Biochemistry 1/2, First Aid for the USMLE Step 1 Flashcards Preview

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Flashcards in Biochemistry 1/2, First Aid for the USMLE Step 1 Deck (500):
1

DNA charge

Negative

2

Histone charge

Positive

3

Negatively charged DNA loops ___ around positively charged histone octamer to form nucleosome "___."

Twice; beads on a string

4

Histones are rich in the amino acids ___

Lysine and arginine

5

___ binds to the nucleosome and to "linker DNA," thereby stabilizing the chromatin fiber

H1

6

DNA and histone synthesis occur during ___ phase of the cell cycle

S phase

7

Condensed chromatin that appears darker on EM

Heterochromatin [Think HeteroChromatin, Highly Condensed]

8

Less condensed chromatin that appears lighter on EM

Euchromatin

9

Transcriptionally inactive chromatin, sterically inaccessible

Heterochromatin

10

Transcriptionally active, sterically accessible

Euchromatin

11

Inactive X chromosomes

Barr bodies

12

Heterochromatin vs Euchromatin: Barr bodies

Heterochromatin

13

Template strand ___ and ___ are methylated in DNA replication, which allows mismatch repair enzymes to distinguish between old and new strands in prokaryotes

Cytosine, adenine

14

What methylation processes make DNA mute or repress DNA transcription

DNA methylation; histone methylation (repress or activate DNA transcription)

15

Relaxes DNA coiling, allowing for transcription

Histone acetylation [Think Acetylation = Active]

16

Purines

Adenine, Guanine [Think PURe As Gold]

17

Pyrimidines

Cytosine, Uracil, Thymine [Think CUT the PY]

18

Purines vs Pyrimidines: 2 rings

Purines [Pyrimidines = PYRamids can stand alone = 1 ring]

19

Which pyrimidine has a methyl

Thymine [ Think THYmine has a meTHYl]

20

What makes uracil

Deamination of cytosine

21

Uracil is found in

RNA

22

Thymine is found in

DNA

23

Base pair with 2 hydrogen bonds

A-T [Think 2 AToms of hydrogen]

24

Base pair with a higher melting point

G-C (3 H bonds)

25

Amino acids necessary for purine synthesis

Glycine, Aspartate, Glutamate [GAG]

26

Amino acid necessary for pyrimidine synthesis

Aspartate

27

A nucleoSide is composed of

Base + Sugar (ribose or deoxyribose)

28

A nucleoTide is made of

Base + Sugar + phosphaTe; linked by 3'-5' phosphodiester bond

29

De novo purine synthesis

1) Sugar + phosphate (PRPP) 2) Add base

30

De novo pyrimidine synthesis

1) Temporary base (orotic acid) 2) Add sugar + phosphate (PRPP) 3) Modify base

31

Which are synthesised first, ribonucleotides vs deoxyribonucleotides

Ribonucleotides are synthesized first and are converted to deoxyribonucleotides by ribonucleotide reductase

32

Carbamoyl phosphate is involved in what 2 metabolic pathways

1) De novo pyrimidine synthesis 2) Urea cycle

33

Inhibits dihydroorotate dehydrogenase (pyrimidine base production)

Leflunomide [dihydrOO leflOO]

34

Inhibit IMP dehydrogenase (purine base production)

Mycophenolate mofetil and ribavirin

35

Inhibits ribonucleotide reductase (pyrimidine base production)

Hydroxyurea

36

Inhibits de novo purine synthesis

6-MP and its prodrug azathioprine

37

Inhibits thymidilate synthase (dUMP>dTMP; pyrimidine base synthesis)

5-FU

38

Inhibits DHFR

1) MTX (humans) 2) TMP (bacteria) 3) Pyrimethamine (protozoa)

39

Inhibited by Allopurinol and Febuxostat in purine salvage pathway

Xanthine oxidase

40

Xanthine oxidase catalyses what 2 reactions in the purine salvage pathway

1) Hypoxanthine > xanthine 2) Xanthine > uric acid

41

Promotes excretion of uric acid in urine

Probenecid

42

Causes excess ATP and dATP > feedback inhibition of ribonucleotide reductase > prevents DNA synthesis > decreases lymphocyte count

Adenosine deaminase deficiency (one of the major causes of SCID)

43

Defective purine salvage due to absent HGPRT

Lesch-Nyhan syndrome

44

HGPRT catalyzes

1) Hypoxanthine to IMP 2) Guanine to GMP

45

Treatment of choice for Lesch-Nyhan

Allopurinol (2nd line: Febuxostat)

46

Genetic code feature: Each codon specifies only 1 amino acid

Unambiguous

47

Genetic code feature: Most amino acids are coded by multiple codons

Degenerate/ redundant

48

Genetic code feature: Read from a fixed starting point as a continuous sequence of bases

Commaless, nonoverlapping

49

Genetic code feature: Conserved throughout evolution

Universal

50

Amino acids encoded by only 1 codon each and are exceptions to degenerate/redundance feature of genetic code

1) Methionine 2) Tryptophan

51

Methionine, codon

AUG

52

Tryptophan, codon

UGG

53

Genetic code is universal except

In mitochondria

54

Y-shaped region along DNA template where leading and lagging strands are synthesized

Replication fork

55

Unwinds DNA template at replication fork

Helicase

56

Prevent strands from reannealing

Single-stranded binding proteins

57

Create a single- or double-stranded break in the helix to add or remove supercoils

DNA topoisomerases

58

Inhibit prokaryotic enzymes topoisomerase II (DNA gyrase) and topoisomerase IV

Fluoroquinolones

59

Prokaryotic DNA polymerase that elongates leading strand by adding deoxynucleotides to the 3_ end; has 5_>3_ synthesis and proofreads with 3_>5_ exonuclease

DNA polymerase III

60

Prokaryotic DNA polymerase that degrades RNA primer and replaces it with DNA

DNA polymerase I

61

Catalyzes the formation of a phosphodiester bond within a strand of double-stranded DNA (i.e., joins Okazaki fragments); SEALS

DNA ligase

62

An RNA-dependent DNA polymerase that adds DNA to 3_ ends of chromosomes to avoid loss of genetic material with every duplication

