D1401-1600 Flashcards
What is the rate-limiting step of the following? • β-Oxidation
Carnitine acyltransferase I
What is the rate-limiting step of the following? • Ketogenolysis
HMG CoA synthase
What is the rate-limiting step of the following? • Cholesterol synthesis
HMG CoA reductase
What direction does RNA polymerase move along the template strand of DNA during transcription?
3’-5’ direction, synthesizing RNA in the 5’-3’ direction
True or false? Histidine activates the histidine operon.
False. Histidine operon is activated when there are low intracellular levels of histidine.
What organ is responsible for the elimination of excess nitrogen from the body?
The kidneys excrete the excess nitrogen from the body as urea in the urine.
What is the only way to increase maximum velocity (Vmax)?
Increase enzyme concentrations
Name the two purine bases found in both DNA and RNA.
Adenine and guanine
What prokaryotic positioning enzyme in translation is blocked by the following? • Tetracycline
EF-Tu and EF-Ts of the 30S ribosomal subunit
What prokaryotic positioning enzyme in translation is blocked by the following? • Erythromycin
EF-G of the 50S subunit
What prokaryotic positioning enzyme in translation is blocked by the following? • Streptomycin
IF-2 of the 30S subunit
True or false? DNA polymerases can correct mistakes, whereas RNA polymerases lack this ability.
True. DNA polymerases have 3’-5’ exonuclease activity for proofreading.
What are the two precursors of heme?
Glycine and succinyl-CoA
What two factors cause PTH to be secreted?
A decrease in Ca2+ and an increase in PO4-
What are the nonoxidative enzymes of the HMP shunt? Are the reactions they catalyze reversible or irreversible?
Transketolase and transaldolase. The reactions they catalyze are reversible.
What are the five AAs that are both ketogenic and glucogenic?
Isoleucine, threonine, tryptophan, tyrosine, and phenylalanine
What artificial sweetener must patients with PKU avoid?
Aspartame
Cri-du-chat syndrome results in a terminal deletion of the short arm of what chromosome?
Chromosome 5
What substrate gets built up in Gaucher’s disease?
Glucosyl cerebroside
What protein prevents ssDNA from reannealing during DNA replication?
Single-strand DNA binding protein
What type of jaundice is seen in Dubin-Johnson syndrome?
Conjugated (direct) hyperbilirubinemia, a transport defect
What type of DNA library is made from the mRNA from a tissue expressing a particular gene?
cDNA libraries are derived from mRNA, are continuous, and contain no introns or regulatory elements.
What is the most common cause of vitamin B6 deficiency?
Isoniazid treatment
What lysosomal enzyme is deficient in • Gaucher’s disease?
Glucocerebrosidase
What lysosomal enzyme is deficient in • Niemann-Pick disease?
Sphingomyelinase
What lysosomal enzyme is deficient in • Tay-Sachs disease?
Hexosaminidase A
What are the three exceptions to the rule of codominant gene expression?
Barr bodies in females, T-cell receptor loci, and immunoglobulin light and heavy chain loci
How many kilocalories per gram are produced from the degradation of fat? CHO? Protein?
9 kcal/g from fat metabolism; 4 kcal/g from both CHO and protein metabolism
What is the only way to increase the Vmax of a reaction?
Increase the concentration of enzymes
From which two substances are phospholipids made?
Diacylglycerols and phosphatidic acid
What intermediate enables propionyl CoA to enter into the TCA cycle?
Succinyl CoA
What vitamin is an important component of rhodopsin?
Vitamin A
What is the term to describe the 5’-3’ sequence of one strand being the same as the opposite 5’-3’ strand?
Palindrome
What gluconeogenic enzyme is absent in muscle, accounting for its inability to use glycogen as a source for blood glucose?
Glucose-6-phosphatase
What is the term for vitamin D deficiency prior to epiphyseal fusion?
Rickets prior to fusion, osteomalacia if the deficiency occurs after epiphyseal fusion.
In what disease is there a genetic absence of UDP-glucuronate transferase, resulting in an increase in free unconjugated bilirubin?
Crigler-Najjar syndrome
What enzyme requires molybdenum as a cofactor?
Xanthine oxidase
At what three sites can the HMP shunt enter into glycolysis?
- Fructose-6-phosphate 2. Glucose-6-phosphate 3. Glyceraldehyde-3-phosphate
What is the term for the pH range where the dissociation of H+ occurs?
pK (think of it as where half is base and half is acid)
What regulates the rate of ketone body formation?
