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Biochemistry > Week 6 > Flashcards

Week 6 Flashcards

1
Q

What are the four types of Mendelian inheritance patterns ?

A

Autosomal dominant
Autosomal recessive
X-linked recessive
X-linked dominant

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2
Q

What are Dominant conditions?

A

manifest in heterozygotes , individuals with just one copy of the mutant allele

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3
Q

What is the effected probability for males vs. females in Autosomal Dominant ?

A

Equal probability of passing trait to offspring , only takes one mutant allele so children can have 50% chance of getting one mutant allele

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4
Q

What are the two examples of Autosomal dominant conditions ?

A

Huntington Disease

Acondroplasia (short-limbed dwarfism)

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5
Q

What are they two examples of autosomal recessive diseases?

A

Cystic fibrosis

Phenylketonuria (PKU)

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6
Q

True or false:

X-linked recessive traits are not clinically manifest when there is a normal copy of the gene?

A

True

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7
Q

What are the two examples of X-linked recessive disorders ?

A

Duchenne muscular dystrophy

Hemophilia A

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8
Q

True or false:

In X-linked dominant , an affected male will always pass the trait and the daughter will be effected

A

True- only takes the single X chromosome the father has to transmit the disease

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9
Q

What are two examples of X-linked Dominant disorders ?

A

Some forms of retinitis pigmentosa

Chondrodysplasia punctate

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10
Q

Mitochondria have_____ copies of a circular chromosome.

A

multiple

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11
Q

Mitochondria are only inherited from the _______ thus only females can transmit the trait to offspring.

A

mothers egg

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12
Q

The mitochondria generate energy for the rest of the cell, therefore disease transmitted through mitochondrial inheritance affects ______.

A

high energy organs

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13
Q

Metabolic disorders can be due to what two things?

A

enzymatic defects or a deficiency in a necessary cofactor

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14
Q

What are the common co-factors for amino acid metabolism?

A

BH4
THF
Cobalamin (B12)

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15
Q

What can be detected in urine for BCAA disorders ?

A

high level of metabolic intermidiates

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16
Q

What is a metabolic disorder that increases chance for thrombosis (blot clot in blood vessel) or cardiovascular disease ?

A

Hyperhomocysteniemia

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17
Q

What is Tyrosinemia ?

A

Mostly heritable disease, body can not break down Tyrosine and leads to accumulation that cases liver/kidney problems, mental impairment, and can be fatal

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18
Q

How many essential AA vs non-essential

A

11 non-essential

9 are Essential- must come from diet

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19
Q

True or false:

Amino acids are not stored.

A

True

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20
Q

What are the primary Ammonia (NH4) carrying amino acids to send to liver?

A

Alanine

Glutamine

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21
Q

What 4 things can Amino acids be used for (since they are not stored) ?

A
  1. Protein synthesis
  2. Precursors for neurotransmitters (glutamine)
  3. Transport ammonia (NH4) in body
  4. Deaminated to use carbon-skeletons for Glucose synthesis or TCA cycle intermediates
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22
Q

What does a glucogenic AA do ?

A

provides substrate to synthesize glucose (gluconeogenesis)

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23
Q

What does a ketogenic AA do ?

A

produces acetyl-CoA or Acetoacetate (accepted through TCA cycle)

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24
Q

Which AA can be converted to Pyruvate ?

A

Alanine
Serine
Cysteine
(three other AA are precursors to these too )

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25
Q

What are the 5 total AA that are in the pathway to produce pyruvate that can be used to make glucose?

A 
Threonine to Glycine
Tryptophan
Alanine
Serine
Cysteine
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26
Q

G or K?

Threonine?

A

Both Glucogenic and Ketogenic

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27
Q

Glycine ?

A

Glucogenic- non essential , can be synthesized from Threonine

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28
Q

Alanine?

A

Glucogenic- non essential, can be synthesized from Tryptophan or Glycine

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29
Q

Serine?

A

Glucogenic - Non essential, can be synthesized from Tryptophan or Glycine

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30
Q

Arginine?

A

Glucogenic

non-essential (essential in some cases)

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31
Q

What are the 9 essential AA ?

and the pneumonic ?

A 
PVT TIM HALL
Phenylalanine 
Valine 
Threonine
Tryptophan
Isoleucine
Methionine
Histidine (conditional)
Arginine (conditional)
Leucine
Lysine
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32
Q

What are the 4 Glucogenic essential Amino Acids? and the pneumonic?

