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Biochem Flashcards

1
Q

Deamination of cytosine gives you what?

A

Uracil (found in RNA)

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2
Q

How many H bonds between C and G?

A

3

*Higher content of C and G have a higher melting temperature

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3
Q

What is need to make purines? (Adenine and Guanine)

A

“Cats PURRRR until the GAG and Cough on Fur balls”

Glycine
Aspartate
Glutamine

+ tetrahydrofolate (Folic Acid)
+ CO2

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4
Q

4 things needed to make pyrimidines?

A

Aspartate

Carbamoyl phosphate synthetase 2
CO2
Glutamine
ATP

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5
Q

What is the rate limiting step of pyrimidine synthesis?

A

Carbamoyl phosphate synthetase 2

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6
Q

High Orotic acid

High ammonia

A

Ornithine transcarbamylase deficiency

*Disruption of urea cycle

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7
Q

High Orotic acid

NORMAL ammonia

A

Orotic aciduria = deficiency in UMP synthase

Can’t make pyrimidines!

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8
Q

Megaloblastic anemia that does NOT correct when giving B12 or folic acid supplements?

A

Orotic Acid Urea = deficiency in UMP synthase

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9
Q

A boy with self mutilating behavior, intellectual disability, uncontrolled spastic muscles and gout

A

Lesch-Nyhan
HGPRT deficiency
Can’t recycle purines

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10
Q

Rate limiting step in purine synthesis

A

Guanine PRPP amidotransferase

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11
Q

Medication that inhibits ribonucleotide reductase

A

Hydroxyurea

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12
Q

Medication that inhibits dihydrofolate reductase

A

Trimethoprime

Methotrexate

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13
Q

Medication that inhibits thymidylate synthase

A

5-FU

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14
Q

Medication that inhibits inosine monophosphate dehydrogenase

A

Mycophenolate

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15
Q

Medication that inhibitis PRPP amidotransferase

A

6-mercaptopure/ Azothioprine

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16
Q

What accounts for positive charge on histones, and neg charge on DNA?

