11a: Genetics/Nutrition Flashcards
1
Q
Histones are rich in which AA?
A
Lys, Arg
2
Q
(H1/H2/H3/H4) histone is outside the core and acts as linker/stabilizer
A
H1
3
Q
Heterochromatin: highly (methylated/acetylated).
A
Methylated (low acetylation) - condensed and inactive
4
Q
Nucleoside is made up of which components? And nucleotide?
A
NucleoSide: base + (deoxy)ribose Sugar
NucleoTide: base + (deoxy)ribose + phosphaTe
5
Q
Deamination of 5-methylcytosine makes:
A
Thymine
6
Q
Deamination of guanine makes:
A
Xanthine
7
Q
Deamination of cytosine makes:
A
Uracil
8
Q
Deamination of adenine makes:
A
Hypoxanthine
9
Q
Methylation of uracil makes:
A
Thymine (“THYmine has a meTHYl”)
10
Q
List the three amino acids necessary for purine synthesis
A
“GAG”
Glycine
Asp
Gln
11
Q
(CG/AT) bonds are stronger, so higher content of these means (higher/lower) melting T of DNA
A
CG (“C-G bonds are like Crazy Glue”) - have 3 H bonds instead of 2
Higher
12
Q
First step in de novo pyrimidine base synthesis
A
Gluamine and CO2 -> Carbamoyl phosphate (via Carbamoyl phosphate synthetase II)
13
Q
Leflunomide inhibits (X) in (Y) pathway
A
X = dihydroorotate dehydrogenase
De novo Pyrimidine synthesis
used as immunosuppressive drug, ex: RA
14
Q
Hydroxyurea MOA:
A
Inhibits ribonucleotide reductase (in de novo pyrimidine synthesis) so UDP can’t become dUDP
15
Q
Ribavirin has same target/MOA as which other drug?
A
Mycophenolate (inhibit inosine monophosphate dehydrogenase; decrease IMP to GMP purine formation)
16
Q
T/F: Low folate means low dUMP and low dTMP
A
False - high dUMP and low dTMP (since it’s that conversion by thymidylate synthase that’s impaired)
17
Q
PRPP is synthesized from:
A
Ribose-5P (via PRPP synthetase)
18
Q
GMP is the (nucleotide/nucleoside/free base). What are the other forms named?
A
Nucleotide (has phosphate)
Nucleoside: guanosine
Free base: guanine
19
Q
Lesch-Nyhan caused by (low/high) (X) enzyme levels
A
Absent
X = HGPRT (defective purine salvage), which normally converts hypoxanthine to IMP and guanine to GMP
20
Q
Autosomal recessive SCID: impaired/deficiency in (X), which causes disease via what mechanism?
A
X = Adenosine deaminase (converts adenosine to inosine for purine degradation)
In ADA deficiency, high dATP levels causes toxicity in lymphocytes
21
Q
Child with intellectual disability and “orange sand” in diaper.
A
Lesch-Nyhan (Na urate crystals in diaper due to hyperuricemia)
22
Q
The genetic code is universal (conserved throughout evolution). What’s the only exception?
A
Mitochondrial DNA
23
Q
Bloom Syndrome: a disorder caused by impaired (X)
A
X = helicase production (BLM gene mutation)
24
Q
Only polymerase with 5’-3’ exonuclease activity in prokaryotes
A
DNA Pol I (removes primer)
25
List the components of telomerase
1. TERT: reverse transcriptase
2. TERC: code (RNA template) repeatedly read by TERT
Adds DNA to 3' ends of chromosomes (to avoid genetic material loss during replication)
26
T/F: Telomerase is only found in eukaryotic cells
True (ex: cancer cells, stem cells)
27
Nonsense mutation means truncated (protein/mRNA).
Protein (NOT mRNA! Stop codon added)
28
Xeroderma pigmentosum: defective (X)
X = DNA endonucleases for NT excision repair
So pyrimidine dimers formed by UV light can't be repaired
29
List the steps/players in DNA Base excision repair
1. Glycosylase (base-specific; removes altered base and creates apurinic/apyrimidinic site)
2. Endonuclease (cleaves 5' end)
3. Lyase (cleaves 3' end)
4. Polymerase-beta (fills gap)
5. Ligase (seals gap)
30
Which (DNA/RNA) polymerase is the only one that's restricted to nucleolus?
RNA Pol I (makes rRNA)
31
Which RNA Pol makes tRNA?
RNA Pol III (three makes t, the tiniest RNA)
32
T/F: There are three different RNA Polymerases in both eukaryotic and prokaryotic cells
False - prokaryotes only have on RNA Pol
33
RNA Processing (capping 5' end, polyadenylation, splicing) occurs in (X) (before/after) transportation to (Y).
