How does ricin (of the castor bean) inhibit translation?
By depurinating 28s rRNA
(and thus targeting it for ubiquination)
Ricin (of the castor bean) halts cellular function at what part of the central dogma?
Translation
What enzyme normally cleaves APP extracellularly?
What enzyme normally cleaves APP intracellularly?
What enzyme is pathological in its extracellular cleavage of APP?
Alpha-secretase;
gamma-secretase (PSEN1);
beta-secretase
What ApoE genotype is protective against Alzheimer’s disease?
What ApoE genotype is increases one’s likelihood of developing Alzheimer’s disease?
What genotypes are associated with familial Alzheimer’s disease?
ApoE2;
ApoE4;
PSEN1, PSEN2
Cholera toxin is produced by Vibrio cholerae.
How does it cause prolonged activity of adenylyl cyclase enzymes in the small intestinal epithelium?
What channel does this effect?
What is the clinical effect?
It binds the Gαs subunit of a GPCR;
cAMP increases and CFTR channels are overactivated;
Cl- movement and subsequent diarrhea
Cholera toxin binds GPCRs in the small intestine and overactivates what effector enzyme?
What effect does this have on cellular channels?
Adenylyl cyclase (increases cAMP);
CFTR channels are overactivated
What are the two mechanisms by which cholera toxin causes fluid and electrolyte leakage into the GI tract?
By causing overactivation of adenylyl cyclase and CFTR;
by causing weakening of the zona occludens
Both cholera toxin (in the small bowel) and bortadella pertussis (in the lungs) cause overactivation of CFTR channels and subsequent movement of intracellular fluid to the extracellular space.
Cholera toxin does it by modifying/stimulating what protein?
Bortadella pertussis does it by modifying/inhibiting what protein?
Gαs (cholera activates stimulatory pathways);
Gαi (pertussis inactivates inhibitory pathways)
(Note: the end effect on CFTR channels is the same)
How does propranolol decrease heart rate and strength of contraction?
(molecular mechanism)
By blocking GPCR adenylyl cyclase activation
(and thus decreasing Ca2+ release from the SR)
B-adrenergic / GPCR / adenylyl cyclase / cAMP / PKA signaling causes what change in cardiac muscle?
Increased intracellular Ca2+ –> increased HR and force of contraction
What trinucleotide repeat causes Huntington’s disease?
CAG
What trinucleotide repeat causes myotonic dystrophy?
CTG
What trinucleotide repeat causes Friedrich’s ataxia?
GAA
What trinucleotide repeat causes Fragile X syndrome?
CGG
What trinucleotide repeat causes myotonic dystrophy?
What trinucleotide repeat causes Fragile X syndrome?
What trinucleotide repeat causes Huntington’s disease?
What trinucleotide repeat causes Friedrich’s ataxia?
CTG;
CGG;
CAG;
GAA
Name the four diseases discussed in class that are associated with trinucleotide repeating of the following:
CAG
CTG
CGG
GAA
Huntington’s disease
Myotonic dystrophy
Fragile X syndrome
Friedrich’s ataxia
In diseases of trinucleotide repeats, what change is associated with manifestation and then increasing severity of S/Sy?
Increasing number of repeat copies
In Tay-Sachs disease, the defect in the enzyme _____________ leads to a buildup of what substance within lysosomes?
Hexosaminidase A;
GM2 ganglioside
A child is born with a clinical presentation that looks a lot like Down syndrome.
What genetic analysis test do you chose to confirm your diagnosis?
Karyotyping
A child is born with a clinical presentation that looks a lot like Cri-du-Chat syndrome.
What genetic analysis test do you chose to confirm your diagnosis?
FISH
(checking a single genetic sequence deletion)
A child is born with a clinical presentation that looks a lot like DiGeorge (velocardiofacial) syndrome.
What genetic analysis test do you chose to confirm your diagnosis?
FISH
(checking a single genetic sequence deletion)
A child is born with some sort of connective tissue disorder, but you aren’t sure which it is.
What test can be used to fish around in multiple genes at once?
