carbs 1

Question 1

what is energy from the sun stored as in chemical energy ?

Answer 1

carbohydrates

Question 2

what are carbohydrates metabolic precursors for ?

Answer 2

most biomolecules

Question 3

what does the breakdown of carbohydrates result in ?

Answer 3

it provides the energy that sustains animal life

Question 4

how come carbohydrates have a structural function ?

Answer 4

ribose and deoxyribose are vital components of RNA and DNA.

Also the polysaccarides ( carbohydrates) are the major structural protein of cell walls for plants and bacteria.

Cellulose is also found in plant cell walls and gives stability as we cannot digest it.

Question 5

what is chitin a main structural component of ?

Answer 5

the exoskeletons found on crustaceans , insects and spiders

Question 6

what are hyaluronates important for ?

Answer 6

important for the vitreous humour of eyes ( transparent lining ) , as well as synovial fluid and cartilage

Question 7

where are chondroitans and collagen found ?

Answer 7

in tendons , cartlidge and connective tissue

Question 8

what is dermatan sulfate a component of ?

Answer 8

the extracellular skin matrix

Question 9

what are glycoproteins ?

Answer 9

these are proteins that have a carbohydrate covalently attached.

Question 10

why are glycoproteins important ?

Answer 10

they are used in cell recognition and cel adhesion.

Question 11

how come the carbohydrate part of a glycoprotein is vital for infection of a cell ?

Answer 11

the virus uses it to bind to the cell

Question 12

what is a carbohydrate made up of and what is it formula ?

Answer 12

glucose C6H1206

Question 13

How many carbons must the simplest carbohydrate have ?

Answer 13

3

Question 14

what 2 molecules can be descried as being a carbohydrate ?

Answer 14

polyhyroxyl ketone

polyhydroxyl aldehyde

Question 15

what is an aldehyde and what is produced if it is oxidised ?

Answer 15

this is a hydrocarbon that has a carbonyl at the end ,the carbonyl group is bonded to at least one hydrogen. it is oxidised to produce an acid

Question 16

what is a ketone ?

Answer 16

this is a hydrocarbon that has a carbonyl group in the middle which is bonded to 2 carbon atoms

Question 17

what are simple carbohydrates and give examples ?

Answer 17

this is when the monomers cannot be hydrolysed to produced smaller carbohydrates as they are sugars , i.e ribose , glucose , fructose.

Question 18

what are these simple carbohydrates called ?

Answer 18

monosaccarides

Question 19

how do you name these simple monosaccharides ?

Answer 19

they are given the suffix -ose
the prefic aldo or keto is used
the prefix describes the number of carbons

Question 20

what are complex carbohydrates ?

Answer 20

these consist of 2 or more monosaccarides that are joined by a covalent bond ( glycosidic linkage)

Question 21

disaccarides hydrolyse to produce ?

Answer 21

2 monosachharodes

Question 22

trisaccardies hydrolyse to produce ?

Answer 22

3 monosachharides

Question 23

how many monosaccharides do oligosaccharides contain ?

Answer 23

between 2-10

Question 24

how many monosaccharides do polysaccharides contain ?

Answer 24

a large number , thousands

Question 25

what is a stereocentre and do carbohydrates contain them ?

Answer 25

yes all carbs contain them , this is a carbon atom that has 4 different groups attached so there is no plane of symmetry

Question 26

what are stereoisomer ?

Answer 26

this is when molecules have the same molecular formula and bond conifuragation but they differ in the position of atoms.

Question 27

if you are converting between 2 configurations then what does this require ?

Answer 27

covalent bonds to be broken and reformed | can also be achieved by rotation

Question 28

what are stereoisomer either ?

Answer 28

an enantiomer or diastereoisomer

Question 29

what are enantiomers ?

Answer 29

pairs of molecules that are non super imposable mirror images. they have identical physical and chemical properties but differ in biological properties

Question 30

how do enantiomers interact with plane polarised light?

Answer 30

they rotate it in opposite directions in equal amounts

Question 31

what is thalidomide a good example of ?

Answer 31

how enantiomers have different biological properties. The R form of thalidomide helps reduce morning sickness however the S form causes birth defects. The R and S describe stereocentres.

Question 32

if a molecule is chiral can it be superimposed ?

Answer 32

nope

Question 33

what does optically active mean ?

Answer 33

if a molecule rotates plane polarised light in opposite directions. Therefore enantiomers are optically active.

Question 34

what is the specific rotation [a]D a quantitive measure of ?

Answer 34

optical activity

Question 35

from this what can the molecules be grouped as ?

Answer 35

dextroroatory ( +) | levorotatory ( -)

Question 36

what are diastereoisomers ?

Answer 36

theses are pair of molecules that are not mirror images , they have different physical properties and different but similar chemical properties

Question 37

what method is the standard to show the stereocentres in 2D?