A 
Has A Valid Medicine 
Histidine 
Arginine
Valine
Methionine
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33
Q

What are the pure ketogenic essential amino acids? (only 2 pure that are not both keto and gluco exisit)

A

Lysine

Leucine

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34
Q

What are the two AA that are only essential in children ?

A

HA HA (laugh a lot)
Histidine
Arginine

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35
Q

What are the Ketogenic Amino Acids ?

A 
Threonine (both)
Lysine
Leucine
Isoleucine (both)
Tryptophan (both)
Phenylalanine (Both)
Tyrosine (both)
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36
Q

What is the converted intermediate for Alanine ?

A

pyruvate

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37
Q

What is the converted intermediate for Cysteine ?

A

pyruvate

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38
Q

What is the converted intermediate for Glycine ?

A

pyruvate

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39
Q

What is the converted intermediate for Serine ?

A

Pyruvate

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40
Q

What is the converted intermediate for Tryptophan?

A

Pyruvate , or Acetyl CoA

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41
Q

What is the converted intermediate for Aspartate ?

A

Oxaloacetate (also made from pyruvate, glucogenic)

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42
Q

What is the converted intermediate for Asparagine?

A

Oxaloacetate (also made from pyruvate, gulogenic, in TCA cycle)

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43
Q

What is the converted intermediate for Arginine?

A

Alpha-Ketogluterate

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44
Q

What is the converted intermediate for Histidine?

A

Alpha-Ketogluterate

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45
Q

What is the converted intermediate for Glutamine?

A

Alpha-Ketogluterate

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46
Q

What is the converted intermediate for Proline ?

A

Alpha-Ketoglutarate

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47
Q

What is the converted intermediate for Glutamate ?

A

Alpha-ketoglutarte

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48
Q

In the metabolism of AA, what four different amino acids are precursors for Glutamate ?

A

Arginine
Histidine
Glutamine
Proline

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49
Q

What is the converted intermediate for Isoleucine ?

A

Succinyl-CoA (glutogenic)

Acetyl Co-A (ketogenic)

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50
Q

What is the converted intermediate for Valine?

A

Succinyl-CoA (glucogenic)

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51
Q

What are the 3 converted intermediates for Threonine?

A
  1. can be converted to glycine for use towards Pyruvate (main interm.)
  2. Succinyl Co-A
  3. Acetyl CoA
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52
Q

What is the converted intermediate for Methionine?

A

Succinyl Co-A

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53
Q

What are the converted intermediates for Phenylalanine?

A
  1. Fumarate (glucogenic)

2. Acetoacetate-keytone bodies (ketogenic)

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54
Q

What are the converted intermediates for Tyrosine ?

A
  1. Fumarate (glucogenic)

2. Acetoacetate-keytone bodies (ketogenic)

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55
Q

What is the converted intermediate for Lysine ?

A

Acetyl CoA

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56
Q

What is the converted intermediate for Leucine ?

A

HMG CoA (Acetyl CoA)

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57
Q

What are the AA for Acetoacetate (keytone bodies) ?

A

Phenylalanine

Tyrosine

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58
Q

What are the AA for direct to Acetyl CoA ? (ketogenic)

A

Threonine
Lysine
Isoleucine
Tryptophan

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59
Q

What are the AA for Fumarate ?

A

Aspartate
Tyrosine
Phenylalanine

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60
Q

What are the AA for Succinyl CoA?

A

Valine
Threonine
Isoleucine
Methionine

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61
Q

What are the AA for Alpha-Ketoglutarate ?

A

Arginine
Histidine
Glutamine
Proline

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62
Q

What are the AA for Oxaloacetate (besides Pyruvate as its precursor) ?

A

Aspartate

Asparagine

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63
Q

What are the AA for Pyruvate ?

A 
Alanine
Serine
Cysteine
Tryptophan
Glycine
Threonine
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64
Q

What is the precursor to Succinyl CoA ?

A

Propionyl CoA

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65
Q

Where does Propionyl CoA come from directly?

A 
Valine
Threonine
Isoleucine
Methionine 
(pathway to Succinyl CoA)
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66
Q

If AA are not being used for protein synthesis they require transamination or (deamination) with what co-factor?

