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Biochemistry Flashcards

1
Q

What are the components of a histone?

A

2 each of: H2A, H2B, H3, H4

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2
Q

What is the role of H1 in histones?

A

Ties nucleosome beads together

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3
Q

Which chromatin protein is not part of the nucleosome core?

A

H1

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4
Q

Which form of chromatin is condensed and inactive?

A

Heterochromatin

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5
Q

Which form of chromatin is open and transcribed?

A

Euchromatin

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6
Q

Histone methylation effects

A

Usually blocks DNA transcription (can activate it in some contexts)

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7
Q

Histone acetylation effects

A

Relaxes DNA coiling, allows transcription

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8
Q

What amino acids are histones rich in?

A

Lysine and arginine (basic, bind negatively-charged DNA)

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9
Q

Name the purines

A

Adenine

Guanine

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10
Q

Name the pyrimidines

A

CUT: cytosine, uracil, thymine

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11
Q

What chemical group does guanine have?

A

Ketone

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12
Q

What chemical group does thymine have?

A

THYmine has a meTHYl

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13
Q

How many hydrogen bonds in G-C pairs? A-T pairs? Significance?

A

GC = 3, AT = 2.

Higher GC content = higher melting temperature.

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14
Q

What amino acids are necessary for purine synthesis?

A

GAG: glycine, aspartate, glutamine

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15
Q

What are the components of a nucleoside?

A

Base + ribose (sugar)

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16
Q

What are the components of a nucleotide?

A

Base + ribose (sugar) + phosphate

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17
Q

Group involved in purine synthesis

A

N10-formyl-tetrahydrofolate

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18
Q

Orotic aciduria defect

A

UMP synthase (AR)

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19
Q

Orotic aciduria findings

A

Orotic acid in urine, megaloblastic anemia (does not improve with B12 administration), no hyperammonemia

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20
Q

Orotic aciduria treatment

A

Oral uridine administration

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21
Q

What converts ribonucleotides to deoxyribonucleotides? What inhibits this enzyme?

A

Ribonucleotide reductase

Hydroxyurea

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22
Q

6-mercaptopurine

A

Blocks de novo purine synthesis

6-MP, prodrug is azathioprine

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23
Q

5-FU

A

Blocks thymidylate synthase (finding: low dTMP)

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24
Q

Methotrexate (MTX)/Trimetoprim (TMP)

A

Block dihydrofolate reductase (finding: low dTMP)

TMP inhibits bacterial enzyme

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25
Q

What two pathways use carbamoyl phosphate?

A

1) De novo pyrimidine synthesis

2) Urea cycle

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26
Q

Adenosine deaminase deficiency pathophysiology

A

Excess ATP and dATP inhibit ribonucleotide reductase (negative feedback) and prevent DNA synthesis.

Autosomal recessive.

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27
Q

Lesch-Nyhan syndrome defect

A

HGPRT (He’s Got Purine Recovery Trouble)
Converts hypoxanthine to IMP and guanine to GMP

X-linked recessive.

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28
Q

What does degenerate/redundant refer to (genetic code)?

A

Most amino acids are coded for by multiple codons (exceptions: Met and Trp)

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29
Q

What does unambiguous refer to (genetic code)?

A

Each codon specifies 1 amino acid

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30
Q

What does commaless/overlapping refer to (genetic code)?

A

Read continuously from a fixed starting point

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31
Q

What does universal refer to (genetic code)?

A

Conserved throughout evolution (exception: mitochondria)

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32
Q

Adenosine deaminase deficiency findings

A

Low lymphocyte count (SCID)

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33
Q

Lesch-Nyhan syndrome findings

A

Excess uric acid (hyperuricemia and gout) and de novo purine synthesis

Retardation, self-mutilation, aggression, choreoathetosis

HGPRT: (Hyperuricemia, Gout, Pissed off (aggression, self-mutilation,) Retardation, dysTonia)

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34
Q

Adenosine deaminase deficiency treatment

A

Gene therapy

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35
Q

Silent DNA mutation

A

Same AA, base change is usually in the third position (tRNA wobble allows this)

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36
Q

Missense DNA mutation

A

Changed AA (conservative = similar properties in new AA - like hydrophobic for hydrophobic)

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37
Q

Nonsense DNA mutation

A

Early stop codon

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38
Q

Frameshift DNA mutation

A

Insertion or deletion results in misreading of all downstream codons

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39
Q

Rank the types of mutations: frameshift, missense, silent, nonsense

A

Silent < missense < nonsense < frameshift

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40
Q

What breaks down dopamine, norepi, and epi?

A

MAO and COMT

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41
Q

Breakdown product of dopamine?

A

HVA

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42
Q

Breakdown product of epinephrine?

A

Metanephrine

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43
Q

Breakdown product of norephinephrine?

A

VMA, normetanephrine

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44
Q

Catecholamine synthesis progression

A

Phe -> Tyr -> Dopa -> Dopamine -> Norepi -> Epi

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45
Q

What converts phenylalanine to tyrosine? What cofactor is required?

A

Phenylalanine hydroxylase

NADPH and THB (NADPH converts DHB to THB)

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46
Q

What converts tyrosine to dopa? What cofactor is required?

A

Tyrosine hydroxylase

NADPH and THB (NADPH converts DHB to THB)

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47
Q

What converts dopa to dopamine? What cofactor is required?

A

Dopa decarboxylase

Vit. B6

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48
Q

What converts dopamine to norepinephrine? What cofactor is required?

A

Dopamine beta-hydroxylase

Vit. C

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49
Q

What converts norepinephrine to epinephrine? What cofactor is required?

A

PNMT

SAM

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50
Q

What does a hydroxylase do?

A

Adds an -OH group

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51
Q

What does a decarboxylase do?

A

Removes COOH

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52
Q

PKU defect

A

Phe hydroxylase or THB cofactor (malignant)

Autosomal recessive

Tyrosine becomes an essential AA

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53
Q

PKU findings

A

Phenylketones in urine (phenylacetate, phenyllactate, phenylpyruvate)

Mental retardation, growth retardation, seizures, fair skin, eczema, musty body odor

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54
Q

PKU treatment

A

Restrict Phe in diet (present in aspartame-containing products) and increase Tyr intake

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55
Q

Maternal PKU

A

Lack of proper dietary therapy during pregnancy

Findings in infant: microcephaly, mental retardation, growth retardation, congenital heart defects

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56
Q

Alkaptonuria (ochronosis) defect

A

Homogentisic acid oxidase in the degrade pathway of tyrosine to fumarate

Autosomal recessive

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57
Q

Alkaptonuria (ochronosis) findings

A

Dark connective tissue, brown sclera, urine turns black on prolonged exposure to air.

May have debilitating arthralgia (homogentisic acid is toxic to cartilage).

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58
Q

Albinism defect

A

Tyrosinase (can’t make melanin from Tyr)
Autosomal recessive

Tyrosine transporters (less tyrosine available)

Also can result from lack of migration from neural crest cells

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59
Q

Albinism findings

A

Increased risk of skin cancer (lack of melanin)

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60
Q

Homocystinuria defects (3 forms)

A

Cystationine synthase deficiency

Low affinity of cystathionine synthase for pyridoxal phosphate

Homocysteine methyltransferase deficiency

(All three are autosome recessive)

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61
Q

Homocystinuria findings

A

Excess homocysteine in urine
Cysteine becomes an essential AA

Mental retardation, osteoporosis, tall stature, kyphosis, lens subluxation (downward and inward), atherosclerosis (stroke and MI)

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62
Q

Homocystinuria treatment

A

Cystathionine synthase deficiency: restrict Met intake, increase Cys, B12, and folate intake in diet

Low affinity cystathionine synthase: B6 in diet

Homocysteine methyltransferase: B12

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63
Q

Cystinuria defect

A

Renal tubular AA transporter for Cys, ornithine, Lys, and Arg in the PCT of the kidneys

Autosomal recessive

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64
Q

Cystinuria findings

A

Excess cysteine in urine

Precipitation of hexagonal crystals and renal staghorn calculi

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65
Q

Cystinuria treatment

A

Hydration and urinary alkalinization

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66
Q

Maple syrup urine disease defect

A

Blocked degradation of branched amino acids (Ile, Leu, Val - I Love Vermont maple syrup) due to low alpha-ketoacid dehydrogenase (B1)

