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IOE > Intro to biomolecules > Flashcards

Intro to biomolecules Flashcards

1
Q

list the 4 major biomolecules

A

1) nucleic acid
2) proteins
3) lipids
4) carbohydrate (MOST ABUNDANT)

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2
Q

what are the building blocks of

a) nucleic acid
b) proteins
c) lipids
d) carbohydrate

A

a) nucleotides
b) amino acids
c) glycerol and fatty acids
d) sugar

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3
Q

what is the significance of the 4 major biomolecules

A

all cells are made entirely of them (building block molecules)

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4
Q

what are biomolecules

A

large molecules (polymers) composed from covalent bonding of many repeat sub-units (monomers)

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5
Q

what do carbohydrates contain and give their general formula

A

carbon, hydrogen, oxygen

(C.H2O)n (n = 3+)

large quantities of hydroxy groups

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6
Q

what functions do carbohydrates have

A
  • provide energy
  • storage form of energy in body
  • cell membrane component (mediates intracellular communication)
  • structural component of many organisms (bacteria cell walls, insect exoskeletons, plants fibrous cellulous)
  • SO essential for ALL living organisms
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7
Q

what are the most common forms of carbohydrates

A
  • sugar fibres

- starch

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8
Q

what 4 categories are carbohydrates divided into

A

1) monosaccharides
(ie glucose which all cells use as energy source)
2) disaccharides
(2 monosaccharides linked by covalent bonds)
3) oligosaccharides
(3-10 monosaccharides linked by covalent bonds)
4) polysaccharides
(100s/1000s of monosaccharides linked by covalent bonds)

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9
Q

monosaccharides: what are they and what is their structure

A

simplest form of carbs + sugars

backbone = unbranched carbon chain (all C atoms linked by single bonds)

one of the C atoms is double bonded to an O atom = carbonile group

each of the other C atoms has a hydroxy group

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10
Q

monosaccharides: how does the position of the carbonyl group influence the name of the monosaccharide

A

carbonyl group at END of chain = ALDEHYDE called ALDOSE

carbonyl group at another position = KETONE called KETOSE

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11
Q

what is the name for simplest monosaccharides containing 3 carbons and name the 2 types

A

TRIOSE

  • glyceraldehyde (an aldotriose)
  • dihydroxyacetone (a ketotriose)
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12
Q

give the category name and examples of monosaccharides with 3 to 9 carbons (excluding 8)

A

3 = triose (glyceraldehyde, dihydroxyacetone)

4 = tetrose (erythrose)

5 = pentose (ribose, ribulose, xylulose)

6 = hexose (glucose, galactose, mannose, fructose)

7 = heptose (sedoheptulose)

9 = nonose (neuraminic / sialic acid)

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13
Q

which monosaccharides are major ones

A

those containing 4 to 6 carbon atoms

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14
Q

how do we number the carbons in the monosaccharide backbone

A

carbon 1 is the carbon on the end closest to the reactive carbonyl group (H-C=O)

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15
Q

what is a feature of all monosaccharides (except for dihydroxyacetone)

A

contain at least 1 asymmetrical (CHIRAL) carbon atom which makes the carbon optically active

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16
Q

what is an asymmetric / chiral carbon

A

a carbon with 4 different types / groups of atoms attached to it

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17
Q

what can we not do with chiral molecules

A

superimpose them on their mirror images by any combination of rotations / translations

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18
Q

what are the 2 different forms from the arrangement around an asymmetric carbon

A

OPTICAL ISOMERS (D isomer and L isomer)

  • image mirror of the order
  • not superimposed
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19
Q

so what are the 2 optical isomers of glyceraldehyde (simplest aldose)

A

D-glyceraldehyde

L-glyceraldehyde

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20
Q

define isomer

A

compounds with the SAME molecular formula but DIFFERENT molecular structures

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21
Q

define stereoisomer

A

subset of isomers
same with respect to which atoms are joined to which other atoms
BUT the atoms are oriented differently in space

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22
Q

define enantiomers

A

stereoisomers which are NON-SUPERIMPOSABLE mirror images
(2+ compounds w same molecular formula and seq of bonded atoms differing in only spatial arrangement of the atoms)
molecule with 1 chiral carbon exist as stereoisomers termed enantiomers

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23
Q

why do carbohydrates have many stereoisomers

A

because of the arrangment of the OH groups around each asymmetric carbon

24
Q

what does the number of stereoisomers a molecule will have depend on

A

a molecule with ‘n’ asymmetric carbons can have 2^’n’ stereoisomers (2 because one D and one L)

example:
aldohexose...
4 asymmetric carbons 
so 2^4 = 16 stereoisomers
8 D-isomers and 8 L-isomers
25
Q

what are D and L conformations determined by in glyceraldehyde (only 1 asymmetric carbon)

A

orientation of the hydroxy group around the asymmetric carbon

D-ISOMER - if hydroxy group is on the right about the asymmetric carbon
L-ISOMER - if its on the left

26
Q

what are D and L conformations determined by in larger molecules (more than 1 asymmetric carbon)

A

based on orientation of hydroxy group on the asymmetric carbon furthest from the carbonile group (on right = D, on left = L)

27
Q

what happens in monosaccharides with 5+ carbon atoms in backbone and how

A

occur in aqueous solutions as cyclic structures forming either alpha or beta form

Carbonile group forms a covalent bond w the O of the OH group along the chain

28
Q

what is the name of the carbon where the ring forms and orientation of the hydroxy group can change and what determines alpha or beta composition

