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Biochem First Aid

DNA exists in the condensed, _________ form in order to fit into the nucleus. chromatin
____________ charged DNA loops twice around positively charged histone octamer to form nucleosome “beads on a string.” negatively
Histones are rich in the amino acids ________ and _________ lysine arginine
In mitosis, DNA condenses to form chromosomes. DNA and histone synthesis occur during _ phase. S
heterorchromatin: Transcriptionally ________, sterically inaccessible. (Increase/decrease) methylation, (increase/decrease) acetylation. inactive increase decrease
Euchromatin: Less condensed, appears lighter on EM (labeled E in A ). Transcriptionally _______, sterically accessible. active
base + (deoxy)ribose (Sugar) nucleoside
base + (deoxy)ribose + phosphate; linked by 3′-5′ phosphodiester bond. nucleotide
Deamination of ________ makes uracil. cytosine
Amino acids necessary for purine (3) synthesis: glycine, aspartate, glutamine
___________ inhibits thymidylate synthase (decreases dUMP --> dTMP) 5-florouracil (5-FU)
inhibit dihydrofolate reductase (decrease deoxythymidine monophosphate [dTMP]) in humans, bacteria, and protozoa, respectively methotrexate, trimethoprim pyrimethamine
Defective purine salvage due to absent HGPRT, which converts hypoxanthine to IMP and guanine to GMP. Results in excess uric acid production and de novo purine synthesis. X-linked recessive. Lesch-Nyhan syndrome
Findings: intellectual disability, self-mutilation, aggression, hyperuricemia (orange “sand” [sodium urate crystals] in diaper), gout, dystonia. Lesch-Nyhan syndrome
Starting 2 molecules for pyrmidine synthesis Glutamine + CO2
One of the major causes of autosomal recessive SCID. Adenosine deaminase deficiency
definition explains Most amino acids are coded by multiple codons. Codons that differ in 3rd, “________” position may code for the same tRNA/amino acid. Specific base pairing is usually only required in the first 2 nucleotide positions of mRNA codon. wobble
Genetic code is conserved throughout evolution. Exception in humans: _______________. mitochondria
DNA replication is ______________, involves both continuous and discontinuous (Okazaki fragment) synthesis, and occurs in the 5′ --> 3′ direction. semi-conservative
function of helicase Unwinds DNA template at replication fork.
Single-stranded binding proteins function: Prevent strands from reannealing.
____________ inhibit prokaryotic topoisomerase II (DNA gyrase) and topoisomerase IV. Fluoroquinolones
Transition mutation purine to purine (eg, A to G) or pyrimidine to pyrimidine (eg, C to T).
Transversion mutation purine to pyrimidine (eg, A to T) or pyrimidine to purine (eg, C to G).
type of mutation: Nucleotide substitution but codes for same (synonymous) amino acid; often base change in 3rd position of codon (tRNA wobble). silent
type of mutation: Nucleotide substitution resulting in changed amino acid (called conservative if new amino acid is similar in chemical structure). missence
type of mutation: Nucleotide substitution resulting in early stop codon (UAG, UAA, UGA). Usually results in nonfunctional protein. nonsense
Type of mutation: Deletion or insertion of a number of nucleotides not divisible by 3, resulting in misreading of all nucleotides downstream. Protein may be shorter or longer, and its function may be disrupted or altered. Frameshift
Duchenne muscular dystrophy, Tay-Sachs disease are caused by a _______________ mutation Frameshift
Lac operon: (low/high) glucose: increased adenylate cyclase activity leads to increased generation of cAMP from ATP leads to activation of catabolite activator protein (CAP) and increases transcription. low
Lac operon: High lactose --> unbinds repressor protein from repressor/operator site leads to (increase or decrease) transcription. increase
Defective in xeroderma pigmentosum, which prevents repair of _________ __________ that are formed as a result of ultraviolet light exposure. pyrimidine dimers
Specific endonucleases release the oligonucleotides containing damaged bases; DNA polymerase and ligase fill and reseal the gap, respectively. Repairs bulky helix-distorting lesions. Occurs in __ phase of cell cycle. G1 (Nucleotide excision repair)
Newly synthesized strand is recognized, mismatched nucleotides are removed, and the gap is filled and resealed. Occurs predominantly in ___ phase of cell cycle. G2 (Mismatch repair)
Promoter mutation commonly results in dramatic __________ in level of gene transcription decrease
α-amanitin, found in Amanita phalloides (death cap mushrooms), __________ RNA polymerase II. Causes severe hepatotoxicity if ingested inhibits
Site of synthesis of secretory (exported) proteins and of N-linked oligosaccharide addition to many proteins. Rough endoplasmic reticulum
Site of steroid synthesis and detoxification of drugs and poisons. Lacks surface ribosomes. ex.Liver hepatocytes and steroid hormone– producing cells of the adrenal cortex and gonads Smooth endoplasmic reticulum
inherited lysosomal storage disorder; defect in N-acetylglucosaminyl-1-phosphotransferase 􀁰 failure of the Golgi to phosphorylate mannose residues (ie, 􀁲 mannose-6-phosphate) on glycoproteins i-cell
Membrane-enclosed organelle involved in catabolism of very-long-chain fatty acids (through β-oxidation), branched-chain fatty acids, amino acids, and ethanol. Peroxisome
Barrel-shaped protein complex that degrades damaged or ubiquitin-tagged proteins. Proteasome
Defects in the ubiquitin-proteasome system have been implicated in some cases of _____________ ____________ Parkinson disease.