X = nucleus
Before
Y = cytoplasm (for translation)
34
mRNA quality control occurs at (X) in cytoplasm
X = Processing (P) bodies
35
Amino acids are linked by (X) bond(s) to (5'/3') end of tRNA
X = covalent
| 3' (CCA)
36
(X) arm of tRNA contains (Y) sequence, necessary for ribosome binding
```
X = T-arm ("Tethers" to ribosome)
Y = T𝚿C (ribothymidine, pseudouridine, cytidine)
```
37
(X) arm of tRNA contains (Y) sequence, necessary for tRNA recognition by correct aminoacyl-tRNA synthetase
```
X = D-arm ("Detection" of tRNA by aminoacyl-tRNA synthetase)
Y = dihydrouridine residues
```
38
Eukaryotes have which ribosome subunits? And prokaryotes?
Eukaryotes have the Even numbers: 40S + 60S = 80S
| prOkaryotes have the Odd numbers: 30S + 50S = 70S
39
tRNA charging with amino acid requires (ATP/GTP)
ATP (for "Activation" of tRNA)
40
Protein synthesis requires (ATP/GTP)
GTP ("tRNA Grips mRNA and Goes places")
41
Which amino acids are exclusively ketogenic?
Lys and Leu (cannot be metabolized to pyruvate)
42
Hypoketotic hypoglycemia most often a deficiency in (X)
X = Acyl-CoA dehydrogenase (first step in beta-ox pathway)
43
First (rate-limiting) step in FA synthesis
Acetyl-CoA decarboxylase
44
N-acetylglucosaminyl-1-phosphotransferase defect, aka (X) disease, is due to failure of which process?
X = I-cell (inclusion cell)
Golgi phosphorylation of mannose residues on glycoproteins (causing them to be extracellularly secreted instead of delivered to lysosomes)
45
COPI and COPII involved in which steps of cell trafficking?
COPII: anterograde from RER to cis-Golgi
COPI: retrograde from cis-Golgi to RER
("Two steps forward, One step back")
46
Membrane-enclosed organelle involved in catabolism of (X) fatty acids, amino acids, and EtOH
Peroxisome
| X = very-long-chain and branched-chain
47
Peroxisomal disorders commonly lead to (X) manifestations/symptoms due to deficits in synthesis of (Y)
```
X = neuro
Y = plasmalogens (important phospholipids in myelin)
```
48
Cilia are (microfilaments/intermediate filaments/MTs)
MTs
49
Microvilli are (microfilaments/intermediate filaments/MTs)
Microfilaments
50
Vimentin is example of (microfilaments/intermediate filaments/MTs) found in (X)
Intermediate filaments;
| X = mesenchymal tissue (fibroblasts, endothelial cells, macros)
51
GFAP and cytokeratin are (microfilaments/intermediate filaments/MTs)
Intermediate filaments
52
Desmin is example of (microfilaments/intermediate filaments/MTs) found in (X)
Intermediate filaments
| X = muscle (ex: rhabdomyosarcoma stains positive for desmin on immunohistochem)
53
Bronchiectasis, recurrent sinusitis, chronic ear infections, and (conductive/sensorineural) hearing loss due to (AD/AR) defect leading to immotile cilia.
Kartagener syndrome (also situs inversus); issue with dynein arm in cilia
Conductive; AR
54
Collagen mRNA undergoes the next few steps in which cell compartment? What are the steps?
RER
1. Translation (into Preprocollagen)
2. Hydroxylation of proline and lysine (needs vit C)
3. Glycosylation of hydroxylysine
4. Procollagen triple helix formation (H and disulfide bonds between 3 collagen alpha chains)
55
Procollagen eventually enters (X) compartment for which subsequent steps, leading to final collagen formation?
X = extracellular (leaves cell)
1. Proteolytic processing and cleavage of terminal regions (via procollagen peptidases; forms insoluble tropocollagen)
2. Cross-linking (covalent lysine-hydroxylysine bonds by lysyl oxidase; needs Cu)
56
Which step(s) in (X) synthesis is/are impaired in ehlers-danlos?
X = Collagen
Either of the extracellular steps (proteolytic processing or covalent cross-linking by lysyl oxidase)
57
T/F: Most common form of osteogenesis imperfecta is AD with defective Collagen I
False - the collagen is normal, but there is just decreased production
58
Classical type of Ehlers-Danlos: mutation in type (X) collagen. And vascular type is mutation in (Y) collagen
```
X = V (joint/skin symptoms; within dermal/epidermal junction)
Y = type III (vascular and organ rupture)
```
59
Menkes disease:
X-linked recessive impaired Cu absorption/transport (low lysyl oxidase activity)
Brittle hair, growth retardation, hypotonia
60
T/F: Niacin can be synthesized endogenously
True - from Tryphtophan
61
Amino acid transamination reactions: which cofactor required?