Autosomal recessive

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67
Q

Maple syrup urine disease findings

A

Urine smells like syrup
Increased alpha-ketoacids in the blood, especially Leu
Severe CNS defects, mental retardation, and death

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68
Q

Hartnup disease defect

A

Defective neutral amino acid transporter on renal cells and intestinal epithelial cells

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69
Q

Hartnup disease findings

A

Tryptophan excretion in urine and decreased absorption from gut

Leads to pellagra (niacin deficiency)

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70
Q

Glycogen bond types

A

Linkages: alpha-1,4
Branches: alpha-1,6

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71
Q

Insulin receptor type

A

Tyrosine kinase

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72
Q

Glucagon receptor type

A

GPCR

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73
Q

Glycogen regulation by insulin

A

Activates protein phosphatases which inactivate glycogen phosphorylase and glycogen phosphorylase kinase (glycogenesis)

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74
Q

Glycogen regulation by glucagon/epinephrine

A

Activate PKA, which activates glycogen phosphorylase kinase, which activates glycogen phosphorylase (glycogenolysis)

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75
Q

Glycogen regulation by Ca++/calmodulin

A

Activates glycogen phosphorylase kinase so that glycogenolysis is coordinated with muscle activity

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76
Q

Glycogenolysis progression (skeletal muscle)

A

Glycogen -> glucose-1-phosphate -> glucose-6-phosphate -> used in glycolysis

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77
Q

Glycogenolysis progression (liver)

A

Glycogen -> glucose-1-phosphate -> glucose-6-phosphate -[glucose-6-phosphatase]-> glucose released into blood

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78
Q

What converts glucose-1-phosphate to UDP-glucose?

A

UDP-glucose phosphorylase

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79
Q

What converts UDP-glucose to glycogen?

A

Glycogen synthase

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80
Q

What adds branches to glycogen?

A

Branching enzyme

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81
Q

What releases glucose-1-phosphate from glycogen?

A

Glycogen phosphorylase

Defect in McArdle’s (type V)

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82
Q

What takes branches off of glycogen?

A

Debranching enzyme (alpha-1,6-glucosidase)

Defect in Cori’s disease (type III)

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83
Q

Type I glycogen storage disease defect

A

Glucose-6-phosphatase

Autosomal recessive

Von Gierke’s disease

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84
Q

Type II glycogen storage disease defect

A

Lysosomal alpha-1,4-glucosidase

Autosomal recessive

Pompe’s disease

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85
Q

Type III glycogen storage disease defect

A

Debranching enzyme (alpha-1,6-glucosidase)

Autosomal recessive

Cori’s disease

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86
Q

Type V glycogen storage disease defect

A

Skeletal muscle glycogen phosphorylase

McArdle’s disease

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87
Q

Type I glycogen storage disease findings

A

Severe fasting hypoglycemia
High glycogen in liver, high blood lactate, hepatomegaly

Von Gierke’s disease

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88
Q

Type II glycogen storage disease findings

A

Cardiomegaly and systemic findings leading to early death

Pompe’s trashes the Pump (heart, liver, muscle)

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89
Q

Type III glycogen storage disease findings

A

Like type I (fasting hypoglycemia, high glycogen in liver, hepatomegaly) but with normal blood lactate

Gluconeogenesis is intact

Cori’s disease

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90
Q

Type V glycogen storage disease findings

A

High glycogen in muscle that can’t be broken down leads to painful cramps and myoglobinuria with exercise

McArdle’s = Muscle

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91
Q

What breaks down glycogen in lysosomes?

A

Alpha-1,4-glucosidase

Defect in Pompe’s disease (type II)

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92
Q

Fabry’s disease deficit

A

Alpha-galactosidase A

X-linked recessive

(Lysosomal storage disease)

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93
Q

Fabry’s disease findings

A

Peripheral neuropathy of hands/feet, angiokeratomas, cardiovascular/renal disease

Ceramide trihexosidase accumulates

(Lysosomal storage disease)

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94
Q

Gaucher’s disease deficit

A

Glucocerebrosidase

Autosomal recessive

(Lysosomal storage disease)

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95
Q

Gaucher’s disease findings

A

Most common lysosomal storage disease

Hepatosplenomegaly, aseptic necrosis of femur, bone crises, Gaucher’s cells (macrophages that look like crumpled tissue paper)

Glucocerebroside accumulates

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96
Q

Niemann-Pick disease deficit

A

Spingomyelinase

Autosomal recessive

(Lysosomal storage disease)

No man picks (Niemann-Pick) his nose with his sphinger (shingomyelinase)

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97
Q

Niemann-Pick disease findings

A

Progressive neurodegeneration, hepatosplenomegaly, cherry-red spot on macula, foam cells

Sphingomyelin accumulates

(Lysosomal storage disease)

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98
Q

Tay-Sachs disease deficit

A

Hexosaminidase A

Autosomal recessive

(Lysosomal storage disease)

Tay-SaX lacks heXosaminidase

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99
Q

Tay-Sachs disease findings

A

Progressive neurodegeneration, developmental delay, cherry-red spot on macula, lysosomes with onion skin, no hepatosplenomegaly (vs. Niemann-Pick)

GM2 ganglioside accumulates

(Lysosomal storage disease)

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100
Q

Krabbe’s disease deficit

A

Galactocerebroside

Autosomal recessive

(Lysosomal storage disease)

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101
Q

Krabbe’s disease findings

A

Peripheral neuropathy, developmental delay, optic atrophy, globoid cells

Galactocerebroside accumulates

(Lysosomal storage disease)

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102
Q

Metachromatic leukodystrophy deficit

A

Arylsulfatase A

Autosomal recessive

(Lysosomal storage disease)

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103
Q

Metachromatic leukodystrophy findings

A

Central and peripheral demyelination with ataxia, dementia

Cerebroside sulfate accumulates

(Lysosomal storage disease)

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104
Q

Hurler’s syndrome deficit

A

Alpha-L-iduronidase

Autosomal recessive

(Lysosomal storage disease)

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105
Q

Hurler’s syndrome findings

A

Developmental delay, gargoylism, airway obstruction, corneal clouding, hepatosplenomegaly

Heparan sulfate and dermatan sulfate accumulate

(Lysosomal storage disease)

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106
Q

Hunter’s syndrome deficit

A

Iduronate sulfatase

X-linked recessive

(Lysosomal storage disease)

Hunters see clearly (no corneal clouding) and aim for the X (X-linked)

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107
Q

Hunter’s syndrome findings

A

Mild Hurler’s (developmental delay, gargoylism, airway obstruction, corneal clouding, hepatosplenomegaly) + aggressive behavior, no corneal clouding

Heparan sulfate and dermatan sulfate accumulate

(Lysosomal storage disease)

Hunters see clearly (no corneal clouding) and aim for the X (X-linked)

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108
Q

Carnitine deficiency: pathophysiology and signs

A

Inability to transport LCFA’s into the mitochondria, results in toxic accumulation

Weakness, hypotonia, hypoketotic hypoglycemia

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109
Q

Citrate shuttle pathway

A

Fatty acid synthesis

SYtrate = SYnthesis

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110
Q

Carnitine shuttle pathway

A

Fatty acid degradation

CARnitine = CARnage of fatty acids

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111
Q

Acyl-CoA dehydrogenase deficiency signs

A

Acyl-CoA dehydrogenase does the first step in beta-oxidation (degradation) of fatty acids

Deficiency gives you increased dicarboxylic acids, decreased glucose and ketones

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112
Q

When might the body make ketone bodies?

A

Prolonged starvation (low glucose), diabetic ketoacidosis (low glucose utilization), alcoholism (excess NADH)

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113
Q

How many calories are in a gram of protein? Carbohydrate? Fat?

A

Protein and carbohydrate: 4 kcal

Fat: 9 kcal

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114
Q

What are two examples of ketone bodies?

A

Acetoacetate and beta-hydroxybutyrate

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115
Q

Why does alcoholism lead to ketone body production?