A

Phosphates in DNA

Histones = lysine & arginine

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17
Q

Alpha DNA pol

A

Lagging strand

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18
Q

Delta DNA pol

A

Leading strand

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19
Q

Beta DNA pol

A

Base excision repair

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20
Q

Gamma DNA pol

A

Mitochondrial DNA

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21
Q

UV radiation damaged DNA

A

Thymine dimers

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22
Q

Mutation found in sickle cell disease

A

Missense mutation = nucleotide substitution resulting in changed amino acid

Significantly changes structural/functional properties

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23
Q

Mutation found in duchenne muscular dystrophy

A

Frameshift mutation

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24
Q

Defective in HNPCC

A

DNA mismatch repair enzyems

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25
DNA pol that synthesizes RNA primer
Alpha
26
3 Stop CODONS
UGA UAA UAG
27
Where are ribosomes made?
Subunits made in the nucleus and then transported to the cytoplasm
28
Most abundant type of RNA in body?
rRNA (80%)
29
Aminoacyl tRNA synthetase
Enzyme that matches amino acids to tRNA
30
Anticipation
disease onset is younger and younger through each generation **Huntingtons and trinucleotide repeat dieseaes
31
Southern Blot Northern Blot Western Blot
``` Western = protein, w/ Ab probe Southern = DNA w/ DNA probe Northern = RNA w/ DNA probe ```
32
Direct ELISA
Testing for antigen in serum
33
Indirect ELISA
Testing for antibody in serum
34
Diagnosing chromosomal abnormailites
Karyotyping
35
Hardy Weinberg
p + q = 1 | p^2 + 2pq + q^2 = 1
36
Enzyme responsible for trapping glucose in cells?
Hexokinase Glucokinase Glucose --> glucose 6 phosphate
37
Differences between Hexokinase and glucokinase?
Glucokinase = - found in liver - induced by insulin - high Km - High Vmax Hexokinase = - Low Km (high affinity) - Low Vmax (low capacity)
38
Rate limiter of glycolysis?
Phosphofructokinase 1
39
2 molecules that stimulate phosphofructokinase 1?
AMP (low energy) fructose 2,6 bisphosphate
40
2 molecules that inhibit phosphofructokinase 1?
ATP (high energy) Citrate (substrate of TCA cycle, indicates overwhelming TCA cycle)
41
How does insulin help regulate glycolysis?
Stimulates PFK-2 in the fed state Produce more Fructose 2,6 BP Stimulates PFK1
42
How does glucagon help regulate glycolysis?
Stimulates fructosebisphosphatase 2 Converts Fructose 2,6 BP back to fructose-6P
43
What is the clinical consequence of a glycolytic enzyme deficiency?
Hemolytic anemia RBC must do anerobic metabolism because they do not have mitochondria... Can't do glycolysis, no ATP, Na+/K+ pump not working, influx of water, swelling, bursting
44
Irreversible enzymes involved in gluconeogenesis
Pyruvate carboxylase PEP-CK Fructose 1,6 bisphosphatase Glucose-6-phosphatase
45
Rate limiting step in gluconeogenesis?
Fructose 1,6 bisphosphatase
46
Glycogen phosphorylase deficiency
McArdle | Type 4
47
Glucose-6-phosphatase Deficiency
Von Gierke | Type 1
48
Lactic acidosis Hyperlipidemia Hyperuricemia
Von Gierke | Type 1
49
alpha-1,6-glucosidase deficiency
= debranching enzyme Cori Disease Type 3
50
alpha-1,4-glucosidase deficiency
Pompe Disease | Type 2
51
Cardiomegaly in a glycogen storage disease
Pompe Disease | Type 2
52
Glycogen storage disease with diaphragm weakness leading to respiratory failure
Adult type pompe disease | Type 2
53
Painful muscle cramps | Myoglobinuria with strenuous exercise
McArdle Disease | Type 4
54
Glycogen storage disease with severe hepatosplenomegaly | Enlarged kidneys
Von Gierke | Type 1
55
Cofactors required for pyruvate dehydrogenase?
"TLC For Nobody" ``` Thiamine pyrophosphate Lipoic Acid Coenzyme A FAD NAD ```
56
Vomiting Rice water stools Garlic Breath
Arsenic Which inhibits lipoic acid (a cofactor for pyruvate dehydrogenase) = acquired pyruvate dehydroenase deficiency
57
Substances that increase permeability of inner mito membrane, decreasing ATP synthesis but increasing heat generation??
2,4 Dinitrophenol Aspirin Thermogenin
58
What 4 things inhibit complex 4 of the electron transport chain?
Cyanide N3- CO H2S
59
Major regulatory enzymes of TCA cycle
CItrate Synthase = starts TCA cycle Isocitrate dehydrogenase = rate limiting alpha ketoglutarate dehydrogenase = heavily regulated due to cofactors (same as pyruvate dehydrogenase)
60
2 main nitrogen transporters in the blood?
Alanine | Glutamine
61
``` "FLAMES" Fatty Liver Anemia Malnutrition Edema Skin Lesions ```
Kwashiorkor Disease = protein deficiency
62
Rate-limiting enzyme in Fatty Acid Synthesis?
Acetyl-CoA carboxylase
63
Rate-limiting enzyme in Fatty acid degradation?
Carnitine Acyltransferase 1
64
Dark connective tissue Brown pigmented sclerae Urine turns black on prolonged exposure to air Debilitating arthralgias
Alkptonuria Congenital deficiency of homogentistate oxidase (degrative pathway of tyrosine to fumarate)
65
``` Intellectual disability Growth retardation Seizures Fair skin Eczema Musty body odor ```
PKU Deficiency of phenylalanine hydroxylase High phenylalanine gets converted to phenylketone Tyrosine becomes essential
66
Two ways to have Albinism?
Defective tyrosinase activity or defective tyrosine transport NORMAL NUMBER OF MELANOCYTES **Vitiligo is autoimmune destruction of melanocytes
67
``` Intellectual disability Tall Stature Osteoporosis Kyphosis Atherosclerosis Subluxation of the lens (downward and inward) ```
