Biochemistry: Exam 4

Front 1

What is the most concentrated storage form of fuel?

Back 1

Fats (mostly hydrocarbon)!

Front 2

Fatty acids are broken down into what?

Back 2

Acetyl CoA

Front 3

Fatty acids are stored as what?

Back 3

Triacylglycerols

Front 4

Fatty acids are degraded and synthesized in what number units?

Back 4

2-carbon units!

Front 5

TRUE OR FALSE: The key intermediates between fatty acid degradation and synthesis are not the same.

Back 5

FALSE. They are the same.

Front 6

What is perilipin?

Back 6

Protein that once phosphorylated by Protein Kinase A makes triacylglycerols more accessible to mobilization and triggers the release of the coactivator adipose triglyceride lipase.

Front 7

Triacylglycerols in adipose tissues are converted into fatty acids in response to what?

Back 7

Hormonal signals that activate the 7TM receptors that activate cAMP and Protein Kinase A.

Front 8

In hormonal regulation of Lipase, protein kinase A activates triacylglycerol lipase which does what?

Back 8

It releases a fatty acid from triacylglycerol converting it into diacylglycerol

Front 9

Glycerol released from fat by lipase is sent to what?

Back 9

Glycolysis pathway!

Front 10

What completes the mobilization of fatty acids with the production of a free fatty acid and glycerol?

Back 10

Monoacylglycerol lipase

Front 11

What 2 things induce lipolysis?

Back 11

1. Epinephrine

2. Glucagon

Front 12

What is albumin?

Back 12

Blood protein that serves as a carrier for insoluble fatty acids in the blood stream.

Front 13

What are the 3 steps to convert glycerol into glyceraldehyde 3-phosphate? When is NADH produced?

Back 13

1. Glycerol to L-Glycerol 3-phosphate

2. L-Glycerol 3-phosphate to Dihydroxyacetone phosphate (NADH IS PRODUCED)

3. Dihydroxyacetone phosphate to glyceraldehyde 3-phosphate

Front 14

Once converted to glycerol, what two pathways can glycerol undergo?

Back 14

1. Glycolysis to Pyruvate

2. Gluconeogenesis to Glucose

Front 15

Where are fatty acids oxidized?

Back 15

Mitochondrial matrix

Front 16

In order to be oxidized, fatty acids must be activated by what?

Back 16

CoA!

Front 17

What are the 2 steps to fatty acid activation?

Back 17

1. Fatty acid reacts with ATP to form acyl adenylate and pyrophosphate

2. Sulfhydryl group of CoA attacks the acyl adenylate to form acyl CoA and AMP

Front 18

How do activated fatty acids cross the inner mitochondrial membrane?

Back 18

They must be linked to the alcohol carnitine

Front 19

What are the 4 basic reactions of fatty acid degradation (The Beta Oxidation Pathway)?

Back 19

1. Oxidation to form alphabeta double bond (FADH2)

2. Hydration across the double bond

3. Oxidation (NADH)

4. Thiolysis by CoA to displace the first 2 carbons

Front 20

What is the first step of fatty acid breakdown?

Back 20

Acyl CoA is oxidized via FAD (forming FADH2) to form trans-delta-enoyl CoA

Front 21

What is the second step of fatty acid breakdown?

Back 21

Trans-delta-enoyl CoA is hydrated to form L-3-hydroxyacyl CoA

Front 22

What is the third step of fatty acid breakdown?

Back 22

L-3-hydroxyacyl CoA is oxidized via NAD+ (forming NADH) to form 3-ketoacyl CoA

Front 23

What is the fourth step of fatty acid breakdown?

Back 23

3-ketoacyl CoA is thiolysed by CoA to form Acyl CoA (which is shortened by 2 C) and Acetyl CoA

Front 24

In each beta oxidation pathway reaction cycle, how many carbon atoms are released from the fatty acid? How many FADH2, NADH, and acetyl CoA molecules are formed?