A

PLP (mainly transamination)

  • Pyridoxal pyrophosphate
  • active form of B6
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67
Q

What is the methyl (CH3) donor (also carbon donor) that acts as a cofactor for AA metabolism ?

A

Cobalamin (B12 vitamin)

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68
Q

What is the other carbon donor besides Cobalamin in the required co-factors for AA metabolism?

A

Folate (carbon donor)

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69
Q

What is the cofactor in AA metabolism that is required for metabolizing cyclic amino acids (Phe, Tyr, Tryptophan) ?

A

BH4

Tetrahydrobiopterin

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70
Q

Instead of storing AA, they are ______ to generate a carbon skeleton that can be metabolized.

A

Deaminated

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71
Q

Once the AA is broken down into Carbon chains after deamination it can be used to synthesize _____.

A

Glucose

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72
Q

What does transamination by PLP do ?

A

Takes one AA then transfers and shifts the amine group from the first one to a keto-acid to generate a different AA

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73
Q

What is the example of transamination by PLP (B6) to create Oxaloacetate ?

A

Aspartate is interacted with alpha-ketoglutarate using the cofactor PLP (B6)

  • through transamination makes products:
    1. Oxaloacetate (same as aspartate but the ammonia group is removed and given to Alpha-ketoglutarate to make Glutamate)
    2. Glutamate is made by alpha-ketoglutarate accepting the NH3 group to make glutamate
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74
Q

What is the product of Glutamate important for in the Transamination reaction involving PLP (B6) and Aspartate/alpha-ketoglutarate ?

A

Glutamate can carry the NH3 (ammonia) to the liver for excretion through the urea cycle

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75
Q

What Oxaloacetate important for ?

A

enters into TCA cycle and used to create glucose

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76
Q

In the Folate cycle, folate is first reduced (Hydrogen added to the N and C on Pteridine ring) in step one by which enzyme ?

A

Dihydrofoate reductase

77
Q

What does the enzyme Dihydrofolate reductase in step one of folate cycle get the H from to give to folate ?

A

Takes H from NADPH (NADPH is oxidized to NADP+)

78
Q

What is the second step in the Folate cycle after Dihydrofolate reductase has acted on the Folate molecule ?

A

the same enzyme acts again on the now Dihydrofolate (FH2) to take H from NADPH and makes Tetrahydrofolate (FH4) - 4 H are now on Pteridine ring on the N and H

79
Q

True or False, the reactions by Dihydrofolate reductase are reversible and often coupled.

A

True

80
Q

What is folate often coupled with and to generate what ?

A

Various metabolic reactions to generate a 1 C donor

81
Q

What is the example of Folate involved with metabolic cycles to generate a 1 C donor ?

A

Glycine interacts with FH4 and a 1 C donor to create the base product in the start of Purine synthesis

82
Q

How is Folate required for dTMP ?

A

Folate donates oxidized carbon group with dUMP to make dTMP in the Pyrimidine synthesis cycle

83
Q

How is folate required for Methionine?

A

Used along with B12 to remethylate Homocysteine back to Methionine

84
Q

How is folate required for Purine biosynthesis ?

A

Required at beginning of pathway with Glycine to make precursor of IMP (Inosine monophosphate) needed to make other purines

85
Q

What two AA is folate required for metabolism of the AA into other molecules ?

A

Histidine into Methenyl FH4

Tryptophan into Formyl FH4

86
Q

What two reactions is Cobalamin (B12) required for in metabolism?

A
  1. Conversion of homocysteine to methionine (remethylation pathway)
  2. Conversion of Methylmalony CoA to Succinyl CoA (part of TCA cycle)
87
Q

How does Cobalamin (B12) interact in the remethylation pathway ?

A

Cobalamin will be charged with a Methyl Group (CH3) that was donated by folate (Methylcobalamin) and can remethylate Homocysteine to methionine

88
Q

Deficiencies of Cobalamin (B12) can manifest as high levels of what two intermediates ?

A

Homocysteine

Methylmalonyl CoA

89
Q

All amino acids except ____ and ____ have the ability to undergo transamination reactions (PLP)

A

Lysine and Threonine

90
Q

What is the alpha keto acid of Aspartate ?

