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MS1 Unit 7 > MCP > Flashcards

MCP Flashcards

1
Q

alpha vs. beta glucose

A

if the OH is down on Carbon 1, then alpha. if up, then beta

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2
Q

monosaccharide

A

1 sugar residue

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3
Q

disaccharide

A

2 sugarrs covalently bound together (lactose, sucrose, etc)

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4
Q

oligosaccharide

A

2-15 sugars covalently linked

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5
Q

polysaccharide

A

many sugars covalently bound

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6
Q

glycosidic linkages

A

named according to the alpha/beta configuration of anomeric carbon and carbon numbers

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7
Q

amylose

A

linear polymer of glucose

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8
Q

amylopectin

A

branched polymer of glucose

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9
Q

lactose

A

disaccharide made of galactose and glucose

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10
Q

sucrose

A

disaccharide made of glucose and fructose

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11
Q

glycogen

A

animal way to store glucose. identical structure to amylopectin

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12
Q

cellulose

A

linear polymer (1,4 beta linked). no enzymes can recognize this linkage so it doesnt get digested

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13
Q

endoglycosidases

A

cleave internal glycosidic bonds

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14
Q

exoglycosidases

A

cleave terminal glycosidic bonds

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15
Q

disaccharidases

A

cleave glycosidic bonds in disaccharides

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16
Q

specificity of glycosidases

A

based on structure of linkage, sugars in link, and position of linkage in polymer

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17
Q

alpha amylase

A

hydrolyzes random internal alpha 1,4 bonds in starch

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18
Q

salivary amylase

A

made by salivary glands in mouth, cleaves starch polymers into smaller polysacc. inactivated by stomach

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19
Q

pancreatic amylase

A

made in pancreas, secreted into duodenum. produces disaccharides and oligosaccharides

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20
Q

glucoamylase

A

exoglucosidase. cleaves alpha 1,4 terminal linkages. makes glucose and isomaltose

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21
Q

maltase

A

cleaves maltose and maltotriose, makes glucose (alpha 1,4)

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22
Q

isomaltase

A

cleaves isomaltose and alpha dextrins, makes glucose (alpha 1,6)

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23
Q

sucrase

A

cleaves sucrose, makes glucose and fructose (alpha 1,2)

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24
Q

lactase

A

cleaves lactose, makes galactose and glucose (beta 1,4)

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25
Q

lactose intolerance

A

undigested lactose in colon is fermented to make gas and lactic acid, causing diarrhea and stuff

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26
Q

glucose homeostasis: fasting

A

decreased blood glucose leads to glucagon release into blood. mobilize fuels to increase blood glucose

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27
Q

glucose homeostasis: fed state

A

increased blood glucose leads to insulin release, promotes fuel storage

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28
Q

glucose –> glucose-6-phosphate

A

hexokinase. done to keep the glucose in the cell. not done in liver cells, too aggressive

uses ATP

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29
Q

glucose-6-phosphate –> fructose - 6 - phosphate

A

phosphoglucose isomerase. switches to a 5 member ring, ketose instead of aldose.

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30
Q

Fructose-6-phosphate –> fructose-1,6-bisphosphate

A

phosphofructokinase (PFK)

transfers a P from ATP

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31
Q

fructose-1,6-bisphosphate –> glyceraldehyde-3-phosphate and dihydroxyacetone phosphate (GAP and DHAP)

A

aldolase.

cleves into two trioses. easy to interconvert between GAP and DHAP (triose-P isomerase)

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32
Q

GAP –> 1,3-bisphosphoglycerate

A

GAP dehydrogenase

oxidizes GAP and makes NADH

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33
Q

1,3-BPG –> 3-phosphoglycerate

A

phosphoglycerate kinase

makes an ATP. since there were two GAPs, we get 2 ATP to make up for the beginning. phosphoglycerate mutase moves the phosphate to the 2 carbon

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34
Q

2-phosphoglycerate –> phosphoenolpyruvate

A

enolase. remove a water molecule

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35
Q

phosphoenolpyruvate –> pyruvate

A

pyruvate kinase.

makes ATP, last step in glycolytic pathway. substrate level phosphorylation

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36
Q

how to regenerate NAD+?