A

Excess NADH shunts oxaloacetate to malate, which stalls the TCA cycle, shunting glucose and FFA toward ketone body production

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116
Q

What are clinical signs of ketone body production?

A

Breath smells like acetone (fruity)

Urine tests for ketones (exception: doesn’t detect beta-hydroxybutyrate)

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117
Q

Cholesterol synthesis: rate-limiting step

A

HMG-CoA reductase converts HMG-CoA to mevalonate

Inhibited by statins

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118
Q

What happens to cholesterol after synthesis?

A

2/3 of plasma cholesterol is esterified by lecithin-cholesterol acyltransferase (LCAT)

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119
Q

Main energy supply in the fed state (after a meal)

A

Glycolysis and aerobic respiration

Insulin stimulates storage of lipids, proteins, and glycogen

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120
Q

Main energy supply in the fasting state

A

Hepatic glycogenolysis (major), hepatic gluconeogenesis, adipose release of FFA

Glucagon and adrenaline stimulate use of fuel reserves

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121
Q

Main energy supply in the starvation state (days 1-3)

A

Hepatic glycogenolysis, adipose release of FFA, muscle and liver shift fuel use from glucose to FFA, hepatic gluconeogenesis from peripheral tissue lactate and alanine, and from adipose tissue glycerol and propionyl-CoA (only odd-chained FFA)

Glycogen reserves depleted after day 1, RBCs can’t use ketones (no mitochondria)

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122
Q

Main energy supply in the starvation state (days 3+)

A

Adipose stores (ketone bodies become the main energy source for brain and heart), protein degradation accelerates

Amount of adipose storage determines survival time

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123
Q

Order of energy stores used in exercise

A

Stored ATP (initial) –> creatine phosphate (seconds) –> anaerobic glycolysis (minutes) –> aerobic metabolism and FA oxdation (hours)

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124
Q

Type IV glycogen storage disease defect

A

Branching enzyme

Autosomal recessive

Andersen’s disease

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125
Q

Type IV glycogen storage disease findings

A

Long unbranched glycogen, cirrhosis, early death

Andersen’s disease

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126
Q

Pancreatic lipase actions

A

Degrades dietary TG in small intestine

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127
Q

Lipoprotein lipase (LPL) actions

A

Degrades TG circulating in chylomicrons and VLDLs

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128
Q

Hepatic TG lipase (HL) actions

A

Degradation of TG remaining in IDL

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129
Q

Hormone-sensitive lipase actions

A

Degradation of TG stored in adipocytes

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130
Q

Lecithin-cholesterol acyltransferase (LCAT) actions

A

Esterification of cholesterol (adds esters to make nascent HDL into mature HDL)

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131
Q

Cholesterol ester transfer protein (CETP) actions

A

Transfer of cholesterol esters to other lipoprotein particles (from mature HDL to VLDL, IDL, LDL)

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132
Q

Rank these lipoproteins from most dense to least dense: LDL, IDL, VLDL, HDL, chylomicron

A

HDL > IDL > LDL > VLDL > chylomicron

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133
Q

Lipid transport in blood overview

A

Chylomicrons synthesized in intestine from dietary fat and released into blood

LPL pulls off FFA’s which get taken up by cells for energy, leaving behind chylomicron remnants which get taken up by the liver

Liver produces and releases VLDL, LPL removes TGs from VLDL, producing IDL and then HL removes TGs to yield LDL, which gets taken up by the liver

Nascent HDL is produced and secreted by the liver and intestine, matures when LCAT adds esters

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134
Q

ApoE function + what lipoproteins have it?

A

Mediates remnant uptake by liver

All except LDL

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135
Q

ApoA-I function + what lipoproteins have it?

A

Activates LCAT

HDL

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136
Q

ApoC-II function + what lipoproteins have it?

A

LPL cofactor

Chylomicrons, VLDL, HDL

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137
Q

ApoB-48 function + what lipoproteins have it?

A

Mediates chylomicron secretion

Chylomicrons, remnants

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138
Q

ApoB-100 function + what lipoproteins have it?

A

Binds LDL receptor

VLDL, IDL, LDL

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139
Q

LDL functions

A

Transports cholesterol from liver to tissues

Formed by HL modification of IDL in the periphery

Taken up by receptor-mediated endocytosis (clathrin)

LDL is Lousy (“bad” cholesterol)

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140
Q

HDL functions

A

Transports cholesterol from periphery to liver (reverse transport)

Repository for ApoC and ApoE (needed for chylomicron and VLDL metabolism)

Secreted by liver and intestine

HDL is Healthy (“good” cholesterol)

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141
Q

Chylomicron functions

A

Delivers dietary TGs to peripheral tissue, delivers cholesterol to liver in the form of chylomicron remnants (depleted of TAGs)

Secreted by intestine

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142
Q

VLDL functions

A

Delivers hepatic TGs to peripheral tissue

Secreted by liver

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143
Q

IDL functions

A

Delivers triglycerides and cholesterol to the liver

Formed by VLDL degradation in the periphery

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144
Q

Hyperchylomicronemia (type I): increased blood level?

A

Chylomicrons, TG, cholesterol

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145
Q

Familial hypercholesterolemia (type IIa): increased blood level?

A

LDL, cholesterol

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146
Q

Hypertryiglyceridemia (type IV): increased blood level?

A

VLDL, TG

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147
Q

Abetalipoproteinemia defect

A

Microsomal triglyceride transport protein (MTP) defect

Autosomal recessive

Low B-48 and B-100 -> low chylomicron and VLDL synthesis and secretion

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148
Q

Hyperchylomicronemia (type I): pathophysiology?

A

Autosomal recessive

LPL deficiency or altered ApoC-II

Pancreatitis, hepatosplenomegaly, eruptive/pruritic xanthomas (no additional atherosclerosis risk)

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149
Q

Familial hypercholesterolemia (type IIa): pathophysiology?

A

Autosomal dominant

LDL receptor defect

Accelerated atherolsclerosis, tendon xanthomas, corneal arcus (white, gray, or blue ring)

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150
Q

Hypertryiglyceridemia (type IV): pathophysiology?

A

Autosomal dominant

Hepatic overproduction of VLDL

Pancreatitis

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151
Q

Microsomal triglyceride transport protein (MTP) functions

A

Important in lipoprotein assembly and secretion, requires B-48 and B-100

Defect in abetalipoproteinemia

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152
Q

Abetalipoproteinemia findings

A

Symptoms appear in the first few months of life

Lipid accumulation within enterocytes in intestines (inability to export absorbed chylomicrons)

Failure to thrive, steatorrhea, acanthoyctosis, ataxia, night blindness

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153
Q

Origin of replication

A

Consensus sequence of base pairs in genome where DNA replication begins

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154
Q

Replication fork

A

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

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155
Q

Helicase

A

Unwinds DNA at the replication fork

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156
Q

Single-stranded binding proteins

A

Prevent strands from reannealing

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157
Q

DNA topoisomerases (what antibiotic blocks them?)

A

Creates a nick in the helix to relieve supercoiling created during replication

Fluoroquinolones (-floxacin) inhibit DNA gyrase

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158
Q

Primase

A

Makes an RNA primer on which DNA polymerase III can initiate replication

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159
Q

DNA polymerase III

A

Prokaryotic only. 5’ -> 3’ synthesis, 3’ -> 5’ proofreading (exonuclease)

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160
Q

DNA polymerase I

A

Prokaryotic only. 5’ -> 3’ synthesis, 5’ -> 3’ exonuclease (to degrade RNA primer)

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161
Q

DNA ligase

A

Forms phosphodiesterase bonds within a strand of dsDNA (joins Okazaki fragments)

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162
Q

Telomerase

A

Adds DNA to 3’ ends to avoid loss of genetic material with duplication

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163
Q

Nucleotide excision repair

A

Repairs bulky helix-distorting lesions (multiple bases)

Endonucleases release the damaged bases, DNA polymerase and ligase fill in the gap

Defect in xeroderma pigmentosum (pyrimidine dimers following UV light exposure)

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164
Q

Base excision repair

A

Glycosylases recognize and remove single bases, apurinic/apyrimidinic endonuclease cuts DNA, empty sugar is removed, gap is filled and sealed

Important for spontaneous deamination repair

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165
Q

Mismatch repair

A

Newly synthesized strand is recognized, mismatched nucleotides are removed, gap is filled and resealed

Mutated in hereditary nonpolyposis colorectal cancer (HNPCC) - autosomal dominant

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166
Q

Nonhomologous end joining

A

Brings together two ends of DNA fragments to repair double-stranded breaks (no homology requirement)

Defect in ataxia telangiectasia

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167
Q

What direction are DNA and RNA synthesized in?