A

Oxaloacetate

91
Q

What is the AA version of Alpha-ketoglutarate

A

Glutamate (carried NH3) in transamination

92
Q

What 4 amino acids are synthesized from intermidates of Glycolysis ?

A

Serine
Glycine
Cysteine
Alanine

93
Q

How is alanine formed ?

A

transamination of pyruvate

94
Q

What is serine used to produce ?

A

Glycine and Cysteine

95
Q

What happens to the four AA that are synthesized from intermediates of Gycolysis ( S, G, C, A) after they are degraded ?

A

Carbon atoms are converted to pyruvate or intermediates in pathway
-can lead to produce glucose or be oxidized to CO2

96
Q

The coenzyme tetrahydrobiopterin (BH4) is required for ring ______.

A

Hydroxylations

  • addition of one Oxygen molecule into product
    ex: tyrosine and neurotransmitters
97
Q

The carbons and nitrogen for cysteine synthesis are provided by _____, and the sulfur is provided by _____.

A

Serine

Methionine

98
Q

Serine reacts with homocysteine (which is produced by methionine) to form _____.

A

Cystathionine

99
Q

What enzyme catalyzes the reaction of Serine with homocysteine to produce cystathionine ?

A

Cystathionine Beta-synthase (Beta elimination)

100
Q

Cleavage of cystathionine by cystathionase (gamma elimination) (PLP is present) produces ______ and ______.

A

Cysteine

Alpha-ketobutyrate

101
Q

What does the Alpha-ketobutyrate go on to form ?

A

Succinyl-CoA

102
Q

True or false
Only Cystathionine Beta-synthase (beta elimination) requires PCP, not the following reaction with cystathionase (gamma elimination)

A

False : PLP is needed for both (B6)

103
Q

What does the product of Cysteine inhibit ?

A

Cystathionine Beta synthase (first step in its own synthesis where serine is reacted with homocysteine)
-Regulates its own production to adjust for dietary supply of cysteine

104
Q

Cysteine becomes essential if ______ is inadequate for cysteine synthesis because it derives its sulfur from the AA. consequently an adequate dietary supply will “spare” the AA as it decreases the amount that must be degraded to create Cysteine.

A

Methionine

105
Q

When cysteine is degraded, the nitrogen is converted to ____ and the carbons are converted to ____, and the sulfur to _____.

A

Urea
Pyruvate
Sulfate

106
Q

What two things can result in homocystinemia (associated with cardiovascular disease) ?

A
  1. PLP (B6) deficiency

2. Congenital cystathionine Beta synthase deficiency

107
Q

What amino acids are degraded to form Succinyl-CoA (TCA intermediate) from conversion of propionyl-CoA ?

A

Methionine, Valine, Isoleucine, Threonine

108
Q

How is propionyl-CoA formed (later used to make Succinyl-CoA) ?

A

oxidation of odd-chain fatty acids

109
Q

Methionine is converted to _____ (SAM) which donates its methyl group to other compounds to form ______ (SAH).

A

S-adenosylmethionine (SAM)

S-adenosylhomocysteine

110
Q

S-adenosylhomocysteine is converted to ______.

A

homocysteine

111
Q

Methionine can be regenerated from Homocysteine by a reaction that requires both ____ and ____.

A

FH4 and B12

112
Q

Alternative to regenerating methionine, Homocysteine can react with PLP and provide the sulfur needed to create cysteine its biosynthesis pathway. If it goes this path, Carbons of homocysteine are metabolized to _______, which undergoes oxidative decarboxylation to ______. Which is then coverted to succinyl-CoA.

A

Alpha-ketobutyrate

Propionyl-CoA

113
Q

Methylene synthase uses ______ after it has been methylated by _______ to remethylate homocysteine to remethylate homocysteine to generate methionine.

A

Cobalamin (B12)

Tetrahydrofolate (FH4 - folate intermediate))

114
Q

What is the name for BH4 ?

A

Tetrahydrobiopterin (BH4)

115
Q

What is BH4 required for ?

A
  1. Synthesis and Conversion of Aromatic AA
116
Q

What does biosynthesis of Aromatic AA start with ?

What is the second step?

A

GTP

Step two = conversion to BH4 (tetrahydrobiopterin)

117
Q

What happens in Aromatic AA synthesis after BH4 is made from GTP ?