A

NADH goes to mitochondrion so it can be used in the electron transport chain and give back NAD+

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37
Q

glycogen branching enzyme

A

needs a chain of at least 11 residues, counts off 6 residues, clips it, and attaches that 7 chain to another chain

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38
Q

von gierke disease

A

defective glucose-6-phosphatase enzyme. affects liver and kidney. raises amount of glycogen causing massive enlargement of liver

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39
Q

anderson disease

A

defective branching enzyme. affects liver and spleen, makes very long polymers of glycogen. causes cirrhosis of the liver and death before age of 2

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40
Q

mcardle disease

A

issue with phosphorylase enzyme. affects muscle, ups the amount of glycogen. inability to perform strenuous exercise

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41
Q

where does citric acid cycle occur

A

matrix of mitochon

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42
Q

functions of citric acid cycle

A

converts a number of fuels to a common mobile fuel (NADH)

serves as final meeting place of nearly all oxidizable substrates

provides intermediates for biosynthesis

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43
Q

pyruvate –> acetyl-CoA

A

pyruvate dehydrogenase complex. E1 does condensation/decarbox (TPP). E2 does oxidative transfer and transacetylation (Lipoamide). E3 does dehydrogenation (FAD)

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44
Q

citrate synthetase

A

condensation and hydrolysis of thioester (acetyl CoA + oxaloacetate –> citrate + CoA

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45
Q

aconitase

A

dehhydration and hydration. Citrate –> isocitrate

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46
Q

isocitrate dehydrogenase

A

oxidative decarboxylation. isocitrate –> alpha ketoglutarate

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47
Q

alpha ketoglutarate dehydrogenaase complex

A

oxidative decarbox and formation of thioester. Alpha ketoglut –> succinyl CoA

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48
Q

succinyl CoA synthetase

A

thioester cleavage coupled to GTP synth. Succinyl CoA –> Succinate

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49
Q

succinate dehydrogenase, fumarase, malate dehydrogenase

A

oxidation, hydration, oxidation

succinate –> fumarate –> Malate –> oxaloacetate

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50
Q

pyruvate carboxylase

A

starts the gluconeogenesis pathway, only found in mitochondria (pyruvate –> oxaloacetate) uses ATP

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51
Q

oxaloacetate –> phosphoenolpyruvate (PEP)

A

PEPCK is the enzyme. releases CO2, uses GTP

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52
Q

mal/asp shuttle

A

transports OAA (oxaloacetate) by first reducing to malate so it can cross membrane

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53
Q

cori cycle

A

lactate converting to glucose to go back into the blood stream

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54
Q

respiratory chain

A

embedded in inner mitochon membrane. not limited by rate of diffusion, and the intermediates are stable.

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55
Q

flavins

A

redox center. 2 electron donor/acceptor. (FMN/FMNH2)

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56
Q

iron-sulfur centers

A

accept e- from flavins and Q. 1 electron donor/acceptor.

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57
Q

ubiquinone

A

2 electron donor/acceptor. 1,6-addition. hydrophobic. functions as electron buffer

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58
Q

hemes

A

1 electron donor/acceptor.

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59
Q

copper centers

A

1 electron donor/acceptor in cytochrome oxidase. only redox centers in the chain that have open coordination sites that will allow O2 to bind. this prevents short circuiting the transport pathway which would decrease efficiency of the energy coupling`

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60
Q

ATP synthase

A

F0 and F1. F1 contains 3 catalytic sites for ATP synthesis. Connected to F0 by a central stalk and an external stalk. F0 is hydrophobic and carries protons from one site to the other.

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61
Q

respiratory control

A

an electrochem gradient functions as a common intermediate linking oxidation to phosphorylation. Oxygen consumption is coupled to ATP synthesis. rate of respiration is controlled by availability of ADP.

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62
Q

mitchell’s chemiosmotic theory

A

delocalized electrochem gradient is a required intermediate in coupling exergonic redox to endergonic synth of ATP.

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63
Q

Q cycle

A
  1. iron sulfur center of dehydrogenase and Cyt bH donate 1 e- each to Q. Q also picks up 2 protons from outside.
  2. QH2 travels to outside surface to be oxidized.
  3. 1 e- is transferred to the iron sulfur center of the b/c1 complex and another to Cyt bL. due to this removal of 2 e-, the 2 H+ are released to the outside to give oxidized Q.
  4. Q then travels back to the inside surface to begin the next cycle, and the e- is passed from bL to bH.
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64
Q

proton pumps

A

the loop cant work in cytochrome oxidase due to no H+ donor/acceptor. here an indirect coupling mech is used. proton pumps couple proton transport indirectly to exergonic redox rxns through protein conformational changes