Homocystinuria | NOTE: Marfan syndrome has subluxation of the lens UPWARD
68
Urine smells sweet..... blocked degradation of what amino acids?
Maple Syrup Urine Disease alpha-ketoacid dehydrogenase deficiency Blocked degradation of branched amino acids Isoleucine, Leucine, Valine "I Love Vermont maples syrup from maples trees with branches"
69
Defective alpha ketoacid dehydrogenase
Maple syrup urine disease
70
Household fire Bright red vessels in eyes Smell of bitter almonds on breath
Cyanide Poisoning Inhibits Complex 4 in electron transport chain (cellular respiration) Bright red vessels due to absent tissue oxygen extraction
71
What is a palindromic sequence in DNA?
Reading 5'-3' on one strand matches reading the complimentary strand 5' to 3 ' in the other direction *TGTACA
72
What is the only DNA polymerase with 5' to 3' exonuclease activity (removal of RNA primers)
DNA pol I
73
Enzyme deficient in Fructose intolerance
Aldolase B = Fructose 1 phosphate accumulates causing a decrease in phosphate available for glycogenolysis and gluconeogeneis Symptoms present after eating fruit, juice, honey Hypoglycemia, jaundice, cirrhosis, vomiting
74
Enzyme deficient in essential fructosuria
Fructokinase = benign, asymptomatic Fructose appears in blood and urine
75
``` FTT Jaundice Hepatomegaly Infantile cataracts Intellecutal disability ```
Classic Galactosemia Deficient Galactose-6-uridyltransferase Build up of products (Galactitiol which accumulates in lens)
76
HYPOKETOTIC hypoglycemia would indicate what?
Defect in fatty acid B-oxidation in the mitochondria
77
Most common defect causing impaired B-oxidation?
acyl-CoA dehydrogenase
78
Mutations at different loci can produce a similar pheontype (Albinism)
Locus heterogeneity
79
Different mutations in the same locus produce the same phenotypes (B-thalassemia)
Allelic heterogeneity
80
``` hyperphagia Obseity Intellectual disability Hypogonadism Hypotonia ```
Prader-Willi Syndrome Maternal silent/imprinted Paternal gets mutated or deleted
81
Inappropriate laughter Seizures Ataxia Severe intellectual disability
AngleMan Syndrome Paternal silent/imprinted Maternal gets mutated or deleted
82
Common associations with Down SYndrome
``` GI: Duodenal Atresia Hirschprung Annular Pancreas Celiacs ``` ASD ALL and AML Alzheimer (APP is on chromosome 21)
83
Decreased AFP Increased B-hCG Decreased estriol Increased Inhibin A Increased nuchal transleuceny
Down SYndrome
84
Describe G6PD deficiency and what you see on a peripheral smear
G6PD deficiency = can't produce NADPH in HMP Shunt No NADPH means we cannot reduce glutiathione No reduced glutiothione means we can't detoxify H2O2 in RBCs H2O2 oxidizes hemoglobin - which precipitates as Heinz bodies Heinz bodies eaten by MACs in the spleen to produce bite cells
85
What does decreased NAPDH in RBCs produce?
Hemolytic anemia due to poor RBC defense against oxidizing agents Fava beans Sulfonamides Primaquine Anti TB durgs
86
Most common human enzyme deficiency?
G6PD deficiency | More common in blacks - refers malarial resistance
87
Fructose appears in blood and urine | Otherwise a benign, asymptomatic condition
Essential Fructosuria Deficiecny = Fructokinase Normally takes fructose to fructose1-P
88
Hypoglycemia Jaundice Cirrhosis Vomiting After consuming fruit, juice, or honey
Fructose Intolerance Deficiency = Aldolase B Fructose-1-P cannot get broken down P gets trapped there, less available Need phosphate to do glycogenolysis and gluconeogenesis
89
``` FFT Jaunidice Hepatomegaly INFANTILE CATARACTS intellectual disability ```
Classic Galactosemia Deficiency of galactose-1-phosphate uridyltransferase Causes accumulation of toxic substances
90
How does high glucose or galactose cause cataracts?
Glucose --> sorbitol by Aldolase reductase Glacatose --> Galacticol by Aldolase reductase Sorbitol/Galacticol converted back by Sorbital dehydrogenase If tissue lacks sorbital dehydrogenase, can get accumulation of Galacticol/Sorbitol and cause osmotic damage
91
What tissues ONLY have aldolase reductase and are at risk for osmotic damage if high glucose or galactose?
Schwann cells Retina Kidneys Lens
92
Dark connective tissue Brown pigements sclerae Urine turns black on prolonged exposure to air Debilitating Arthralgias
Alkaptonuria Deficiency = Homongentisate Oxidase Can't degrade tyrosine, homogentisic acid accumulates in tissues Autosomal recessive
93
``` Increased homocysteine in urine Intellectual disability Osteoporosis Marfanoid habitus Kyphosis Lens subluxation (downward) ```
Homocystinuria Defect - cystathionine synthase Can't convert homocysteine to cystathionine
94
Recurrent precipitation of hexagonal radiolucent renal stones in children
Cystinuria + sodium cyanide nitroprusside test Defect in renal PCT, prevents reasborption of cysteine, ornithine, lysine, arginine Tx = alkalinization of urine
95
Inheritance pattern of all lysosomal storage disease (except Fabry)?
Autosomal Recessive
96
``` GM2 ganglioside accumulation Development delay Cherry red spots on Macula Lysosomes with onion skin NO HEPATOSPLENOMEGALY ```
Tay-Sachs Deficiency of Hexosaminidase A
97
``` Accumulations of shingomyelin Progressive neurodegeneration HEPATOSPLENOMEGALY Foam cells Cherry red spots on Macula ```
Neimann-Pick disease Deficiency of Sphingomyelinase
98
``` Hepatosplenomegaly Pancytopenia Osteoporosis Aseptic necrosis of femur Bone Crises ``` Lipid-laden macrophages resembling crumpled tissue paper
Gaucher Disease Deficiency Glucocerebrosidase Accumulations of glucocerebroside **Most common

USMLE REVIEW (25 decks)

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