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FB1 Flashcards > Biochemistry-Endterm > Flashcards

Biochemistry-Endterm Flashcards

1
Q

Inborn errors of metabolism

A

Monogenic disease but can be polygenic.

Leads to changing in an enzyme in a primary pathway or in a secondary pathway

Treat through diet restrictions

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2
Q

Disorders of amino acid metabolism

A
  • Phenylketonuria
  • Urea cycle enzymes
  • Hypergylcinemia
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3
Q

Disorders of carbohydrate metabolism

A
  • Glycogen storage disease
  • Diabetes
  • Galactosemia
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4
Q

Disorders of lipid and lipoprotein metabolism

A
  • Familial hypercholesterolemia

- Tangier disease (HDL deficiency)

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5
Q

Disorders of purine and pyrimidine metabolism

A
  • Lesch-Nyhan syndrome
  • ADA
  • SCID
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6
Q

Hormone disorders

A
  • Thyroid diseases

- Androgen resistance syndrome

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7
Q

Nutritional disorders

A
  • Obesity

- Problems in transporting folate

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8
Q

Organelle diseases

A

-Mucopolysaccharidosis in lysosomes

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9
Q

Tissue disorders

A
  • Collagen diseases

- Muscular dystrophies

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10
Q

Systemic disorders

A

-Hemophilia

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11
Q

Marfans syndrome

A

Autosomal dominant condition due to a defect in fibrillin on the FBN1 gene located on chromosome 15

Affects:

  • Cardiovascular system (weak heart+blood vessels)
  • Ocular problems
  • Skeletal system: spine, chest & joints
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12
Q

Major criteria for diagnosing Marfans syndrome

A
  • Enlarged aorta and tear in aorta
  • Skeletal problems
  • Family history
  • Dislocation of lens
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13
Q

Minor criteria for diagnosing Marfans syndrome

A
  • Loose joints
  • Short sightedness (myopia)
  • Unexplained stretch marks
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14
Q

Akhenetons Marfans syndrome

A
  • Long face and fingers
  • Slit-like eyes
  • Arachnodactyl: spider-like fingers
  • Wide hops
  • Protruding belly
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15
Q

Fibrillin

A

Major component of microfibrils. Need 3 fibrillin to make a microfibril. Serves as a substrate for elastin

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16
Q

2 mutations of FBN1

A
  • In-frame mutation (missense)

- Premature termination (nonsense)

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17
Q

Diagnosing Marfans syndrome

A
  • Reliable reverse transcriptase PCR

- Next generation sequencing

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18
Q

Reliable reverse transcriptase PCR

A

Single cell genotyping

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19
Q

Next generation sequencing

A

Take the patients DNA and make specific primers to check if the patient has Marfans syndrome

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20
Q

Treating Marfans syndrome

A

There is no treatment

Can take beta blockers to reduce stress on the aorta

Gene therapy is also an option but not reliable
-Would use ribozymes and RNA anti-sense technology to reduce mutant FBN1

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21
Q

Hemophilia

A

Condition in which a person is unable to form a stable clot

Phenotype: easily bruised, prolonged bleeding

Can lead to death since person will have an internal hemmorhage

X-linked recessive inheritance

Three types of hemophilia: A, B, C

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22
Q

Hemophilia A

A

Absence or almost no clotting factor 8

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23
Q

Factor 8

A

Serves as a coenzyme to change X to Xa in the clotting cascade (tense reaction)

Produced by the HEMA gene

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24
Q

HEMA gene

A

Located on X chromosome on position 28

2 mutations of HEMA gene:

  • Point mutation: less severe as have some activity of factor 8
  • Inversion: severe
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25
Q

Hemophilia B

A

Lack of clotting factor 9

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26
Q

Detecting mutations in hemophilia

A

Amplify the factor 8 and 9 genes by PCR. Then screen by restriction fragment length polymorphism analysis (RFLP) or repeat sequence polymorphism

This will show the genotype and the transition of it through generations

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27
Q

Treatment of hemophilia

A
  • Replacement therapy: injecting the clotting factors
  • Desmopressin: an analogue of the diuretic vasopressin found to increase the levels of clotting factor 8 slightly. Used when there is a minor surgery
  • Gene therapy: not effective as the clotting factors are too big
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28
Q

Cystic fibrosis

A

An autosomal recessive condition that affects the exocrine glands. People with cystic fibrosis have thick mucus and high levels of chlorine in their sweat.