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65
Q

binding change mechanism

A

energization needed to promote release of ATP from binding site. tight binding of substrate and product release occur simultaneously on separate but interacting sites. coupling of H_ transport to binding changes requires rotation of subunits

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66
Q

role of the transmembrane gradient

A

ATP synth, transport of ADP and ATP, Heat, rotation of bacterial flagella, antiports/symports cations/sugars/AAs, transports phosphate, acidification of endomembrane compartments

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67
Q

rate limiting enzymes

A

enzymes that operate far from equilibrium. modulation of these enzyme’s activity will have a significant effect on flux through a pathway

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68
Q

rate limiting glycolytic steps

A

hexokinase, phosphofructokinase, and pyruvate kinase (1, 3, 10)

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69
Q

optimal point to regulate in glycolysis/gluconeogenesis pathway

A

PFK (phosphofructokinase). pyruvate kinase is also ok

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70
Q

inhibitor of PFK

A

ATP (allosteric inhibitor, feedback inhibitor) places a negative charge (destabilizing) near the negatively charged substrate

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71
Q

activator of PFK

A

AMP. places a stabilizing positive charge near the negatively charged substrate. F2,6BP is also an activator as it competes with ATP

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72
Q

inhibitors of FBPase

A

AMP and F2,6BP. slowing gluconeogenesis when glycolysis is active.

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73
Q

F2,6P

A

made when enzyme is dephosphorylated, broken down when enzyme is phosphorylated. regulated by hormones.

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74
Q

inhibitors of pyruvate kinase

A

acetyl coA, ATP, cAMP-dependent phosphorylation. inhibited by feedback inhibitors

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75
Q

activators of pyruvate kinase

A

FBP (earlier substrate in the pathway)

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76
Q

activator of pyruvate carboxylase

A

Acetyl CoA

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77
Q

phosphorylase

A

when Glu is low, phosphorylase is in phosph form, and is in active form. when Glu is high, ATP and G6P is high and dephosph phosphorylase is in inactive form.

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78
Q

pyruvate dehydrogenase complex regulation

A

kinase activated by NADH and acetyl CoA, inactivating E1 by phosphorylating it. Pyruvate and ADP inhibit the kinase. Phosphatase is activated by Ca ions to make E1 active.

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79
Q

standard state (chemist’s)

A

all substrates and products are at 1M concentration and the temp is specified

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80
Q

delta G = delta G (biochem)

A

when substrate and product = 1M and H20 = 55.5M and H+ = 10^-7M

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81
Q

limitations for delta G calcs

A

deviations from standard state for H20 and H+, special environments at catalytic sites, concentrations of substrate and product not able to be measured

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82
Q

why store metabolic energy as fat?

A

lower oxidation state, fat is stored in an anhydrous state (light weight), fats dont participate in the cells osmotic balance so they can be stored to a large fraction of the cell volume

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83
Q

two sources of non-esterified fatty acids

A

dietary fat via exogenous pathway, and FA synthesized de novo made via endogenous pathway

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84
Q

fat as fuel

A

free fatty acids are released from Triglycerides. they are broken down to acetyl-CoA and enter the TCA cycle, giving ATP

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85
Q

digestion of triglycerides

A

bile is a detergent. needed for lipid dispersion. bile contains bile acids, phosphatidyl choline, and cholesterol.

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86
Q

pancreatic lipase

A

digests triglycerides in lipid droplets. requires formation of a complex with colipase and a droplet of lipid, stabilizing the open conformation and allowing access to substrate while shielding against bile salts that inactivate the enzyme

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87
Q

absorption of lipid digestion products

A

bile acids form mixed micelles with the digestion products (2-MAG and NEFA) which allows them to translocate across the stationary aqueous boundary layer at the intestinal wall. use fatty acid transport protein family (FATP5) to get in cell. AQP3, an aquaporin, mediates glycerol transport.