Microarray
What are some treatment options for multiple sclerosis?
Beta-interferon and steroids
A patient suffers from leukoencephalopathy with vanishing white matter due to a mutation in what?
eIF2
(eukaryotic initiation factor 2)
(responsible for slowing down / halting translation during heat stress)
In a mutation of WT1, this loss of function mutation leads to a decrease in transcriptional ___________.
This results in the most common abdominal solid tumor among pediatric patients:
Repression;
Wilms’ tumor (nephroblastoma)
Can Turner’s syndrome be described as 45,X aneuploidy?
Yes.
The improper folding of which protein is associated with Parkinson’s Disease?
The improper folding of which protein is associated with type II diabetes?
The improper folding of which protein is associated with ALS?
Alpha-synuclein;
amylin;
superoxide dismutase I
The improper folding of which protein is associated with prion diseases?
The improper folding of which protein is associated with Alzheimer’s disease?
PrPc;
amyloid precursor protein (or β-amyloid)
The improper folding of which protein is associated with spinal cerebellar ataxia? Due to what trinucleotide repeat?
The improper folding of which protein is associated with Huntington’s disease? Due to what trinucleotide repeat?
Ataxin, CAG;
HTT (Huntington’s protein) CAG
One of your patients comes into your office complaining of weakness and dizziness. You find that he is anemic and send for a mutation analysis for JAK2. You find that he has the mutation V617F found in Polycythemia Vera. You remember that JAK signaling is primarily in the cytokine family of receptors.
Name a difference between kinases of the receptor tyrosine kinase family and the cytokine family of receptors.
Cytokine receptors have an extrinsic kinase
(it is not built into the intracellular receptor structure)
Cholera toxin induces the secretion of Cl- and rapid dehydration in the small intestine by permanently activating:
The G-alpha stimulatory (Gαs) subunit
A 3 month old infant presents to the ER after turning red then purple from a coughing spell. The mother states the child initially had common cold symptoms—runny nose, sneezing, cough and low-grade fever for approximately 2 weeks, but has not improved. The mother states the child’s cough has become progressively worse and is now characterized as dry, coughing spells that can last up to a minute or more and this last spell caused the child to turn purple. As a first year resident you take a mucous swab, which comes back positive for Bortedella pertussis.
Modification of what G-protein causes this illness?
What substance does the modification prevent the release of from this G-protein?
Gα inhibitory (Gαi) subunit;
GDP
A patient presents with polycythemia vera. This is a mutation in the ______ gene and subsequent mutation to the ________ of a cytokine receptor.
JAK2;
kinase
What is an example of a type of receptor expressed in some breast cancers that utilizes the Ras-MAPK pathway?
What percentage of breast cancers express this receptor?
HER-2;
25%
Of in-patient pediatric disease, what percentage have a major genetic component?
What percentage of chronic disorders of childhood are genetically determined?
71%
97%
What is the leading cause of death among infants?
Congenital and/or chromosomal malformation
What is the leading cause of death among infants?
What is the second leading cause of death among infants?
Congenital and/or chromosomal malformation;
Prematurity / low birth weight
What is the leading cause of death among infants?
What is the second leading cause of death among infants?
What is the third leading cause of death among infants?
Congenital and/or chromosomal malformation;
Prematurity / low birth weight;
SIDS
What is the leading cause of death among infants?
What is the second leading cause of death among infants?
What is the third leading cause of death among infants?
What is the fourth leading cause of death among infants?
Congenital and/or chromosomal malformation;
Prematurity / low birth weight;
SIDS;
maternal complications
What is the leading cause of death among infants?
What is the second leading cause of death among infants?
What is the third leading cause of death among infants?
What is the fourth leading cause of death among infants?
What is the fifth leading cause of death among infants?
Congenital and/or chromosomal malformation;
Prematurity / low birth weight;
SIDS;
maternal complications;
accidents
A chronic leukemia is defined by what characteristic?
An acute leukemia is defined by what characteristic?