The rate of β-oxidation
What are the eight liver-specific enzymes?
- Fructokinase 2. Glucokinase 3. Glycerol kinase 4. PEPCK 5. Pyruvate carboxylase 6. Galactokinase 7. Fructose-1, 6-bisphosphatase 8. Glucose-6-phosphatase
How many bases upstream is the eukaryotic TATA box promoter?
There are two eukaryotic upstream promoters. The TATA box is -25 base pairs upstream; the CAAT box is -75 bases upstream.
What is needed to initiate translation?
IF and GTP (eIF for eukaryotes)
What part of the 30S ribosome binds to the Shine-Dalgarno sequence?
16S subunit
What component of the ETC is inhibited by the following? • Barbiturates
Complex I
What component of the ETC is inhibited by the following? • Antimycin A
Cytochrome b/c1
What component of the ETC is inhibited by the following? • Cyanide
Cytochrome a/a3
What component of the ETC is inhibited by the following? • Oligomycin
Fo/F1 complex
What component of the ETC is inhibited by the following? • Atractyloside
ATP/ADP Translocase
What component of the ETC is inhibited by the following? • CO
Cytochrome a/a3
What component of the ETC is inhibited by the following? • Rotenone
Complex I
What component of the ETC is inhibited by the following? • Azide
Cytochrome a/a3
What AA is a precursor of the following substances? • Serotonin
Tryptophan
What AA is a precursor of the following substances? • GABA
Glutamate
What AA is a precursor of the following substances? • Histamine
Histidine
What AA is a precursor of the following substances? • Creatine
Glycine/arginine
What AA is a precursor of the following substances? • NAD
Tryptophan
What AA is a precursor of the following substances? • N2O
Arginine
What two enzymes are vitamin B12-dependent
Homocysteine methyl transferase and methylmalonyl CoA transferase
What two post-transcriptional enzymes in collagen synthesis require ascorbic acid to function properly?
Prolyl and lysyl hydroxylases
What three organs participate in production of vitamin D?
- Skin 2. Liver 3. Kidney
What water-soluble-vitamin deficiency is associated with neural tube defects in the fetus?
Folic acid
What phase of Interphase is haploid (N)?
G1 phase; G2 and S phase are diploid (2N).
What neurotransmitter inhibits the optic nerve bipolar cell and shuts off in response to light?
Glutamate
Which of the following—DNA methylating enzymes, scaffolding proteins, histone acetylases, or deacetylases—is a regulator of eukaryotic gene expression?
Histone acetylases is a regulator favoring gene expression. All of the others favor inactivation.
Name the pattern of genetic transmission characterized thus: both M and F affected; no M-to-M transmission; affected M passes trait to all daughters, every generation; affected F passes trait to both sons and daughters; a single mutant allele can produce the disease.
X-linked dominant
What fat-soluble vitamin is connected to selenium metabolism?
Vitamin E
Why are eukaryotes unable to perform transcription and translation at the same time like prokaryotes?
In eukaryotes transcription occurs in the nucleus and translation in the cytoplasm.
What is determined by the secondary structure of an AA?
The folding of an AA chain
What three vitamin deficiencies are associated with homocystinemia?
Folate, vitamin B12, and vitamin B6
If the pH is more acidic than the pI, does the protein carry a net positive or net negative charge?
When the pH is more acidic than the pI, it has a net positive charge, and when the pH is more basic than the pI, it has a net negative charge.
What form of continuous DNA, used in cloning, has no introns or regulatory elements?
cDNA, when it is made from mRNA
What is the start codon, and what does it code for in eukaryotes? Prokaryotes?
The one start codon, AUG, in eukaryotes codes for methionine and in prokaryotes formylmethionine.
What parasite found in raw fish can produce vitamin B12 deficiency?
Diphyllobothrium latum
Methylating uracil produces what pyrimidine base?
Thymine
Name the eukaryotic RNA polymerase based on the following: • Synthesizes tRNA, snRNA, and the 5S rRNA
RNA polymerase III
Name the eukaryotic RNA polymerase based on the following: • Synthesizes hnRNA, mRNA, and snRNA
RNA polymerase II
Name the eukaryotic RNA polymerase based on the following: • Synthesizes 28S, 18S and 5.8S rRNAs
RNA polymerase I
What is the primary screening test used to detect HIV-infected individuals? Confirmatory test?
ELISA is used as a screening test because it is very sensitive; Western blot is used as a confirmatory test because it detects antibodies (protein) to the HIV virus.