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88
Q

steatorrhea

A

excessively fatty stools. caused by failure of bile production, blockage of bile flow, exocrine pancreas dysfunction or obstruction of pancreatic dut, failure of uptake into intestinal mucosal cells (enterocytes)

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89
Q

acyl-CoA synthetase

A

catalyzes formation of acyl-coA derivatives of long chain fatty acids

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90
Q

acyltransferases

A

catalyze the transfer of 2 LCFA moieties to 2-MAG

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91
Q

chylomicrons

A

lipoproteins used to transport TG through lymph and blood

92
Q

Apo-B48

A

principal protein component of chlyomicrons as they are produced in the intestinal mucosa

93
Q

lipoprotein lipase

A

clears FAs from lipoproteins. located in the capillary endothelial walls of various tissues

94
Q

essential amino acids

A

histidine, isoleucine, eucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, arginine

95
Q

most abundant AAs in serum

A

glutamine and alanine

96
Q

hartnup’s disease

A

defect in transport system for neutral and aromatic amino acids, including tryptophan from the gut and renal tubules. Diarrhea, dematitis, dementia, death. treat with niacin

97
Q

cystinuria

A

defect in the transport system for basic amino acids and cystine from gut and renal tubules. symptoms include crustals leading to UTIs and kidney stones. treat with fluid and penicillamine

98
Q

cystic fibrosis problems with amino acid transportation

A

defect in chloride channels in pancreatic secretory ducts, they harden and block leading to a lack of pancreatic enzymes

99
Q

how to get rid of ammonia ions

A

3 ways to remove ammonia ions

glutamate dehydrogenase (turns alpha ketoglutarate into glutamate), glutamine synthase (reversible by glutaminase, turns glutamate into glutamine) and carbamoyl phosphate synthase 1 and 2.

done in order to remove free amonia ions.

100
Q

transamination

A

transfer of an amino group from an AA to an alpha keto acid to form a new AA and a new keto acid

101
Q

pridoxal phosphate (vitamin b6)

A

essential cofactor for all transamination

102
Q

oxidative deamination by glutamate dehydrogenase

A

located in mitochondria. Uses either NAD or NADP as cofactor. activated by ADP and GDP and inhibited by GTP/ATP

103
Q

amino acid oxidases

A

L and D amino acid oxidases occur in kidneys and liver. use flavins as cofactors, and turn an AA and water into corresponding keto acid and ammonia

104
Q

direct deamination by dehydratases

A

hydroxyl side chain of threonine and serine allow them to be directly deaminated. pyridoxal phosphate is cofactor

105
Q

desulfhydrases

A

removes ammonia and sulfur from homocysteine (pyridoxal phosphate cofactor)

106
Q

urea cycle

A

conversion of free ammonia to urea

107
Q

carbamoylphosphate

A

formed from ammonia and CO2 through carbamoylphosphate synthetase. uses 2 ATP

108
Q

citrulline

A

formed from carbamoylphosphate and ornithine. catalyzed by OTC (X linked gene)

109
Q

argininosuccinate

A

formed from citrulline and aspartate. argininosuccinate synthetase. 1 ATP needed

110
Q

arginine and fumarate

A

formed from cleavage of argininosuccinate, done by argininosuccinate lysase

111
Q

urea and ornithine

A

formed from cleavage of arginine. arginase enzyme.

112
Q

regulation of urea cycle

A

protein free diet-levels of urea cycle enzymes decline. high protein diet- or starvation, urea cycle enzymes go way up

113
Q

ammonia toxicity

A

seen in liver failure, inborn errors of metabolism. occurs through reduced flux of TCA cycle due to brain making glutamate. glutamate turns to glutamine from excess NH3, and leaves brain in exchange for tryptophan. trp goes to serotonin, and you get sleepy

114
Q

glucagenic

A

can be converted to glyolytic intermediates

115
Q

ketogenic

A

end up in acyl coA or acetyl CoA. once you get to acetyl CoA, you cant go back to glucose

116
Q

alanine transaminase (ALT)

A

alanine is a glucogenic AA. common AA in the blood. gets converted to glutamate by ALT. efficient way to send carbon and ammonia from tissue

117
Q

serine dehydratase

A

removes a water from serine, then adds it back and removes NH3 to get pyruvate. glucogenic

118
Q

desulfhydrase

A

cysteine –> pyruvate. glucagenic

119
Q

serine hydroxymethyl transferase

A

serine to glycine with THF as a cofactor. THF is an important carbon carrier. chemo can block this folate synthesis. this is a reversible reaction

120
Q

threonine degradation

A

glucogenic (goes to glycine). makes acetyl CoA, so it is ketogenic too! not reversible. uses NAD->NADH

121
Q

asparaginase

A

asparagine –> aspartate. removes an NH4, adds a water

122
Q

histidine degradation

A

glucogenic. goes to glutamate, using THF as cofactor again. another source of charged folate

