Biochemistry 1- Boards And Beyond Flashcards
What is the mutation in alpha 1 antitrypsin deficiency
Mutation in AAT gene
What is the definition of expressivity
Variations in phenotype of gene
What is the definition of pleiotropy
One gene= multiple phenotypic effects and traits
What is the mutation in lynch syndrome (HNPCC)
Germaine mutation in DNA mismatch repair genes
What are some main criteria of McCune-Albright Syndrome
Affects many endocrine organs, precocious puberty (menstruation may occur 2 years old), fibrous growth in bones, skin pigmentation (cafe-au-lait spots)
What is the mutation in McCune-Albright syndrome
Somatic mutation of GNAS gene
What stage do primary oocytes arrest in until puberty
In prophase of meiosis I until puberty
Where do secondary oocytes arrest until fertilization
Metaphase 2
What are the Acrocentric chromosomes
13, 14, 21, 22
What are some classic examples of incomplete dominance
Achondroplasia, familial hypercholesterolemia
What are some classic examples of X-linked recessive
Hemophilia A and B
What is the classic example of X-linked dominant
Fragile X syndrome
What are some common findings with Edward syndrome (trisomy 18)
Poor intrauterine growth, abnormally shaped head, low set ears, small jaw and mouth, rocker bottom feet, GI defects
What are some common characteristics of Patau syndrome (trisomy 13)
Severe intellectual disability, severe structural malformations, eye abnormalities, cleft lip and palate, post-axial polydactyly
What is the repeat associated with fragile X syndrome
CGG repeats
What chromosome is the frataxin gene involved in friedreichs ataxia on
9
What repeat is associated with huntington’s disease
CAG repeat
What expansion is associated with Myotonic dystrophy
CTG expansion
What is the disorder classified as deletion of part of short arm (p) of chromosome 5
Cri-du-chat syndrome
What is the disorder caused by partial deletion on long arm of chromosome 7
Williams syndrome
What are some characteristics of Williams syndrome
Elfin-facial appearance (small nose, chin; wide mouth), intellectual disability, well-developed verbal skills, extremely friendly with strangers, supravalvular aortic stenosis
What is the goal of purine synthesis
Create AMP and GMP
What is step one and 2 of purine synthesis
Step one is create PRPP; step 2 is create IMP
What are the nitrogen sources of purine synthesis
Aspartate, glycine, glutamine
What is the rate limiting step of purine synthesis
Glutamine-PRPP-amidotransferase
What is the classic presentation of lesch-Nyhan syndrome
Male child with motor symptoms, self-mutilation, gout
What is step one and 2 of pyrimidine synthesis
Step one is make carbamoyl phosphate; step 2 is make orotic acid
What is the defect with orotic aciduria
UMP synthase
What are some key findings with orotic aciduria
Orotic acid in urine, megaloblastic anemia (but no B12/folate response), growth retardation
What occurs with there is ornithine transcarbamylase deficiency
Increased carbamoyl phosphate
What 2 monosaccharides make up lactose
Galactose and glucose
What 2 monosaccharides make up sucrose
Fructose and glucose
Where is GLUT-1 and is it insulin dependent or independent
Brain, RBC; independent
Where is GLUT-4 and is it insulin dependent or independent
Fat tissue, skeletal muscle; insulin dependent
Where is GLUT-2 and is it insulin independent or dependent
Liver, kidney, intestine, pancreas; independent
What inhibits glucokinase in glycolysis
F6P
What does glucokinase deficiency result in medically
Hyperglycemia
What is the rate limiting step of glycolysis
Phosphofructokinase
What are key regulators of phosphofructokinase in glycolysis
Citrate, ATP
What are key inducers of phosphofructokinase in glycolysis
AMP, fructose-2,6-bisphosphate
What type or heredity is pyruvate kinase deficiency
Autosomal recessive
What must be present in order for pyruvate carboxylase to be active
Acetyl CoA
What is the first step in gluconeogenesis and what is the required cofactor
Pyruvate carboxylase; biotin
What are some clinical signs of biotin deficiency
Dermatitis, glossitis, loss of appetite, nausea
What is the rate limiting step of gluconeogenesis
Fructose-1,6-bisphosphatase 1
Where do you get glucose-6-phosphatase for the conversion of glucose-6-phosphate to glucose in gluconeogenesis
Endoplasmic reticulum
How does thyroid hormone effect gluconeogenesis
Increases it
What is deficient in Von Gierke’s disease