Back 24

2 carbons are released

1 FADH2, NADH, and acetyl CoA are formed

Front 25

Palmitate has 16 carbons. In the breakdown of this molecule, how many times is it cut and how many acetyl CoA molecules are formed? Why?

Back 25

It is cut 7 times forming 8 acetyl CoA molecules. This is because the last cut produces TWO acetyl CoA!

Front 26

Palmitate has 16 carbons. In the breakdown of this molecule, how many times is it cut and what is the total energy yield?

Back 26

It is cut 7 times and produces 106 ATP molucules

Front 27

How many ATPs per acetyl CoA in the citric acid cycle?

Back 27

10

Front 28

How are odd-numbered fatty acids broken down?

Back 28

An enzyme using vitamin B12 as a cofactor adds 1 carbon to the left over 3-carbon fragment

Front 29

How are unsaturated fatty acids broken down?

Back 29

Enzymes move double bonds to be in register with the beta oxidation pathway

Front 30

Excess acetyl CoA is converted into what 3 thing? What are these referred to as?

Back 30

1. Acetoacetate

2. 3-hydroxybutyrate

3. Acetone

They are referred to as KETONE BODIES

Front 31

Ketone bodies are released into the blood for what purpose?

Back 31

To be used by some tissues as fuel instead of glucose

Front 32

Ketone body synthesis takes place where?

Back 32

Mitochondria of the liver

Front 33

In the formation of ketone bodies, what are the 5 steps?

Back 33

1. acetyl CoA to Acetoacetyl CoA

2. 3-hydroxy-3-methyl-glutaryl CoA

3. Acetoacetate

4. 3-hydroxybutyrate OR Acetone

Front 34

Acetone, under starvation conditions, can be captured to do what?

Back 34

Synthesize glucose

Front 35

3-Hydroxybutyrate can be oxidized to form what?

Back 35

TWO molecules of acetyl CoA (which goes on into the citric acid cycle)

Front 36

Fatty acid synthesis occurs where and by how many carbon atoms at a time?

Back 36

In the cytoplasm by 2 carbon atoms at a time

Front 37

What is the reducing agent of fatty acid synthesis?

Back 37

NADPH

Front 38

What is the raw material of fatty acid synthesis?

Back 38

Acetyl CoA

Front 39

How are acetyl CoA transported out of the mitochondria and into the cytoplasm so that fatty acids can be synthesized?

Back 39

Acetyl CoA is converted into citrate via condensation with oxaloacetate

Front 40

What is the activated form of acetyl CoA?

Back 40

Malonyl CoA

Front 41

Fatty acid synthesis starts with what?

Back 41

The carboxylation of acetyl CoA to malonyl CoA

Front 42

What is the first committed step in fatty acid synthesis?

Back 42

Acetyl CoA with HCO3- to form Malonyl CoA

Front 43

What are the 2 steps of malonyl CoA synthesis?

Back 43

1. Acetyl CoA carboxlylase containing BIOTIN hydrolyzes acetyl CoA

2. Activated CO2 group is then transferred to form malonyl CoA

Front 44

Fatty acids are synthesized by the repetition of what 4 reactions?

Back 44

1. Condensation

2. Reduction

3. Dehydration

4. Reduction

Front 45

The elongation phase of fatty acid synthesis in bacteria starts when acetyl CoA and malonyl CoA react with what? What is formed?

Back 45

A scaffold protein called acyl carrier protein (ACP) which forms acetyl ACP and malonyl ACP

Front 46

In the 1st round of fatty acid synthesis, acetyl ACP and malonyl ACP form what by what process?

Back 46

Acetoacetyl ACP via CONDENSATION

Front 47

Acetoacetyl ACP forms what by what process? What does it use?

Back 47

D-3-hydroxybutyrl ACP via REDUCTION using NADPH

Front 48

D-3-hydroxybutyrl ACP forms what by what process?

Back 48

Crotonyl ACP via DEHYDRATION

Front 49

Crotonyl ACP forms what by what process? What does it use?