A

Phenylalanine reacts enzyme Phenylalanine hydroxylase (requires BH4 and O2 to be present)
-takes the O from O2 and one H to Hydroxylate the ring structure to make = Tyrosine

118
Q

Deficiencies in Phenylalanine hydroxylase will lead to what condition?

A
  • High levels of Phenylalanine

- Disease: Phenylketonuria (PKU)- cant break down phenylalanine

119
Q

After the reaction with Phenylalanine hydroxylase that will hydroxylate phenylalanine into tyrosine, what happens to the BH4 ?

A
  • it lost 2 H so it becomes BH2 moiety (Quinonoid dihydrobiopterin)
  • BH2 will be reduced taking H from NADH with the enzyme Dihydropteridine reductase back into BH4 for reuse
120
Q

One carbon donors function in all of the following processes except:

  1. DNA methylation
  2. Charging of cobalamin
  3. Synthesis of purines
  4. Production of tyrosine
A

Production of Tyrosine - does not require 1 Carbon donor, but BH4 instead to Hydroxylate the ring from phenylalanine

121
Q

What does DNA usually get its One carbon donor from (methylation)?

A

S-adenosine or S-adenosyl methionine

SAM

122
Q

Where does the charging of Cobalamin (B12) get its one carbon donor from ?

A
  • FH4 (folate)

- will transfer the Carbon onto Cobalamin who then transfers it back to Homocysteine that will create Methionine

123
Q

Where does the synthesis of Purines get its one carbon from it needs?

A

Folate group (FH4)

124
Q

What are the 4 main Autosomal inherited disorders we will study that are disorders of Amino Acid metabolism?

A
  1. Phenylketonuria (PKU)
  2. Maple Syrup Urine Disease (MSUD)
  3. Homocystinuria (HCY)
  4. Alcaptonuria
125
Q

What type of inheritance is a pink flower (blending) ?

A

Incomplete dominance (blending of traits)

126
Q

What type of inheritance is a red and white spotted flower ?

A

Codominance (expression of two alleles)

127
Q

What is Maple Syrup Urine Disease generally caused by ?

A

Defects in branched chain amino acid metabolism

128
Q

What is Phenylketonuria and Alcaptonuria generally caused by ?

A

Defects in cyclic amino acid metabolism

129
Q

What is Hyperhomocysteinemia generally caused by ?

A

Defects in metabolism of methionine and cysteine

130
Q

Branched chain AA are metabolized mainly where ?

A

Skeletal muscle

131
Q

What are the three main BCAA that are involved in metabolism in the skeletal muscle ?

A

Valine
Isoleucine
Leucine

132
Q

What is the first step in BCAA metabolism ?

A
  1. Transamination -deaminates BCAA leaving it as ketoacid or carbon backbone
133
Q

What is the second step of BCAA after transamination ?

A

Decarboxylation of the ketoacid (carbon backbone)
-done by Branch Chain AA Decarboxylase (BCK DH) named Alpha-ketoacid dehydrogenase) - commit oxidative decarboxylation (remove CO2 and NADH)

134
Q

What type of inheritance is Maple Syrup Urine Disease ?

A

Autosomal recessive (rr is required)

135
Q

In MSUD, what is happening or where is the process being blocked ?

A

the skeletal muscle can no longer decarboxylate the alpha-ketoacid skeletons left by the deamination of BCAA (step 2 is blocked)
-several enzyme defects may cause this , but mainly the Branch Chain Keto-acid Dehydrogenase

136
Q

What does Valine turn into after transamination ?

A

Alpha-Ketoisovalerate (intermediate)

137
Q

What does Isoleucine turn into after transamination ?

A

Alpha-keto-beta-methylvalerate (intermediate)

138
Q

What does Leucine turn into after transamination ?

A

Alpha-Ketoisocaproate (intermediate)

139
Q

What happens if the intermediates of BCAA are being accumulated due to Maple Syrup Urine Disease ?

A

They will accumulate and be excreted in urine (“sweet smell”)

140
Q

Several forms of MSUD are responsive to vitamin supplementation, what vitamin may be effective in reducing serum levels of BCAA’s that are not being metabolized ?

A

PLP - pyridoxal phosphate (B6)- needed for transamination

MOST IMPORTANT = Thiamine (B1)- required by BC dehydrogenase for the step two to process the intermediates

141
Q

Branched chain AA metabolism involves a Dehydrogenase complex similar to pyruvate dehydrogenase complex and both require ______ as a cofactor.