A

5’ -> 3’

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168
Q

What direction are proteins synthesized in?

A

N-terminus to C-terminus (C is the caboose)

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169
Q

What reaction happens when you add another base to DNA or RNA?

A

Triphosphate bond of the incoming nucleotide is attacked by the 3’-OH of the last base on the existing chain

Drugs that block DNA synthesis (also used in lab a lot) have no 3’-OH so chain terminates

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170
Q

3 types of RNA

A

rRNA (most abundant) - ribosomes, protein synthesis
mRNA (longest) - transcription product
tRNA (smallest) - carry charged AA’s to ribosome

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171
Q

mRNA start codon

A

AUG (rarely GUG)

AUG inAUGurates protein synthesis

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172
Q

What AA does AUG code for in eukaryotes?

A

Methionine

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173
Q

What AA does AUG code for in prokaryotes?

A

f-Met (formyl-methionine)

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174
Q

mRNA stop codons

A

UAA, UGA, UAG

U Are Annoying
U Go Away
U Are Gone

175
Q

What base number is the transcription start point

A

+1

176
Q

Promoter function, location, effect of mutation

A

Site where RNA polymerase and other transcription factors bind to DNA

Upstream of gene locus, TATA and CAAT boxes

Mutations result in dramatic reduction in gene transcription

177
Q

Enhancer function, location

A

Activates gene expression by binding transcription factors

Can be close to, far from, or within the gene it regulates

178
Q

Silencer function, location

A

Inactivates gene expression by binding negative regulators (repressors)

Can be close to, far from, or within the gene it regulates

179
Q

RNA polymerase I

A

Makes rRNA

180
Q

RNA polymerase II

A

Makes mRNA

181
Q

RNA polymerase III

A

Markes tRNA

182
Q

What inhibits RNA polymerase II? What happens if you ingest it?

A

Alpha-amanitin from death cap mushrooms

Causes severe hepatotoxicity if ingested

183
Q

Prokaryotic RNA polymerase

A

Only one, makes all 3 kinds of RNA (r, m, t)

184
Q

RNA processing: initial transcript name

A

hnRNA (heterogeneous nuclear RNA)

If destined for translated, pre-mRNA

185
Q

RNA processing steps

A

Addition of 5’ cap (addition of 7-methylguanosine cap) and 3’ polyadenylation

Splicing

186
Q

Polyadenylation signal

A

AAUAAA

187
Q

Splicing steps (+ what component might lupus patients make antibodies against?)

A

1) Primary transcript combines with snRNPs to form the spliceosome
2) Lariat-shaped (looped) intermediate is generated
3) Lariat is released to remove the intron and join two exons

Lupus patients can have snRNP antibodies

188
Q

Are introns or exons expressed into protein?

A

Exons

189
Q

tRNA structure (+ what is the 3’ sequence?)

A

75-90 nucleotides, cloverleaf form with secondary structure and anticodon opposite of the 3’ end

3’ sequence is CCA: Can Carry Amino acids

190
Q

tRNA charging enzyme

A

Aminoacyl-tRNA synthetase

191
Q

tRNA wobble

A

Accurate base pairing often only required for the first 2 nucleotides

Codons differing in the 3rd position frequently code for the same AA (degeneracy)

192
Q

What makes sure the right AA charges a tRNA?

A

Aminoacyl-tRNA synthetase reads the amino acid before and after it binds the tRNA. Hydrolyzes bond if incorrect.

193
Q

What antibiotic binds the 30S ribosome and prevents the attachment of aminoacyl-tRNA to the ribosome?

A

Tetracyclines (-cyclines)

194
Q

Posttranslational modificiations: trimming

A

Removal of N- or C-terminal pro peptides from zymogens

195
Q

Posttranslational modificiations: covalent alterations

A

Phosphorylation, glycosylation, hydroxylation, methylation, acetylation

196
Q

Posttranslational modificiations: proteasomal degradation

A

Attachment of ubiquitin to target them for breakdown

197
Q

Eukaryotic ribosome components

A

40S + 60S = 80S

198
Q

Prokaryotic ribosome components

A

30S + 50S = 70S

199
Q

Protein synthesis initiation

A

Initiation factors (eIF’s) help assemble the 40S ribosomal subunit with the initiator tRNA and are released when the mRNA and the ribosomal subunit assemble with the complex

200
Q

What molecule provides the energy for tRNA charging?

A

ATP

201
Q

What molecule provides the energy for AA translocation?

A

GTP

202
Q

Protein synthesis elongation

A

1) Aminoacyl-tRNA binds to the A site (except initiator Met, which binds the P site)
2) rRNA catalyzes peptide bond formation, transfers growing peptide to AA in the A site
3) Ribosome advances 3 nucleotides toward the 3’ end of the mRNA, pushing peptidyl tRNA to the P site (translocation)

203
Q

Protein synthesis termination

A

Stop codon is recognized by release factor, completed protein is released from the ribosome

204
Q

Ribosome sites: A, P, E

A

A: incoming Aminoacyl-tRNA
P: accommodates the growing Peptide
E: holds Empty tRNA as it Exits

205
Q

What antibiotic binds the 30S subunit to inhibit formation of the initiation complex?

A

Aminoglycosides (-micin or -mycin, though azithromycin and vancomycin and others are exceptions)

206
Q

What antibiotic binds the 50S subunit and inhibits peptidyl transferase activity?

A

Chloramphenicol

207
Q

What antibiotic binds 50S subunit and prevents release of uncharged tRNA from the E site?

A

Macrolides (azithromycin, erythromycin, other -mycins)

208
Q

What phase of the cell cycle do Rb and p53 function in?

A

Prevent the transition from G1 to S phase

209
Q

Permanent cell cycle characteristics + examples

A

Remain G0

Neurons, skeletal muscle, cardiac muscle, RBCs

210
Q

Stable (quiescent) cell cycle characteristics + examples

A

Enter G1 from G0 when stimulated

Hepatocytes, lymphocytes

211
Q

Labile cell cycle characteristics + examples

A

Never go to G0, divide rapidly with a short G1

Bone marrow, gut epithelium, skin, hair follicles, germ cells

212
Q

RER functions

A

Synthesis of secretory proteins and N-linked oligosaccharide addition to proteins

213
Q

Nissl bodies

A

RER in neurons, synthesize enzymes and peptide neurotransmitters (like ACh)

214
Q

Free ribosomes

A

Synthesis of cytosolic and organeller proteins

215
Q

Cell types rich in RER

A

Mucus-secreting goblet cells of the small intesting and antibody-secreting plasma cells

216
Q

Cell types rich in SER

A

Liver hepatocytes and steroid hormone-producing cells in the adrenal cortex

217
Q

Cell cycle phases

A

Interphase (G1, S, G2) and metaphase (Prophase, Metaphase, Anaphase, Telophase) + G0

218
Q

Peroxisome functions

A

Membrane-enclosed, catabolism of very long fatty acids and AAs

219
Q

Proteasome functions

A

Barrel-shaped protein complex that degrades proteins tagged with ubiquitin

220
Q

Clathrin vesicles

A

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

221
Q

COPI vesicles

A

Retrograde golgi -> golgi, golgi -> ER

222
Q

COPII vesicles

A

Anterograde golgi -> golgi, ER -> golgi

223
Q

I-cell disease defect

A

Failure of addition of mannose-6-phosphate to lysosome proteins (get secreted outside of cell instead of targeted to lysosome)

224
Q

I-cell disease findings

A

Coarse facial features, clouded corneas, restricted joint movement, high plasma levels of lysosomal enzymes

Fatal in childhood

225
Q

Golgi apparatus function

A

Trafficking center

226
Q

What amino acid(s) are modified with N-oligosaccarharides?