Telomerase

63

T/F Telomerase is found in both prokaryotes and eukaryotes

F, eukaryotes only

64

Severity of DNA damage from least to greatest

Silent, missense, nonsense, frameshift

65

Point mutations

1) Silent 2) Missense 3) Nonsense

66

Point mutation in which purine is replaced by purine or pyrimidine by another pyrimidine

Transition

67

Point mutation in which purine is replaced by a pyrimidine or pyrimidine by a purine

Transversion

68

Nucleotide substitution but codes for same (synonymous) amino acid

Silent

69

Nucleotide substitution resulting in changed amino acid

Missense

70

Nucleotide substitution resulting in early stop codon

Nonsense [Think STOP the NONSENSE]

71

Deletion or insertion of a number of nucleotides not divisible by 3, resulting in misreading of all nucleotides downstream, usually resulting in a truncated, nonfunctional protein

Frameshift

72

Type of mutation in Duchenne muscular dystrophy

Frameshift

73

Base change in silent mutation is usually at which position

3rd position

74

What do you call the base change in 3rd position of codon

tRNA wobble

75

A missense is called "conservative" if

The new amino acid is similar in chemical structure

76

Sickle cell disease is what type of mutation

Missense (glutamic acid>val)

77

Single strand DNA repair: Specific endonucleases release the oligonucleotides containing damaged bases; DNA polymerase and ligase fill and reseal the gap, respectively

Nucleotide excision repair

78

Nucleotide excision repair occurs in what phase of the cell cycle

G1

79

Single strand DNA repair: Important in repair of spontaneous/toxic deamination; occurs throughout the cell cycle

Base excision repair

80

What DNA repair mechanism is defective in xeroderma pigmentosum, which prevents repair of pyrimidine dimers because of ultraviolet light exposure

Nucleotide excision repair

81

What single strand DNA repair mechanism is defective in hereditary nonpolyposis colorectal cancer (HNPCC)

Mismatch repair

82

Mismatch repair occurs predominantly in which phase of the cell cycle

G2

83

Double strand DNA repair mechanism: Some DNA may be lost; mutated in ataxia telangiectasia and Fanconi anemia

Nonhomologous end joining

84

DNA and RNA are both synthesised in what direction

5'>3'

85

The ___ of the incoming nucleotide bears the triphosphate (energy source for bond)

5_ end

86

Protein synthesis is ___ to ___

N-terminus, C-terminus

87

mRNA is read from what end to what end

5' to 3'

88

Target of the 3_ hydroxyl attack

Triphosphate bond

89

Drugs blocking DNA replication often have modified ___, preventing addition of the next nucleotide ("chain termination")

3_ OH

90

mRNA start codon

AUG (rarely GUG) [Think inAUGurates protein synthesis]

91

AUG in eukaryotes codes for what amino acid

Methionine

92

AUG in prokaryotes codes for

N-formylmethionine (fMet)

93

Function of fMet

Stimulates neutrophil chemotaxis

94

mRNA stop codons

UGA, UAA, UAG [Think U Go Away, U Are Away, U Are Gone]

95

Site in the gene where RNA polymerase II and multiple other transcription factors bind to DNA upstream from gene locus

Promoter

96

AT-rich upstream sequence with TATA and CAAT boxes

Promoter

97

Stretch of DNA that alters gene expression by binding transcription factors

Enhancer

98

Site in the gene where negative regulators (repressors) bind

Silencer

99

RNA polymerase: Makes rRNA

RNA polymerase I

100

RNA polymerase: Makes mRNA

RNA polymerase II

101

RNA polymerase: Makes tRNA

RNA polymerase III

102

Most numerous RNA

rRNA [Rampant]

103

Largest RNA

mRNA [Massive]

104

Smalles RNA

tRNA [Tiny]

105

RNA polymerase: Opens DNA at promoter site

RNA polymerase II

106

RNA polymerase II is inhibited by what substance, which causes severe hepatotoxicty if ingested

alpha-amanitin, found in Amanita phalloides (death cap mushrooms)

107

Drug that inhibits RNA polymerase in prokaryotes

Rifampin

108

Drug that inhibits RNA polymerase in both prokaryotes and eukaryotes

Actinomycin D

109

How many RNA polymerases are then in prokaryotes?

Only 1 (makes all 3 kinds of RNA)

110

Initial RNA transcript in eukaryotes that is subsequently modified and becomes mRNA

Heterogenous nuclear RNA (hnRNA)

111

3 processes that occur in the nucleus following transcription

1) Capping of 5' end (7-methylguanosine cap) 2) Polyadenylation of 3' end 3) Splicing out of introns

112

Capped, tailed, and spliced RNA transcript is called

mRNA

113

Where does transcription occur

Nucleus

114

Where does translation occur

Cytosol

115

mRNA quality control occurs at

P-bodies in cytoplasm (also the site of mRNA storage)

116

Polyadenylation signal

AAUAA

117

Primary transcript combines with ___ and other proteins to form spliceosome

Small nuclear ribonucleoproteins (snRNPs)

118

Antibodies to snRNPs

Anti-Smith antibodies

119

Introns vs. exons: Contain the actual genetic information coding for protein

Exons

120

Introns vs. exons: Intervening noncoding segments of DNA

Introns

121

Introns vs. exons: Stay in the nucleus

Introns

122

RNA that assumes a cloverleaf form

tRNA

123

At which end of the tRNA is the anticodon found

Opposite the 3' aminoacyl end

124

Amino acid is covalently bound to which end of tRNA

3' end

125

This enzyme scrutinizes amino acid before and after it binds to tRNA, and if incorrect, bod is hydrolyzed

Aminoacyl-tRNA synthetase

126

T/F Accurate base pairing is usually required only in the first 2 nucleotide positions of an mRNA codon, so codons differing in the 3rd "wobble" position may code for the same tRNA/amino acid

T

127

Protein synthesis is initiated by

GTP hydrolysis

128

Ribosome site that receives incoming aminoacyl-tRNA

A site

129

Ribosome site that accommodates the growing peptide

P site

130

Ribosome site that holds empty tRNA as it exits

E site

131

At which ribosome subunit are the A, P, and E sites found

60S

132

___ catalyzes peptide bond formation and transfers growing polypeptide to amino acid in A site

rRNA ("ribozyme")