Peroxisomal disorders commonly lead to neurologic diseases due to deficits in synthesis of plasmalogens, important phospholipids in myelin. Name 2 Zellweger syndrome (hypotonia, seizures, hepatomegaly, early death) and Refsum disease (scaly skin, ataxia, cataracts/night blindness, shortening of 4th toe, epiphyseal dysplasi
Most common collagen (90%)—Bone (made by osteoblasts), Skin, Tendon, dentin, fascia, cornea, late wound repair. type 1
Cartilage (including hyaline), vitreous body, nucleus pulposus. Type II: cartwolage.
Hydroxylation—hydroxylation of specific proline and lysine residues. Requires vitamin _, defiency leads to ________ C, Scurvy
XR connective tissue disease caused by impaired Cu absorption and transport due to defective _____ protein (ATP7A). decreases activity of lysyl oxidase. Results in brittle, “kinky” hair, growth retardation, and hypotonia. (disease same as protien) Menkes disease
Lac operon: Low glucose Lactose available Lac genes strongly expressed
Lac operon: High glucose Lactose unavailable Lac genes not expressed
Lac operon: Low glucose Lactose unavailable Lac genes not expressed
Lac operon: High glucose Lactose available Very low (basal) expression
Promoter mutation commonly results in dramatic ____________ in level of gene transcription. Decrease
_____________ deficiency results in excess elastase activity, which can cause emphysema. Wrinkles of aging are due to 􀁲 collagen and elastin production. α1-Antitrypsin
Marfan syndrome—autosomal ___________ connective tissue disorder affecting skeleton, heart, and eyes. FBN1 gene mutation on chromosome 15 results in defective fibrillin, a glycoprotein that forms a sheath around elastin. dominant
disease: tall w/ long extremities; pectus carinatum or pectus excavatum; hypermobile joints; long, tapering fingers & toes (arachnodactyly);and dissecting aortic aneurysms; floppy mitral valve. Subluxation of lenses, Marfan syndrome
acronym for remembering differents in blot: SNoW DRoP Southern = DNA Northern = RNA Western = Protein
Thousands of nucleic acid sequences are arranged in grids on glass or silicon. DNA or RNA probes are hybridized to the chip, and a scanner detects the relative amounts of complementary binding. Microarrays
A process in which metaphase chromosomes are stained, ordered, and numbered according to morphology, size, arm-length ratio, and banding pattern Karyotyping
Can be performed on a sample of blood, bone marrow, amniotic fluid, or placental tissue. Used to diagnose chromosomal imbalances (eg, autosomal trisomies, sex chromosome disorders). Karyotyping
dsRNA is synthesized that is complementary to the mRNA sequence of interest. When transfected into human cells, dsRNA separates and promotes degradation of target mRNA, “knocking down” gene expression. RNA interference
Both alleles contribute to the phenotype of the heterozygote. eg.Blood groups A, B, AB; α1-antitrypsin deficiency. Codominance
Patients with the same genotype have varying phenotypes. eg.2 patients with neurofibromatosis type 1 (NF1) may have varying disease severity. Variable expressivity
Not all individuals with a mutant genotype show the mutant phenotype. eg.BRCA1 gene mutations do not always result in breast or ovarian cancer. Incomplete penetrance
One gene contributes to multiple phenotypic effects. eg.Untreated phenylketonuria (PKU) manifests with light skin, intellectual disability, and musty body odor. Pleiotropy
Increased severity or earlier onset of disease in succeeding generations. eg. Trinucleotide repeat diseases (eg, Huntington disease). Anticipation
If a patient inherits or develops a mutation in a tumor suppressor gene, the complementary allele must be deleted/mutated before cancer develops. This is not true of oncogenes. Loss of heterozygosity
Mutations at different loci can produce a similar phenotype. eg. Albinism. Locus heterogeneity
Different mutations in the same locus produce the same phenotype. eg. β-thalassemia. Allelic heterogeneity
Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrially inherited disease. Heteroplasmy
Hardy-Weinberg law assumptions include: (4) No mutation occurring at the locus Natural selection is not occurring Completely random mating No net migration
At some loci, only one allele is active; the other is inactive (imprinted/inactivated by methylation). With one allele inactivated, deletion of the active allele --> disease. Imprinting
Sons of heterozygous mothers have a 50% chance of being affected. No male-to-male transmission. Skips generations. X-linked recessive note bono: Commonly more severe in males. Females usually must be homozygous to be affected.