Back 49

Butyryl ACP (4-carbons) via REDUCTION using NADPH

Front 50

All the carbon atoms of fatty acids containing an EVEN number of carbon atoms are derived from what?

Back 50

Acetyl CoA

Front 51

What two things start the 2nd round of fatty acid synthesis?

Back 51

Butyryl ACP (4 C) and Malonyl ACP

Front 52

Half of the NADPH needed for fatty acid synthesis comes from where? Where does the other half come from?

Back 52

Half comes from the pentose phosphate pathway

Other half comes from mitochondrial export of acetyl CoA when Malate is converted into Pyruvate

Front 53

After the formation of acetyl CoA, the resulting oxaloacetate is transported back into the mitochondria to form what?

Back 53

NADPH

Front 54

Both triacylglycerol and phospholipid synthesis begin with what precursor?

Back 54

Phosphatidate

Front 55

Phosphatidate is formed by the addition of what?

Back 55

2 fatty acids to glycerol 3-phosphate

Front 56

Fats and phospholipids connect to glycolysis via what?

Back 56

Glycerol 3-phosphate

Front 57

What are the 2 steps to make phosphatidate? Via what?

Back 57

1. Glycerol 3-phosphate to lysophosphatidate (via saturated acyl CoA)

2. Lysophosphatidate to phosphotidate (via unsaturated acyl CoA)

Front 58

What are the 2 steps to make triacylglycerol?

Back 58

1. Phosphatidate to Diacylglycerol (DAG) (via hydrolysis)

2. DAG to triacylglycerol (via acyl CoA)

Front 59

What are the 2 ways to make phospholipids?

Back 59

1. Biosynthesis from the activation of phosphatidase by CTP

2. Biosynthesis from the activation of the "head group" of DAG by CTP

Front 60

Activation of phosphatidate to CDP-diacylglycerol is driven forward by what?

Back 60

The hydrolysis of pyrophosphate!

Front 61

What are the 3 steps to form phosphatidylethanolamine?

Back 61

1. Ethanolamine to Phosphorylethanolamine

2. CDP-ethanolamine

3. Phosphatidylethanolamine

Front 62

What is the role of CTP activation in the formation of phosphatidylethanolamine?

Back 62

CTP activates the alcohol phosphorylethanolamine to form CDP-ethanolamine

Front 63

Phosphatidylcholine is synthesized from phosphatidylethanolamine how? Why?

Back 63

It is methylated with S-Adenosylme-thionine 3 times when dietary choline is insufficient.

Front 64

Sphingolipids are synthesized from what?

Back 64

Ceramide

Front 65

All 27 carbon atoms of cholesterol are derived from what?

Back 65

Acetyl CoA

Front 66

What is the 3 stage synthetic process of cholesterol?

Back 66

1. Isopentenyl pyrophosphate synthesis

2. Condensation of 6 isopentenyl pyrophosyhtate molecules to form squalene

3. Squalene cyclizes into cholesterol

Front 67

The formation of isopentenyl pyrophosphate from acetyl CoA starts with the formation of what?

Back 67

3-hydroxy-3-methylglutaryl CoA (HMG CoA) from acetyl CoA and acetoacetyl CoA

Front 68

What is the role of HMG CoA Reductase?

Back 68

It catalyzes the formation of mevalonate from 3-hydroxy-3-methylglutaryl CoA in Cholesterol formation.

Front 69

What is mevalonate?

Back 69

An important intermediate formed from HMG CoA in the formation of cholesterol

Front 70

What is the committed step of cholesterol biosynthesis?

Back 70

Formation of mevolonate

Front 71

In the Cytosol, HMG-CoA forms what?

Back 71

Cholesterol

Front 72

In the mitochondria, HMG-CoA forms what?

Back 72

Ketone bodies

Front 73

What is the building block of cholesterol biosynthesis?

Back 73

Isoprene

Front 74

Mevalonate is converted into what in 3 consecutive ATP reactions?