133

Posttranslational modification of protein: Removal of N- or C-terminal propeptides from zymogen to generate mature protein (e.g., trypsinogen to trypsin)

Trimming

134

Posttranslational modification of protein: Phosphorylation, glycosylation, hydroxylation, methylation, acetylation, and ubiquitination

Covalent alterations

135

Intracellular protein involved in facilitating and/or maintaining protein folding, e.g. heat shock proteins

Chaperone protein

136

Shortest phase of cell cycle

M phase

137

Constitutive regulator of the cell cycle

CDKs

138

Regulatory proteins that control cell cycle events; phase specific; activate CDKs

Cyclins

139

Phosphorylate other proteins to coordinate cell cycle progression; must be activated and inactivated at appropriate times for cell cycle to progress

Cyclin-CDK complexes

140

Inhibit G1-to-S progression, the mutation of which result in unrestrained cell division

Tumor suppressors, p53 and Rb

141

Phase of the cell cycle where DNA synthesis occurs

S phase

142

Phases of the cell cycle

G0 > G1 > S > G2 > M > G0 or G1

143

Cells that remain in G0, regenerate from stem cells

Permanent cells (neurons, skeletal and cardiac muscle, RBCs)

144

Cells that enter G1 from G0 when stimulated

Stable (quiescent) (hepatocytes, lymphocytes)

145

Cells that never go to G0, divide rapidly with a short G1. Most affected by chemotherapy.

Labile cells (bone marrow, gut epithelium, skin, hair follicles, germ cells)

146

Site of synthesis of secretory (exported) proteins and of N-linked oligosaccharide addition to many proteins

RER

147

Site of synthesis of cytosolic and organellar proteins

Free ribosomes

148

Site of steroid synthesis and detoxification of drugs and poisons

SER

149

SER is rich in

1) Hepatocytes 2) Steroid hormone- producing cells of the adrenal cortex 3) Gonads

150

Distribution center for proteins and lipids from the ER to the vesicles and plasma membrane

Golgi

151

Abundant, cytosolic ribonucleoprotein that traffics proteins from the ribosome to the RER; the absence or dysfunction of which causes protein accumulation in the cytosol

Signal recognition particle (SRP)

152

Vesicular trafficking protein: Golgi > Golgi (retrograde); cis-Golgi > ER

COPI

153

Vesicular trafficking protein: ER > cis-Golgi (anterograde)

COPII

154

Trans-Golgi > lysosomes; plasma membrane > endosomes (receptor- mediated endocytosis)

Clathrin

155

Membrane-enclosed organelle involved in catabolism of very-long-chain fatty acids, branched-chain fatty acids, and amino acids

Peroxisome

156

Barrel-shaped protein complex that degrades damaged or ubiquitin-tagged proteins

Proteasome

157

Cell filament: Muscle contraction, cytokinesis

Microfilaments, e.g. actin

158

Cell filament: Maintain cell structure

Intermediate filaments, e.g. Vimentin, desmin, cytokeratin, lamins, glial fibrillary acid proteins (GFAP), neurofilaments

159

Cell filament: Movement, cell division

Microtubules, e.g. Cilia, flagella, mitotic spindle, axonal trafficking, centrioles

160

Immunohistochemical stain: Connective tissue

Vimentin

161

Immunohistochemical stain: Muscle

Desmin

162

Immunohistochemical stain: Epithelial cells

Cytokeratin

163

Immunohistochemical stain: Neuroglia

GFAP

164

Immunohistochemical stain: Neurons

Neurofilaments

165

Cylindrical structure composed of a helical array of polymerized heterodimers of _- and _-tubulin

Microtubule

166

Drugs that act on microtubules

[Microtubules Get Constructed Very Poorly] 1) Mebendazole (antihelminthic) 2) Griseofulvin (anti fungal) 3) Colchicine (anti gout) 4) Vincristine/Vinblastine (anticancer) 5) Paclitaxel (anticancer)

167

9 + 2 arrangement of microtubule doublets

Cilia

168

Immotile cilia due to a dynein arm defect; immotility in both men and women (immotile sperm and dysfunctional fallopian tube cilia)

Kartagener syndrome/primary ciliary dyskinesia

169

Inhibits Na-K ATPase pump by binding to K+ site

Ouabain

170

Drugs that directly inhibit the Na+-K+ ATPase, which leads to indirect inhibition of Na+/Ca2+ exchange > increase in [Ca2+]i > increase in cardiac contractility

Cardiac glycosides (digoxin and digitoxin)

171

Most abundant protein in the human body

Collagen

172

MC type of collagen (90%)

Type I

173

Synthesizes type I collagen in bone

Osteoblasts

174

Sites of type I collagen

Bone (made by osteoblasts), Skin, Tendon, dentin, fascia, cornea, late wound repair

175

Sites of type II collagen

Cartilage (including hyaline), vitreous body, nucleus pulposus

176

Sites of type III collagen

Reticulin—skin, blood vessels, uterus, fetal tissue, granulation tissue

177

Sites of type IV collagen

Basement membrane, basal lamina, lens

178

Collagen type: Decreased production in osteogenesis imperfecta type I

I

179

Collagen type: Deficient in the uncommon, vascular
type of Ehlers-Danlos syndrome

III

180

Collagen type: Defective in Alport syndrome

IV

181

Collagen type: Targeted by autoantibodies in Goodpasture syndrome

IV

182

In what cells is collagen synthesized

Fibroblasts

183

In what organelle is collagen synthesized

RER

184

Steps in collagen synthesis that take place in fibroblasts

1) Synthesis (preprocollagen) 2) Hydroxylation of proline and lysine residues 3) Glycosylation and formation of procollagen

185

Steps in collagen synthesis that take place outside fibroblasts

1) Proteolytic processing (formation of tropocollagen by cleavage of disulfide-rich regions of procollagen) 2) Cross-linking

186

Structure of preprocollagen (collagen alpha chains)

Gly-X-Y (Gly is glycine; X and Y are proline or lysine)

187

Best reflects collagen synthesis

Glycine

188

Collagen is 1/3 ___ (amino acid)

Glycine

189

What step in collagen synthesis requires Vitamin C?