123
Q

arginine and proline degradation

A

both go to glutamic acid and go through a common intermediate, glutamic acid semialdehyde. proline is reversible, but to remake arginine you need to go through urea cycle again

124
Q

branch chain amino acid degradation

A

valine, isoleucine, leucine. uses branch chain transaminase. if you inhibit these enzymes, you can build up leucine which promotes insulin insensitivity and weight loss. valine is glucogenic, isoleucine is both, and leucine is ketogenic

125
Q

alpha keto acid dehydrogenase

A

second enzyme in branch chain AA degradation. if defectve, can lead to a build up of alpha keto acid, leading to maple syrup urine. giving one of the branch chain AAs will cure this

126
Q

phenylalanine and tyrosine degradation

A

ketogenic. if you have a deficiency of phenylalanine hydroxylase, this leads to PKU and inhibits brain development

127
Q

regeneration of BH4

A

uses dihydrobiopterin reductase to go from BH2 to BH4. some people can have a deficiency in this enzyme, and BH4 is needed in other reactions in the body

128
Q

homogentisic acid 1,2-dioxygenase defect

A

alkaptonuria. usually converts homogentisic acid to acetoacetic acid. the acid deposits in the cartilege and leads to arthritis

129
Q

serine synthesis

A

made out of glycolysis and glycolytic intermediates. main source of 1 carbon groups.

130
Q

cysteine synthesis

A

made from methionine

131
Q

homocystinuria

A

high levels of homocysteine. increased risk of atherosclerosis. leads to oxidized LDL. severe heart disease in young age (teens, early 20s)

132
Q

cystathionuria

A

high levels of cystathionine and homocysteine. same symptoms as homocystinuria, but later deaths

133
Q

what promotes fat storage

A

insulin

134
Q

perilipins

A

proteins that coat the surface of peripheral lipid droplets. targets for cAMP-dependent protein kinase. they get phosphorylated by protein kinase A which allows access to the droplet due to a conformation change

135
Q

step 1 of beta oxidation: activation of fatty acid

A

fatty acid –> acyl CoA + AMP. Acyl-CoA synthetase. gets energy by splitting a pyrophosphate into 2 phosphate groups

136
Q

step 2 of beta oxidation: transfer of LCFA moiety from CoA

A

transfers LCFA to carnitine. uses Acyl-CoA-carnitine transacylaase (CPT I). gives you a fatty acyl carnitine. happens in mitochondial inter membrane space, the acyl carnitine can transfer across the inner mitochon membrane. here, carnitine palmitoyl transferase 2 makes acyl CoA again.

137
Q

malonyl-CoA

A

inhibits CPT I. malonyl CoA is the product of the first committed step in FA biosynthesis.

138
Q

step 3 of beta oxidation: oxidize bond to a double bond

A

acyl-CoA dehydrogenase does this. different isoenzymes for different length fatty acids. produces an FADH which will eventually make ATP

139
Q

step 4 of beta oxidation: adding a water across the double bond yielding beta hydroxy acyl CoA

A

enoyl-CoA hydratase. adds a hydroxyl group to the beta carbon

140
Q

step 5 of beta oxidation: oxidize the beta hydroxyl to a beta ketoacyl-CoA

A

done using hydroxyacyl CoA dehydrogenase. makes a beta ketone

141
Q

step 6 of beta oxidation: thiolysis reaction

A

splits off acetyl CoA and leaving acyl CoA shorter by 2 carbons. done using thiolase enzyme. each round makes another acetyl coA

142
Q

comparison with glycolysis

A

glycolysis is 6 ATP per carbon, beta oxidation is 8 ATP per carbon

143
Q

ketogenesis

A

only happens in the liver. produced from acetyl-CoA. KB not used as fuel by liver, exported by liver as water-soluble equivalents of FA.

144
Q

regulation of ketone body metabolism

A

in fasting, low concentrations of TCA cycle intermediates. Acetyl-CoA diverted to KB. Ketosis (state of making KB) begins after overnight fast.

too little glucose = ketogenesis. too little oxaloacetate = ketogenesis

145
Q

ketone overproduction

A

problem in type 1 diabetes. zero insulin, so there is no break on lipolysis. no insulin to counter regulate. max production of NEFAs. liver cant handle it, so excess FA make ketone bodies. other tissues havent upregualted the enzymes they need to break down KB, so they end up going to kidney, who cant filter them all, so they go to blood

146
Q

formation of dopa

A

tyrosine –> dopa

uses tyrosine hydroxylase
needs tetrahydrobiopterin. this is the rate limiting step.