Back 74

3-isopentenyl pyrophosphate

Front 75

Squalene (30 C) is synthesized from 6 molecules of what?

Back 75

Isopentenyl pyrophosphate (5 C)

Front 76

What must happen to isopentenyl pyrophosphate before condensation can take place?

Back 76

It must isomerize into dimethylallyl pyrophosphate

Front 77

Farnesyl pyrophosphate is converted into what using what?

Back 77

Squalene using farnesyl pyrophosphate and NADPH

Front 78

Cholesterol and other lipids in excess of those needed by the liver are exported in what form?

Back 78

Low density lipoproteins (LDLs)

Front 79

Liver and peripheral-tissue cells take up LDL by what?

Back 79

Receptor-mediated endocytosis

Front 80

What does the LDL receptor do?

Back 80

Binds LDL and mediates its entry into the cell

Front 81

The absence of LDL receptors in the homozygous form of familial hypercholesterolemia leads to what?

Back 81

Elevated plasma levels of LDL cholesterol and the deposition of cholesterol in blood vessels leading to heart attacks.

Front 82

Homozygous familial hypercholesterolemia can only be treated by what?

Back 82

A liver transplant

Front 83

What is the major carrier of cholesterol in the blood?

Back 83

Low-density lipoprotein

Front 84

What 4 things surround the LDL?

Back 84

1. Unesterified cholesterol

2. Phospholipid

3. Cholesteryl ester

4. Apoprotein B-100

Front 85

What is the purpose of Apoprotein B-100?

Back 85

Directs LDL to the proper cells

Front 86

What is the role of LDL?

Back 86

Transport cholesterol to peripheral tissues and regulate de novo cholesterol synthesis at these sites

Front 87

What are the 3 steps to receptor-mediated endocytosis of LDL?

Back 87

1. LDL binds to receptor protein on cell surface

2. Cell internalizes the receptor-LDL complex

3. LDL is hydrolyzed in lysosomes

Front 88

What are the 2 steps to amino acid catabolism?

Back 88

1. Remove alpha-amino group

2. Deliver carbon "skeleton" to glycolysis and/or citric acid cycle for oxidation

Front 89

The carbon skeleton of alanine (once the NH4 is removed) is what?

Back 89

Pyruvate!

Front 90

The alpha amino group of many amino acids is transferred to what to form what? What happens next?

Back 90

To alpha-ketoglutarate to form glutamate which is then oxidatively deaminated to yield ammonium (NH4+)

Front 91

What catalyzes the transfer of an alpha-amino group from an alpha amino acid to an alpha-ketoacid?

Back 91

Aminotransferases!

Front 92

What does aspartate aminotransferase do?

Back 92

Transfers the alpha-amino group of aspartate to alpha-ketoglutarate to form oxaloacetate and glutamate AND VICE VERSA

Front 93

What happens to the nitrogen atom that is transferred to alpha-ketoglutarate in the transamination reaction?

Back 93

It is converted into free ammonium ion by the oxidative deamination of glutamate, regenerating alpha-ketoglutarate

Front 94

How is nitrogen removed from glutamate?

Back 94

Glutamate dehydrogenase

Front 95

Which amino acids can be directly converted into ammonium ion? By what?

Back 95

Serine and threonine by serine and threonine dehydratase, respectively.

Front 96

During fasting or exercise, muscle can use amino acids as fuel, exporting nitrogen as what?

Back 96

Alanine

Front 97

If pyruvate is exported as alanine without reoxidizing NADH by forming lactate, how can glycolysis continue?

Back 97

NADH is oxidized by the citric acid cycle

Front 98

What 6 amino acid carbon skeletons can feed into pyruvate of the citric acid cycle?

Back 98

1. Alanine

2. Cysteine

3. Glycine

4. Serine

5. Threonine

6. Tryptophan

Front 99

What 2 amino acid carbon skeletons can feed into oxaloacetate of the citric acid cycle?

