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MC Biochem 2 > Extra SHIT > Flashcards

Extra SHIT Flashcards

1
Q

Steroid Hormones

-synthesis of 5 hormones

A

Cholesterol (27C)
Pregnenolone (21C)
Progestagens (21C)**startof 5 classes of steroid hormones

Branches:INTO

  • Glucocorticoids (21C)
  • Mineralocorticoids (21C)
  • Androgens (19C) convert to Estrogens (18C)
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2
Q

5 classes of steroid hormones

A 
Progestagens (21C)
-synthesized in corpus luteum 
Ex: Progesterone
-prepares lining of uterus for implantation of an ovum 
-maintenance of pregnancy

Glucocorticoids (21C)
-synthesized in adrenal cortex
Ex; Cortisol
-promotes gluconeogenesis and glycogen synthesis

Mineralocorticoids (21C)
-synthesized in adrenal cortex
Ex:Aldosterone:
-act at distal tubules of kidney to increase the reabsorption of Na+ and excretion of K+ and H+
-increases blood volume and blood pressure

Androgens (19C)
Synthesized in testes
Ex: Testosterone
-developement of male secondary sex characteristics

Estronges (18C)
Ex: Estrone
-developement of female secondary sex characteristics

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3
Q

Cytochrome P450 System

A

family of proteins containing a cytochrome with a bound heme

Localization:

1) Cellular: 2 forms:
- Mitochondrial-hydroxylation of steroid hormones
- ER-detoxification of drugs/toxins
2) Organs
- liver, small intestine, kidney, steroid hormone producing tissue

Function:
Detoxification of foreign substances
-Hydroxylation of phenobarbital and polycyclic aromatic hydrocarbons
-metabolizing drugs (caffeine, ibuprofen etc)

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4
Q

Bile Salts

A

Polar derivatives (break down particles) of cholesterol that solubilize dietary lipids

  • Glycocholate
  • Taurocholate

**Detergent

Solubilization:

  • exposes more surface area of cholesterol to digestive action of lipases
  • increases absorption of cholesterol in intestines

Localization:

  • synthesized in liver
  • Stored in gall bladder
  • function in small intestine
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5
Q

Cells that need cholesterol?

A

take up LDLs by receptor-mediated endocytosis

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6
Q

Cholesterol Synthesis

Overview

A

27 Carbons are derived from acetyl CoA

Cellular Localization:

  • cytoplasm
  • ER

Organ Localization:

  • Liver parenchymal cells
  • intestine (secondary)

3 stages:

  • synthesis of IPP in cytopplasm
  • 6 molecules of IPP condense to form squalene-ER
    3) Cyclization of squalene
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7
Q

10 Steps of Cholesterol

A

1) HMG-CoA Synthase
- Acetyl CoA + AcetoAcetyl CoA-> 3-HMG-CoA

2) HMG-CoA reductase
-commited step/regulated
-integral membarne protein of ER with catalytic domain into cytoplasm where reaction occurs
HMG-CoA->Mevalonate
-coenzyme: 2NADPH to NADP+

3,4,5) Melavonate-> IPP
Kinase, Kinase, Kinase/Decarboxylase
-6 molecules of IPP used to synthesize 1 cholesterol molecule

6) IPP-> DPP
- isomerization

7)Geranyl transferase
-catalyzes a series of transferase reactions of 5C molecules
IPP+DPP-> GPP
GPP + IPP-> FPP (15C) does this twice

8) Squalene synthase
- 2 FPP molecules combine at tail to form squalene (30C)
- NADPH to NADP+

9) Squalene Monooxygenase
- Squalene-> Squalene Epoxide
- requires moleculare oxygen
- coenzyme NADPH to NADP+

10)Oxidosqualene cyclase
Squalene epoxide-> Lanosterol
-ring closure

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8
Q

HMG

A

used to synthesize cholesterol and ketone bodies

2 isozymes of HMG-CoA reductase

  • cytoplasm-cholesterol
  • mitochondria-ketone bodies
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9
Q

Lanosterol-> Cholesterol

A 
19 steps
conversion involves:
-reduction of carbon chain from 30 to 27
-removal of 2 methyl on C4
-removal of methyl on C4
-migartion of double bond from C8 to C5
-reduction of Double bond C25-C25
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10
Q

SLOS

A

Smith-Lemli-Opitz syndrome
-due to deficiency of
7-dehydrocholesterol-7-reductase
enzyme involved in migration of the double bond

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11
Q

Synthesis of Sphingomyelin

A

Ceramide-> Sphingmyelin

  • Phosphatidyl choline drops of head group phosphate+ ethanol amine +3ch3 or (CHOLINE)
  • DAG released
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12
Q

Synthesis of Cerebroside

A

Ceramide + UDP glucose-> Cerebroside

-attachment of 1 Carb to serine OH

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13
Q

Synthesis of Gangliosides

A

Ceradmide + multiple carbohydrates after cerebroside

  • carbs added one at a time
  • are activated UDP-glucose/galactose
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14
Q

Phosphatidylcholine synthesis:

-2way

A

1) activation of choline which is then attached to head group
2) Methylation of ethanol amine by Phosphatidylethanol amine methyltransfers
- requires 3SAMS as methyl donor

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15
Q

Where is Cardiolipin found?