Transmitted through both parents. Mothers transmit to 50% of daughters and sons; fathers transmit to all daughters but no sons. X-linked dominant
Robertsonian translocation: Chromosomal translocation that commonly involves chromosome pairs __,__,__,__,__, 13, 14, 15, 21, and 22
Congenital microdeletion of short arm of chromosome __ (46,XX or XY, 5p−). Findings: microcephaly, moderate to severe intellectual disability, high-pitched crying/ meowing, epicanthal folds, cardiac abnormalities (VSD). 5
Congenital microdeletion of long arm of ch.7 deleted region includes elastin gene). Findings: distinctive “elfin” facies, intellectual disability, hypercalcemia, well-developed verbal skills, extreme friendliness with strangers, cardiovascular problems. wilson's disease
rare disorders; often present with myopathy, lactic acidosis, and CNS disease, eg, MELAS syndrome 2° to failure in oxidative phosphorylation. Muscle biopsy often shows “ragged red fibers” (due to accumulation of diseased mitochondria Mitochondrial myopathies
Autosomal recessive; defect in CFTR gene on chromosome 7; commonly a deletion of Phe508. Most common lethal genetic disease in Caucasian population. Cystic fibrosis
X-linked dominant inheritance. Trinucleotide repeat in FMR1 gene 􀁰 hypermethylation Fragile X syndrome
Most common cause of inherited intellectual disability and autism and 2nd most common cause of genetically associated mental deficiency (Down syndrome#1). Post-pubertal macroorchidism (big testes), long face w/ a large jaw, large everted ears, autis Vitamin A (retinol) deficiency
Acute toxicity—nausea, vomiting, vertigo, and blurred vision. Chronic toxicity—alopecia, dry skin (eg, scaliness), hepatic toxicity and enlargement, arthralgias, and pseudotumor cerebri. Vitamin A (retinol) excess
vitamin co-factor -Pyruvate dehydrogenase (links glycolysis to TCA cycle) -α-ketoglutarate dehydrogenase (TCA cycle) -Transketolase (HMP shunt) -Branched-chain ketoacid dehydrogenase Vitamin B1 (thiamine)
_________________ syndrome—confusion, ophthalmoplegia, ataxia (classic triad) + confabulation, personality change, memory loss (permanent). Damage to medial dorsal nucleus of thalamus, mammillary bodies. Wernicke-Korsakoff
vitamin deficiency: Impaired glucose breakdown 􀁰 ATP depletion worsened by glucose infusion; highly aerobic tissues (eg, brain, heart) are affected first. In alcoholic or malnourished patients, Vitamin B1 (thiamine)
vitamin def: Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth), Corneal vascularization. Vitamin B2 (riboflavin) (The 2 C’s of B2).
Constituent of NAD+, NADP+ (used in redox reactions). Derived from tryptophan. Synthesis requires vitamins B2 and B6. Used to treat dyslipidemia; lowers levels of VLDL and raises levels of HDL. Vitamin B3 (niacin)
Symptoms of________ : Diarrhea, Dementia (also hallucinations) , Dermatitis (C3/C4 dermatome circumferential “broad collar” rash [Casal necklace], hyperpigmentation of sunexposed limbs A ). pellagra (The 3 D’s of B3.)