It is diagnosed within the first month of life

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29
Q

Rates of cystic fibrosis

A

Highest in Europe and lowest in Asia

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30
Q

Cause of cystic fibrosis

A

Caused by a defect in the CFTR gene which is located in chromosome 7. CFTR gene is responsible for producing the CFTR protein

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31
Q

CFTR protein

A

Helps transport chlorine and sodium in epithelial cells by hydrolyzing ATP to transport the ions

Without the protein, thick mucus accumulates in the body leading to respiratory insufficiency and systemic obstruction

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32
Q

Mutations of CFTR gene

A

Most common mutation is the delta F508 mutations. However, there are a lot more mutations

Mutation means that there is no ATP hydrolysis for chlorine transport

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33
Q

Delta F508 mutation

A

Caused by a deletion of 3 nucleotides on exon 10 which results in the deletion of phenylalanine at position 508.

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34
Q

Classes of CFTR mutation

A

Six classes and each class has a different severity level

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35
Q

Class 1

A

Can’t produce the protein so need to find a way to fix protein synthesis

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36
Q

Class 2

A

No trafficking of proteins so need to correct protein folding

The delta F508 mutation belongs to this class

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37
Q

Class 3

A

No protein function so need to restore channel conductance

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38
Q

Class 4

A

Less protein function so need to restore channel conductance

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39
Q

Class 5

A

Less protein production so need mature protein and correct misplicing

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40
Q

Class 6

A

Less stable protein so need to stabilize it

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41
Q

Cystic fibrosis and sweat glands

A

Normally, sodium chloride carry water to skins surface and then is tea sorbet back in the body

In the case of cystic fibrosis, the sodium chloride is not reabsorbed leading to the skin to be salty

Also, when a person exercises, they experience fatigue, nausea, dizziness, etc.

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42
Q

Screening cystic fibrosis

A

Done by:

  • Mutation testing
  • Sweat test
  • Immunoreactive trypsinogen
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43
Q

Mutation testing

A

At birth, babies are screened for cystic fibrosis. Common mutations are detected however less common ones aren’t detected

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44
Q

Sweat test

A

Is the gold standard for diagnosing cystic fibrosis. Chlorine levels in the sweat is 5 times higher than in normal sweat. This allows for the diagnosis of cystic fibrosis in hound children and in adults

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45
Q

Immunoreactive trypsinogen

A

Mucus blocks the pancreatic ducts so trypsinogen can’t go to the intestine. However, if a person tests positive for this test, should also do the sweat test as well

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46
Q

Treating cystic fibrosis

A

Can’t treat it but can alleviate symptoms

Can use CFTR modulators to correct the defective function of the CFTR protein. However, it only works for a couple of mutations

If the lungs are severely damaged, then a lung transplant is required

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47
Q

Nucleotides

A

Composed of a nitrogenous base, sugar, and phosphate group (either 1,2, or 3)

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48
Q

Purine

A

Nitrogenous bases that are made of fused rings

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49
Q

Pyrimidine

A

Nitrogenous bass that is made of a single ring

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50
Q

Roles of nucleotides

A
  • Carry activates metabolic intermediates (UDP-glucose)
  • Part of coenzyme structures (NAD, FAD)
  • Energy currency
  • Secondary messenger signals
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51
Q

Nucleoside

A

Base and sugar. No phosphate groups

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52
Q

Adenyalte kinase

A

Enzyme responsible for turning AMP into ADP and vice versa. Uses ATP to help in the conversion.

So AMP+ATP -> 2 ADP

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53
Q

Guanylate cyclase

A

Changes GMP to GDP with the help of ATP

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54
Q

ATP helps change…

A
  • GDP to GTP

- CDP to CTP

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55
Q

De novo purine synthesis

A

Ribose 5 phosphate (from PPP) is changed to PRPP by PRPP synthetase with the help of magnesium and ATP

PRPP is changed to amido PRT by GPAT and this is the rate limiting step.