A

Thiamine

142
Q

What can help in a case of non-heritable mutation of MSUD to treat it ?(supplementation)

A

Thiamine (B1) supplementation - improves the second step involving Oxidative decarboxylation of the alpha-ketoacid intermediates of BCAA

143
Q

In the BCAA metabolism pathway, what are they degraded into after step 2 ?

A
  1. Propionyl CoA (Valine, Isoleucine )
  2. Acetyl CoA (Isoleucine , Leucine)
  3. Acetoacetate (Leucine)
144
Q

In BCAA metabolism, after the products of Propionyl CoA, Acetyl CoA, and Acetoacetate are made, what are the two eventual outcomes ?

A

Acetoacetate can lead to Ketogenic process
AcetylCoA can lead to Ketogenic process
Propionyl CoA can lead to Succinyl CoA and Gluconeogenic process

145
Q

What 3 things can Phenylalanine be metabolized to ?

A

First - Tyrosine

Last- Fumarate or Acetoacetate

146
Q

Metabolism of Phenylalanine requires what cofactor?

A

BH4 and Thiamine (B1)

147
Q

What can Classic Phenylketonuria lead to if undetected ?

A
  1. Mental retardation due to elevated Phe levels

2. Deficiency in dopamine (because tyrosine is precursor to Dopamine)

148
Q

What are the two causes of PKU ?

A
  1. BH4 deficiency
  2. Deficiency in phenylalanine hydroxylase (turns to tyrosine)
    (screened for at birth)
149
Q

What two pathways can Phenylalanine take ?

A
  1. Transamination by PLP - forms Phenylpyruvate

2. Phenylalanine hydroxylase enzyme (with BH4 cofactor) to form Tyrosine

150
Q

What two pathways can Tyrosine take after it has been created from Phenylalanine ?

A
  1. Tyrosinase (with BH4) will generate downstream metabolites like melanin or dopamine
  2. Converted to Hydroxyphenyl pyruvic acid then to Homogentisic acid then Aceto acetic acid
151
Q

In second option pathway for Tyrosine, what are the three steps and where can it go wrong ?

A
  1. Hydroxyphenyl pyruvic acid
  2. Homogentisic acid
  3. Aceto acetic acid
    (Homogentisic dehydrogenase is required from step 2 to 3, if defect, then Alkaptonuria is caused )
152
Q

What is Alkaptonuria ?

A

Homogentisic acid that came from phe then tyrosine builds up in the body due to defect in Homogentisic dehydrogenase , “black urine disease”

153
Q

What is BH4 (tetrahydrobiopterin) required for ?

A
  1. Tyrosine to Dopamine
  2. Tryptophan to Serotonin
  3. Phenylalanine to Tyrosine
154
Q

Methionine metabolism involves what 3 independent pathways ?

A
  1. Transsulfuration
  2. Remethylation
  3. Folate cycle
155
Q

Methionine from the diet can be converted to _____.

A

Homocysteine

156
Q

Homocysteine can be transssulfurated via ________ to generate Cysteine.

A

Cystathione-beta-synthase

157
Q

Conversion of Homocysteine to Cysteine requires _____ that is a cofactor to react with Cystathione-beta-synthase .

A

PLP (pyridoxal phosphate)

158
Q

What does Cysteine further metabolize to ?

A
  1. Pyruvate
  2. Glutamate
  3. Sulfate (excreted in urine)
159
Q

In methionine metabolism, what is the first step it is charged with ?

A

ATP comes in and gives its Adenine (phosphates released) to charge Methionine
-generates S-Adenosyl-Methionine (SAM)

160
Q

What is S-adenosylmethionine(SAM) important for ?

A

Intermediate that functions as an important methyl donor to many compounds (CH3)

161
Q

What compound remains after S-adenosyl-methionine (SAM) has donated its CH3 (methyl) group to any “R” compound ?

A

changed to S-adenosyl homocysteine

162
Q

How is S-adenosyl homocysteine converted to Homocysteine ?

A

removal of Adenosine

163
Q

What two outcomes does Homocysteine have ?

A
  1. Remethylated back to Methionine

2. Transsulfurated into Cysteine

164
Q

What does remethylation of Homocysteine need to get back to methionine need?