Back 99

1. Asparagine

2. Aspartate

Front 100

What 3 amino acid carbon skeletons can feed into fumarate of the citric acid cycle?

Back 100

1. Aspartate

2. Phenylalanine

3. Tyrosine

Front 101

What 4 amino acid carbon skeletons can feed into Succinyl CoA of the citric acid cycle?

Back 101

1. Isoleucine

2. Methionine

3. Threonine

4. Valine

Front 102

What 5 amino acid carbon skeletons can feed into alpha-ketoglutarate of the citric acid cycle?

Back 102

1. Arginine

2. Glutamate

3. Glutamine

4. Histidine

5. Proline

Front 103

Where do the nitrogen atoms of urea come from? Where does the carbon atom come from?

Back 103

One N comes from aspartate, the other comes from free ammonium ions

The C comes from HCO3- (derived from the hydration of CO2)

Front 104

The urea cycle begins in the mitochondria with the coupling of what 2 things to form what?

Back 104

Free NH4+ and HCO3- to form carbamoyl phosphate

Front 105

What are the 3 steps to form carbamoyl phosphate? What catalyzes all of these reactions?

Back 105

1. Bicarbonate to carboxyphosphate

2. Carboxyphosphahte to Carbamic acid

3. Carbamic acid to carbamoyl phosphate

Catalyzed by carbamoyl phosphate synthetase

Front 106

The carbamoyl group of carbamoyl phosphate is transferred to what to form what? What catalyzes it?

Back 106

Transferred to ornithine to form citrulline via ornithine transcarbamoylase

Front 107

What are the 4 steps to the Urea Cycle starting with Citrulline?

Back 107

1. Citrulline (w/ Aspartate) forms Argininosuccinate

2. Argininosuccinate to Arginine (releasing Fumarate)

3. Arginine to Ornithine (releasing UREA)

4. Ornithine (w/ Carbamoyl Phosphate) to Citrulline

Front 108

Ammonia is carried on what activated molecule that then goes on to form carbamoyl phosphate?

Back 108

Bicarbonate!

Front 109

Urea is produced by removing Nitrogen from what?

Back 109

Arginine

Front 110

TRUE OR FALSE: The urea cycle only spans one compartment, the mitochondrial matrix.

Back 110

FALSE. It spans both the cytoplasm and the mitochondrial matrix

Front 111

Fumarate from the urea cycle can go on to make what? What can it also do?

Back 111

Glucose via gluconeogenesis

OR

it can enter the citric acid cycle

Front 112

Cytoplasmic malate enters the matrix and exits as what?

Back 112

Aspartate

Front 113

What 2 things can happen to oxaloacetate?

Back 113

1. Converted into glucose via gluconeogenesis

2. Transaminated to aspartate

Front 114

The carbon skeletons of amino acids are funneled into what 7 molecules?

Back 114

1. Pyruvate

2. Acetyl CoA

3. Acetoacetyl CoA

4. Alpha-ketoglutarate

5. Succinyl CoA

6. Fumarate

7. Oxaloacetate

Front 115

Amino acids that are degraded into acetyl CoA or acetoacetyl CoA are called what? Why?

Back 115

Ketogenic amino acids because they can give rise to ketone bodies or fatty acids and CANNOT be used to synthesize glucose

Front 116

Which 2 amino acids are SOLELY ketogenic?

Back 116

Leucine and lysine

Front 117

Which 5 amino acids are both ketogenic and glucogenic?

Back 117

1. Threonine

2. Isoleucine

3. Phenylalanine

4. Tryptophan

5. Tyrosine

Front 118

Atmospheric nitrogen is converted into what?

Back 118

Ammonia

Front 119

Ammonium + alpha-ketoglutarate --> ???

Back 119

Glutamate

Front 120

Glutamate + alpha-keto acid --> ???

Back 120

Alpha-ketoglutarate + amino acid

Front 121

What is biological nitrogen fixation?

Back 121

Conversion of atmospheric nitrogen into

Front 122

What is industrial nitrogen fixation?