9 more reactions form inosine monophosphage (IMP)

In general, the nitrogenous base is added to the sugar which is PRPP

Low PRPP means that the de novo synthesi

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56
Q

IMP

A

IMP can be changed to GMP and AMP. ATP is required to make GMP and GTP is required to make AMP

Feedback inhibition of the products leads to stoping of the reaction of IMP

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57
Q

PRPP synthetase regulation

A

Activated by inorganic phosphate

Inhibited by purines since already have a lot of purines in the body so don’t need to make more

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58
Q

Regulation of GPAT

A

PRPP activates the enzyme in a positive feedback manner

Purines inhibit the enzyme

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59
Q

Salvage pathway

A

Taking free nitrogenous bases and changing them into nucleotides

Have two enzymes:HGPRT and APRT

Uses PRPP so depletes the supply of PRPP

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60
Q

HGPRT

A

Changes hypoxanthine to IMP and guanine to GMP

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61
Q

APRT

A

Changes adenine to AMP

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62
Q

Creating deoxyribonucleotides

A

Need to convert ribonucleotodes into deoxyribonucleotides by reducing it at the 2’ end

Reduction is carried out by ribonucleotode reductase

Creates the correct amount of each deoxyribonucleotides by binding to specific allosteric sites

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63
Q

Ribonucletoide reductase

A

Needs ribonucleoside diohospahte as a substrate

After ribonucleotide reductase reduces, it becomes divided so need to reduce it again and this is done by thioredoxin

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64
Q

Thioredoxin

A

Regulated by thioredoxin reductase

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65
Q

De novo pyrimidine synthesis

A

The nitrogenous ring is first created and then it attaches to PRPP.

Orotic acid is added to PRPP by orotate phospho-ribosyl tranferase to form orotic monophosphate (OMP)

OMP is changed to UMP by orotidine carboxylase and releases carbon dioxide

UMP is further metabolized into the different pyrimidine bases

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66
Q

Purine nucleotide cycle

A

Need it to replenish the supply of TCA molecules.

AMP is changed to adelynosuccinate which is then converted back to AMP. Whole process is done by adenylate kinase

Aspartate is changed to fumarate (TCA intermediate) and this cycle can continue since large reservoir of aspartate in the cell and can get more from the bloodstream

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67
Q

If no purine nucleotide cycle…

A

Then muscles become very fatigued

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68
Q

Pyrimidine metabolism

A

Happens readily in humans

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69
Q

Purine matabolism

A

Can’t be done by human cells so turned into uric acid as a waste product

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70
Q

Breaking down AMP

A

Changed into adenosine by nucleotidase

Converted to inosine by adenine deaminase

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71
Q

Breaking down IMP

A

Converted into inosine by nucleotidase.

Changed to hypoxanthine by PRP.

Hypoxanthine changed to xanthine by xanthine oxidase

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72
Q

Breaking down GMP

A

Converted into guanosine by nucloeotidase

Changed into xanthine by guanine deaminase

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73
Q

Breaking down XMP

A

Changed into xanthosine by nucleotidase

Changed into xanthine by PRP

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74
Q

Uric acid

A

Formed by xanthine oxidase

Soluble at alkaline pH in its anionic form

When uric acid precipitates, it leads to gout

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75
Q

Xanthine oxidase

A

Is a bifunctional enzyme

  • Changes hypoxanthine to xanthine
  • Changes xanthine to uric acid
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76
Q

Gout

A

Inflammatory joint disease mostly located in the distal parts of the body since low temperature leads to low solubility

Caused by the formation of uric acid crystals

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77
Q

Treatment of gout

A
  • Inhibiting xanthine oxidase by drugs such as allopurinol
  • Dialysis removal of uric acid
  • Taking in a low purine diet
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78
Q

Breakdown of dietary nucleic acids

A

Broken down by nucleases in the GI tract

Nucleotides consumes do not form the nucleotides that are in our body

79
Q

Free radical

A

Any molecule that has an unpaired valence electron

80
Q

Atmospheric oxygen

A

Is a biradical but it highly unreactive since it’s electrons are in two different orbitals

Can also take electrons one at a time and can be excited to move its electron to a higher orbital (same orbital as first electron) to form the singlet oxygen

81
Q

Reactive oxidative species (ROS)

A

Free radicals and non-radicals derived from oxygen

82
Q

Reactive nitrogen species (RNS)

A

Free radical and non-radicals derived from nitrogen

83
Q

Reactive species and their half-lives

A

Have an inversely proportional relationship

The hydroxyl radical has the lowest half-life (10 to the power of -9) which means its barely found as a free radical

84
Q

Endogenous sources of ROS

A
  • Mitochondrial respiratory chain (main source of ROS)
  • Xanthine oxidase
  • NADPH oxidase
  • Cyclo-oxygenase
85
Q

Exogenous source of ROS

A
  • Pollutants
  • Radiants
  • Smoking
86
Q

Restoration to make ROS

A

The Q cycle gives off one superoxide radical as well as complex 1. Since we always need respiration to make energy, this production of radicals is unavoidable