B6 (pyridoxine)
62
5 year old boy with developmental delay, elongated limbs, bilateral lens subluxation. Dies from massive stroke. Dx?
Homocystinuria
63
Elastin is rich in which (hydroxylated/nonhydroxylated) AA residues?
Non-hydroxylated
| Lys, Gly, Pro
64
The effect of UV(A/B) wavelengths on aging/wrinkles is due to (increase/decrease) (collagen/elastin)
UVA
Decrease
Collagen and elastin production (due to ROS and inflammation)
65
(X) is a glycoprotein that forms a sheath around (collagen/elastin)
X = fibrillin
| Elastin (defective in Marfan syndrome)
66
RT-PCR is used for what purpose?
To ID specific mRNA sequence (uses reverse transcriptase to create cDNA and then amplify that by PCR)
67
Microarrays are used to detect:
Relative amounts of DNA or RNA probe complementary binding (ex: gene expression levels) of thousands of genes simultaneously
68
Example of Co-dominance
Blood groups (A, B, AB) - both alleles contribute to phenotype
69
Two patients with NF-1 have different disease severity. Which phenomenon?
Variable expressivity
70
McCune-Albright syndrome is either lethal or survivable, depending on:
Whether mutation affects all cells (occurs before fertilization; lethal) or whether mosaicism is present
71
List the law assumptions of Hardy-Weinberg
1. Random mating
2. No natural selection
3. No net migration
4. No mutations at locus
72
As the distance between a gene and linkage marker gets smaller, recombination frequency approaches:
0%
73
LOD score refers to probability that:
A particular gene and marker are linked (higher score associated with more accurate recombination frequency in table)
74
Prader-willi: (maternal/paternal) gene deleted
Paternal (so maternal imprinting; gene from mom normally silent)
75
List three key examples of X-linked dominant disorders
1. Hypophosphatemic rickets (vit D-resistant; PO4 wasting at prox tubule)
2. Fragile X
3. Alport syndrome
76
CF: newborn screen detects (X)
X = immunoreactive trypsinogen (IRT)
Which is released into blood when pancreas is damage
77
CF: (high/low) chloride levels in primarily which organs?
Low in pancreas and lungs (can't be secreted; so water isn't pulled in to thin out secretions)
High in sweat (can't be reabsorbed; skin tastes salty)
78
Explain the Nasal Transepithelial Potential Diff Test for (X) disease
X = CF
Normal saline applied to nasal mucosa >> high Na reabsorption, Cl retained in lumen >> more negative transepithelial potential difference than normal
79
CF patient can present with (acidosis/alkalosis) and (hyper/hypo)-kalemia. Why?
Alkalosis (contraction) and hypokalemia - ECF effects analogous to patient on loop diuretic;
ECF H2O/Na losses causes concomitant renal H/K wasting
80
Two key pathogens responsible for recurrent pulm infections in CF patients are:
1. S. aureus (in early infancy)
| 2. P. aeruginosa (in adolescence)
81
Congenital bilateral absence of vas deferens (CBAVD) is strongly associated with:
CF
82
T/F: Hypertonic saline is used to treat CF
True (facilitates mucous clearance); salt supplementation recommended for all CF patients
83
Becker versus Duchenne muscular dystrophies
Both X-linked mutations in dystrophin gene
Duchenne: frameshift or nonsense mutation leading to absent dystrophin protein (early onset, more severe)
Becker: non-frameshift mutations with partially functional protein (later onset in adolescence/early adulthood)
84
Lyonization is:
F carriers of X-linked R disorders can be affected/symptomatic depending on pattern of X inactivation
85
Function of dystrophin protein
Links intracellular actin to dystrophin-associated protein complex (which is anchored to ECM); stabilized sarcolemma (muscle cell membrane)
86
Myotonic dystrophy: (AR/AD/X-linked) disorder with which key symptoms?
```
AD tri-NT repeat (CTG)
"CTG":
1. Cataracts
2. Toupee (early balding)
3. Gonadal atrophy
```
And muscle atrophy/myotonia obv
87
List the key genetic diseases that arise from trinucleotide repeat expansion
"Tri (NT) HUNTING for MY FRAGILE cage-FREE eggs (X)"
1. Huntington's (CAG - "Caudate with low Ach and Gaba")
2. Myotonic dystrophy (CTG - "Cataracts, Toupee, Gonad atrophy")
3. Fragile X (CGG - "Chin (protruding), Giant Gonads")
4. Friedreich ataxia (GAA - "ataxic GAAit")
88
First trimester serum screen findings for Down syndrome:
Low PAPP-A, high free beta-hCG
89
Second trimester serum screen findings for Down syndrome:
Low alpha-fetoprotein and estriol
| High beta-hCG and inhibin A
90
All serum screens in first/second trimester (PAPP-A, beta-hCG, alpha-fetoprotein, estriol, inhibin A) are low. Which genetic syndrome?