Essential component of coenzyme A (CoA, a (vitamin) cofactor for acyl transfers) and fatty acid synthase. Vitamin B5 (pantothenic acid) (B5 is “pento”thenic acid)
Converted to tetrahydrofolic acid (THF), a coenzyme for 1-carbon transfer/methylation reactions. Important for the synthesis of nitrogenous bases in DNA and RNA. Vitamin B9 (folate)
vit. def: Macrocytic, megaloblastic anemia; hypersegmented polymorphonuclear cells (PMNs); glossitis; no neurologic symptoms (as opposed to vitamin B12 deficiency) Vitamin B9 (folate)
Cofactor for methionine synthase (transfers CH3 groups as methylcobalamin) and methylmalonyl-CoA mutase. Important for DNA synthesis. Vitamin B12 (cobalamin)
Antioxidant; also facilitates iron absorption by reducing it to Fe2+ state. Necessary for hydroxylation of proline and lysine in collagen synthesis. Necessary for dopamine β-hydroxylase, which converts dopamine to NE. Vitamin C (ascorbic acid)
________ - swollen gums, bruising, petechiae, hemarthrosis, anemia, poor wound healing, perifollicular and subperiosteal hemorrhages, “corkscrew” hair. Weakened immune response Scurvy (vit. C deficiency)
Vit excess: Nausea, vomiting, diarrhea, fatigue, calcium oxalate nephrolithiasis. Can 􀁱 risk of iron toxicity in predisposed individuals (eg, those with transfusions, hereditary hemochromatosis). Vitamin C (ascorbic acid)
vitamin D_ = ergocalciferol—ingested from plants. 2
vitamin D__ = cholecalciferol—consumed in milk, formed in sun-exposed skin (stratum basale). 3
what is '1,25-(OH)2 D3 (calcitriol)' activie form of vit. D
vit def: Rickets in children, osteomalacia in adults (bone pain and muscle weakness), hypocalcemic tetany. Breastfed infants should receive oral vitamin __. Exacerbated by low sun exposure, pigmented skin, prematurity. Vitamin D
Antioxidant (protects RBCs and membranes from free radical damage). High-dose supplementation may alter metabolism of vitamin K --> enhanced anticoagulant effects of warfarin. Vitamin E (tocopherol/tocotrienol)
vit def: Hemolytic anemia, acanthocytosis, muscle weakness, posterior column and spinocerebellar tract demyelination. Vitamin E (tocopherol/tocotrienol)
Activated by epoxide reductase to the reduced form, which is a cofactor for the γ-carboxylation of glutamic acid residues on various proteins required for blood clotting. Synthesized by intestinal flora. Vitamin K (phytomenadione, phylloquinone, phytonadione)
Necessary for the maturation of clotting factors II, VII, IX, X, and proteins C and S. Warfarin inhibits vitamin __–dependent synthesis of these factors and proteins. K, K is for Koagulation. Necessary for the maturation of clotting factors II, VII, IX, X
Mineral essential for the activity of 100+ enzymes. Important in the formation of ____ fingers (transcription factor motif). zinc
Delayed wound healing, hypogonadism, 􀁲 adult hair (axillary, facial, pubic), dysgeusia, anosmia, acrodermatitis enteropathica A . May predispose to alcoholic cirrhosis. zinc DEFICIENCY
__________—inhibits alcohol dehydrogenase and is an antidote For Overdoses of Methanol or Ethylene glycol. FOMEpizole
__________—inhibits acetaldehyde dehydrogenase (acetaldehyde accumulates, contributing to hangover symptoms), discouraging drinking. Disulfiram
____ NADH/NAD+ causes: 􀁰 Pyruvate--> lactate (lactic acidosis) 􀂃 Oxaloacetate--> malate (prevents gluconeogenesis-->fasting hypoglycemia) 􀂃 DHAP-->glycerol- 3-phosphate (combines with fatty acids to make triglycerides--> hepatosteatosis high
________ metabolism: Fatty acid oxidation (β-oxidation), acetyl- CoA production, TCA cycle, oxidative phosphorylation, ketogenesis. Mitochondria
________ metabolism :Glycolysis, HMP shunt, and synthesis of steroids (SER), proteins (ribosomes, RER), fatty acids, cholesterol, and nucleotides. cytooplasm
type of enzyme: Catalyzes transfer of a phosphate group from a high-energy molecule (usually ATP) to a substrate (eg, phosphofructokinase). Kinase