Back 122

Conversion of atmospheric nitrogen into ammonia carried out at 500 C and 300 atm pressure using Fe catalyst (Haber process)

Front 123

Biological nitrogen fixation is catalyzed by what?

Back 123

Nitrogenase

Front 124

Glutamate synthesis is catalyzed by what?

Back 124

Glutamate dehydrogenase (which is the same enzyme used in both degadation and biosynthesis of amino acids)

Front 125

How is glutamate synthesized?

Back 125

Alpha-ketoglutarate and ammonium is dehydrolyzed then protonated to form glutamate.

Front 126

What are the 2 basic steps to form glutamine?

Back 126

1. Glutamate to acyl-phosphate intermediate

2. acyl-phosphate intermediate to glutamine

Front 127

Glutamate is converted into acyl-phosphate intermediate using what?

Back 127

ATP

Front 128

Acyl-phosphate intermediate is converted into glutamine using what? What is released?

Back 128

NH3 which releases an inorganic phosphate

Front 129

What 3 things are formed from 3-phosphoglycerate?

Back 129

1. Serine

2. Cysteine

3. Glycine

Front 130

What is tetrahydrofolate?

Back 130

Coenzyme essensial for the synthesis of amino acids that is a carrier of activated 1-carbon units.

Front 131

What are the 3 groups of tetrahydrofolate?

Back 131

1. a substituted pteridine

2. p-aminobenzoate

3. 1+ glutamate residue chain

Front 132

In the formation of glycine, the side chain methylene group of serine is transferred to what?

Back 132

Tetrahydrofolate, a carrier of one-carbon units

Front 133

What are the 9 essential (CANNOT be synthesized) amino acids?

Back 133

1. Histidine

2. Isoleucine

3. Leucine

4. Lysine

5. Methionine

6. Phenylalanine

7. Threonine

8. Tryptophan

9. Valine

Front 134

TRUE OR FALSE: Non-essential amino acids have complex pathways.

Back 134

FALSE. They have simple pathways.

Front 135

Alpha-ketoglutarate goes to glutamate which goes to what 3 amino acids?

Back 135

1. Glutamine

2. Proline

3. Arginine

Front 136

Pyruvate makes what 3 amino acids?

Back 136

1. Alanine

2. Valine

3. Leucine

Front 137

Oxaloacetate goes to aspartate which can make what 5 amino acids?

Back 137

1. Asparagine

2. Methionine

3. Threonine

4. Isoleucine (From threonine)

5. Lysine

Front 138

What are the 3 steps to make serine?

Back 138

1. 3-phosphoglycerate to 3-phosphohydroxypyruvate

2. 3-phosphoserine

3. Serine

Front 139

How is 3-phosphoglycerate converted into 3-phosphohydroxypyruvate?

Back 139

It's oxidized via NAD+ (forming NADH)

Front 140

How is 3-phosphohydroxypyruvate converted into 3-phosphoserine?

Back 140

Transamination via glutamate (forming alpha-ketoglutarate)

Front 141

How is 3-phosphoserine converted into serine?

Back 141

Hydrolysis!

Front 142

The one-carbon group carried by tetrahydrofolate is bonded to what?

Back 142

Tetrahydrofolate's N-5 or N-10 or to both!

Front 143

The most reduced form of tetrahydrofolate carries what? What does the intermediate carry?

Back 143

A methyl group

The intermediate carries a methylene group

Front 144

The most oxidized form of tetrahydrofolate can carry what 3 things?

Back 144

1. Formyl

2. Formimino

3. Methenyl groups

Front 145

The fully oxidized one carbon unit, CO2, is carried by what rather than by tetrahydrofolate?

Back 145

Biotin!

Front 146

What is the major donor of methyl groups?

Back 146

S-adenosylmethionine (SAM)

Front 147

SAM is synthesized by what?

Back 147

The transfer of an adenosyl group from ATP to the sulfur atom of methionine

Front 148

How is serine converted into glycine?