A

Asparagine

227
Q

What amino acid(s) are modified with O-oligosaccharides?

A

Serine and threonine

228
Q

Microtubule components

A

Polymerized dimers of alpha-tubulin and beta-tubulin (each dimer has 2 GTP bound)

229
Q

What structures are made of microtubules?

A

Flagella (eukaryotic), cilia, mitotic spindles, axonal trafficking

230
Q

Dynein motor direction

A

Retrograde (+ -> -)

231
Q

Kinesin motor direction

A

Anterograde (- -> +)

Kinesin Keeps going forward

232
Q

Chediak-Higashi syndrome defect

A

Mutation in lysosomal trafficking regulator gene (LYST), which is required for microtubule-dependent sorting of endosomal proteins into late endosomes

233
Q

Chediak-Higashi findings

A

Recurrent pyogenic infections, partial albinism, peripheral neuropathy

234
Q

Drugs that act on microtubules

A

Mebendazole/thiabendazole (antihelminthic)

Griseofulvin (antifungal)

Vincristine/vinblastine (chemo)

Paclitaxel (breast cancer)

Colchicine (gout)

Microtubules Get Constructed Very Poorly

235
Q

Cilia structure

A

9 + 2 arrangement of microtubules with dyne in arms on the outer doublets

236
Q

Kartagener’s syndrome defect

A

Dynein arm defect

237
Q

Kartagener’s syndrome findings

A

Male infertility (immotile sperm) and reduced female fertility, bronchiectasis, recurrent sinusitis, situs inversus (congenital inversion of organs)

238
Q

Connective tissue IHC intermediate filament stain

A

Vimentin

239
Q

Muscle IHC intermediate filament stain

A

Desmin

240
Q

Epithelial cell IHC intermediate filament stain

A

Cytokeratin

241
Q

Neuroglia IHC intermediate filament stain

A

GFAP

242
Q

Neruonal IHC intermediate filament stain

A

Neurofilaments

243
Q

Plasma membrane composition

A

Asymmetric lipid bilayer composed of cholesterol (adds fluidity), phospholipids, sphingolipids, glycolipids, proteins

244
Q

Intermediate filaments function

A

Structural

245
Q

Microtubule function

A

Movement

246
Q

Actin and myosin function

A

Microvilli, muscle contraction, cytokinesis, adherens junctions

247
Q

Collagen type I

A

Most common

Bone, skin, tendon

Defect in osteogenesis imperfecta

248
Q

Collagen type II

A

Cartilage, vitreous body, nucleus pulposus

Type II: car-two-lage

249
Q

Collagen type III

A

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

Defective in vascular type Ehlers-Danlos (threE D)

250
Q

Collagen type IV

A

Basement membrane

Defect in Alport syndrome

251
Q

What does ouabain inhibit?

A

Na-K ATPase

Leads to indirect inhibition of Na/Ca exchange, which increases intracellular Ca and contractility

252
Q

What do cardiac glycosides inhibit?

A

Na-K ATPase

Leads to indirect inhibition of Na/Ca exchange, which increases intracellular Ca and contractility

253
Q

What does the Na/K ATPase exchange?

A

3 Na+ go out, 2 K+ come in

254
Q

Collagen mnemonic

A

Be So Totally (I) Cool (II), Read (III) Books (IV)

255
Q

Collagen synthesis steps: overview

A

1) synthesis (RER), 2) hydroxylation (ER), 3) glycosylation (ER), 4) exocytosis, 5) proteolytic processing (extracellular), 6) cross-linking (extracellular)

256
Q

Collagen synthesis steps: synthesis

A

Translation of collagen alpha chains (preprocollagen) - usually Gly-X-Y (X and Y are proline or lysine)

RER

257
Q

Collagen synthesis steps: hydroxylation

A

Hydroxylation of specific proline and lysine residues

Requires Vit. C (deficiency = scurvy)

ER

258
Q

Collagen synthesis steps: glycosylation

A

Glycosylation of pro-alpha-chain hydroxylysine residues and formation of procollagen via hydrogen and disulfide bonds (triple helix of 3 collagen alpha chains)

Problems with this = osteogenesis imperfecta

ER

259
Q

Collagen synthesis steps: exocytosis

A

Exocytosis into extraceullar space

260
Q

Collagen synthesis steps: proteolytic processing

A

Cleavage of disulfide-rich terminal regions of procollagen

Produces insoluble tropocollagen

261
Q

Collagen synthesis steps: cross-linking

A

Reinforcement of staggered tropocollagen molecules via covalent lysine-hydroxylysine cross-linkage

Lysyl oxidase, requires Cu+2

Problems with this = Ehlers-Danlos

262
Q

Osteogenesis imperfecta: most common defect

A

Abnormal type I collagen

Autosomal dominant

263
Q

Osteogenesis imperfecta: findings

A

Fractures with minimal trauma (including during birth), blue sclerae (due to translucency of connective tissue), hearing loss, dental imperfections

264
Q

Ehlers-Danlos findings

A

Hyperextensible skin, tendency to bleed and bruise easily, hyper mobile joints

6 types, inheritance and severity vary, can be autosomal recessive or dominant

Can be associated with joint dislocation, berry aneurysms, organ rupture

265
Q

Alport syndrome defect

A

Abnormal type IV collagen

X-linked recessive

266
Q

Elastin

A

Stretchy protein within skin, lungs, larger arteries, elastic ligaments, vocal cords, ligament flava

Rich in proline and glycine (nonhydroxylated)

Broken down by elastase, which is inhibited by A1AT

267
Q

Polymerase chain reaction (PCR)

A

Used to amplify a specific DNA fragment

Steps: 1) denaturation (hot), 2) annealing (cool), 3) elongation (hot)

Uses DNA polymerase from heat-stable bacteria (Taq)

Run samples out on agarose gels (smaller runs father)

268
Q

Fibrillin

A

Scaffold for elastase formation

269
Q

Elastase findings in emphysema

A

In congenital emphysema (A1AT deficiency), you get excess elastase activity (less elastin)

270
Q

Alport syndrome findings

A

Progressive hereditary nephritis and deafness

Ocular disturbances

Type IV collagen is important in kidney, ears, and eyes

271
Q

Southern blot

A

DNA

SNoW DRoP

272
Q

Northern blot

A

RNA

SNoW DRoP

273
Q

Western blot

A

Protein

SNoW DRoP

274
Q

Southwestern blot

A

DNA-binding proteins

SNoW DRoP

275
Q

Microarray

A

Stick nucleic acid sequences to a slide, prepare labeled DNA or RNA probes and hybridize them to the slide, compare binding between samples

Used to profile expression in a ton of genes at once

Can detect SNPs

276
Q

ELISA (enzyme-linked immunosorbent assay)

A

Tests for antibody-antigen reactivity

Determine if a particular antibody or antigen is present in a sample (HIV antibody is an example)

277
Q

Indirect ELISA

A

Uses a test antigen to see if a specific antibody is present in a patient’s sample

278
Q

Direct ELISA

A

Uses a test antibody to see if a specific antigen is present in the patient sample

279
Q

FISH (fluorescence in situ hybridization)

A

Fluorescent DNA or RNA probe binds to a specific gene

Used for specific localization of genes and direct visualization of anomalies (things that are too small to be seen by karyotping)

Fluorescence = gene is present because probe can bind

280
Q

Cloning methods

A

1) isolate mRNA, 2) use reverse transcriptase to generate a cDNA (lacks introns!), 3) insert cDNA fragments into plasmids with antibiotic resistance genes (so you can select for these colonies in culture), 4) transform the plasmids into bacteria, 5) grow bacteria on antibiotic-containing medium to generate a cDNA library

281
Q

Gene expression modifications

A

Knock-outs and Knock-ins (either through random insertion or targeted homologous recombination0

Cre-lox: useful for studying genes that are necessary for embryonic development - can knock them out in adulthood with tamoxifen

RNAi: dsRNA separates and promotes degradation and silencing of a specific mRNA

282
Q

Karyotyping

A

Metaphase chromosomes are stained, matched up, and numbered

Used to diagnose chromosome imbalances

283
Q

Codominance (+ example)