87
Q

Phagocytes to produce ROS

A

Phagocytes are able to men their killing liquid by a series of reactions

  • Oxygen is changed to superoxide radical by NADPH oxidase
  • The superoxide radical is changed to hydrogen peroxide by superoxide dismutase
  • Hydrogen peroxide is changed to perchlorate (killing substance) by myeloperoxide
88
Q

If defect in NADPH oxidase…

A

Then can’t form bleach and will form a phagosome which will secrete substances but it won’t kill the bacteria

89
Q

Important ROS’s

A
  • Singlet oxygen
  • Superoxide radical
  • Hydrogen peroxide
  • Hydroxyl radical
90
Q

Singlet oxygen

A

Is selective and reacts with lipids, guanine, and amino acids (tyrosine, histidine, cysteine, and methionine)

No enzymatic defense but it can be neutralized by beta-carotene

Since singlet oxygen can kill cells, can be used in cancer therapy to kill cells

91
Q

Superoxide dismutase

A

Is moderately reactive and acts as both an oxidizing and reducing agent

Reacts with iron-sulfur clusters to release free iron. Iron will react with hydrogen peroxide and form the hydroxyl radical which is really bad

In order to prevent this from happening, superoxide dismutase changes two superoxide radicals and hydrogen to hydrogen peroxide and oxygen

92
Q

Hydrogen peroxide

A

Produced by superoxide dismutase and by xanthine oxidase and monoamine oxidase. Is the the only ROS that isn’t a free radical

Is generally unreactive but is highly reactive with reduced transition metals to form the hydroxyl radical. This is known as the Fenton reaction

Protect against peroxide by catalase, glutathione, and peroxidase. Glutathione (GSS) reacts with peroxide to form GSSG and this needs to be reduced and done by glutathione reductase

93
Q

Hydroxyl radical

A

Formed by the Fenton reaction and by ionizing radiation. Is very reactive and reacts with all biomolecules at the site of formation.

No protection against this radical except for making it

94
Q

Lipid peroxidation

A

Free radicals will attach to lipids and this will change the structure of lipids

Affects:

  • Fluidity of lipids
  • Causes direct toxicity
  • Forms lipid oxidation products
95
Q

Antioxidants

A

Antioxidants are molecules that inhibit oxidation (so reduce)

When an antioxidant reacts with a radical, it forms a radical with lower reactivity. This new radical needs to be recycled in order to use it again

96
Q

Examples of antioxidants

A

Endogenous:
-Ascorbic acid, glutathione, alpha-tocopherol, uric acid

Enzymes:
-Superoxide dismutase, catalase, glutathione peroxidase/reductase

Exogenous:
-Flavanoids, alkaloids

97
Q

Tocopherols

A

Also known as vitamin E

Stops chain reaction of lipid peroxidation

Has a quinone ring that stabilizes it

98
Q

Ascorbate

A

Known as vitamin C

Reduces iron and copper

Cofactor for hydroxylases (ex:collagen synthesis)

Reduces radicals such as superoxide radical, hydroxyl radical

Reforms tocopherol from its radical form

99
Q

If oxidants more than antioxidants…

A

High oxidation in the body and biomolecules are impaired

100
Q

If antioxidants more than oxidants…

A

Impairs signaling processes which leads to growth and developmental defects

101
Q

Acetyl CoA

A

Can branch into two different pathways:

  • Enter the TCA cycle
  • Go to fatty acid synthesis

Acetyl CoA is the major precursor of fatty acid synthesis

102
Q

Fatty acid synthesis

A

Happens in the cytoplasm in three stages:

  • Transporting acetyl CoA from the mitochondria to the cytoplasm
  • Synthesizing Maloney CoA
  • Synthesizing fatty acid
103
Q

Transporting acetyl CoA

A

Acetyl CoA can’t cross the inner mitochondrial membrane due to the CoA part. So acetyl CoA and and oxaloacetate combine together to form citrate by citrate synthase. The CoA part stays in the mitochondria

In the cytoplasm, citrate lyase reconverts the citrate into oxaloacetate and acetyl CoA

104
Q

Synthesizing Malonyl CoA

A

Acetyl CoA is converted to Malonyl CoA by acetyl CoA carboxylase by an ATP and magnesium and carbon dioxide. The magnesium holds the carbon dioxide

