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chem compostella > BIOMOLECULES > Flashcards

BIOMOLECULES Flashcards

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1
Q

2 diff types of carbohydrate groups

A

POLYHYDROXY aldehyde and ketone

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2
Q

why can carbs have either aldehyde or ketone groups

A

parent molecule = glycerol
any one of the 3 OH in glycerol can be oxidised to form sugar –> if the first is oxidised it creates an aldehyde, if the second it creates a ketone

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3
Q

simplest monossaccarides that can be defined

A
  1. in case of 1st OH oxidation in glycerol: ALDOTRIOSE
  2. in case of 2nd OH oxidation in glycerol: KETOTRIOSE
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4
Q

what enantiomer of carbs is always present in nature

A

D

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5
Q

epimer definition

A

diastereoisomers that have one chiral carbon swapped

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6
Q

relationship between glucose and galactose/mannose

A

GALACTOSE: epimers at c4

MANNOSE: epimers at c2

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7
Q

when does cyclization of monossacharides occur

A

in nature they exist as acyclic, but form cyclic srtuctures when added to WATER (bcos of hydroxyl and carbonyl groups coming in contact)

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8
Q

Anomeric position of glucose def

A

carbon of the hayworth projection that was originally the carbonyl carbon

CRETES ALPHA (down) AND BETA (up) ANOMERS A

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9
Q

what does pyranose denote when it is present in the name of a carb? (eg. glucopyranose)

A

that the glucose has formed its 6 carbon cyclic structure

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10
Q

equilibrium of glucose isomers in water (concs) and reason

A

beta > alpha > open

beta has OH groups in a comformation where they dont collide so there is less steric hinderence and it is more stable

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11
Q

Mutarotation def

A

a change in optical power given by the equilibrium established of the 2 anomers of glucopyranoses

-similar MP/BP bcos the same intermolecular forces
-diff optical power

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12
Q

2 types of oxidation of glucose and what reagents are used

A
  1. CU2+ (weak oxidising agent) oxidises the aldehyde and forms gluconic acid
  2. enzymes (not done in lab)
    oxidises C6 hydroxyl group into COOH (aldehyde unchanged) to form glucuronic acid
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13
Q

What is a reducing sugar

A

sugar that can be oxidised

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14
Q

how are reducing sugars tested for

A

positive fehlings and tollens

Fehlings = Cu2+ to CuO forming dark red ppt

Tollens = Ag+ to Ag(s) forming silver mirror

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15
Q

amino acids within carbs

A

C2 of monosaccharide can be connected to an amino acid group

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16
Q

Phosphorylation of glucose

A

occurs at C6 (primary hydroxyl) to form glucose-6-phosphate

ESTERIFICATION REACTION

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17
Q

glycoside formation in carbs

A

hemiacetal cyclic form (eg. alpha glucopyranose) reacts with another alcohol to form acetal

glycosidic bond forms between anomeric carbon hydroxyl and the R group of the alcohol

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18
Q

Disaccharides and components (that we need to know) + type of carbon linkage

A
  1. Maltose = 2 a-glucose (1,4)
  2. Cellobiose = 2 b-glucose (1,4)
  3. Sucrose = a-glucose + b-fructose (1,2)
  4. Galactose = a-glucose + lactose (b1,4)
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19
Q

2 components of starch

A

amylose + amylopectin

POLYSACCHARIDE

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20
Q

amylose structure

A

-linear (non branched)
-glucose monomers
-1,4 bonding

!! makes up starch

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21
Q

amylopectin structure

A

-glucose monomers
-linear chains with 1-4 bonding
-branched projections of 1-6 bonding

!! makes up starch

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22
Q

glycogen structure

A

-polysaccharide
-glucose monomers
-same as amylopectin but with more frequence branching

1-4 linear and 1-6 branches

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23
Q

cellulose structure

A

-b-glucose monomers that form cellulobiose disaccharides that repeat in the structure
-linear molecule, alternating bonds
-b1,4 glycosidic bonding
-H bonds and cross links between molecules