Back 148

Tetrahydrofolate removes the side chain of serine to produce glycine and N5,N10-methylenetetrahydrofolate.

Front 149

Along with NADPH, N5,N10-methylenetetrahydrofolate is converted into what for further methylation reactions?

Back 149

N5-methyltetrahydrofolate

Front 150

Methionine + ATP ---> ???

Back 150

S-Adenosylmethionine + Pi + PPi

Front 151

Methionine is regenerated from what?

Back 151

N5-Me-THF and Homocysteine

Front 152

Serine inhibits its own synthesis at what point?

Back 152

The oxidation reaction between 3-phosphoglycerate and NAD+

Front 153

What are the 2 pathways of nucleotide biosynthesis?

Back 153

1. De novo

2. Salvage

Front 154

What is De novo?

Back 154

Nucleotide synthesis built up from small precursors

Front 155

What is Salvage?

Back 155

Nucleotide recovery from other reactions and added to ribose

Front 156

In pyrimidine synthesis, N1 and C4,5,6 come from where?

Back 156

Aspartate

Front 157

In pyrimidine synthesis, C2 and N3 come from where?

Back 157

Carbamoyl phosphate

Front 158

What are the 3 precursors of pyrimidine rings?

Back 158

1. Bicarbonate

2. Aspartic acid

3. Ammonia

Front 159

What are the 3 steps of carbamoyl phosphate synthesis? Where do all three steps occur?

Back 159

1. Bicarbonate to Carboxyphosphate (ATP)

2. Carboxyphosphate to Carbamic Acid (NH3 from Gln)

3. Carbamic Acid to Carbamoyl Phosphate (ATP)

All three steps occur on carbamoyl phosphate synthase!

Front 160

In pyrimidine nucleotide synthesis, what are the 3 acts?

Back 160

1. Pyrimidine ring formation

2. Attachment to ribose phosphate

3. 2' deoxy

Front 161

The Urea cycle uses which carbamoyl phosphate synthase?

Back 161

CPS-1: NH3 from ammonium

Front 162

Pyrimidine synthesis uses which carbamoyl phosphate synthase?

Back 162

CPS-2: NH3 from glutamine

Front 163

What is 5-phosphoribosyl-1-pyrophosphate (PRPP)? How is it synthesized?

Back 163

Activated ribose for base attachment that is synthesized from ribose 5-phosphate (from the pentose phosphate pathway).

Front 164

Deoxyribonucleotide synthesis is catalyzed by what?

Back 164

Ribonucleotide reductase

Front 165

In deoxyribonucleotide synthesis, deoxyribonucleotides are made via what mechanism?

Back 165

Cysteine free radical mechanism

Front 166

Oxidized cysteines are reduced by what in Deoxyribonucleotide synthesis?

Back 166

NADPH

Front 167

What is the role of tetrahydrofolate in the formation of thymidylate?

Back 167

N5,N10-methylenetetrahydrofolate is the methyl donor for deoxyuridine monophonphate (dUMP) that creates thymidylate (TMP) and dihydrofolate.

Front 168

Dihydrofolate, which is made during thymidylate synthesis, is reduced to form what?

Back 168

Tetrahydrofolate via dihydrofolate reductase and NADPH

Front 169

Carbamoyl phosphate is converted into what in nucleotide synthesis?

Back 169

Carbamoylaspartate via aspartate and aspartate transcarbamoylase

Front 170

Carbamoylaspartate is converted into what?

Back 170

Orotate (NADH is formed as well)

Front 171

Orotate reacts with what to form what?

Back 171

Reacts with PRPP to form orotidylate, a pyrimidine nucleotide

Front 172

Orotidylate is then decarboxylated via what to form what?

Back 172

Uridylate (Uridine Monophosphate, UMP) via orotidylate decarboxylase

Front 173

How is cytidine monophosphate (CMP) formed?

Back 173

UMP is converted to UTP via ATP, then UTP's carbonyl group is replaced by an amino group donated by glutamine to form CTP.