Hydroxylation of specific proline and lysine residues

190

Problems forming triple helix of 3 collagen _ chains (glycosylation and formation of procollagen)

Osteogenesis imperfecta

191

Problems with collagen cross-linking lead to

1) Ehler-Danlos 2) Menkes disease

192

AKA Brittle bone disease

Osteogenesis imperfecta

193

Why is there hearing loss in osteogenesis imperfecta

Abnormal ossicles

194

Faulty collagen synthesis causing hyperextensible skin, tendency to bleed (easy bruising), and hypermobile joints

Ehlers-Danlos syndrome

195

MC type of Ehlers-Danlos syndrome

Hypermobility type

196

Classical type of Ehlers-Danlos is due to mutation of what collagen type

V

197

Vascular type (vascular and organ rupture) of Ehlers-Danlos is due to deficiency of

Type III collagen

198

X-linked recessive connective tissue disease caused by impaired copper absorption and transport due to defective ATP7A

Menkes disease

199

Menkes disease is associated with decreased activity of what enzyme

Lysyl oxidase (copper is a necessary cofactor)

200

Elastin is rich in what amino acids

1) Proline 2) Glycine 3) Lysine

201

Where does elastin cross-linking take place

Extracellularly

202

Where is elastin found

Skin, lungs, large arteries, elastic ligaments, vocal cords, ligamenta flava (connect vertebrae)

203

Elastin is broken down by elastase, which is normally inhibited by

_1-antitrypsin

204

A glycoprotein that forms a sheath around elastin

Fibrillin (defective in Marfan syndrome)

205

Wrinkles of aging are due to decreased production of what proteins

Collagen and elastin

206

Steps in PCR

1) Denaturation 2) Annealing 3) Elongation

207

Denaturating agent in PCR that generates 2 separate strands

Heating

208

Anneal to a specific sequence on each strand to be amplified during cooling

DNA primers

209

Replicates the DNA sequence following each primer

Heat-stable DNA polymerase

210

Used for size separation of PCR products (smaller molecules travel further) and compared against DNA ladder

Agarose gel electrophoresis

211

Blotting procedures and corresponding biomolecule electrophoresed

[SNoW DRoP] Southern: DNA, Northern: RNA, Western: Protein

212

Blotting procedure used as confirmatory test for HIV after a (+) ELISA

Western blot

213

Blotting procedure used to identify DNA-binding proteins such as transcription factors

Southwestern blot

214

Used to detect the presence of either a specific antigen or a specific antibody in a patient's blood sample

ELISA

215

Direct vs Indirect ELISA: Uses a test antibody to see if a specific antigen is present

Direct

216

Direct vs Indirect ELISA: Uses either a test antigen or antibody to see if a specific antibody or antigen, respectively, is present

Indirect

217

Karyotyping makes use of chromosomes at what phase of the cell cycle

Metaphase

218

Karyotyping can be performed on what samples

Blood, bone marrow, amniotic fluid, or placental tissue

219

When is FISH used instead of karyotyping

When deletion is too small to be visualized by karyotype

220

Fluorescence vs no fluorescence: Gene is absent/deleted

No fluorescence

221

Production of a recombinant DNA molecule that is self-perpetuating

Cloning

222

RNA used in cloning

mRNA

223

Cloned DNA (cDNA) lacks what part of the gene

Introns

224

Can be used to study a gene whose deletion causes embryonic death

Cre-lox system

225

Both alleles contribute to the phenotype of the heterozygote, e.g. Blood groups A, B, AB

Codominance

226

Phenotype varies among individuals with same genotype, e.g. more severe in some and less severe in others

Variable expressivity

227

Not all individuals with a mutant genotype show the mutant phenotype, e.g. BRCA1 mutations do not always result in breast or ovarian CA

Incomplete penetrance

228

One gene contributes to multiple phenotypic effects

Pleiotropy

229

Increased severity or earlier onset of disease in succeeding generations

Anticipation

230

A mosaicism and is due to mutation affecting G-protein signaling

McCune-Albright syndrome

231

2 syndromes that are both due to mutation or deletion of genes on chromosome 15

1) Prader-Willi 2) Angelman

232

Maternal imprinting: gene from mom is normally silent and Paternal gene is deleted/ mutated

Prader-Willi

233

Paternal imprinting: gene from dad is normally silent and Maternal gene is deleted/mutated

Angelman

234

Mode of inheritance: Often due to defects in structural genes. Many generations, both male and female, affected.

Autosomal dominant

235

to diagnosis

Autosomal dominant

236

Mode of inheritance: Often due to enzyme deficiencies. Usually seen in only 1 generation.

Autosomal recessive

237

T/F Autosomal recessive diseases are commonly more severe than dominant disorders

T

238

Mode of inheritance: Increased risk in consanguineous families

Autosomal recessive

239

Mode of inheritance: Sons of heterozygous mothers have a 50% chance of being affected. No male-to-male transmission. Skips generations.

X-linked recessive

240

Mode of inheritance: Transmitted through both parents. Mothers transmit to 50% of daughters and sons; fathers transmit to all daughters but no sons.

X-linked dominant

241

Disease with X-linked dominant inheritance

Hypophosphatemic rickets, formerly known as vitamin D-resistant rickets

242

Mode of inheritance: Transmitted only through the mother. All offspring of affected females may show signs of disease

Mitochondrial inheritance

243

Muscle biopsy of mitochondrial myopathies often shows

Ragged red fibers

244

Autosomal dominant diseases

1) Autosomal dominant polycystic kidney disease (ADPKD) 2) FAP 3) Familial hypercholesterolemia 4) Hereditary hemorrhagic telangiectasia 5) Hereditary spherocytosis 6) Huntington disease 7) Li-Fraumeni syndrome 8) Marfan 9) MEN 10) NF 1 (von Recklinghausen) and 2 11) Tuberous sclerosis 12) von Hippel-Lindau

245

Colon becomes covered with adenomatous polyps after puberty, which may progress to colon cancer unless colon is resected

FAP

246

Severe atherosclerotic disease early in life, corneal arcus, tendon xanthomas (classically in Achilles tendon)