147
Q

formation of dopamine

A

AA decarboxylase forms dopamine from dopa

148
Q

formation of norepinephrine

A

mixed function oxidase hydroxylates dopamine on the side chain to yield norepinephrine

149
Q

formation of epinephrine

A

methylated by methyltransferase to form epinephrine. SAM used as methyl donor

150
Q

biosynthesis of melanins

A

made in melanocytes (pigment producing cells). made from tyrosine. defect = albinism

151
Q

what AA is the precursor of serotonin, melatonin, and NAD+?

A

tryptophan

152
Q

pellagra

A

deficiency of tryptophan leading to a deficiency of niacin. symptoms are dermatitis, dementia, diarrhea, and death

153
Q

GABA production

A

made from glutamate by glutamate decarboxylase

154
Q

Histamine production

A

made from histidine. histidine decarboxylase catalyzes the formation of histamine

155
Q

what does the body need single carbon fragments for?

A

formation of methionine from homocysteine, biosynth of purines and pyrimidines, and biosynth of glycine from CO2 and NH4 by glycine synthase

156
Q

biotin

A

carrier of CO2, the most oxidized one carbon group

157
Q

THF (tetrahydrofolate)

A

carries one carbon groups of all oxidation states except CO2. can serve as an acceptor of one carbon fragments in degradative reactions and as a donor of one carbon fragments in biosynth reactions

158
Q

synthesis of THF

A

get folate from the diet. usually ingested as polyglutamines, which get cleaved by conjugase leaving folic acid. intestinal mucosal cells reduce folic acid to THF using dihydrofolic acid reductase. this carbon is then bound to either N5, N10, or both in 3 diff oxidation states

159
Q

problem with N5-methyl form of THF

A

N5 methyl form is used in a rxn to make methioninesome people have a deficiency in the enzyme that makes this. they have hgiher risk of heart disease and a lower risk of colon cancer

160
Q

interconversion of serine and glycine

A

uses N5,N10 methylene THF.

161
Q

drugs that inhibit dihydrofolate reductase

A

aminopterin and methotrexate. leads to low levels of THF in tumors which is needed for DNA replication. other things that have low levels of THF are also impacted, like bone marrow, hair follicles, and GI mucosa

162
Q

S-adenosylmethionine

A

major carrier of methyl groups. involved in the following reactions

  1. norepi to epi
  2. guanidinoacetate to creatine
  3. acetylserotonin to melatonin
  4. phosphatidylethanolamine to phosphatidylcholine
  5. methylation of DNA
163
Q

homocysteine production

A

methionine –> S-adenosylmethionine.
methyl transfer from S-adenosylmethionine to acceptor molecule.
S-adenosylhomocysteine is hydrolyzed to adenosine and homocysteine.

Methionine can be regenerated from homocystein using homocysteine methyl transferase

164
Q

elevated levels of homocysteine

A

strongly correlated with high risk of atherosclerosis. vitamin B12 can help with this

165
Q

production of cysteine from homocysteine

A

homocysteine and serine condense to make cystathionine using cystathionine synthase. cystathionine is hydrolyzed to form cysteine and homoserine which goes to alpha ketobutyrate using cystathionase

166
Q

homocystinuria

A

caused by inability to convert homocysteine to methionine due to defect in methyltransferase or deficiency of THF or methylcobalamin

167
Q

vitamin b12 (cobalamin)

A

coenzyme. central core of cobalt. several forms, vary by the group attached to the fifth bond above the plain of the ring.

168
Q

reactions involving cobalamin

A

conversion of L-methylmalonyl CoA to succinyl CoA

action of homocysteine methyltransferase

169
Q

megablastic anemia

A

deficiency of B12 and THF. immature redblood cells are released into bloodstream

170
Q

demyelination and degradation of spinal cord

A

caused by b12 deficiency

171
Q

folate trap

A

occurs when b12 is deficient. causes a folate deficiency by trapping folate in the N5 methyl form. this is then manifested as anemia. if folate is supplemented, b12 is still deficient and you get brain problems without anemia

172
Q

source of NADPH for FA synth

A

pentose phosphate pathway. also malic enzyme

173
Q

2 enzymes needed for FA synth

A

acetyl CoA carboxylase and Fatty Acid synthase

174
Q

rate controlling step in FA synth?