A

Both alleles contribute to the phenotype

Blood type AB

284
Q

Variable expressivity (+ example)

A

Phenotype varies among individuals with the same genotype

Patients with NF1 have varying disease severity

285
Q

Incomplete penetrance (+ example)

A

Not all individuals with a mutant genotype end up showing the mutant phenotype

Not everyone with BRCA1 mutations get breast cancer

286
Q

Pleiotropy (+ example)

A

One gene contributes to multiple phenotypes

PKU causes many symptoms ranging from retardation to hair changes

287
Q

Imprinting (+ example)

A

Differences in expression depending on whether the mutation is maternal or paternal

Prader-Willi and Angelman’s syndrome - 15(q11-13)

288
Q

Anticipation (+ example)

A

Increased severity or earlier onset in succeeding generations

Huntington’s disease

289
Q

Loss of heterozygosity (+ example)

A

A patient with a mutation in a tumor suppressor gene requires the second allele to be mutated before cancer develops (NOT true with proto-oncogenes)

Retinoblastoma, MEN I

290
Q

Dominant negative mutation (+ example)

A

In a heterozygote, the mutant allele produces a product that prevents the normal produce from functioning

A transcription factor that can still bind DNA but has a mutation in its allosteric site (so normal signals don’t pull it off) that prevents the normal transcription factor from binding

291
Q

Linkage disequilibrium

A

Tendency for certain alleles at linked loci to occur together more often than chance

Indicates genes are close together on the chromosome

292
Q

Mosaicism (+ example)

A

Cells in the body differ in genetic makeup due to post-fertilization loss or change. Can be germ-line and produce disease that is not carried in parent’s somatic cells

McCune-Albright is lethal if somatic but survivable if mosaic

293
Q

Locus heterogeneity (+ example)

A

Mutations at different loci produce the same phenotype

vHL disease and MEN 2B both cause pheochromocytomas

294
Q

Heteroplasmy

A

Prescence of both normal and mutated mitochondrial DNA resulting in variable expression of mitochondrially-inherited diseases

295
Q

Allelic heterogeneity (+ example)

A

Mutations within one gene can produce the same phenotype

Multiple mutations of the CFTR gene can give CF like symptoms

296
Q

Uniparental disomy (+ example)

A

Offspring receives 2 copies of a chromosome from one parent and no copies from the other parent

Uniparental is eUploid, not aneuploid

Consider in a parent with a recessive disorder and only one affected parent

297
Q

Hardy-Weinberg equation

A 
p^2 + 2pq + q^2 = 1
p + q = 1
p^2 = frequency of homozygosity for p
q^2 = frequency of homozygosity for q
2pq = frequency of heterozygosity
298
Q

Imprinting

A

At some loci, only one allele is active and the other is inactive (imprinted, inactivated by methylation)

Disease can occur from deletion of the active allele or from uniparental disomy

299
Q

Prader-Willi syndrome imprinting

A

Paternal allele is not expressed

300
Q

Prader-Willi findings

A

Mental retardation, hyperphagia, obesity, hypogonadism, hypotonia

301
Q

Angelman’s syndrome imprinting

A

Maternal allele is not expressed

302
Q

Angelman’s findings

A

Mental retardation, seizures, ataxia, inappropriate laughter

303
Q

When does the error occur in heterodisomy?

A

Meiosis I

304
Q

When does the error occur in isodisomy?

A

Meiosis II

305
Q

Hardy-Weinberg differences with X-linked genes

A

Frequency of a recessive disease in males = q, in females = q^2

306
Q

Mitochondrial inheritance disease

A

Often present with myopathy and CNS disease

Muscle biopsy shows ragged red fibers

307
Q

Autosomal dominant pedigree characteristics

A

Multiple generations, both male and females affected

308
Q

Autosomal recessive pedigree characteristics

A

Often only seen in one generation, both parents have to be carriers but likely not affected

Enzyme deficiencies

309
Q

X-linked recessive pedigree characteristics

A

Sons of heterozygous mothers get 50% of disease

No male-to-male transmission

310
Q

X-linked dominant pedigree characteristics

A

Transmitted through both parents

All female offspring of an affected father are affected

311
Q

Mitochondrial inheritance pedigree characteristics

A

Transmitted only through mother, all offspring of affected females have the disease

312
Q

Hypophosphatemic rickets

A

Vit. D-resistant Rickets

Increased phosphate wasting at the proximal tubule

X-linked dominant

313
Q

Achondroplasia defect

A

FGF receptor 3

Autosomal dominant

314
Q

Autosomal-dominant polycystic kidney disease (ADPKD) defect

A

PKD1 (vs. PKHD1 for AR childhood form)

Chromosome 16 (16 letters in “polycystic kidney”)

Autosomal dominant

315
Q

Familial adenomatous polyposis defect

A

APC gene

Chromosome 5 (5 letters in “polyp”)

Autosomal dominant

316
Q

Familial hypercholesterolemia (hyperlipidemia type IIA) defect

A

LDL receptor

Autosomal dominant

317
Q

Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome) defect

A

Disorder of blood vessels resulting in abnormal formation and weakened vasculature (more bleeding)

Autosomal dominant

318
Q

Hereditary spherocytosis defect

A

Spectrin or ankyrin defect

Autosomal dominant

319
Q

Huntington’s disease defect

A

Trinucleotide repeat (CAG)

Chromosome 4 (HUNTING 4 food)

Autosomal dominant

320
Q

Marfan’s syndrome defect

A

Fibrillin-1

Results in abnormal elastase

Autosomal dominant

321
Q

Multiple endocrine neoplasias (MEN) defect

A 
MEN1 - menin (tumor suppressor)
Autosomal dominant (loss of heterozygosity)

MEN2A/B - RET (proto-oncogene)
Autosomal dominant

322
Q

Neurofibromatosis type I (von Recklinghausen’s disease) defect

A

Gene on chromosome 17

(17 letters in “von Recklinhausen”)

Autosomal dominant

323
Q

Neurofibromatosis type II defect

A

NF2 gene on chromosome 22

(type 2 is 22)

Autosomal dominant

324
Q

Tuberous sclerosis defect

A

TSC gene

Autosomal dominant

325
Q

von Hippel-Lindau disease defect

A

VHL deletion results in constitutive expression of HIF (transcription factor)

Chromosome 3 (3 letters in v H L)

Autosomal dominant

326
Q

Achondroplasia findings

A

Dwarfism, short limbs, large head, normal trunk size

Associated with advanced paternal age

327
Q

Autosomal-dominant polycystic kidney disease (ADPKD) findings

A

Bilateral, massive enlargement of kidneys due to multiple large cysts

Flank pain, hematuria, hypertension, progressive renal failure, polycystic liver disease, berry aneurysms, mitral valve prolapse

Infantile form is recessive

328
Q

Familial adenomatous polyposis findings

A

Colon becomes covered with adenomatous polyps after puberty

Progresses to colon cancer unless resected

329
Q

Familial hypercholesterolemia (hyperlipidemia type IIA) findings

A

Elevated LDL

Heterozygotes: 300 level cholesterol
Homozygotes: 700+ level cholesterol

Atherosclerotic disease early in life, tendon xanthomas, MI and stroke

330
Q

Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome) findings

A

Telangiectasia, recurrent epistaxis, skin discolorations, arteriovenous malformations (AVMs)

331
Q

Hereditary spherocytosis findings (+ treatment)

A

Spheroid erythrocytes, hemolytic anemia, increased MCHC (mean corpuscular hemoglobin concentration)

Splenectomy is curative

332
Q

Huntington’s disease findings

A

Depression, progressive dementia, choreiform movements, caudate atrophy, lower levels of GABA and ACh

Appears between 20 and 50 (anticipation is a factor)

333
Q

Marfan’s syndrome findings

A

Tall with long extremities, pectus excavatum, hypermobile joints, long and tapering fingers and toes (arachnodactyly), cystic medial necrosis of aorta which can lead to incompetence and dissecting aortic aneurysms, floppy mitral valve, subluxation of lenses