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24
Q

type of enantiomer that all amino acids are present naturally

A

L isomer

25
Q

types of groups present in amino acids that determine properties

A

ALL AMINO ACIDS ARE POLAR BCOS OF COOH GROUPS AND FORM ZWITTERIONS

  1. non polar chains
  2. polar chains
  3. aromatic R chains
  4. positive charged groups
  5. negative charged groups
26
Q

lysine form in pH 7

A

chain has an amino group at the end which is PROTONATED

27
Q

value of Ka of zwitterion dissociation

A

10^-10

28
Q

why can amino acids work as buffers

A

undergo dissociations between zwitterions at diff pHs

+ and neutral ions can buffer
neutral and - ions can buffer

!! bcos they are one H+ apart

29
Q

what is the isoionic point in amino acid solutions

A

when the concentration of positive and negative zwitterion forms are equal

!! half equivalence hence the pH = pKa of the specific buffer

30
Q

isoelectricity def

A

isoeletricity: refers to proteins when the overall charge = 0 (neutral). this allows them to form precipitates and crystalise in water

31
Q

types of lipids that exist

A
  1. Hydrolysable: waxes, triglycerols and phospholipids
  2. Non hydrolysable: steroids, vitamins, eicosanoids
32
Q

naming fatty acid chains

A

Cnum: double bonds (delta (positions of double bonds))

eg:
18:2 (delta4,9)

33
Q

waxes charactertistics

A

-non polar
-ester compounds
-very hydrophobic
-can be broken into fatty acid chain and alcohol parents

34
Q

triglycerides structure and function

A

-glycerol +3 fatty acid chains
-fatty acid chains can be the same but dont have to be
-chains are either saturated or unsaturated
-if all chains are diff a chiral carbon center on glycerol is created

35
Q

saponification

A

ester hydrolysis in alkaline conditions

36
Q

Phospholipids structure and characteristics

A

-2 types are phosphoglycerols and sphingolipids

PGs: glycerol backbone, 2 fatty acid chains and one phosphate head connected to X group

SLs: sphingosine backbone, one fatty acid tail and a phosphate head connected to X group

!!diff types of phospholipids have diff X groups

37
Q

what is the parent structure of glycerophospholipids

A

phosphatidic acid

38
Q

steroids structure and characteristics

A

-fusion of 4 rings
-cholesterol derivatives
-estrogen
-progesterone
-androgens
-aldosterone

39
Q

vitamin types

A

fat soluble: A,D,E,K
water soluble

40
Q

eicosanoids structure and characteristics

A

-derivatives of arachidonic acid
-used as local mediators / synthesised in response to stimuli
eg. prostaglandin

41
Q

structure of nucleotides

A

pentose
nitrogen base
phosphate group

42
Q

2 types of nitrogenous bases

A

purines: AG - 2 rings

pyrimidines: CUT - 1 ring

43
Q

what part of the nitrogenous base makes a bond with the sugar in nucleotides

A

the NH group present in all bases

44
Q

what type of bond connects base to sugar in nucleotides

A

a-N- glycosidic bond

45
Q

nucleoside def

A

nucleotide without the phosphate:
hence only the sugar and base

46
Q

bond linking the phosphate to the sugar in nucleotides

A

phosphoester bond between C5 of sugar (5’)

47
Q

nucleic acid definition

A

polymers of nucleotides joined by phosphodiester bonds (at the 3’ position)

48
Q

what is the activated form of a nucleotide

A

when there are 3 phosphates present instead of just one (ATP)

49
Q

what form is a nucleotide in at pH7

A

the phosphate group is ionised, hence it is acidic

50
Q

deamination def

A

SIDE REACTION
removal in amino group from base (eg cytosine to uracil modification)

51
Q

depurination def

A

SIDE REACTION
when at acidic pH, the glycosidic bond between purine base and sugar breaks -> gives an apurinic residue (phosphate and connected sugar)

52
Q

guanine modification def

A

modification of the carbonyl group in guanine base to give tautomers

(however the carbonylic form is favoured unless a special agent is present that promotes modifications)

53
Q

what bond is present between the phosphates in di/tri phosphate nucleotides

A

initial bond between sugar and phosphate = ESTER

additional bonds between the phosphates = ANHYDRIDE

54
Q

what is the need for nucleotides to be activated

A

anhydride bonds are much more reactive than ester bond so they are more easily hydrolysed to release energy

55
Q

how many kcal/mol energy released by ATP hydrolysis

A

7.3

56
Q

which is the gamma phosphate in a nucleotide

A

the last one to be added (hence the one hyrolysed first in reactions)

57
Q

what sugar does ATP contain

A

ribose

58
Q

what is an ampiphilic molecule

A

a molecule that has both polar and apolar parts

59
Q

what bond links the fatty acid in sphingolipids to the backbone

A

amide bcos they do not contain a glycerol backbone

hence sphingolipids do not contain an ester bond

chem compostella (3 decks)

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