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Biochemistry (aka hell) > Chapter 11 > Flashcards

Chapter 11 Flashcards

1
Q

what are the six classes of lipids and their definitions?

A

free fatty acids: a common fuel

triacylglycerols: storage for of fatty acid

wax esters: nonpolar lipids, waxes

phospholipids: membrane lipids
spingolipids: membrane lipids that contain long- chain amino alcohol
isoprenoids: contains isoprene units, terpenes and steriods

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2
Q

fatty acids are are chains of hydrogen-bearing carbon atoms that have a ______ at one end and a ___________ at the other end

A

carboxylic acid at one end

methly group at the other end

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3
Q

fatty acids can also be numbered from the methyl carbon atom, which is called the _________ carbon

A

omega (w) carbon

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4
Q

because fatty acids are ionized at physiological pH, they are usually referred to as their ______ form, rather than the unionized acid

A

carboxylate form

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5
Q

most naturally occuring fatty acids have an _______ number of carbons in an unbranched chain.

fatty acids that contain only single carbon-carbon bonds are ________

fatty acids that contain one or more double bonds are __________. this can be cis or trans

A

even number of carbons

saturated

unsaturated

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6
Q

why do unsaturated fatty acids have lower melting temperature than saturated fatty acids?

A

unsaturated fatty acids are often found in cis configuration, in which double bonds are present. This creates a kink in the molecule not allow for it to stack has tightly or as efficiently. thus the intermolecular interaction between the molecules are weaker allowing it to have lower melting temperature. It should be noted that saturated fatty acids stack tighter and they have a higher melting temperature, due from the higher intermolecular interactions

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7
Q

cis polyunsaturated fatty acids are essential components of our diets because we ____________

A

cannot synthesize them

these fatty acids are precursors to a variety of hormones and appear to offer some protection from coronary heart disease

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8
Q

what are 3 omega 3 fatty acids

A

EPA
DHA
ALA

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9
Q

what are 3 non essential fatty acids (ones we make ourselves)

A

omega 5, omega 7, omega 9

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10
Q

what are important chemical reactions of fatty acids?

A
  • esterification
  • hydrogenation
  • oxidation
  • protein acylation
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11
Q

what are eicosanoids?

A

they are signaling molecules made by oxidation of 20 carbon fatty acids

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12
Q

give example of three eicosanoids?

A

prostaglandin, thromboxane, leukotriene

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13
Q

what is the storage form of fatty acids?

A

triacylglyerols

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14
Q

define triacylglycerols?

also what type of fat are they and why?

A

triacylglycerols are esters of glycerol with three fatty acids

neutral fats because they have no charge

they contain fatty acids of varying length and can be a mixture of saturated and unsaturated

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15
Q

why are triglycerols better for storage than glucose??

A
  1. Hydrophobic and coalesce into droplets; store an equivalent amount of energy in about one-eighth the space
  2. More reduced and thus can release more electrons per molecule when oxidized
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16
Q

wax esters define and what are they composed of?

A

they are complete mixture of nonpolar lipids

they provide a protective coating on leaves, fruits, and skin.

wax esters are composed of long-chain fatty acids and long-chain alcohols are prominent constituents of most waxes

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17
Q

what are the common types of membrane lipids?

A

phospholipids

glycolipids

cholesterol

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18
Q

phospholipids are __________ with a ______ head (phosphate and other polar or charged groups) and hydrophobic fatty acids

act in membrane formation, emulsification, and as surfactant, spontaneously rearranged into ordered structure when suspended in water

A

amphipathic with a polar head group

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19
Q

what are some general features of phospholipid?

A

small molecules

amphipathic

spontaneously form vesicles, micelles, and bilayers in aqueous solution

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20
Q

what are the two types of phospholipids?

A
  1. sphingomyelin= contain sphingosine instead of glyerol (also classified as spingolipids)
  2. phosphoglycerides- contain a glycerol, fatty acids, phosphates, and an alcohol.
    - -simplest phosphoglyceride is phosphatidic acid composed of glycerol-3-phosphate and two fatty acids
    - -phosphatidylcholine (lecithin) is an example of alcohol esterified to the phosphate group as choline
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21
Q

what phsphoglyceride is important with GPI anchors. And what are GPI anchors?