105
Q

Acetyl CoA carboxylase

A

Is the rate limiting step of fatty acid synthesis so it has a lot of regulation:

  • Regulation by citrate
  • Regulation by fatty acid
  • Regulation by G3P
  • Regulation by hormones
106
Q

Regulation by citrate

A

High citrate level activate the enzyme so it promotes fatty acid synthesis

107
Q

Regulation by fatty acids

A

Fatty acids will inhibit acetyl CoA carboxylase since there’s already a lot of fatty acid in the body so don’t need more

108
Q

Regulation by G3P

A

G3P will translocations the carbohydrate responsive element binding protein (ChREBP) to move from the cytoplasm to the nucleus

ChREBP will bind to the carbohydrate responsive element (ChoRE) and will initiative synthesis of acetyl CoA carboxylase

109
Q

Regulation by hormone

A

Can be regulated by:
-Insulin: insulin will activate protein phosphates which will dephosphorylate ACC and activate it

-Glucagon: activates AMPK which phosphorylates ACC and inactive it

110
Q

Fatty acid synthase

A

Fatty acid synthase is a dimer. Each part is make of 8 domains:

  • 3 ketoacyl ACP-synthase (KS)
  • Acetyl CoA ACP transacylase (AT)
  • Malonyl CoA ACP transacylase (AT)
  • Enoyl ACP reductase (ER)
  • 3 ketoacyl ACP reductase (KR)
  • 3 hroxyacyl ACP dehydratase (HD)
  • Thiolesterase (TE)
  • Acetyl binding protein (ACP)
111
Q

Structural division

A

Each unit by itself has all the components to the synthesize a fatty acid but it can’t do it

112
Q

Functional division

A

The dimers are divided in half so that both units share the binding domains. In this way, two fatty acids can be synthesized at the same time

113
Q

Fatty acid synthesis

A

Divided into two main cycles

114
Q

Cycle 1

A
  • Acetyl CoA is moved to the ACP domain by AT and a CoA is removed
  • The acetyl group is moved to the KS domain to empty out the ACP domain
  • Malonyl CoA is moved to the ACP domain by MT
  • The acetyl group and malonyl CoA condense together to release a carbon dioxide by KS
  • The keto group is reduced to an alcohol by KR and NADPH is oxidized in the process
  • A double bind is created between carbons 2 and 3 forming a water molecule by HD
  • Double bone is reduce by the ER domain and NADPH is oxidized again

This forms a 4 carbon fatty acid called butyric acid

115
Q

Summary of cycle 1

A

1 acetyl CoA+ 1 malonyl CoA+ 2NADPH -> 1 butyryl (4 carbon fatty acid)+ 2NADP+ + 2H+ + 1CO2+ 1H2O

116
Q

Cycle 2

A
  • Butyric acid is moved to the KS domain to allow a malonyl CoA to bind to the ACP domain
  • The stems are repeated from malonyl CoA

In each successive cycle, two additional carbons are added and they come from malonyl CoA

117
Q

Summary of making palmitic acid (16 carbons)

A

1 acetyl CoA+ 7malonyl CoA+ 14 NADPH-> palmitic acid+ 14 NADP+ + 14 H++ 6 H2O+ 7H2O

118
Q

Cleaving palmitic acid

A

Thioesterase cleaves the fatty acid and uses one water molecule in the process

119
Q

Elongating fatty acids

A

The fatty acids in our body can only make a fatty acid chain of up to 16 carbons long

Add additional carbons through elongate which adds malonyl CoA amino acids (so 2 carbons at a time)

This is in the endoplasmic reticulum

120
Q

Desaturation fatty acids

A

Fatty acid synthase can’t produce unsaturated fatty acids. So this is done by desaturase

121
Q

Monounsaturated fatty acids

A

Have only one double bond

Ex: oleic acid at carbon 9

122
Q

Polyunsaturated fatty acids

A

Have more than one double bonds

Ex: a linoleic acid (omega 3, 3 double bonds), linoleic acid (omega 6, 2 double bonds)

123
Q

Omega nomenclature

A

Start naming from the end opposite to the COOH group. Number based in first double bond that appears from that side

124
Q

Problems with desaturase

A

Desaturase can only put double bonds from carbons 1 to 9 (ex: oleic acid) so double bonds after that can’t be synthesized like omega 3 and 6 so need to get them from diet

125
Q

Arachidonic acid

A

Is a derivative of omega 6 and is synthesized by using the precursor double bonds in omega 6.