A

Acetyl CoA carboxylase

175
Q

acetyl CoA carboxylase (ACC)

A

converts acetyl CoA to malonyl CoA. Uses ATP, and biotin as a cofactor.

176
Q

regulation of acetyl CoA carboxylase

A

regulated by citrate which causes it to polymerize, activating it. insulin activates, along with caloric intake.

glucagon/epi levels inactivate it. palmitoyl CoA inactivates it. AMP inactivates

177
Q

Fatty acid synthase (FAS)

A

homodimer. each subunit has 3 catalytic domains in the N portion, and a C portion with 4 domains.

178
Q

phosphopantethenyl residue of FAS

A

derived from pantothenic acid. linked to a serine in the acyl carrier protein portion of FAS, and the SH group reacts with a malonyl CoA to form a thioester bond

179
Q

steps in FA synth

A
  1. activation 2. condensation (ketone C=O) 3. reduction (C-OH) 4. dehydration (C=C) 5. reduction (C-C)

each cycle adds carbons until it gets to 16 carbons (palmitate)

180
Q

elongation of fatty acids

A

palmitate gets activated to palmitoyl-CoA. elongated 2 carbons at a time in the ER by enzymes called elongases.

181
Q

desaturation of fatty acids.

A

oxidation of fatty acids resulting in cis double bonds. creates lipids of increasing structural and functional complexity with distinct biological roles. uses desaturases. regulated in response to diet. decrease during starvation, increase with feeding.

182
Q

monounsaturdated fatty acids (MUFAs)

A

3 distinct desaturases. delta 9, 6, and 5 desaturase. most common desaturation reactions involve an oxidation leading to a double bond between C9 and C10.

183
Q

polyunsaturated fatty acids (PUFAs)

A

PUFAs with double bonds 3 or 6 carbons from methyl end are needed for eicosinoid synth. must come from diet.

184
Q

lineoleic acid to arachidonic acid

A

elongation and desaturation.

185
Q

eicosanoids

A

prostaglandins, thromboxanes, and leukotrienes. derived from arachidonic acid. hormone like effects on cells.

186
Q

cyclic pathway for eicosanoid synth

A

forms prostaglandins, thromboxanes, and prostacyclins

187
Q

linear pathway for eico synth

A

forms leukotriens, HETEs, and lipoxins from HPETE

188
Q

cytochrome p450 pathway of eico synth

A

makes epoxides

189
Q

COX-1 and 2

A

COX1 is in all tissues. COX 2 is regulated by cytokins and growth factors, and responds to inflammation

prostaglandin and thromboxanes

190
Q

reciprocal regulation

A

agents that promote catabolism inhibit anabolism

191
Q

catabolic enzymes

A

active when phosphorylated.

glycogen phosphorylase, phosphorylase kinase, hormone-sensitive lipase

192
Q

anabolic enzymes

A

inactive when phosphorylated

acetyl-CoA carboxylase, glycogen synthase, HMG-CoA reductase

193
Q

futile cycle in adipocytes during fasting conditions

A

cAMP turns on lipolysis, but also turns on CREB, which causes fats to be stored. futile cycle, meaning fat is made and broken down in equal parts using ATP. thought to act as a brake on lipolysis so NEFAs aren’t released too quickly

194
Q

starved state

A

more KB production, less urea formation, less protein breakdown, less glucose formation. brain can utilize KB now for fuel. glycerol, AA, and lactate are now converted to glucose

195
Q

epinephrine

A

stimulates glycogen breakdown in muscle and liver, gluconeogenesis in liver, and lipolysis in adipose tissue

196
Q

glucocorticoids

A

stim lipolysis in adipose tissue and the release of AA from muscle protein. in liver, they stim gluconeogenesis and stim synthesis of glycogen

197
Q

PRPP

A

an intermediate of major significance in nucleotide metabolism

required in de novo synth of pyrimidine and purine nucleotides. salvage pathways of purine nucleotides. biosynth of nucleotide coenzymes NAD and FAD

5’-phosphoribosyl-1-pyrophosphate

198
Q

PRPP formation

A

formed from ribose-5-phosphate and ATP. catalyzed by PRPP synthetase

199
Q

synth of purines

A

built on a molecule of PRPP. precursors of the ring are glutamine, glycine, CO2, aspartate, and 2 one carbon fragments.