How many covalent bonds per purine-pyrimidine base pairing are broken during denaturation of dsDNA?
None. Denaturation of dsDNA breaks hydrogen bonds, not covalent bonds.
How many hydrogen bonds link A-T? C-G?
A-T are linked by 2 hydrogen bonds, C-G by 3 hydrogen bonds.
What DNA replication enzyme breaks the hydrogen bond of base pairing, forming two replication forks?
Helicase (requires ATP for energy)
What test is done to diagnose CGD?
Nitroblue tetrazolium reduction test (NBT). It is negative in patients with CGD because there is no production of oxygen radicals.
What is the valence of an Ig molecule equal to?
The number of Ags that the Ab can bind
What is the name of the process that ensures that each B cell produces only one heavy-chain variable domain and one light chain?
Allelic exclusion. It is to ensure that one B cell produces only one Ab.
What is the major Ab of the primary immune response?
IgM
What form of immunity is responsible for removal of intracellular infections?
Cell-mediated immunity
True or false? Direct fluorescent Ab test is used to detect Abs in a patient?
False. Direct tests detect Ags; indirect tests detect Abs.
What is the triad of Wiskott-Aldrich syndrome?
Thrombocytopenia, eczema, and immunodeficiency is the triad of this X-linked recessive disorder.
What complement factor deficiency leads to • Increased susceptibility to pyogenic infections?
C3 deficiency
What complement factor deficiency leads to • Recurrent gonococcal infections?
C5-C8 deficiency
What complement factor deficiency leads to • Leukocyte adhesion deficiency with poor opsonization?
C1, C2, or C4 deficiency
What complement factor deficiency leads to • Hereditary angioedema?
C1 inhibitor (C1-INH)
Which IgG cannot activate complement?
IgG4
Name the T-cell CD marker: • Essential for Ab isotype switching (for B cell binding)
CD40 ligand
Name the T-cell CD marker: • Interacts with MHC class I molecules
CD8
Name the T-cell CD marker: • Expressed on all T cells and is needed as a signal transducer for the T cell receptor
CD3
Name the T-cell CD marker: • Interacts with MHC class II molecules
CD4
Name the T-cell CD marker: Is a costimulatory molecule in T cell activation
CD28
What three cells are essential for T-cell differentiation in the thymus?
Dendritic cells, macrophages, and thymic epithelial cells
What is the only specific Ag-presenting cell?
B cells; macrophages and dendritic cells are nonspecific.
What is the tetrad of Jarisch-Herxheimer reaction?
Rigors, leukopenia, decrease in blood pressure, and increase in temperature
What is the name of the B cell that secretes Ig?
Plasma cell (mature B lymphocyte)
What would be the result if an Ab were cleaved with papain?
There would be two Fab and Fc regions.
What is the bone marrow maturation time for a phagocytic cell?
14 days
Which leukotrienes are associated with the late-phase inflammatory response?
LTC4 and LTD4
What is the term for the strength of the association between Ag and an Ab?
Affinity (one of each)
True or false? More Ag is needed to produce a secondary immune response than a first immune response.
False. Fewer Ags are needed to trigger a secondary response.
What is the term for the strength of association between multiple Abbinding sites and multiple antigenic determinants?
Avidity (more than one binding site)
What Ig mediates ADCC via K cells, opsonizes, and is the Ig of the secondary immune response?
IgG
What test is used to detect anti-RBC Abs seen in hemolytic anemia?
Coombs test
What subset of T cells recognizes the MHC class I Ags?
CD8+ T cells (cytotoxic) Remember, 8×1=8 (CD×8×MHC class I=8); 4×2=8 (CD×4 MHC class II 8)
What cell surface marker is found on activated helper T cells?
CD40
What are the five Ig isotypes?
IgA, IgD, IgE, IgG, and IgM
Which integrin mediates the adhesion to endothelial cells for migration in and out of the blood during an immune response?
Beta2-integrins
What type of hypersensitivity is an Ab-mediated response against our own cells, receptors, or membranes via IgG or IgM?
Type II hypersensitivity reaction
What is the term to describe the limited portion of an Ag that is recognized by an Ab?
Antigenic determinant (epitope)
What cytokine do Th1 cells secrete to inhibit Th2 cell function?
INF-gamma
What three cells are essential for T-cell maturation?
Thymic epithelial cells, dendritic cells, and macrophages
What is the term for a single isolated antigenic determinant?