Familial hypercholesterolemia

247

Elevated LDL in familial hypercholesterolemia is due to

Defective or absent LDL receptor

248

Inherited disorder of blood vessels; branching skin lesions (telangiectasias), recurrent epistaxis, skin discolorations, arteriovenous malformations (AVMs), GI bleeding, hematuria

Hereditary hemorrhagic telangiectasia

249

Hereditary hemorrhagic telangiectasia is aka

Osler-Weber-Rendu syndrome

250

Hereditary spherocytosis is due to defect of

1) Spectrin 2) Ankyrin

251

Treatment for hereditary spherocytosis

Splenectomy

252

Depression, progressive dementia, choreiform movements, and caudate atrophy

Huntington disease

253

Neurotransmitter derrangement in Huntington

Increased dopamine, decreased GABA, decreased ACh

254

CAG repeat disorder

Huntington disease

255

Multiple malignancies at an early agar, aka SBLA cancer (sarcoma, breast, leukaemia, adrenal gland)

Li-Fraumeni syndrome

256

Pectus excavatum, hypermobile joints, and long, tapering fingers and toes (arachnodactyly)

Marfan

257

Cystic medial necrosis of aorta > aortic incompetence and dissecting aortic aneurysms

Marfan

258

Floppy mitral valve

Marfan

259

Direction of lens subluxation in Marfan

Upward and temporally

260

Optic gliomas, pheochromocytomas, Lisch nodules

NF1

261

What are Lisch nodules

Pigmented iris hamartomas

262

Bilateral acoustic schwannomas, juvenile cataracts, meningiomas, and ependymomas

NF2

263

Neurocutaneous disorder with multi-organ system involvement, characterized by numerous benign hamartomas

Tuberous sclerosis

264

Development of numerous tumors, both benign and malignant

von Hippel-Lindau disease

265

MC gene mutated in ADPKD

PKD1

266

Gene mutated in FAP

APC

267

Abnormal in Li-Fraumeni syndrome

TP53

268

Gene mutated in Marfan

FBN1

269

Gene mutated in MEN 1

MEN1

270

Gene mutated in MEN 2A and 2B

RET

271

Gene deleted in von Hippel-Lindau disease

VHL gene (tumor suppressor)

272

Deleted in cystic fibrosis

Phe508

273

Chromosome: ADPKD

16 [POLYCYSTIC KIDNEY = 16]

274

Chromosome: FAP

5q [POLYP = 5]

275

Chromosome: Huntington

4 [Hunting 4 food]

276

Chromosome: Marfan

15 [MARFAN SYNDROME = 15 including the space]

277

Chromosome: NF1

17 [VON RECKLINGHAUSEN = 17]

278

Chromosome: NF2

22

279

Chromosome: von Hippel-Lindau disease

3 [VON HIPPEL LINDAU = 3 words]

280

Autosomal recessive diseases

Albinism, autosomal recessive polycystic kidney disease (ARPKD), cystic fibrosis, glycogen storage diseases, hemochromatosis, Kartagener syndrome, mucopolysaccharidoses (except Hunter syndrome), phenylketonuria, sickle cell anemia, sphingolipidoses (except Fabry disease), thalassemias, Wilson disease

281

Most common lethal genetic disease in Caucasian population

Cystic fibrosis

282

Concentration of chloride in sweat that is diagnostic of CF

>60 mEq/L

283

GI complication seen in newborns with CF

Meconium ileus

284

T/F Patients with CF may have infertility

T, male absence of vas deferens, female amenorrhea and abnormally thick cervical mucus

285

Vitamin deficiency in CF

Fat-soluble vitamins (ADEK)

286

Treatment for CF

N-acetylcysteine (cleaves disulphide bonds within mucus glycoproteins

287

Gene defect in cystic fibrosis

CFTR

288

What does the CFTR gene encode

ATP-gated chloride channel that secretes chloride in the lungs and GIT, and reabsorbs chloride in sweat glands resulting in a compensatory increase in Na reabsorption

289

Chromosome: Cystic fibrosis

7

290

X-linked disorder typically due to frameshift (deletions, duplications, or nonsense) mutations

Duchenne muscular dystrophy

291

Gene deleted in Duchenne muscular dystrophy

Dystrophin gene (DMD)

292

The largest protein-coding human gene

Dystrophin gene (DMD)

293

Progress of muscle weakness in Duchenne muscular dystrophy

Pelvic girdle > superiorly

294

Pseudohypertrophy of calf muscles in Duchenne muscular dystrophy is due to

Fibrofatty replacement of muscle

295

Maneuver: Patients use upper extremities to help them stand up

Gower maneuver

296

Gait in Duchenne muscular dystrophy

Waddling

297

Onset of Duchenne muscular dystrophy

Less than 5 y/o

298

Preliminary diagnosis of Duchenne muscular dystrophy

Elevated CPK and aldolase

299

Confirmatory diagnosis of Duchenne muscular dystrophy

Western blot and muscle biopsy

300

X-linked disorder typically due to non-frameshift insertions in dystrophin gene

Becker

301

Becker vs Duchenne: More severe

Duchenne

302

Onset of Becker

Adolescence or adulthood

303

2nd most common cause of genetic intellectual disability (after Down syndrome)

Fragile X syndrome

304

CGG repeat disorder

Fragile X syndrome

305

Findings in Fragile X syndrome

Xtra large testes, jaw, and ears

306

Gene affected in Fragile X syndrome

FMR1

307

Cardiac abnormality associated with Fragile X syndrome

Mitral valve prolapse

308

GAA repeat disorder

Friedreich ataxia

309

CTG repeat disorder

Myotonic dystrophy

310

3 autosomal trisomies

13 [Puberty] Patau; 18 [Elect] Edward; 21 [Drink] Down

311

Gap between 1st 2 toe

Down

312

Brushfield spots

Down

313

Rocker- bottom feet

Edward and Patau

314

Micrognathia

Edward

315

Microphthalmia and microcephaly

Patau

316

Cleft liP/Palate

Patau

317

Early-onset Alzheimer disease

Chrom 21 codes for amyloid precursor protein

318

Increased risk of ALL and AML

Down

319

95% of cases of Down syndrome is due to

Meiotic nondisjunction

320

Clenched hands with overlapping fingers

Edward

321

2nd most common trisomy resulting in live birth

Edward

322

Most common viable chromosomal disorder

Down

323

Most common cause of genetic intellectual disability

Down

324

Chromosome: Cri-du-chat

5, short arm (p)