A

glycosyl phosphatidylinositol

GPI anchors= attach certain proteins to the membrane surface. proteins are attached via and amide linkage

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22
Q

proteins acylation makes what type of proteins?

A

prenylated proteins

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23
Q

what do phospholipases do?

A

they hydrolyze ester bonds in glycerophospholipid molecules.

They have three major functions: membrane remodeling, signal transduction, and digestion

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24
Q

In relation to phospholipases

  1. membrane remodeling=?
  2. signal transduction=?
  3. Digestion=?

toxic phospholipases-

A

through use of phospholipases,

  1. membrane remodeling involves the removal of fatty acids to adjust the ratio of saturated to unsaturated or repair a damaged fatty acid
  2. signal transduction- phospholipid hydrolysis initiates the singal transduction by numerous hormones
  3. digestion- pancreatic phospholipases degrade dietary phospholipids in the small intestine

toxic phospholipases- various organisms use membrane-degrading phospholipases as means of inflicting damage. bacterial a-toxin and necrosis from snake venom

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25
Q

what are the functions of sphingolipids?

A

Important components of animal and plant membranes

sphingosine (long chain amino alcohol) and ceramide in animal cells

26
Q

_________ is found in most cell membrane but is most abundant in the myelin sheath of nerve cells

A

sphingomyelin

27
Q

Sphingolpid: ceramide

cermaides are also precursors of ____________.

and what are these?

A

glycolipids

A monosaccharide, disacchaaride, or oligosaccharide attached to a ceramide through an O-glycosidic bond

Most important classes are cerebrosides, sulfatides, and gangliosides (may bind bacteria and their toxins)

28
Q

lipid classes:

cerebrosides:
galactocerebroside:
sulfatides:
gangliosides:

A

cerebrosides= have a monosaccharide for their head group

galactocerebrosides are found in brain cell membranes

sulfaides are negatively charged at physiological pH

gangliosides possess oligosaccharide groups; occur in most animal tissue and Gm2 is involved in
tay-Sachs disease

29
Q

several lysosomal storage diseases involve sphingolipid metabolism or ________

A

sphingolipidoses

30
Q

Isoprenoids:

  1. terpenes:
  2. Steroids:
A

Terpenes- essential oils of plants

steroids- derivatives of hydrocarbon ring of cholesterol

31
Q

give an example of sex hormone. and define

A

progesterone, testosterone, estradiol

these are molecules that regulate the development of primary and secondary sex characteristics and various reproductive behaviors

32
Q

give an example of a mineralocorticoid? and define

A

aldosterone

regulates plasma concentration of several ions, especially sodium

33
Q

give an example of an glucocortiocoid? and define

A

cortisol. it regulate the metabolism of carbs, fats, and proteins

34
Q

give an example of an bile acid? and define

A

cholic acid

it is converted into bile salts, aid the absorption of dietary fats and fat-soluble vitamins in the intestine

35
Q

define lipoproteins?

A

any protein covalently attached to lipid group

plasma- transport of lipid molecules

apoproteins synthesized in liver/ intestine

36
Q

what are the five classes of apolipoproteins?

There are different types of lipoproteins with different ratios of lipid and protein components

A

A, B, C,D,E

37
Q

a membrane is a noncovalent heteropolymer of a __________ and associated proteins (__________)

A

lipid bilayer

fluid mosaic model

38
Q

Membrane structure?

A

proportions of lipid, protein, and carbohydrate vary considerably amond cel ltypes and organelles

39
Q

proteins are sometimes covalently bound to ______ to localize the protein to the cell membrane

A

lipids

40
Q

______________: phospholipids form biomolecular layers at relatively low concentrations; this is the basis of membrane structure

A

membrane lipids

41
Q

____________________ refers to the viscosity of the lipid bilayer

A

membrane fluidity

42
Q

The movements of molecules from one side of a membrane to the other requires a _________

A

flipase

Membrane fluidity largely depends on the percentage of unsaturated fatty acids and cholesterol

Cholesterol contributes to stability with its rigid ring system and fluidity with its flexible hydrocarbon tail