Hapten (not immunogenic)
What are the two opsonizing factors?
The Fc region of IgG and C3b
What is the most common Ig deficiency?
IgA deficiency; patients commonly present with recurrent sinopulmonary infections and GI disturbances.
What is the name of the B cell-rich area of the spleen?
Primary follicle (in the white pulp)
What IL, produced by macrophages, is chemotactic for neutrophils?
IL-8. It not only is chemotactic, it also acts as an adhesive for neutrophils.
What Ig prevents bacterial adherence to mucosal surfaces?
IgA
What are the three rules of clonal selection?
- One cell type 2. One Ab type 3. Random selection of hypervariable regions, and only cells with bound Ag undergo clonal expansion
What is a plasma cell’s life expectancy?
7 to 14 days
What are defined by Ag-binding specificity?
Idiotypes
What type of binding occurs with one Fab or one idiotype of IgG?
Affinity
What molecule that is needed to trigger T cell activation is noncovalently linked to TCR?
CD3 molecule. It transmits signals to the inside of the T cell to trigger activation
What is the term for Ags that activate B cells without T-cell signaling?
Thymus-independent Ags
What are the three rules governing a secondary immune response?
- Covalent bonding between the hapten and carrier 2. B-cell exposure to hapten twice 3. T-cell exposure to carrier twice
What type of hypersensitivity is a T cell-mediated response to Ags that are not activated by Ab or complement?
Type IV hypersensitivity reaction (delayed type because of the 48-96 hour latency)
Name the macrophages by location: • Liver
Kupffer cells
Name the macrophages by location: • Lungs
Alveolar macrophages
Name the macrophages by location: • CNS
Microglial cells
Name the macrophages by location: • Kidney
Mesangial macrophages
What is the first human disease successfully treated with gene therapy?
Adenosine deaminase (ADA) deficiency
What receptors are the best markers for NK cells?
CD16 and CD56
True or false? Ag-Ab binding is irreversible
False. It is reversible because the Ags and Abs are not linked covalently.
What three major cell lines participate in the acquired immune system?
T cells, B cells, and macrophages
What test is used to screen for HIV?
ELISA. It detects anti-p24 IgG.
During what stage of B-cell development is IgM first seen on the surface?
Immature B cells
What Ig is responsible for Antibody-Dependent Cell-mediated Cytotoxicity of parasites, has a high-affinity Fc receptor on mast cells and basophils, and is responsible for the allergic response?
IgE
True or false? B-cell Ag receptors can be secreted.
True. B cell antigen receptors are Abs.
Are more Abs produced in a primary or a secondary immune response?
More Ab is produced in less time in a secondary immune response (shorter lag period).
By which process do Abs make microorganisms more easily ingested via phagocytosis?
Opsonization
What MHC class acts to remove foreign Ags from the body?
MHC class II Ags. This is accomplished via CD4 T cells.
What disorder is characterized by autoantibodies to IF?
Pernicious anemia
What cytokines do Th2 cells secrete to inhibit Th1 cell function?
IL-4, IL-10, and IL-13
What is the term for the number of Ag-binding sites on an Ig?
Valence
Which major cell type is found in the red pulp of the spleen?
RBCs. That is why it is called red pulp.
What is the name of the pathway that produces leukotrienes?
Lipoxygenase pathway, from arachidonic acid
What is the term to describe basophils that have left the bloodstream and entered a tissue?
Mast cells
What are the three major functions of secretory IgA?
- IgA receptor 2. Transport of IgA across epithelial barriers 3. Protection of IgA from degradative proteases
What IL is important in myeloid cell development?
IL-3 (3 face down is an M)
What is the term for different classes and subclasses of the same gene products?
Isotypes
What is the first Ab a baby makes?
IgM
What test, by using specific Abs to different receptors, allows for rapid analysis of cell types in a blood sample?
Flow cytometric analysis
What is the name of the T cell-rich area of the spleen?
PALS (Parietolateral lymphocytic sheath)
What three complement fragments are also anaphylatoxins?
C3a, C4a, and C5a
Name the B-cell CD marker: • Required for class switching signals from T cells
CD40
Name the B-cell CD marker: • Receptor for EBV
CD21; it is a complement receptor for cleaved C3
Name the B-cell CD marker: • Used clinically to count B cells in blood
CD19
What immunologic test checks for a reaction between Abs and a particular Ag? (hint: ABO typing)
Agglutination test
Which leukotriene is chemotactic for neutrophils?