Edwards
91
46, XX, 5p-
Cru di chat (congenital deletion of short arm of chromosome 5)
92
Cleft palate, bifid uvula, and cardiac defects : (X) syndrome
X = DiGeorge
93
Pantothenic acid
Vit B5 (component of CoA)
Think "PENTOthenic acid"
94
List the essential AAs. Star the one(s) only essential in certain cases.
"PVT TIM HALL"
1. Phe
2. Val
3. Thr
4. Trp
5. Ile
6. Met
7. His
8. Arg* (only when there's pos nitrogen balance)
9. Leu
10. Lys
95
Active sites of enzymes. Which AA comes to mind?
His
96
Homocysteine produced from:
Met (after it donates 1 methyl group)
97
Triangular white or yellowish foamy spots on bulbar conjunctiva (either side of cornea)
Bitot spots; keratinizing squamous metaplasia of conjunctiva (seen in vit A deficiency)
98
Vit A found in which food sources?
Liver and leafy veggies
99
Thiamine is cofactor for:
Dehydrogenases (Pyruvate, alpha-KG, branched-chain ketoacid) and transketolase
100
Riboflavin is important for which two key enzymes/processes?
(Vit B2; component of FAD, FMN)
1. Succinate dehydrogenase (TCA)
2. Complex II (ETC)
101
Which vitamins are required for niacin synthesis?
B2 (riboflavin) and B6 (pyridoxine)
102
List 3 main causes of niacin deficiency (apart from decreased intake)
1. Hartnup disease (decreased Trp reabs in kidney/gut)
2. Carcinoid syndrome (high Trp metabolism)
3. Isoniazid use (due to low vit B6)
103
Diarrhea, rash/hyperpigmentation, and high neutral AA in urine
Hartnup disease (AR eficiency in neutral AA transporters in PCT kidney and on enterocytes; leads to pellagra)
104
Hartnup disease Rx:
High protein diet and niacin/nicotinic acid supplementation daily
105
Niacin toxicity/excess:
Flushing (caused by PGE), hyperglycemia, hyperuricemia
106
Vit (X): essential cofactor for acyl transfers and FA synthase
X = B5 (pantothenic acid; component of CoA)
107
AA important in transamination reactions
B6
108
AA important in decarboxylation and glycogen phosphorylase reactions
B6
109
Convulsions, hyperirritability, and peripheral neuropathy: which vit deficiency?
B6
110
Sideroblastic anemia: which vit deficiency?
B6
111
Biotin cofactor for:
```
(vit B7)
Carboxylation enzymes (pyruvate carboxylase, acetyl-coa carboxylase, propionyl-coa carboxylase)
```
112
Vit B(X) deficiency may cause metabolic acidosis. Why?
X = 7 (biotin)
| High pyruvate levels (can't be converted to oxaloacetate via pyruvate carboxylase) causes lactic acid buildup
113
Homocysteine to cysteine: which vit required?
B6
114
Homocysteine to methionine: which vit required?
B12 (enzyme: Met synthase)
115
B12 required for synthesis of (X)-CoA from (Y)-CoA.
X = succinyl
Y = methylmalonyl
(enzyme: methylmalonyl-coa mutase)
116
Synthesis of heme from (X) requires vit B(Y)
```
X = Succinyl-CoA
Y = 6 (pyridoxine)
```
117
Vitamin C facilitates (X) absorption and is necessary for which NT synthesis?
X = Fe (by reducing it to Fe2+ state)
| NE from Dopamine (enzyme: dopamine beta-hydroxylase)
118
Hemolytic anemia, muscle weakness, posterior column and spinocerebellar tract demyelination. Vit (X) (deficiency/excess).
X = E
Deficiency
Similar to vit B12 deficiency but without megalobl. anemia/hyperseg PMNS or high serum methylmalonic acid
119
Delayed wound healing, hypogonadism, and decreased adult hair (axillary, facial, pubic). Caused by (X) nutritional (deficiency/excess)
X = Zn
| Deficiency
120
Anosomia and dysgeusia (distorted taste). Caused by (X) nutritional deficiency
X = Zn
121
Fomepizole inhibits (X) and is used for (Y)
```
X = alcohol dehydrogenase (EtOH to acetaldehyde rxn)
Y = overdoses of MeOH or Ethylene glycol
```
"FOMEpizole is For Overdose of Methanol or Ethylene glycol"
122
Disulfuram inhibits (X) and is used for (Y)
```
X = acetaldehyde dehydrogenase (acetald. to acetate rxn)
Y = discourage drinking (buildup of acetald causes hangover sx)
```
123
EtOH metabolism: what's the limiting reagent?
NAD+