325

Chromosome: Wilms tumor

11

326

Chromosome: DiGeorge

22 (22q11)

327

X-chromosome

1) Fragile X 2) X-linked agammaglobulinemia 3) Klinefelter

328

Occurs when the long arms of 2 acrocentric chromosomes (chromosomes with centromeres near their ends) fuse at the centromere and the 2 short arms are lost

Robertsonian translocation

329

Cardiac abnormality in Cri du chat

VSD

330

Elfin facies; extreme friendliness with strangers

Williams syndrome

331

Chromosome: Williams syndrome

7

332

Aberrant development of 3rd and 4th branchial pouches

DiGeorge (thymic, parathyroid, cardiac defects; Velocardial syndrome (palate, facial, cardiac defects)

333

All water-soluble vitamins wash out easily from body except ___

B12 and folate (stored in liver)

334

Clenched hands with overlapping fingers

Edward

335

Uses ATP to add high-energy phosphate group onto substrate

Kinase

336

Adds inorganic phosphate onto substrate without using ATP

Phosphorylase

337

Removes phosphate group from substrate

Phosphatase

338

Catalyzes oxidation-reduction reactions

Dehydrogenase

339

Adds hydroxyl group (_OH) onto substrate

Hydroxylase

340

Transfers CO2 groups with the help of biotin

Carboxylase

341

Relocates a functional group within a molecule

Mutase

342

Rate-limiting enzyme: Glycolysis

PFK-1

343

Rate-limiting enzyme: Gluconeogenesis

Fructose-1,6-bisphosphatase

344

Rate-limiting enzyme: TCA cycle

Isocitrate dehydrogenase

345

Rate-limiting enzyme: Glycogenesis

Glycogen synthase

346

Rate-limiting enzyme: Glycogenolysis

Glycogen phosphorylase

347

Rate-limiting enzyme: HMP shunt

Glucose-6-phosphate dehydrogenase (G6PD)

348

Rate-limiting enzyme: De novo pyrimidine synthesis

Carbamoyl phosphate synthetase II

349

Rate-limiting enzyme: De novo purine synthesis

Glutamine-phosphoribosylpyrophosphate (PRPP) amidotransferase

350

Rate-limiting enzyme: Urea cycle

Carbamoyl phosphate synthetase I

351

Rate-limiting enzyme: Fatty acid synthesis

Acetyl-CoA carboxylase (ACC)

352

Rate-limiting enzyme: Fatty acid oxidation

Carnitine acyltransferase I

353

Rate-limiting enzyme: Ketogenesis

HMG-CoA synthase

354

Rate-limiting enzyme: Cholesterol synthesis

HMG-CoA reductase

355

Rate-limiting enzyme: Heme synthesis

ALA synthase

356

Regulators of enzyme: PFK-1

AMP _, fructose-2,6-bisphosphate _; ATP _, citrate _

357

Regulators of enzyme: Fructose-1,6-bisphosphatase

ATP _, acetyl-CoA _; AMP _, fructose-2,6-bisphosphate _

358

Regulators of enzyme: Isocitrate dehydrogenase

ADP_; ATP _, NADH _

359

Regulators of enzyme: Glycogen synthase

Glucose-6-phosphate _, insulin _, cortisol _; Epinephrine _, glucagon _

360

Regulators of enzyme: Glycogen phosphorylase

Epinephrine _, glucagon _, AMP _; Glucose-6-phosphate _, insulin _, ATP _

361

Regulators of enzyme: Glucose-6-phosphate dehydrogenase (G6PD)

NADP+ _; NADPH _

362

Regulators of enzyme: Carbamoyl phosphate synthetase II

ATP _; UTP _

363

Regulators of enzyme: Glutamine-phosphoribosylpyrophosphate (PRPP) amidotransferase

AMP _, inosine monophosphate (IMP) _, GMP _

364

Regulators of enzyme: Carbamoyl phosphate synthetase I

N-acetylglutamate _

365

Regulators of enzyme: Acetyl-CoA carboxylase (ACC)

Insulin _, citrate _; Glucagon _, palmitoyl-CoA _

366

Regulators of enzyme: Carnitine acyltransferase I

Malonyl-CoA _

367

Regulators of enzyme: HMG-CoA reductase

Insulin _, thyroxine _; Glucagon _, cholesterol _

368

Enzyme deficient in mild galactosemia

Galactokinase

369

Enzyme deficient in severe galactosemia

Galactose-1-phosphate uridyltransferase

370

Catalyzes INTERCONVERSION of glucose-1-phosphate and glucose-6-phosphate

Hexokinase/glucokinase

371

Enzyme deficient in von Gierke

Glucose-6-phosphatase (INTERCONVERSION between glucose and glucose-6-phosphate)

372

Glucose-6-phosphate dehydrogenase, catalyzes what

Glucose-6-phosphate to 6-phosphogluconolactone

373

Require thiamine as a cofactor

1) Transketolase 2) Pyruvate dehydrogenase 3) _-ketoglutarate dehydrogenase

374

Aerobic metabolism of glucose produces ___ net ATP via malate-aspartate shuttle

32

375

Malate-aspartate shuttle is found in what organs

Heart and liver

376

Aerobic metabolism of glucose produces ___ net ATP via glycerol-3-phosphate shuttle

30

377

Glycerol-3-phosphate shuttle is found in what organ

Muscle

378

Anaerobic glycolysis produces ___ net ATP per glucose molecule

2

379

___ causes glycolysis to produce zero net ATP

Arsenic

380

Carrier molecule: Phosphoryl groups

ATP

381

Carrier molecule: Electrons

NADH, NADPH, FADH2

382

Carrier molecule: Acyl groups

CoA, lipoamide

383

Carrier molecule: CO2

Biotin

384

Carrier molecule: Aldehydes

TPP

385

Carrier molecule: 1-carbon units

Tetrahydrofolates

386

NAD+ is from what vitamin

B3

387

FAD+ is from what vitamin

B2

388

Electron acceptor that is generally used in catabolic processes to carry reducing equivalents away