200
Q

IMP formation

A

10 step process using 6 phosphate bonds for energy. first step is rate limiting and regulated stp. 2 steps need folate and are blocked by drugs that block folate synth. nucleotide ring is made from glutamine, glycine, CO2, aspartate, and 2 1 carbon fragments. 2 steps require glutamine amino transfer reactions, inhibited by azaserine. expensive process, would rather salvage.

201
Q

synth of AMP from IMP

A

adenylosuccinate formed by adding aspartate to IMP. fumarate is cleaved to give AMP. GTP is cleaved to make this.

202
Q

synth of GMP from IMP

A

xanthylate or XMP is formed by oxidation of IMP. an amino group from glutamine is then added to give GMP. ATP is cleaved to make this

203
Q

what regulates synth of purine nucleotides?

A

feedback inhibition. PRPP synthetase and PRPP amidotransferase (2 enzymes that make IMP) are regulated by IMP, GMP, and AMP.

204
Q

HGPRT

A

catalyzes formation of nucleotides from either hypoxanthine or guanine. inhibited by IMP and GMP..

defects in HGPRT can lead to gout

205
Q

APRT

A

catalyzes formation of AMP from adenine. inhibited by AMP

206
Q

Nucleoside kinase

A

makes AMP + ADP from adenosine + ATP

207
Q

purinosome

A

localization of purine biosynthetic machinery. presence of this organelle is regulated by purine abundance

208
Q

synth of pyrimidine nucleotides

A

ring is formed first, then it reacts with PRPP. precursors of the ring are carbamoylphosphate and aspartate. makes UMP

209
Q

carbamoylphosphate

A

made in cytosol from glutamine and CO2. also made in liver as in intermediate in urea synth

210
Q

orotic aciduria

A

genetic disorder of pyrimidine biosynth. orotic acid accumulates in blood and is excreted in urine. give uridine or cytidine to fix.

211
Q

synth of UTP from UMP

A

First step done by UMP kinase, second done by nucleoside diphosphate kinase. addition of 2 ATPs

212
Q

regulation of pyrimidine synth

A

a single protein does the first 3 steps, the last 2 steps done by another protein. pryimidines decrease enzyme activity, but molecular basis is unknown

213
Q

uracil to UMP

A

2 sequential reactions. 1st is a reverse of a reaction that occurs in the degradation of nucleotides. Uracil -> uridine. Then an ATP is added by uridine kinase to give UMP. uridine kinase can also phosphorylate cytidine.

214
Q

formation of deoxyribonucleotides

A

formed by reduction of ribonucleoside diphosphates. done by ribonucleotide reductase. products are dADP, dCDP, dGDP, dUDP. inhibited by hodryoxyurea

215
Q

dTMP formation

A

formed from dUMP, catayzed by thymidylate synthase. only made by cells in S phase

216
Q

5-fluorouracil

A

anticancer agent. converts to F-UMP in cells. can be turned to F-dUMP. prevents synthesis of dTMP

217
Q

methotrexate

A

analog of folic acid that inhibits dihydrofolate reductase. cant make THF, so dTMP synth is inhibited

218
Q

salvage of thymine deoxyribonucleotides

A

thymine phosphorylase and thymadine kinase give dTMP

219
Q

nucleotidases

A

remove 5’-phosphates from purine and pyrimidine ribo and deoxyribonucleotides, converting them to ribo and deoxyribonucleosides

220
Q

nucleoside phosphorylases

A

catalyze the phosphorolysis of nucleosides to free bases and ribose or deoxyribose 1-phosphate

221
Q

purine degradation

A

gives uric acid. hypoxanthine –> xanthine (xanthine oxidase). guanine -> xanthine through deamination. xanthine -> uric acid through xanthine oxidase

222
Q

pyrimidine degradation

A

gives B alanine and B aminoisobutyrate. undergo dephosphorylation, separation of base from ribose, deamination, and degradation of base

223
Q

Gout

A

precipitation of sodium urate crystals in joints and kidneys. can be caused by PRPP synthase being abnormal and not responding to inhibition. Allopurinol treats it by blocking uric acid production

224
Q

lesch-nyhan syndrome

A

x linked condition due to deficiency of HGPRT. increaed purine synth, increased PRPP with decreased IMP and GMP. symptoms are gout, urinary stones, brain problems. treat with allopurinol

225
Q

adenosine deaminase deficiency

A

high levels of dATP inhibit DNA synth, causing white blood cells to not proliferate. associated with SCID. bone marrow transplant and enzyme replacement are treatments

MS1 Unit 7 (3 decks)

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