LTB4
What Ig is associated with mucosal surfaces and external secretions?
IgA
What are the genetic variants of a molecule within members of the same species?
Allotypes
What cytokine do CD4 T cells secrete to activate B cells when the specific peptide in the groove of the MHC II molecule interacts with the TCR?
IL-4 is secreted to activate B cells. This begins the second step in the immune response, known as Activation. CD4 T cells secrete INF-alpha to activate macrophages
Which protein prevents internal binding of self proteins within an MHC class II cell?
Invariant chain
What would be the result if an Ab were cleaved with pepsin?
There would be a Fab’ region; thus, it would still be able to participate in precipitation and agglutination.
Why are patients with Chronic Granulomatous Disease not prone to develop infections from catalase-negative bacteria?
Catalase-negative bacteria secrete H2O2 as a byproduct (remember, catalase breaks down H2O2), allowing the neutrophils to use it as the substrate for the other toxic metabolites. Patients with CGD are prone to catalase-positive bacterial infections.
What are the two chains of the TCR that are mainly found on the skin and mucosal surfaces?
gamma and delta chains
Which IL is associated with increases of IgG and IgE?
IL-4
What branch of the immune system is acquired in response to an Ag?
Adaptive branch. The adaptive branch of the immune system has a slow initiation with rapid responses thereafter.
True or false? T cells can recognize, bind, and internalize unprocessed Ags.
False. B cells recognize unprocessed Ags, but T cells can recognize only processed Ags.
What type of hypersensitivity is a result of high circulating levels of soluble immune complexes made up of IgG or IgM Abs?
Type III hypersensitivity reaction
At what stage of B-cell development can IgM or IgD be expressed on the cell surface?
Mature B cell; the memory B cell can have IgG, IgA, or IgE on its surface.
What T cell deficiency syndrome is associated with facial anomalies, hypoparathyroidism, thymic hypoplasia, and recurrent viral and fungal infections?
DiGeorge syndrome, which is due to a failure of the third and fourth pharyngeal pouch development. Remember, B cell deficiencies are associated with extracellular infection. T cell deficiencies are associated with intracellular infections
What is the stimulus for the classical pathway activation?
Ag-Ab complexes. The alternative pathway protects without use of Abs; the pathogen is the stimulus.
What is the first membrane-bound Ig on B cell membranes?
IgM; IgD follows shortly thereafter.
What region of the Ig does not change with class switching?
Hypervariable region
In MHC class II molecules, what chain blocks access to the peptide-binding groove during transportation within the cell, ensuring that the MHC class II-peptide complex is transported to the surface?
Invariant chain. This is essential because the CD4 T cells have antigen receptors only for peptides bound to the MHC II molecule. (MHC restriction)
What chromosome codes for HLA gene products?
The short arm of chromosome 6
What cells are atypical on a peripheral blood smear in heterophil-positive mononucleosis?
T cells, not B cells
What is the major Ig of the secondary immune response in the mucosal barriers?
IgA
What AR disorder is seen by age 1 to 2 with recurrent sinopulmonary infections, uncoordinated muscle movements, and dilation of the blood vessels?
Ataxia-telangiectasia
What are the four chemotactic agents?
- C5a 2. Leukotriene B4 3. IL-8 4. Bacterial peptides
What subset of CD4 helper T cells stimulate B-cell division and differentiation?
Th2
Which region of the variable domain comprises the Ag-binding site of the Ab?
Hypervariable region (three per light chain; three per heavy chain)
True or false? The increased oxygen consumption after phagocytosis is for ATP production.
False; it is for the production of toxic metabolites.
What is the limited portion of a large Ag that will actually be recognized and bound to an Ab and that contains approximately five to six amino acids or four to five hexose units?
Antigenic determinant (epitope). (Idiotypes bind to epitopes.)
What complement factor or factors are associated with • Chemotaxis?
C5a
What complement factor or factors are associated with • Membrane attack complex (MAC)?
C5-C9
What complement factor or factors are associated with • Opsonization?
C3b
What complement factor or factors are associated with • Anaphylaxis?
C3a, C4a, C5a
What happens to the Ab specificity when class switching occurs in mature B cells?
As the isotype is switched, the Ab specificity does not change because it does not affect the variable chains.
What IL down-regulates cell mediated immunity?
IL-10
Name the type of graft described by these transplants: • From one site to another on the same person
Autograft
Name the type of graft described by these transplants: Between genetically identical individuals
Isograft