< 10% blasts;
≥ 20% blasts
(the accelerated stage is between these two)
CML is caused by chromosomal translocation of involving which two chromosomes?
9 and 22
What karyotypic finding is pathognomic for CML?
A Philadelphia chromosome t(9;22)
(the tip of chromosome 9’s q arm and all of 22’s tiny q arm)
What genetic sequence is produced in the creation of a Philadelphia chromosome?
This results in what disorder?
BCR-ABL
(and the BCR-ABL fusion protein which activates JAK/STAT signalling);
CML
What drug is used to treat CML?
How does it work?
Imatinib (Gleevec);
binds the ABL kinase domain of the BCR-ABL fusion protein
CML will become the more aggressive _____ if the percentage of blast cells rises.
AML
What is a blast crisis in regards to CML?
The CML has accelerated into AML and symptom severity has increased
(e.g. increasing tiredness, fever, splenomegaly)
How does Burkitt’s lymphoma typically present?
Nontender lymph node swellings in the neck, groin, below the jaw, under the arms or abdomen (amongst other locations)
The majority of Burkitt’s lymphoma cases are seen in which sex?
Males
Burkitt’s lymphoma is a type of __-cell lymphoma.
It is caused most often by a translocation between chromosomes __ and __ (but it can also be caused by __ and __ or __ and __).
What gene is inappropriately expressed in this malignancy?
B;
t(8; 14) [t(8;22); t(8;2)];
c-Myc
Translocations of chromosomes 8 and 14 are most associated with what malignancy?
What gene is overexpressed?
Burkitt’s lymphoma;
c-Myc
c-Myc is overexpressed in what malignancy involving chromosomes 8 and 14?
Burkitt’s lymphoma
A tumor cell shows a t(8;14). What gene is likely overexpressed?
c-Myc
What is the notation for normal amyloid protein?
What is the notation for the abnormal amyloid protein seen in Alzheimer’s disease? This is after what enzyme’s improper cleavage?
Aβ;
Aβ42, β-secretase
What gene is associated with late-onset AD?
What genes are associated with early-onset, familial AD?
APOE4;
APP, PSEN1, PSEN2
Which protein in this image is targeted by antibodies in bullous pemphigoid?
Which protein in this image is congenitally defective in epidermolysis bullosa simplex?
Which protein in this image is congenitally defective in dystrophic epidermolysis bullosa?
BPAG1, BPAG2;
keratin 5, keratin 14;
type VII collagen
Which protein in this image is targeted by antibodies in Goodpasture’s syndrome?
Which protein in this image is targeted by antibodies in bullous pemphigoid?
Which protein in this image is congenitally defective in Alport’s syndrome?
Type IV collagen;
BPAG1, BPAG2;
type IV collagen
Name the antibiotic:
prevents the binding of aminoacyl tRNA to the A-site of bacterial ribosomes.
Tetracycline
Name the antibiotic:
- inhibits elongation phase in translation;*
- also causes miscoding*
Streptomycin
Name the antibiotic:
inhibits peptidyl transferase
Chloramphenicol
Name the antibiotic:
blocks translocation reaction of translation
Erythromycin
Name the antibiotic:
prevents transcription by binding bacterial RNA polymerase
Rifamycin
Describe the type of drug and mechanism of action: chloramphenicol.
This stops what phase of the central dogma?
Antibiotic;
inhibits peptidyl transferase;
translation
Describe the type of drug and mechanism of action: streptomycin.
This stops what phase of the central dogma?
Antibiotic;
inhibits initiation complex movement to the elongation phase;
translation
Describe the type of drug and mechanism of action:
Rifamycin
This stops what phase of the central dogma?
Antibiotic;
binds RNA polymerase;
transcription
Describe the type of drug and mechanism of action: Tetracycline
This stops what phase of the central dogma?
Antibiotic;
blocks aminoacyl-tRNA binding to the ribosomal A-site;
translation
Describe the type of drug and mechanism of action: Erythromycin
This stops what phase of the central dogma?
Antibiotic;
blocks translocation reaction;
translation