Glucose-6-phosphatase
Describe the presentation of von gierkes disease
Presents in infancy (2-6 months), severe hypoglycemia between meals (seizures), No effect on muscle
What is deficiency in pompe’s disease
Acid alpha glucosidase deficiency
What is the clinical presentation of pompes disease
Presents in infancy, enlarged muscles (cardiomegaly, enlarged tongue), hypotonia, death from heart failure
What is deficient in cori’s disease
Debra Ching enzyme
What is the clinical presentation of cori’s disease
Similar to type 1 (von gierkes) except milder hypoglycemia, no lactic acidosis (cori cycle intact), muscle involvement
What is deficient in McArdle disease
Muscle glycogen phosphorylase
What is the clinical presentation of McArdles disease
Presents in adolescence/early adulthood; exercise intolerance, fatigue, cramps; myoglobinuria and CK release; urine may turn dark after exercise
Where does the HMP shunt occur (Pentose phosphate pathway)
Cytosol
What is the first enzyme involved in the oxidative reactions of the HMP shunt
Glucose-6-phosphate dehydrogenase
What is the required cofactor for transketolase
Thiamine (B1)
What are the 3 key enzymes in the respiratory burst
NADPH oxidase, superoxide dismutase, myeloperoxidase
What are the 5 organisms that cause almost all Chornic granulomatous disease infections
Staph aureus, pseudomonas, serratia, nocardia, aspergillosis
What are bite cells in G6PD deficiency
Phagocytic removal by splenic macrophages
What are Heinz bodies of G6PD deficiency
Oxidized Hgb precipitated in RBCs
What is deficient in essential fructosuria
Fructokinase
What is deficiency in hereditary fructose intolerance
Aldolase B
What is teh clinical presentation typically seen with hereditary fructose intolerance
Baby just weaned from breast milk, failure to thrive, hypoglycemia (seizures), enlarged liver
What is deficient in classic galactosemia and what is the typical clinical presentation
Deficiency of galactose-1 phosphate uridyltransferase; presents in infancy shortly after consumption of milk; liver failure, jaundice, hepatomegaly
What are the 5 cofactors required for pyruvate dehydrogenase complex
NAD+, FAD+, coenzyme A, thiamine, lipoid acid
What 4 enzymes is thiamine a cofactor for
Pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, alpha-ketoacid dehydrogenase, transketolase
What is FAD+ synthesized from
riboflavin (B2)
What are the key lab findings with PDH complex deficiency
Elevated alanine; lactic acidosis
Where do all reactions of the TCA occur
Mitochondria
What is the rate limiting enzyme in the TCA cycle
Isocitrate dehydrogenase (isocitrate to alpha-ketoglutarate)
What is another name for complex 1 of the Electron transport chain
NADH dehydrogenase
What are the key intermediates of complex 1 of ETC
Flavin mononucleotide (FMN) and iron sulfur compounds (FeS)
What is another name for complex 2 of the ETC
Succinate dehydrogenase (also part of TCA cycle)
What is another name for complex 3 of ETC
Cytochrome bc1 complex
What is the rate limiting step of fatty acid synthesis
Acetyl-CoA converted to malonyl CoA (via acetyl-CoA carboxylase)
What activates fatty acid breakdown
Glucagon and epinephrine
What are some characteristics of the infantile phenotype of primary systemic carnitine deficiency
Encephalopathy, hepatomegaly, hyperammonia, hypoketotic hypoglycemia, low serum carnitine
What are the 3 major Ketone bodies
Acetone, acetoacetate, 3-hydroxybutyrate
Where does the conversion of ethanol to acetaldehyde via alcohol dehydrogenase occur
Cytosol
Where does the conversion of acetaldehyde to acetate via aldehyde dehydrogenase occur
Mitochondria
What is the trigger for all biochemical problems related to ethanol
Increased NADH
What is inadequate in kwashiorkor and marasmus
In kwashiorkor it is inadequate protein intake; in marasmus it is inadequate overall energy intake (insufficient total calories)
What type of disorders of hypoketotic hypoglycemia
Mitochondrial disorders
What are lab findings that suggest inborn errors of metabolism
Hypoglycemia, kerosine, hyperammonemia, lactic acidosis
What glycogen storage diseases have no hypoglycemia
McArdles disease (type 5), pompes disease (type 2)
What is deficient in maple syrup urine disease
Alpha ketoacid dehydrogenase
What is elevated in all mitochondrial disorders
Alanine
What are the lab findings with PDH complex deficiency
Elevated alanine, lactic acidosis, no hypoglycemia