A

ANOMERIC CARBON

thus the 2 forms are called ANOMERS…
ALPHA FORM = when hydroxy group on anomeric carbon points DOWN

BETA FORM = when hydroxy group on anomeric carbon points UP

29
Q

what can the rings of cyclic monosaccharides do

A

open and re-close allowing rotation to occur about the anomeric carbon (this yields the 2 distinct configurations)

30
Q

what is the name of the process where carbohydrates change spontaneously between alpha and beta configurations

A

MUTAROTATION

31
Q

what are 3 diagrams to depict monosaccharide structures

A

1) cyclic fischer projections (in alpha = places hydroxy attached to anomeric carbon to right toward the ring)
2) haworth projection
3) chair conformation
(in alpha the 2 above place the hydroxy downwards)

32
Q

what happens in alpha and beta anomeric forms of ketahexoses

A

hydroxy group on carbon 5 reacts with ketone group at carbon 2 to form a 5 or 6 membered ring

the 5 membered ring structures resemble furan (an organic molecule) so are termed FURANOSES

the 6 resemble pyran so termed PYRANOSES

33
Q

how is a disaccharide formed

A

2 monosaccharides bond together through a dehydration reaction which forms a covalent glycosidic bond (between anomeric hydroxyl of 1 sugar and hydroxyl of a 2nd)

34
Q

what is a glycoside

A

molecule where a sugar is bound to another functional group via a glycosidic bond

35
Q

what are the 3 important disaccharides

A

sucrose
maltose
lactose

36
Q

what is lactose

A 
galactose + glucose monosaccharides bound by beta 1,4 glycosidic bond
principle sugar (carbohydrate) found naturally in milk of mammals / dairy
37
Q

what is lactose digested by and what happens if this is lacking

A

lactase
(+ by bacteria in the gut through FERMENTATION producing H2, CO2 + CH4)

lactose intolerance

38
Q

what is sucrose

A

glucose + fructose joined by alpha 1,2 glycosidic bond

obtained from sugar cane and bead

39
Q

what is sucrose used in (medically)

A

cough medicine = makes it taste sweet

sweetener in pharmaceuticals

40
Q

what is maltose

A

2 glucose molecules connected by alpha 1,4 glycosidic bonds
a product of starch breakdown (2 step) during digestion
found in germination

41
Q

what are oligosaccharides

A
  • composed of 3-10 monosaccharides connected by glycosidic bonds
  • large numbers of them = prepared by partially breaking down polysaccharides
  • most of few naturally occuring ones are in plants
  • examples = raffinose, stachyose, verbascose
42
Q

what are polysaccharides

A
  • most complex + important carbohydrates
  • long chains of monosaccharides linked by glycosidic bonds
  • can be branched or unbranched
  • high molecular weight
43
Q

what is the most common monomer used to generate polysaccharides

A

D-glucose

44
Q

which 3 types of polysaccharides have been recognised depending on component monosaccharides

A

1) homopolysaccharides
2) heteropolysaccharides
3) congegated polysaccharides

45
Q

what are homopolysaccharides

give examples

A

polysaccharides with only 1 type of monosaccharide in the chain

starch, glycogen, cellulose

46
Q

what is starch

A
  • major form of stored carbohydrates in plant cells
  • identical structure to glycogen BUT lower degree of branching
  • made up of a mixture of amylose and amylopectin
47
Q

what is amylose

A

linear chain of 100s of alpha glucose monomers linked by alpha 1,4 glycosidic bonds

48
Q

what is amylopectin

A

branched molecule
1000s of alpha glucose monomers linked by alpha 1,4 glycosidic bonds
branches = formed by alpha 1,6 glycosidic bonds

49
Q

how is starch digested

A

hydrolysis reaction by amylase
2 step
starch -> maltose -> glucose (by maltase)

50
Q

what is glycogen

A
  • long term energy store in animal cells
  • made primarily by liver + muscles
  • made of alpha glucose monomers linked by alpha 1,4 glycosidic bonds
    branched bc of alpha 1,6 glycosidic bonds
51
Q

what is the structure of glycogen

compare this to amylopectin

A

compact because of coiling of polymer chains (allows large amounts of carbon energy to be stored in small volume with little effect on cellular osmolarity)

more extensively branched with branches 1 in every 10 units (amylopectin = 1 in 30)

52
Q

what is cellulose

A
  • firbous carbohydrate found on all plants
  • thousands of d-glucose sub-units linked by beta 1,4 glycosidic bond
  • unbranched + linear (chains arranged parallel)
  • no coiling or helix formation
53
Q

how is cellulose broken down

A

humans = digestive juice lacks enzymes to hydrolyse glycosidic bond

BUT certain microorganisms make cellulase so can digest it

54
Q

what are derivative carbohydrates

A
  • sugar molecules modified with substitute other than hydroxy groups
  • can contain nitrogen, phosphate + sulphur compounds (glycosaminoglycans, sugar phosphates / acetates)
55
Q

MOST sugar derivatives…

A
  • occur naturally
  • important biological function

(ie chondroitin sulphate - imp structural component of cartilage providing its resistance to compression)

56
Q

what are a number of carbohydrates (large polysaccharides and small oligosaccharides found in association with)

A

molecules other than carbs ie lipids + proteins

carbs with lipids = GLYCOLIPIDS
carbs with proteins = GLYCOPROTEINS

57
Q

what are heteropolysaccharides

A

2+ different monosaccharides linked to form a polysaccharide

USUALLY repeating units of disaccharide
BUT SOMETIMES the polymer has 2 alternating disaccharides

IOE (22 decks)

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