43
Q

biological membrane features:

A
  • highly selective permeability barriers
  • amphiphillic organization
  • self-sealing
  • asymmetry
  • fluid mosaic model: liquid and asymmetric
  • fluidity and thickness of membrane are determined by their lipid composition

saturated, longer chains=less fluid

  • hydrophoic core
  • hydrophillic surface
44
Q

___________________ is provided by the hydrophobic chains of the lipid bilayer, which is impermeable to most all molecules (except small nonpolar molecules)

Membrane proteins help regulate the movement of ionic and polar substances
Small nonpolar substances may diffuse down their concentration gradient

A

selective permeability

45
Q

Different functions=different protein compositions

A 
Pure lipid:  insulation (neuronal cells)
Other membranes:  on average 50%
Energy transduction membranes (75%)
-Internal membranes of mitochondria and chloroplast
-Purple membrane of halobacteria
46
Q

membrane protiens

A

25-35% of genome
>17,000 structures of water soluble proteins
~150 unique structure of membrane proteins
-Many functions that are important therapeutic targets

  • Receptors
  • Transporters
  • Ion channels
47
Q

membrane proteins

A

integral-membrane spanning-interaction with HC of bilaer

peripheral-do not penetrate HC; mainly electrostatic interaction with one hydrophillic surface of bilayer

48
Q

structural features of membrane proteins

how are they similar to soluble proteins
what are the difference to soluble proteins

A

similar?
interior is nonpolar, they are tightly packed, H-bonded alpha helices and b sheets, hydrophobicity of interiors of membrane proteins are the same

differences?
outer surfaces are more hydrophobic, lengths of secondary structures are greater

directionality defined by membrane orientation-positive inside rule

49
Q

membrane and microdomains

A

lipids and proteins in membranes are not uniformly distributed

specialized microdomains like “lipid rafts” can be found in the external leaflet of the plasma membrane

50
Q

lipid rafts

include what? and describe

A

include cholesterol, spingolipids, and certain proteins.

lipid molecules are more ordered (less fluid) than non-raft regions

lipid rafts have been implicated in a number of processes: exocytosis, endocytosis, and signal transdution

51
Q

what is the importance of asymmetry?

A

all membrane proteins function in a directed way

correct insertion in the membrane is essential for their biologic function

52
Q

what are two transport processes?

A

active:

  • requires energy
  • pump against concentration gradient

passive:

  • with gradient
  • diffuse/osmosis
  • equilibrium
53
Q

______ transport has two forms: primary and secondary

A

active transport

in _______ active transport, transmembrane ATP-hydrolyzing enzymes provide the energy to drive the transport of ions or molecules, Na,K, ATPase (primary active transport)

54
Q

in _______ active transport, transmembrane ATP-hydrolyzing enzymes provide the energy to drive the transport of ions or molecules, Na,K, ATPase (primary active transport)

A

primary active transport

55
Q

in ____________ transport, concentration gradients formed by primary active transport are used to move other substance across the membrane
-NaK ATPase pum in kidney drives the movement of D-glucose against its concentration gradient

A

secondary active transport

56
Q

cardiotonic steriods, such as ________ strengthen heart contranctions and are used to treat heart disease.

by inhibiting the Na^+, ATPase,Ca^+2 ion remains in the cell longer leading to more robust heart contractions

__________ isolated from the efoxglove plant digitalis purpurea

A

digoxin

digoxin

57
Q

mutations in what gene leads to cystic fibrosis?

A

CFTR

58
Q

impaired membrane transport mechanisms can have very serious consequences. Cystic fibrosis, is a fatal autosomal recessive genetic disorder, is one of the best understood examples. the disorder is caused by a ________________

A

__________ a missing or defective cystic fibrosis transmembrane conductance regualtor (CFTR)

59
Q

give an example of an alosteric regulated channel

A

GABA gates Cl^-

60
Q

what is a combined voltage and ligand gating NMDA channelal?

A

glutamate

61
Q

charge repulsion amoung the four ion binding sites in the potassium channel accounts for the reapid transport of K ions ______ their concentration gradient

A

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Biochemistry (aka hell) (14 decks)

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