NAD+

389

Electron acceptor that is used in anabolic processes (steroid and fatty acid synthesis) as a supply of reducing equivalents

NADPH

390

NADPH is a product of the ___ shunt

HMP

391

NADPH is used in (4)

1) Anabolic processes 2) Respiratory burst 3) Cytochrome P-450 system 4) Glutathione reductase

392

1st step of glycolysis which also serves as the 1st step of glycogen synthesis in the liver

Phosphorylation of glucose to yield glucose-6-phosphate

393

Phosphorylation of glucose to yield glucose-6-phosphate is catalyzed by

Hexokinase/glucokinase

394

Hexokinase vs glucokinase: Induced by insulin

Glucokinase

395

Hexokinase vs glucokinase: Feedback-inhibited by glucose-6-phosphate

Hexokinase

396

Hexokinase vs glucokinase: Gene mutation associated with maturity-onset diabetes of the young (MODY)

Glucokinase

397

Steps in glycolysis that require ATP

1) Gluc > Gluc6P by hexokinase/glucokinase 2) Fruc6P > Fruc1,6BP

398

Steps in glycolysis that produce ATP

1) 1,3BPG > 3PG via phosphoglycerate kinase 2) PEP > pyruvate via pyruvate kinase

399

___ and ___ are the same bifunctional enzyme whose function is reversed by phosphorylation by protein kinase A

FBPase-2 (fructose bisphosphatase-2) and PFK-2

400

FBPase-2 vs PFK-2, active in fasting state

FBPase-2 (Fruc2,6BP is converted to Fruc6P > more glycolysis, less gluconeogenesis)

401

FBPase-2 vs PFK-2, active in fed state

PFK-2 (Fruc6P is converted to Fruc2,6BP instead of Fruc1,6BP > less glycolysis, more gluconeogenesis

402

Mitochondrial enzyme complex linking glycolysis and TCA cycle

Pyruvate dehydrogenase complex

403

Pyruvate dehydrogenase complex is active in, fed vs fasting state

Fed

404

Pyruvate dehydrogenase complex is activated vs inhibited by exercise

Activated

405

Pyruvate dehydrogenase complex is similar to the ___ (same cofactors, similar substrate and action) of the TCA cycle

_-ketoglutarate dehydrogenase complex

406

Pyruvate dehydrogenase complex, reaction catalyzed

_-ketoglutarate > succinyl-CoA

407

Inhibits lipoic acid

Arsenic

408

Findings in arsenic poisoning

Vomiting, rice-water stools, garlic breath

409

Treatment for pyruvate dehydrogenase complex deficiency

Inc intake of ketogenic nutrients

410

The only purely ketogenic amino acids

Lysine, Leucine [Think onLy pureLy ketogenic]

411

Pyruvate metabolic pathway: Carries amino groups to the liver from muscle

Alanine of alanine aminotransferase (cofactor: B6)

412

Pyruvate metabolic pathway: Oxaloacetate can replenish TCA cycle or be used in gluconeogenesis

Pyruvate carboxylase (cofactor: biotin)

413

Pyruvate metabolic pathway: Transition from glycolysis to the TCA cycle

Pyruvate dehydrogenase (co-factors: B1, B2, B3, B5, lipoic acid)

414

Pyruvate metabolic pathway: End of anaerobic glycolysis (major pathway in RBCs, WBCs, kidney medulla, lens, testes, and cornea)

Lactic acid dehydrogenase (c0-factor: B3)

415

Products of TCA cycle

1) 3 NADH 2) 2 CO2 3) 1 FADH2 4) 1 high-energy compound (GTP)

416

Electrons from glycolysis enters the mitochondria via

1) Malate-aspartate shuttle 2) Glycerol-3-phosphate shuttle

417

FADH2 from glycolysis are transferred to what complex of the ETC

II

418

How many ATP are produced via ATP synthase

1.5

419

Inhibit the ETC by causing a decrease in proton gradient and block of ATP synthesis

Electron transport inhibitors

420

Inhibit the ETC by causing an increase in proton gradient

ATP synthase inhibitors

421

Increases mitochondrial membrane permeability, causing a decrease in proton gradient and increase in O2 consumption; ATP synthesis stops but ETC continues

Uncoupling agents

422

ATP synthase inhibitor of the ETC

Oligomycin

423

What are the uncoupling agents

1) 2,4-dinitrophenol 2) Aspirin 3) Thermogenin

424

Irreversible enzymes of gluconeogenesis

1) Pyruvate carboxylase 2) PEP carboxykinase 3) Fructose-1,6- bisphosphatase 4) Glucose-6-phosphatase [Think Pathway Produces Fresh Glucose]

425

Irreversible enzyme of gluconeogenesis seen in the mitochondria

Pyruvate carboxylase

426

Irreversible enzymes of gluconeogenesis seen in the cytosol

1) PEP carboxykinase 2) Fructose-1,6-bisphosphatase

427

Irreversible enzyme of gluconeogenesis seen in the ER of liver cells

Glucose-6-phosphatase

428

Pyruvate > oxaloacetate

Pyruvate carboxylase

429

Oxaloacetate > PEP

PEP carboxykinase

430

Fructose-1,6-bisphosphate > fructose-6-phosphate

Fructose-1,6- bisphosphatase

431

Glucose-6-phosphate> glucose

Glucose-6-phosphatase

432

Gluconeogenesis occurs primarily in the

Mitochondria and cytosol of liver (other sites: kidney, intestinal epithelium)

433

Metabolic process that serves to maintain euglycemia in fasting

Gluconeogenesis

434

Muscle cannot participate in gluconeogenesis because it lacks

Glucose-6-phosphatase

435

Odd-chain vs even-chain fatty acids: Source of substrate for gluconeogenesis

Odd-chain

436

Even-chain fatty acids cannot produce new glucose because ___

They yield only acetyl-CoA equivalents

437

Odd-chain fatty acids yield ___ during metabolism, which can enter the TCA cycle and undergo gluconeogenesis

1 propionyl-CoA

438

1 propionyl-CoA from odd-chain fatty acids can enter the TCA cycle as

Succinyl-CoA

439

Provides a source of NADPH from abundantly available glucose-6-P

HMP shunt (pentose phosphate pathway)