Double bond created at carbon 6. Add elongase so changes position. Double bond at carbon 5

So double bonds at 5, 8, 11, 14 and is a 20 carbon lipid

126
Q

DHA

A

Derivative if omega 3

Put double bond at carbon 6. Add elongase. Add double bond at carbon 5. Add elongase. Add double bond at carbon 4

So have 5 double bonds: 4, 7, 10, 13, 16, 19 and is 22 carbon lipid

127
Q

Triacylglycerides

A

Three fatty acids bound to a glycerol molecule through an Easter reaction (OH of glycerol and COOH of fatty acid)

Done in 3 steps:

  • Activating glycerol
  • Activating fatty acid
  • Making triacylglycerol
128
Q

Activating glycerol

A

In liver and adipose, dihydroxyacetone phosphate (DHAP) from glycolysis is converted into activates glycerol (G3P) by glycerol-3 phosphate dehydrogenase

Only in the liver is there glycerol kinase which changes glycerol to G3P

129
Q

Activating fatty acid

A

Done by adding an acetyl CoA to the COOH end of the fatty acid carried out by fatty acyl CoA synthase

130
Q

Traicylglyecerol synthesis

A

Glycerol 3 phosphate acyl transverse adds a fatty acid to form lysophosphitic acid (monoacyl glycerol 3 phosphate)

Lysophophitic acid gets another fatty acid by monoacyl glycerol 3 phosphate acyl tranferase to form phosphatic acid (diacyl glycerol 3 phosphate)

Phophatidic phosphate seems cleaves the phosphate to just have diacyl glycerol

Diacyl glycerol acyl transferase adds the last fatty acid to form triacylglyceride

131
Q

Lipolysis takes place…

A

When there is low glucose

132
Q

Lipogenesis takes place when…

A

There is high glucose

133
Q

Adipose triglyceride lipase

A

Breaks down the triglyceride into diglycerides and releases one fatty acid

134
Q

Hormone sensitive lipase

A

Breaks down diglycerides into monoglycerides and releases one fatty acid

135
Q

Monoglyceride lipase

A

Breaks down the monoglyceride into fatty acid and glycerol

136
Q

Regulation of hormone sensitive lipase by glucagon

A

Glucagon or epinephrine binds to its receptor and activated adenykate cyclase which activates cAMP

cAMP activates protein kinase A which phosphorylates hormone sensitive lipase and activates it

137
Q

Regulation of hormone sensitive lipase by insulin

A

When there’s high glucose, insulin will activate a phosphates which will inactivate hormone sensitive lipase

138
Q

Perilippin

A

Coat protein present on lipid droplets in adipose

Changes the confirmation of lipid droplets and exposes triglycerides for lipolysis

139
Q

Regulation of perilipin

A

When glucose levels are low, glucagon will bind to its receptor and activate adenylate cyclase and form cAMP

cAMP will activate protein kinase A which will activate the protein

140
Q

Transport of glycerol

A

After degradation of triglycerides in adipose, glycerol is transported to the liver

141
Q

Transporting fatty acids

A

Transported to muscles and enters the cytoplasm of muscle cells and enters the mitochondria for oxidation

142
Q

Albumin

A

Carrier protein of fatty acids

143
Q

Activating fatty acids

A

Fatty acids are activated in the cytoplasm by adding an acetyl CoA by fatty acyl CoA synthase to form fatty acyl CoA

Uses 1 ATP in the process

By activating the fatty acid, it can easily diffuse into the outer mitochondrial membrane but not the inner mitochondrial membrane

144
Q

Transporting fatty acyl CoA into the matrix

A

Can’t enter matrix because of CoA so use the carnitine shuttle

145
Q

Carnitine shuttle

A

Done in 3 steps:

  • Carnitine palmitoyl transferase 1 removes the CoA and adds a Carnitine
  • Carnitine acylcarnitine translocase transfers the complex into the matrix and in exchange, a carnitine is shuttled to the mitochondrial space
  • Carnitine palmitoyl transferase 2 removes the carnitine and puts the CoA. This step uses an ATP in the process
146
Q

Regulating carnitine cycle

A

High levels of malonyl CoA inhibit the carnitine shuttle

147
Q

B oxidation

A

Removing the carbons from the 2-3 group which is known as the B carbon from the COOH side

Involves cleaving 2 carbons at a time and completed in 4 reactions

  • Oxidizing reaction generating FADH2 by acyl CoA dehydrogenase
  • Hydration reaction catalyze by enoyl CoA hydratase
  • Oxidation reaction generating NADH by 3-OH-acyl CoA dehydrogenase
  • Cleavage by B-ketoacyl CoA thiolase
148
Q