type of enzyme: Adds inorganic phosphate onto substrate without using ATP phosphorylase
type of enzyme: Removes phosphate group from substrate Phosphatase
type of enzyme: Catalyzes oxidation-reduction reactions Dehydrogenase
type of enzyme: Adds hydroxyl group Hydroxylase
type of enzyme: Transfers CO2 groups with the help of biotin Carboxylase
type of enzyme: Relocates a functional group within a molecule Mutase, (eg, vitamin B12–dependent methylmalonyl-CoA mutase)
type of enzyme:Combines 2 molecules into 1 (condensation reaction) either using an energy source or not. Synthase/synthetase
NADPH is a product of the ____________ and used for: (4) HMP shunt. 􀂃 Anabolic processes 􀂃 Respiratory burst 􀂃 Cytochrome P-450 system 􀂃 Glutathione reductase
Location of Hexokinase and is it induced by insulin? Most tissues, except liver and pancreatic β cells and no
Causes a buildup of pyruvate that gets shunted to lactate (via LDH) and alanine (via ALT). X-linked. Neurologic defects, lactic acidosis, increased serum alanine starting in infancy. Pyruvate dehydrogenase complex deficiency
2,4-Dinitrophenol (used illicitly for weight loss), aspirin (fevers often occur after aspirin overdose), thermogenin in brown fat. these can cause what? Uncoupling agents
ATP synthase inhibitor Oligomycin. Directly inhibit mitochondrial ATP synthase, causing an 􀁱 proton gradient. No ATP is produced because electron transport stops.
Essential fructosuria Involves a defect in fructokinase. Autosomal recessive. A benign, asymptomatic condition, since fructose is not trapped in cells. Symptoms: fructose appears in blood and urine.
Hereditary deficiency of aldolase B. Autosomal recessive. Fructose-1-phosphate accumulates, causing a 􀁲 in available phosphate, which results in inhibition of glycogenolysis and gluconeogenesis. Fructose intolerance
Hereditary deficiency of galactokinase. Galactitol accumulates if galactose is present in diet. Relatively mild condition. Autosomal recessive. Symptoms: galactose appears in blood (galactosemia) and urine (galactosuria); Galactokinase deficiency
Galactokinase deficiency
absence of galactose-1-phosphate uridyltransferase. Autosomal recessive. Damage is caused by accumulation of toxic substances (including galactitol, which accumulates in the lens of the eye). Classic galactosemia
DEFICIENT ENZYME : Glucose-6-phosphatase Von Gierke disease (type I)
DEFICIENT ENZYME: Lysosomal acid α-1,4- glucosidase with α-1,6- glucosidase activity (acid maltase) Pompe disease (type II) (PomPe trashes the PumP (1,4) (heart, liver, and muscle)
DEFICIENT ENZYME; Debranching enzyme (α-1,6-glucosidase) Cori disease (type III) (Gluconeogenesis is intact)
DEFICIENT ENZYME; Skeletal muscle glycogen phosphorylase (Myophosphorylase) McArdle disease (type V)
Disease and Enzyme: Early: Triad of episodic peripheral neuropathy, angiokeratomas B , hypohidrosis. Late: progressive renal failure, cardiovascular disease. Fabry disease, α-galactosidase A
Disease and Enzyme: Progressive neurodegeneration, developmental delay, “cherry-red” spot on macula A , lysosomes with onion skin, no hepatosplenomegaly (vs Niemann-Pick). Tay-Sachs disease, HeXosaminidase A
Disease and Enzyme; Peripheral neuropathy, destruction of oligodendrocytes, developmental delay, optic atrophy, globoid cells. Krabbe disease, Galactocerebrosidase
Disease and Enzyme: Most common. Hepatosplenomegaly, pancytopenia, osteoporosis, avascular necrosis of femur, bone crises, Gaucher cells C (lipid-laden macrophages resembling crumpled tissue paper). Gaucher disease, Glucocerebrosidase (β-glucosidase); treat with recombinant glucocerebrosidase
Disease and Enzyme: Progressive neurodegenera tion, hepatosplenomegaly, foam cells (lipid-laden macrophages) D, “cherry-red” spot on macula A . Niemann-Pick disease, Sphingomyelinase
Created by: moore420
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