A

Mitochondria

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16
Q

In mammals, this is the major site of triacylglycerol synthesis

A

Liver

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17
Q

The reduction of this metabolite supplies Glycerol 3 Phosphate for acylglycerol synthesis

A

Dyhydroxy 3-Phosphate

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18
Q

Component of myeline sheath

A

Sphingomyeline

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19
Q

All of the carbons in cholesterol are derived from this molecule?

A

Acetyl CoA

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20
Q

This the process by which LDL enter the cell

A

receptor-mediated endocytosis

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21
Q

Cholesterol and triacylglycerols are transported in the body fluids in this form

A

Lipoprotein particles

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22
Q

Vitamin is a derivative of cholesterol

A

Vit D

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23
Q

Primary bile salt

A

glycocholate

-or taurocholate

24
Q

This is a derivative of cholesterol and the precursor of the steroid hormones

A

Pregnonenolene

25
Q

In mammalian cells, phosphatidate is synthesized in?

A

Cytoplasmic face of smooth ER

-Outer mitochondrial membrane

26
Q

Is composed of a fatty acid linked to sphingosine via an amide bond

A

Ceramide

27
Q

In the biosynthesis of phosphatiidates, the fatty acyl group attached to the C-2 position is usually?

A

unsaturated

-c1 usually saturated

28
Q

Is the 9 Carbon sugar that is a component of gangliosides

A

Sialic acid or N-acetylneuramic acid

29
Q

In biosynthesis of sphingosine, the condensation of palmitoyl-CoA and serine requires the coenzyme

A

PLP

30
Q

In membrane lipid biosynthesis, the nucleotide___ is used to activate the components in the reaction

A

CTP

31
Q

The synthesis of ___ is the committed step in cholesterol biosynthesis

A

mevalonate

32
Q

___ is the 30C (triterpene) precursor of cholesterol biosynthesis

A

Squalene

33
Q

is the major carrier of cholesterol esters in the blood

A

LDL

34
Q

Vit D3 is converted into ___ which is an active hormone that functions as a transcription factor

A

Calcitriol

35
Q

What is the common precursor for both phosphatidyl inositol and triacylglycerol

A

Phosphatidylate

36
Q

Phosphatidate is formed from?

A

Glycerol 3-Phosphate

2 Fattty acyl CoA

37
Q

In phosphatidate inositol, what usually occupies C1 and C2

A

C1=stearic acid

C2=arachidonic acid

38
Q

The highest concentration of sphingolipids is found in the?

A

CNS

39
Q

The starting materials necessary to synthesize sphingosines?

A

Palmitoyl CoA and Serine=Ceramide

40
Q

What is the major component of LDLs?

A

Cholesterol Linoleate

41
Q

Respiratory distress syndrome is caused by?

A

a failure in the biosynthetic pathway of dipalmitoyl phosphatidyl choline

42
Q

Tay Sachs is caused by

A

an inability to degrade gangliosides

43
Q

HMG Coa is synthesized from?

A

Acetyl CoA and AcetoAcetyl CoA

44
Q

Feedback regulation of cholesterol synthesis is mainly controlled at the step catalyzed by the enzyme?

A

3-hydroxy-3-methylglutary CoA reductase

45
Q

The role of lipoprotein particles are to:

A

Solubilize hydrophobic lipids

Contain cell-targeting signals

46
Q

The major carrier of dietary fat from the intestine is

A

chylomicrons

47
Q

The LDL receptors on the plasma membarne are localized in

A

coated pits that contain the receptors of clathirin coated proteins

48
Q

What combines to form major bile salt

A

Cholic acid and Glycine

49
Q

Hydroxylation of cholesterol by cytochrome P450 requires:

A

NADPH

activated O2

50
Q

What are the causes and symptoms of Familial hypercholesterolemia

A

Hallmark-Genetic disease is elevated cholesterol levels in serum

  • cholesterol deposits in blood vessels and cause heart attacks, even in young children
  • caused by a deficiency in the LDL receptor
51
Q

What is the role of CTP in the synthesis of Phospholipids

A

In de novo synthesis

  • CTP is used to activate Phosphatidate to form CDP-diacylglycerol and pyrophosphate
  • pyrophosphate is hydrolyzed and drives reaction
  • Activated DAG can then react with another alcohol, such as inositol and CMP is released
52
Q

What are the 3 steps of cholesterol synthesis

A

1> synthesis of isoprene units (IPP)

2) condensation of 6 units to form squalene
3) cyclization of squalene

53
Q

What is the role of phosphatidyl choline in the synthesis of sphingomyelin

A

Phosphatidyl choline provides the polar head form sphingomyelin
-phosphocholine group is transferred to ceramide from phosphatidyl choline to form sphingomyelin and DAG

54
Q

List the types of lipoproteins and give primary physiological role of the lipoprotein

A 
Chylomicrons-transport dietary fat
VLDL-transport endogenous fat
IDL-precursor to LDL
LDL-transport cholesterol
HDL-reverse transport of cholesterol form tissue to liver
55
Q

How do blood levels of lipoproteins serve diagnostic purposes?

A

The ratio of LDL to HDL is important
-to much LDL (bad cholesterol) can be dangerous because increased resistance for plaque formation and heart disease.
HDL serves in a protective capacity, shuttling cholesterol forms eh cells back to liver to maintain proper levels

LDL/HDL ratio should be 3.5 in humans

MC Biochem 2 (31 decks)

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