A
  1. B12 (cobalamin)- cofactor for the synthase
  2. FH4 (folate) cycle
  3. Methionine synthase
165
Q

What does the folate give to the cobalamin for use to remethylate Methionine ?

A

FH4 gives a CH3 (methyl) group to B12 (cobalamin) that is then charged and can react and give its CH3 to Homocysteine to make Methionine

166
Q

What happens when SAM is used with Nucleotides (for instance Cytosine)?

A

Cystosine becomes methylated and it repressed transcription (makes DNA more negative so tighter binding)

167
Q

What products is SAM involved in making

A
  1. Epinephrine from Norepinephrine
  2. Creatine from Guanidinoacetate
  3. Methylated nucleotides from Nucleotides
  4. Phosphatidylcholine from Phosphatidylethanolamine
  5. Melatonin from Acetylserotonin
168
Q

What vitamin would be most effective for the treatment of an individual who is heterozygous for a genetic defect of the gene for cystathionine Beta synthase ?

A

(transsulfuration of Homocysteine to Cysteine)

answer: B6 or PLP (pyridoxal phosphate)- required in pathway

169
Q

What is used by SAM to transfer its Methyl group to various compounds ?

A

Methyltransferase

170
Q

Elevated levels of Homocysteine are correlated to ?

A

Cardiac disease - used as diagnostic tool when elevated levels in blood

171
Q

What are two purposes of BCAA valine and isoleucine metabolism in the muscles ?

A
  1. Energy generation (NADH and FADH production for usage)

2. forming precursors for TCA cycle intermediates (Propionyl CoA to Succinyl CoA-gluconeogenic)

172
Q

Which BCAA can be considered strictly ketogenic as it leads to Acetyl CoA and Acetoacetate (key tone bodies) ?

A

Leucine

173
Q

Which AA are both ketogenic and glucogenic ?

A

Isoleucine
Threonine
All Aromatic AA (Phenylalanine, Tyrosine, Tryptophan)

174
Q

_____ AA produce Acetyl-CoA or Acetoacetate and therefore are categorized as _______.

A

Seven (Leucine, Lysine, Isoleucine, Threonine, Aromatic AA- 3)
Ketogenic

175
Q

BH4 can be synthesized not from a vitamin, but from within the body from _____.

A

Guanosine Triphosphate (GTP)

176
Q

Tryptophan is ______ to produce Alanine (from the non ring carbons), Formate, and Acetyl-CoA. Therefore, it is both glucogenic and ketogenic.

A

oxidized

177
Q

____ and _____ can be produced from the ring structure of Tryptophan. Therefore it spares the dietary requirement for niacin. The higher the levels of dietary tryptophan, the lower are the levels of niacin required to prevent symptoms of deficiency.

A

NAD+ and NADP+

178
Q

Leucine is a universal fuel, with its primary metabolism occurring in _____.

A

Muscle

179
Q

Lysine cannot be directly ____ at either of its two amino groups. Lysine is degraded by a complex pathway of intermediates, leading to production of ____ and ____ for energy usage.

A

transaminated

NADH and FADH2

180
Q

Lysine ultimately generates _____ and is strictly ketogenic.

A

Acetyl-CoA

181
Q

What product accumulates in PKU classical and nonclassical ?

A

phenylalanine

182
Q

What product accumulates in Alcaptonuria “black urine”disease?

A

Homogentisic acid

183
Q

What product accumulates in Cystathioninuria?

A

Cystathionine (benign)

184
Q

What product accumulates in Homocysteinemia ?

A

Homocysteine (cardiovascular complications)

185
Q

What product accumulates in Maple Syrup urine disease ?

A

Alpha-keto acids of BCAAs (mental retardation)

186
Q

Classic PKU is caused by a defect in ?

A

phenylalanine hydroxylase

187
Q

Nonclassic PKU is caused by defect in ?

A

Dihydropteridine reductase (ability to synthesize tetrahydrobiopterin BH4) - lead to mental retardation

188
Q

What is the only reaction that methyl-FH4 can donate its methyl group ?

A

In combo with B12 - converting homocysteine back to Methionine

189
Q

What are the two reactions requiring B12 (Cobalamin)

A
  1. Homocysteine to Methionine (Cobalamin bound to FH4)

2. Methylmalonyl CoA conversion to Succinyl CoA

Biochemistry (20 decks)

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