334
Q

NF type I (von Recklinghausen’s disease) findings

A

Cafe-au-lait spots, neural tumors, Lisch nodules (pigmented iris hamartomas), skeletal disorders (scoliosis) and optic pathway gliomas

335
Q

NF type II findings

A

Bilateral acoustic schwannomas, juvenile cataracts

336
Q

Tuberous sclerosis findings

A

Facial lesions (adenoma sebaceum), hypopigmented “ash leaf spots,” cortical and retinal hamartomas, seizures, mental retardation, renal cysts and angiomyolipmas, cardiac rhabdomyomas, astrocytomas

Incomplete penetrance, variable presentation

337
Q

von Hippel-Lindau findings

A

Hemangioblastomas of retina/cerebellum/medulla, bilateral renal cell carcinoma, pheochromocytoma

338
Q

Albinism inheritance pattern

A

Autosomal recessive

339
Q

Autosomal recessive polycystic kidney disease: inheritance pattern and defect

A

Autosomal recessive

PKHD1 (vs. PKD1 for the AD adult form)

340
Q

Cystic fibrosis defect

A

CFTR on chromosome 7 (Phe 508 is most common)

Mutation causes abnormal protein folding, resulting in degradation of channel in the ER (never reaches cell surface)

Apical Cl- channel expressed in the lungs, GI trace, vas deferens

Autosomal recessive

341
Q

Cystic fibrosis pathophysiology

A

CFTR secretes Cl- in lungs and GI tract and reabsorbs Cl- in sweat glands

Mutant protein gets retained in RER and not transported to cell membrane

Abnormal Cl- secretion causes less H2O secretion and compensatory Na+ reabsorption via epithelial Na+ channels, which causes H2O reabsorptionŽ

Abnormally thick mucus secreted into lungs and GI tract.

Na+ reabsorption also causes more negative transepithelial potential difference

342
Q

Cystic fibrosis findings

A

Infertility in males (bilateral absence of vas deferens), fat-soluble vitamin deficiencies and steatorrhea, bronchiectasis, pancreatic insufficiency, nasal polyps, meconium ileus in newborns, failure to thrive in infancy is possible

343
Q

Cystic fibrosis diagnosis

A

High Cl- concentration in sweat test

Alkalosis and hypokalemia because ECF water and Na+ losses lead to renal K+/H+ wasting

344
Q

Cystic fibrosis infections

A

Recurrent pulmonary infections from Pseudomonas aeruginosa and S. aureus

345
Q

List X-linked recessive disorders

A

Bruton’s agammaglobulinemia, Wiskott-Aldrich syndrome, Fabry’s disease, G6PD deficiency, Ocular albinism, Lesch-Nyhan syndrome, Duchenne’s (and Becker’s) muscular dystrophy, Hunter’s syndrome, Hemophilia A and B, Ornithine transcarbamoylase (OTC) deficiency

“Be Wise, Fool’s GOLD Heeds Silly HOpe”

346
Q

Duchenne’s muscular dystrophy defect

A

X-linked frameshift mutation

Deletion of dystrophin gene leads to accelerated muscle breakdown. Normally anchors muscle fibers in skeletal and cardiac muscle to alpha- and beta-dystroglycan (ECM proteins) -> myonecrosis

Duchenne’s = Deleted Dystrophin

DMD is the longest gene, which predisposes it to higher rates of mutation

347
Q

Duchenne’s muscular dystrophy findings

A

Weakness beginning in the pelvic girdle and progressing superiorly, pseudohypertrophy of calves (muscle replaced by fat), cardiac myopathy, Gower’s maneuver (using your arms to stand up)

Starts before age 5

348
Q

Becker’s muscular dystrophy defect

A

X-linked frameshift mutation

Deletion of dystrophin gene leads to accelerated muscle breakdown. Normally anchors muscle fibers in skeletal and cardiac muscle

Less severe than Duchenne’s

349
Q

Becker’s muscular dystrophy findings

A

Similar to Duchenne’s (pelvic girdle weakness, pseudohypertrophy of calves, cardiac myopathy, Gower’s maneuver) but less severe

Onset in adolescence or early adulthood

350
Q

Fragile X syndrome defect

A

X-linked defect affecting the methylation and expression of the FMR1 gene

(CGG)n repeat

351
Q

Fragile X syndrome findings

A

Macroorchidism (enlarged testes), long face with a large jaw, large everted ears, autism, mitral valve prolapse

Fragile X = eXtra large testes, jaws, ears

2nd most common genetic

352
Q

List trinucleotide repeat expansion diseases

A

Huntington’s disease (CAG), myotonic dystrophy (CTG), Friedrich’s ataxia (GAA), fragile X syndrome (CGG)

353
Q

Lesch-Nyhan treatment

A

Allopurinol and febuxostat

Xanthine oxidase inhibitors

354
Q

Down syndrome defect

A

Trisomy 21

95% Meiotic nondisjunction, 4% Robertsonian translocation, 1% mosaicism

Most common viable chromosomal disorder and most common genetic mental retardation

355
Q

Down syndrome clinical findings

A

Mental retardation, flat facies, prominent epicanthal folds, simian crease, gap between 1st two toes, duodenal atresia, congenital heart disease (ostium primum-type ASD)

Associated with ALL (acute lymphoblastic leukemia) and Alzheimer’s disease

356
Q

Down syndrome pregnancy quad screen and US results

A

Up: beta-hCG, inhibin A

Down: alpha-fetoprotein, estriol

US: increased nuchal translucency

357
Q

Edwards’ syndrome defect

A

Trisomy 18

358
Q

Edwards’ syndrome clinical findings

A

Severe mental retardation, rocker-bottom feet (also in Patau’s), micrognathia (small jaw), low-set ears, clenched hands, prominent occiput, congenital heart disease

Death usually occurs within 1 year

Edwards’: Ears

359
Q

Edwards’ syndrome quad screen

A

Up: none

Down: alpha-fetoprotein, beta-hCG, estriol

Normal: inhibin A

360
Q

Patau’s syndrome defect

A

Trisomy 13

361
Q

Patau’s syndrome clinical findings

A

Severe mental retardation, rocker-bottom feet (also in Edwards), microphtalmia, microcephaly, cleft lip/palate, holoprosencephaly, polydactyly, congenital heart disease

Death usually occurs within 1 year

Patau’s: liP/Palate, holoProsencephaly, Polydactyly

362
Q

Patau’s syndrome quad screen and US results

A

Up: none

Down: free b-HCG, PAPPA-A

US: increased nuchal translucency

363
Q

Robertsonian translocation

A

Nonreciprocal chromosomal translocation commonly involving 13, 14, 15, 21, 22 (acrocentric, have short arms)

Long arms from two chromosomes fuse at the centromere, short arms are lost

Can result in miscarriage, stillbirth, and chromosomal imbalance (trisomies)

Balanced translocations are often normal

364
Q

Down syndrome age of presentation

A

21 (Drinking age for Down)

365
Q

Edwards’ syndrome age of presentation

A

18 (Election age for Edwards’)

366
Q

Patau’s syndrome age of presentation

A

13 (Puberty for Patau’s)

367
Q

Cri-du-chat syndrome defect

A

Microdeletion of short arm of chromosome 5 (46XX, 5p- or 46XY, 5p-)

368
Q

Cri-du-chat findings

A

Microcephaly, mental retardation, high-pitched crying/mewing, epicentral folds, cardiac abnormalities (VSD)

Cri du chat = cry of the cat (mewing)

369
Q

Williams syndrome defect

A

Microdeletion of the long arm of chromosome 7 (includes elastin)

370
Q

Williams syndrome findings

A

Distinctive “elfin” facies, intellectual disability, hypercalcemia (sensitive to vit. D), well-developed verbal skills and extreme friendliness, CV problems

371
Q

22q11 deletion syndrome findings

A

CATCH-22: Cleft palate, Abnormal facies, Thymic hyperplasia (t-cell deficiency), Cardiac defects, Hypocalcemia secondary to parathyroid aplasia due to microdeletion at 22q11

372
Q

22q11 deletion syndrome defect

A

Microdeletion of 22q11 due to aberrant development of 3rd and 4th branchial pouches

373
Q

DiGeorge syndrome

A

22q11 deletion syndrome

Thymic, parathyroid, and cardiac defects

374
Q

Velocardiofacial syndrome

A

Palate, facial, and cardiac defects

375
Q

Methylation of CpG islands

A

Blocks transcription

376
Q

Fat-soluble vitamins

A

KADE

377
Q

Water-soluble vitamins

A

B (1-12) and C

378
Q

Vit. A function

A

Antioxidant, constituent of visual pigments (retinal), essential for normal differentiation of epithelial cells into specialized tissue (pancreatic cells and mucus-secreting cells), prevent squamous metaplasia

379
Q

Vit. A deficiency

A

Night blindness, dry scaly skin (xerosis cutis), alopecia, corneal degeneration (keratomalacia), immune suppression

380
Q

Vit. A excess

A

Arthralgia, fatigue, headache, skin changes, sore throat, alopecia, cerebral edema, pseudotumor cerebri (high intracranial pressure in the absence of a tumor), osteoporosis

Teratogenic (cleft plate and cardiac abnormalities): people going on isotretinoin for severe acne need to take a pregnancy test and be on contraception

381
Q

Is toxicity from fat-soluble or water-soluble vitamins more common? Why?