Each B oxidation cycle for even number of carbons generates

A

1 acetyl Co A, 1 NADH, and 1 FADH2

In the last cycle, 2 acetyl CoA are generated

149
Q

Each acetyl CoA gives…

A

3 NADH, 1 FADH2, 1 GTP which go to the electron transport chain to make 12 ATP

150
Q

1 NADH

151
Q

1 FADH2 gives

152
Q

Breaking down odd number of fatty acid chain

A

Humans can’t do it but bacteria can

Reaction is the same except in the last cycle, 1 acetyl CoA and 1 propional CoA are produced

153
Q

Propinoly CoA

A

Is converted to succinyl CoA which is a TCA cycle intermediate and uses one ATP in the process.

Can generate 1 NADH, 1 FADH2, AND 1 GTP so gives off 6 ATP

154
Q

Cholesterol

A

27 carbon compound that has an 8 carbon chain attached to at at carbon 17. Made up of 4 rings

155
Q

Cholesterol synthesis

A

Divided into 3 stages:

  • Acetyl CoA synthesis
  • Mevalonate synthesis
  • Cholesterol synthesis
156
Q

Mevalonate synthesis

A
  • 2 acetyl CoAs come to form acetoacetyl CoA by thiolase
  • Another acetyl CoA is added forming HMG CoA by HMG CoA synthase
  • HMG CoA is converted to mevalonate by HMG CoA reductase. Uses 2 NADPH in the process
157
Q

Statin

A

Inhibits HMG CoA reductase

158
Q

Regulating HMG CoA reductase by cholesterol

A

SREBP-2 binds to its cleaving activating protein (SCAB) in the ER and moves to the Golgi where it cleaves SREBP-2 and produces a DNA binding protein of SREBP-2 (DBD)

DBD goes to the nucleus and binds to the SRE and initiates transcription of HMG CoA reductase

Process happens when the cell is low on cholesterol

When cholesterol levels are high, INSIG binds to SREBP-2 so it doesn’t leave the ER

159
Q

Regulating HMG CoA reductase degradation by cholesterol

A

HMG CoA will bind to INSIG when there are high amounts in the body. This will allow the complex to leave the ER and enter the cytoplasm where uniquitin will attach and take it to a proteosome complex to degrade it

160
Q

Regulating HMG CoA reductase by insulin

A

Insulin will activate a phosphates which will activate HMG CoA reductase

161
Q

Regulating HMG CoA reductase by glucagon

A

Glucagon will activate AMPK and phosphorylates HMG CoA reductase which inactivated it

162
Q

Forming cholesterol

A
  • Kinases convert mevalonate into 5-pyrophosphomevalonate by adding 2 Ps
  • Decarboxylase changes 5 pyrophosphomevalonate into isopentyl pyrophosphate (IPP)
  • Isomerase will change IPP into DPP
  • Transferase adds an IPP to DPP to form GPP
  • Tranferase adds IPP to GPP to form FPP
  • Sqalene synthase adds 2 FPPs together to form squalene
  • Squalene monoxygenase converts squalene into lanosterol
  • Lanisterol is converted to cholesterol by 19 more reactions
163
Q

Cholesterol esterification

A

A fatty acid is added to cholesterol by acyl CoA cholesterol transferase

164
Q

Transporting cholesterol

A

Needs to be transported by a carrier protein because it’s so hydrophobic

165
Q

Cholesterol uses

A

Can’t be used for energy purposes

Instead used for steroid synthesis such as:

  • Androgens
  • Testosterone
  • Progestrone
  • Estrogen
166
Q

Cholesterol ester uses

A

Maintains integrity+fluidity in lipid bilateral

167
Q

Forming bile salts

A

Cholesterol is converted to 7 alpha hydroxycholesterol by 7 alpha hydroxylase (rate-limiting step)

Undergoes a lot of reactions to form bile acids:

  • Cholic acid
  • Chenodeoxycholic acid
168
Q

Glycocholic acids

A

Formed by glycine and cholic acid

169
Q

Taurocenodeoxycholic acid

A

Formed by taurine and chenodeoxycholic acid

170
Q

Recycling bile salts

A

When bile salts are given to the intestine, 95% of them will be recycled back to the liver

