

E.

Which of the following vectors would be able to carry the largest fragment of human DNA surrounding the HFE gene? A. bacterial artificial chromosome B. bacterial virus vector (phage) C. cosmid D. plasmid E. yeast artificial chromosome

D. Interferon-alpha or -beta E. MHC I

Which of the following would be considered a normal product made by all nucleated cells in the body (choose all that apply)? A. CD4 B. Complement C3 C. Immunoglobulin IgG D. Interferon-alpha or -beta E. MHC I F. MHC II G. T cell receptor

C. Elevated erythrocyte sedimentation rate and high levels of C reactive protein Rationale: during inflammation, excess acute phase proteins are made by the liver (such as C-reactive protein), which leads to a modest thickening of blood. This can cause erythrocytes to stick together

Which of the following would most likely be seen in a patient experiencing systemic acute inflammation due to infection? A. Decreased erythrocyte sedimentation rate and high levels of C reactive protein B. Decreased erythrocyte sedimentation rate and low levels of C reactive protein C. Elevated erythrocyte sedimentation rate and high levels of C reactive protein D. Elevated erythrocyte sedimentation rate and low levels of C reactive protein

D. In (A), the woman's age puts her risk same as the population risk. In (B), most women with Turner syndrome are infertile; the woman with a mosaic 46,XX/45,X may have offspring and so there is risk of chromosomal abnormality in the child. Carriers paracentric inversion (in (C)) never produce viable offspring and so the risk is low. In (E), the brother's Down syndrome resulted from non-disjunction during gametogenesis in one of the parents and most likely should not affect the woman's risks. Carriers of pericentric inversion (D) are at the highest risk of having an offspring with chromosomal abnormality.

Which one of the following hypothetical risk factors gives a woman the highest risk of having a live born child with a chromosomal abnormality? A) Her age, which is 25 years old B) Her blood chromosome karyotyping result, which shows 46, XX/45, X C) Her blood chromosome result, which shows a large paracentric inversion of chromosome 2 D) Her blood chromosome result, which shows a large pericentric inversion of chromosome 2 E) Her family history, which shows that she has a brother with 47,XY,+21.

B. We know that patient 1 does not have a copy of any of the mutant alleles tested for. Similarly, we know that patient 3 is homozygous for the mutant allele C and is affected. Thus, we can eliminate any answer that contains patients 1 and 3, which is all answers but B. Why is 4 "possibly" a carrier? We know he has mutations D and E. We don't know if both mutations occur on the same allele or on different alleles. If they are on the same allele, he is a carrier. If the mutations are on different alleles, he is affected with cystic fibrosis, having different mutations on each allele.

Which one or more of the patients is most likely a carrier of cystic fibrosis? a. patient 1 and possibly patient 2 b. patient 2 and possibly patient 4 c. patient 3 and possibly patient 4 d. patient 4 and possibly patient 1 e. patient 3 and possibly patient 1

C. The dots represent the presence in the individual of either a normal or mutant allele. At allele C, the patient has no copies of the normal allele, but does have the mutant allele. Thus, the patient is affected with CF. Patient 4 is also quite likely affected. We do not know whether both mutations occurred on the same chromosome (a very rare occurrence) or one mutation on each chromosome, making the patient a compound heterozygote with cystic fibrosis.

Which one or more of the patients is/are most likely affected with cystic fibrosis? a. patient 1 b. patient 2 c. patient 3 d. patient 4

A.

While filming a movie in an area endemic for malaria, the famous actor Gino Casetta developed symptoms of anemia (labored breathing, and fatigue with mild exertion). The film director thought it was caused by the anti-malarial drugs Gino was taking but the producer disagreed, because two other actors, Jim Stone and Boris Mossowski, took the same medication without any ill effects. Gino Casetta's blood was assayed for Heinz bodies. Which of the following would you expect to find at high levels in the aggregates? A. MetHb B. HbA C. HbCO D. HbF E. HbS

E.

While filming a movie in an area endemic for malaria, the famous actor Gino Casetta developed symptoms of anemia (labored breathing, and fatigue with mild exertion). The film director thought it was caused by the anti-malarial drugs Gino was taking but the producer disagreed, because two other actors, Jim Stone and Boris Mossowski, took the same medication without any ill effects. If you could get the CBC (complete blood count) report on Gino Casetta, you would most likely find: [In this table, "decrease" and "increase" are relative to normal.]

D.

While filming a movie in an area endemic for malaria, the famous actor Gino Casetta developed symptoms of anemia (labored breathing, and fatigue with mild exertion). The film director thought it was caused by the anti-malarial drugs Gino was taking but the producer disagreed, because two other actors, Jim Stone and Boris Mossowski, took the same medication without any ill effects. Which of the following biochemical alterations would you most likely find in Gino Casetta's red blood cells? [In this table, "high" and "low" are relative to normal.]

D.

While filming a movie in an area endemic for malaria, the famous actor Gino Casetta developed symptoms of anemia (labored breathing, and fatigue with mild exertion). The film director thought it was caused by the anti-malarial drugs Gino was taking but the producer disagreed, because two other actors, Jim Stone and Boris Mossowski, took the same medication without any ill effects. Which of the following enzymes is most likely affected in Gino Casetta? A. glucose 6-phosphatase B. UDP (uridine diphosphate)-glucose dehydrogenase C. liver isozyme of glucose 6-phosphate dehydrogenase D. erythrocyte isozyme of glucose 6-phosphate dehydrogenase E. muscle isozyme of lactate dehydrogenase

B.

You wish to analyze the pattern of genes expressed in a breast cancer in order to identify potential differences to normal breast tissue cells. Which of the following techniques would be most useful to you in your anticipated studies? A) Western blot B) Microarray gene expression profiling C) Comparative genomic hybridization D) Northern blot E) Restriction fragment length polymorphism