A

Fat-soluble: accumulate in fat, difficult to wash away

382
Q

What causes fat-soluble vitamin deficiencies?

A

Malabsorption syndromes (steatorrhea), such as CF or sprue

Mineral oil intake is also a possible cause

383
Q

What conditions can give you B-complex deficiencies?

A

Dermatitis, glossitis, diarrhea

384
Q

Which B vitamins are stored in the liver?

A

B12 (cobalamin) and folate (B9)

385
Q

Vit. B1 function

A

Cofactor (TPP - thiamine pyrophosphate) for enzymes that do decarboxylation reactions (dehydrogenases - pyruvate (links glycolysis to TCA cycle), alpha-ketoglutare (TCA cycle), branched chain AA and transketolase (HMP shunt))

Alpha-ketoglutarate DH, Transketolase, and Pyruvate DH required for ATP synthesis

386
Q

Vit. B1 deficiency (+ causes)

A

Impaired glucose breakdown (ATP depletion), worsened by glucose infusion. Brain and heart affected first

Wernicke-Korsakoff, beriberi

Caused by malnutrition and alcoholism

387
Q

Wernicke-Korsakoff findings

A

Confusion, ophthalmoplegia, ataxia, confabulation, personality change, memory loss

388
Q

Dry beriberi findings

A

Polyneuritis, symmetrical muscle wasting

389
Q

Wet beriberi findings

A

High-output heart failure (dilated cardiomyopathy), edema

390
Q

Where is Vit. A found?

A

Liver and leafy vegetables

391
Q

What can Vit. A be used to treat?

A

Wrinkles, acne, measles, AML (subtype M3)

392
Q

Vit. A other name

A

Retinol

“retin-A”

393
Q

Vit. B1 other name

A

Thiamine

394
Q

Glutamate derivatives (+ cofactor required)

A

GABA and glutathione

B6

395
Q

Arginine derivatives

A

Creatinine, urea, NO

396
Q

Glycine derivatives (+ cofactor required)

A

Porphyrin and heme

B6

397
Q

Histidine derivatives (+ cofactor required)

A

Histamine

B6

398
Q

Tryptophan derivatives (+ cofactor required)

A

Two pathways

Niacin and NAD+/NADP+ require B6

Serotonin and melatonin require BH4

399
Q

Ornithine transcarbamoylase deficiency (OTC) defect

A

OTC gene

X-linked recessive

Interferes with ability to eliminate ammonia, excess carbamoyl phosphate gets converted to orotic acid

400
Q

Ornithine transcarbamoylase deficiency (OTC) findings

A

Increased orotic acid in blood and urine, low BUN, hyperammonemia symptoms

No megaloblastic annemia (vs. orotic aciduria)

401
Q

Hyperammonemia causes

A

Can be acquired liver disease or hereditary urea cycle defects

402
Q

Hyperammonemia pathophysiology

A

Excess NH4+ depletes alpha-ketoglutarate, leading to inhibition of the TCA cycle

403
Q

Hyperammonemia symptoms

A

Tremor (asterixis), slurring of speech, somnolence, vomiting, cerebral edema, blurring of vision

404
Q

Hyperammonemia treatment

A

Limit protein in diet

Benzoate or phenylbutyrate (bind AAs and lead to exertion)

Lactulose acidifies the GI tract and traps NH4+ for excretion

405
Q

What form of AA is present in proteins?

A

L-form

406
Q

Essential AAs

A

Glucogenic: Met, Val, His
Glucogenic/ketogenic: Ile, Phe, Thr, Trp
Ketogenic: Leu, Lys

Need to be supplied in the diet

407
Q

Acidic AAs

A

Aspartate and Glutamate

Negatively charged at body pH

408
Q

Basic AAs

A

Arginine (most basic), Lysine, Histidine

Arg and Lys are positively-charged at body pH, Histidine has no charge

409
Q

Urea cycle metabolites

A

Ornithine + carbamoyl phosphate -> citrulline + aspartate -> arginosuccinate -> arginine - fumarate (fumarate leaves cycle) -> urea

Ordinarily, Careless Cats Are Also Frivolous About Urination

410
Q

What is the urea cycle for?

A

Degradation of excess nitrogen (NH4+) generated during amino acid catbalosim

411
Q

What amino acids are involved in ammonium transport?

A

Alanine and glutamate

412
Q

What metabolite couples to NH3 from amino acids? Where does this occur?

A

alpha-Ketolglutarate (also part of the TCA cycle)

Muscle

413
Q

What transports NH3 from the muscle to the liver?

A

Alanine cycle

414
Q

What is the Cori cycle?

A

Lactate produced in lactic acid fermentation (anaerobic fermentation) is transported to the liver and converted to glucose

415
Q

Pyrimethamine

A

Blocks dihydrofolate reductase (finding: low dTMP)

416
Q

Leflunomide

A

Blocks dihydroorotate dehydrogenase (carbamoyl phosphate -> orotic acid conversion)

417
Q

Mycophenolate

A

Inhibit IMP dehydrogenase

Ribavirin does the same thing

418
Q

Ribavirin

A

Inhibit IMP dehydrogenase

Mycophenolate does the same thing

419
Q

Chaperone proteins

A

Facilitate protein folding

In yeast, some are heat-shock proteins expressed at high temperatures to prevent denaturing

420
Q

CDKs

A

Cyclin-dependent kinases, constitutive and inactive alone

421
Q

Cyclins

A

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

422
Q

Cyclin-CDK complexes

A

Must be both activated and inactivated for cell cycle to progress

423
Q

Signal recognition particle (SRP) (+ what happens when it is dysfunctional)

A

Abundant cytosolic ribonucleoprotein that traffics proteins from the ribosome to the RER

When absent, proteins accumulate in the cytosol

424
Q

What can osteogenesis imperfecta be confused with?

A

Child abuse

425
Q

Menkes disease defect

A

Connective tissue disease caused impaired copper absorption and transport

Leads to decreased lysyl oxidase activity (requires Cu++)

426
Q

Menkes disease findings

A

Brittle “kinky” hair, growth retardation, hypotonia

427
Q

Lysyl oxidase: function, cofactor

A

Extracellular tropocollagen cross-linkage

Requires Cu++

428
Q

Hardy-Weinberg law assumptions

A

No mutations, no natural selection, completely random mating, no net migration of individuals

429
Q

Cystic fibrosis treatment

A

N-acetylcysteine to loosen mucus plugs (cleaves disulfide bonds within mucus glycoproteins)

Dornase alfa (DNAse) to clear leukocytic debris

430
Q

Myotonic type I muscular dystrophy

A

Finish this card

431
Q

N-acetylglutamate deficiency findings

A

Hyperammonemia with high ornithine and normal urea cycle enzymes

432
Q

N-acetylglutamate deficiency defect

A

Required cofactor for carbamoyl phosphate synthetase I

Absence leads to hyperammonemia

433
Q

Start at B2

A

Page 91-105 left to finish

First Aid Flashcards (2 decks)

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