Intestinal bacteria change primary bile acids to secondary bile acids

Primary/secondary bile acids/salts are all reabsorbed by iliac mucosal cells back to the liver to be used again

171
Q

Essential fatty acids

A

Aren’t synthesized in the body and are essential for growth and development

Deficiency of essential fatty acids leads to rash, decreased growth, susceptibility to infection

Ex: omega 3 and 6

172
Q

Arachidonic acid

A

Important for cell signaling, making eicosanoids (prostaglandins and leukotriens)

173
Q

DHA

A

Structural component in the brain, cerebral cortex, and retina

174
Q

Modifications of DHA

A

When the 5 double bond is added and elongase is added need to add two carbons since lack of desaturase 4 in the body

Desaturase 6 is then added and then decrease 2 carbons

175
Q

Desaturates in the body

176
Q

Mead acid

A

Made from oleic acid. Desaturase 6 is added and then elongated and then desaturase 5 is added

Mead acid is high when omega 3 and omega 6 is low

177
Q

Omega 3 derivatives

A

Plays a role in:

  • Blood coagulation
  • Inflammation
  • Regulating blood vessel contractiliy
  • Helps in brain and retina function
178
Q

Lipoprotein

A

Pack lipids into vesicles

Inner core is hydrophobic and has triglycerides and cholesterol esters

Outer core has apolipoproteins, phospholipids, and free cholesterol

179
Q

Types of lipoproteins

A
  • Chylomicrons (highest TAGs)
  • VLDL
  • LDL (highest cholesterol)
  • HDL (most dense)
180
Q

Apolipoproteins

A

Structural component of lipoproteins

Function:

  • Provide recognition sites: Apo E and Apo A
  • Activating enzymes: Apo CII
  • Specific to lipoproteins: Apo A, ApoB10, Apo B48
  • Exchangeable between lipoproteins: Apo E and ApoCII
181
Q

Chylomicrons

A

Transport TAGs from intestinal mucosal cells to peripheral tissue to liver

182
Q

Chylomicrons synthesis

A

Dietary lipids are absorbed by intestinal mucosal cells and are converted in TAGs, cholesterol esters, and phospholipids

Attached to Apo B48 to form Chylomicrons. Process is mediated by microsomal triacylglycerol transfer protein (MTP)

Released into circulation

183
Q

Chylomicrons transport and metabolism

A

In circulation, HDL gives Apo E and Apo CII

Apo CII activates lipoprotein lipase and breaks down TAGs. When finished, Apo CII leaves

By this time, Chylomicrons is very small and is called remnant so goes to liver

184
Q

Chylomicron in liver

A

Bind through ApoE on specific receptors. When enters the cell, lysosome degrades the remnant and releases it content

185
Q

Lipoprotein lipase regulation

A

When there is high dietary fat, insulin senses it and starts creating LPL and releases it into the circulation

186
Q

VLDL metabolism

A

Goes from liver to peripheral tissue.

Apo B100 binds and liver releases it into circulation. Recieves Apo E and Apo CII

LPL degrades TAGs and Apo CII goes back to HDL

187
Q

Making LDL

A

In the circulation, some TAGs go from VLDL to HDL and HDL gives cholesterol esters and this forms LDL

188
Q

LDL metabolism

A

Apo B100 of LDL binds with LDL receptor in periphery and Clathrin forms a coat bringing it in

Clathrin then degrades and an endosome forms over the LDL

Endosomal ATPase separates LDL from receptors and receptors go back to cell surface

LDL is hydrolyzed by lysosomal acid hydrolase

189
Q

LDL cholesterol and effects in homeostasis

A
  • High cholesterol means stop making more cholesterol
  • High cholesterol reduces LDL receptors
  • High cholesterol will be esterified and stored for later
190
Q

HDL

A

Goes from peripheral tissue to liver

Bound to Apo A, Apo CII and Apo E and phospitidylcholine

Takes up free cholesterol through ATP-binding cassette protein 1. Free cholesterol is esterified by lecithin cholesterol acyltransferase by taking fatty acid from phosphatidylcholine. Activated by Apo A

191
Q

HDL2

A

As cholesterol esters accumulate, becomes HDL 2

192
Q

HDL3

A

Cholesterol ester poor HDL

193
Q

HDL2 metabolism

A

Binds with scavenger receptor class B type 1 receptors on the liver and gives cholesterol

194
Q

Cholesterol ester transfer protein

A

Transfers some cholesterol esters from HDL to VLDL

FB1 Flashcards (6 decks)

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