440

NADPH is required for biosynthesis of (3)

1) Fatty acids 2) Cholesterol 3) Nucleotides (ribose) 4) Glycolytic intermediates

441

2 phases of HMP shunt

1) Oxidative 2) Non-oxidative

442

HMP shunt occurs in

Cytoplasm

443

Number of ATP used and produced in HMP shunt

NONE

444

Organs where HMP shunt can be found

1) Lactating mammary glands 2) Liver 3) Adrenal cortex 4) RBCs

445

Site of fatty acid or steroid synthesis

Adrenal cortex

446

HMP reaction that is irreversible

Oxidative reaction: G6PD

447

HMP reaction that is reversible

Non-oxidative: Phosphopentose isomerase, transketolases

448

Most common human enzyme deficiency; more prevalent in blacks

G6PD deficiency

449

Inheritance pattern of G6PD deficiency

X-linked recessive

450

G6PD deficiency increases resistance against what infection

Malaria

451

RBCs contain ___ in patients with G6PD deficiency

Heinz bodies (denatured/precipitated Hgb due to oxidative stress)

452

RBCs appear as ___ in patients with G6PD

Bite cells, due to phagocytic removal of Heinz bodies by splenic macrophages

453

Metabolic disorder resulting from deficiency of fructokinase

Essential fructosuria

454

Essential fructosuria is a benign, asymptomatic condition because

Fructose is not trapped in cells

455

Fructose intolerance is a hereditary deficiency of ___

Aldolase B

456

In fructose intolerance, ___ accumulates

Fructose-1-phosphate

457

Glucose level in fructose intolerance

Hypoglycemia

458

Why is there hypoglycemia in fructose intolerance

Decrease in available phosphate > inhibition of glycogenolysis and gluconeogenesis

459

Symptoms of fructose intolerance present following consumption of ___

Fruit, juice, or honey

460

T/F In fructose intolerance, urine dipstick will be positive

F

461

T/F In fructose intolerance, reducing sugar can be detected in the urine

T

462

Nonspecific test for inborn errors of carbohydrate metabolism

Detection of reducing sugars in urine

463

Treatment for fructose intolerance

Decrease intake of both fructose and sucrose (glucose + fructose)

464

In galactokinase deficiency, ___ accumulates if galactose is present in diet

Galactitol

465

Important finding in galactokinase deficiency that manifests as failure to track objects or develop a social smile

Infantile cataracts

466

Classic galactosemia is due to deficiency of

G1PUT

467

Classic galactosemia can lead to ___ sepsis in neonates

E. coli

468

Treatment for classic galactosemia

Exclude galactose and lactose (galactose + glucose) from the diet

469

Galactose is converted to galactitol (its alcohol counterpart) by what enzyme

Aldose reductase

470

Glucose is converted to sorbitol (its alcohol counterpart) by what enzyme

Aldose reductase

471

Some tissues convert sorbitol to fructose using ___; tissues with an insufficient amount of this enzyme are at risk for intracellular sorbitol accumulation, causing osmotic damage

Sorbitol dehydrogenase

472

BOTH aldose reductase and sorbitol dehydrogenase are found in what organs

1) Liver 2) Ovaries 3) Seminal vesicles

473

Organs/cells that have only aldose reductase

1) Schwann cells 2) Retina 3) Kidneys

474

Organ that has both aldose reductase and sorbitol dehydrogenase but PRIMARILY aldose reductase

Lens

475

Lactose intolerance characterized by an age-dependent decline after childhood, common in people of Asian, African, or Native American descent

Primary lactose intolerance

476

Lactose intolerance characterized by loss of brush border due to gastroenteritis (rotavirus), autoimmune disease, etc

Secondary lactose intolerance

477

Rare form of lactose deficiency and is due to defective gene

Congenital

478

Amino acids found in proteins

L-amino acids

479

Essential amino acids

[PVT TIM HALL always Argues but never TYRes] 1) Phenylalanine 2) Valine 3) Threonine 4) Isoleucine 5) Methionine 6) Histidine 7) Arginine 8) Lysine 9) Leucine

480

Amino acids that are both glucogenic and ketogenic

[KiLL PITT] 1) Phenylalanine 2) Isoleucine 3) Tryptophan 4) Threonine

481

Acidic amino acids

1) Aspartic acid 2) Glutamic acid

482

Basic amino acids

Basic HAL 1) Histidine 2) Arginine 3) Lysine

483

Most basic amino acid

Arginine

484

Amino acids that are negatively charged at body pH

Acidic a.a.

485

Amino acids that have no charge at body pH

Basic a.a.

486

Amino acids that are required during period of growth

1) Arginine 2) Histidine

487

Conversion of alanine to glucose and vice versa; an intermediate in amino acid catabolism

Cahill cycle

488

Conversion of lactate to glucose and vice versa; an intermediate in amino acid catabolism

Cori cycle

489

Hyperammonemia results in excess NH4+ (ammonium ion), which depletes what substrate of the TCA cycle

_-ketoglutarate

490

Given to patients with hyperammonemia to acidify the GI tract and trap NH4+ for excretion

Lactulose

491

Given in patients with hyperammonemia to decrease colonic ammoniagenic bacteria

Rifaximin

492

___ or ___ may be given to patients with hyperammonemia (both of which bind amino acid and lead to excretion)

Benzoate or phenylbutyrate

493

Required cofactor for carbamoyl phosphate synthetase I of urea cycle, the deficiency of which leads to hyperammonemia

N-acetylglutamate synthase deficiency

494

Most common urea cycle disorder

Ornithine transcarbamylase deficiency

495

The only X-linked recessive urea cycle disorder

Ornithine transcarbamylase deficiency

496

Ornithine transcarbamylase deficiency leads to excess ___ which is converted to orotic acid (pyrimidine synthesis)

Carbamoyl phosphate

497

In contrast to orotic aciduria, ornithine transcarbamylase does not present with

Megaloblastic anemia

498

Glycine derivatives

1) Porphyrin 2) Heme

499

Glutamate derivatives

1) GABA 2) Glutathione

500

Arginine derivatives

1) NO 2) Creatine 3) Urea