Answer 37

fisher projections

Question 38

how do you differentiate between L and D fischer projections ?

Answer 38

if OH on highest numbered stereocentre is on left then L but if oH on right then D

Question 39

whats the most abundant monnosacharide ?

Answer 39

D-

Question 40

how do you work out the possible number of stereoisomers ?

Answer 40

2*(N-2) where N is the number of carbons

Question 41

what is the most common aldose ?

Answer 41

hexose

Question 42

what is an epimer ?

Answer 42

this is when a pair of sugars differ in configuration at only one carbon

Question 43

whats most common aldoses or ketoses ?

Answer 43

aldoses

Question 44

what does cyclisation of glucose result in ?

Answer 44

this creates a cyclic hemiacetal. there is 2 forms as a new stereocentre is created at C1 . Theres a a-D-glucopyranose ( OH below) and a B-D-glucopyranose (OH above)

Question 45

what are the 2 cyclic forms called and are they diastereoisomers or enantomers ?

Answer 45

they are both anomers and are diastereoisomer ( not mirror images)

Question 46

Why does glucose have unexpected properties ?

Answer 46

the formation of cyclic hemiacetal resulted in there being no free aldehyde group

Question 47

what does glucose normally exist as ?

Answer 47

a six membered cyclic hemiacetal

Question 48

what are the 6 membered sugar rings called ?

Answer 48

pyranoses

Question 49

pyranose rings can adopt a boat or chair form. These forms are not flat ( planar) , so how are they described ?

Answer 49

they are puckered

Question 50

between the boat and the chair form , what has the lowest energy arrangement ?

Answer 50

The chair form

Question 51

what determines the stability of each confirmation ?

Answer 51

the hydrogen atoms

Question 52

how are cyclic hemiacetals often drawn ?

Answer 52

as haworth projections

Question 53

what is the ether oxygen ?

Answer 53

the oxygen in the upper right

Question 54

what is the anomeric carbon ?

Answer 54

the carbon on the right vertex

Question 55

on converting a fisher projection to a haworth , how are the OH on the right drawn ?

Answer 55

OH are down in haworth

Question 56

OH on left in fischer , how in haworth ?

Answer 56

OH face up in haworth

Question 57

what is the CH2OH group in haworth for D monosaccharides?

Answer 57

they face up

Question 58

what are furanoses ?

Answer 58

theses are 5 membered sugar rings

Question 59

what mainly gives pyranose forms ?

Answer 59

aldohexoses and aldopentoses

Question 60

what does ketohexoses mainly form ?

Answer 60

a mixture of pyransoes and furanoses

Question 61

what rings are the most stable and why ?

Answer 61

5 and 6 membered rings as they have the strongest bonding.

Question 62

what is mutarotation and why does it occur ?

Answer 62

this is when there is a change in the optical rotation because there is a change in the equilibrium between the 2 anomers. Caused by a reversible ring opening of cyclic hemiacetal to an open chain which then recloses.

Question 63

what is mutaroation accelerated by ?

Answer 63

acids and bases

Question 64

why does the boat form have the highest energy ?

Answer 64

it is a result of the hydrogen - hydrogen repulsions

Question 65

are cyclohexane rings rigid and what does this lead to ?

Answer 65

no they can flip between 2 chair forms which is called ring flipping

Question 66

what occurs during ring flipping ?

Answer 66

the equatorial positions become axial and the axial positions become equatorial

Question 67

during ring flipping is there a lot of bonds breaking and reforming ?

Answer 67

no just a lot of rotating of atoms

Question 68

the 2 chair forms exist in equilibrium however , what will exist in the greatest amount ?

Answer 68

the form with the lowest energy

Question 69

what repulsions are most significant ?

Answer 69

repulsions between axial substituents

Question 70

what chair form is said to be most stable ?

Answer 70

the chair form with the fewest bulky axial substituents

Question 71

what conformation of b-D- glucopyranose is said to be most stable ?

Answer 71

the conformation with the all equatorial

Question 72

between a-D-glucopyranose and B-D-glucopyranoses what one is most abundant and why ?

Answer 72

B -D-glucopyranose as it is most stable

Question 73

what is the anomeric effect ?

Answer 73

this is the preference for the A anomer. It is a stabilizing electronic effect as the oxygen lone pair is trans coplanar to a C-X bond.

Question 74

what can the anomeric effect often result in ?

Answer 74

electronegative substituents forming axial e.g a halogen

Question 75

what is the arrangment of the furanose ring ?

Answer 75

it is also puckered as it isnt flat. It takes an evelope conformation as the four atoms are coplanar while the fifth atom is out of the ring plane.

Question 76

the ribose rings in nucleic acids are puckered , why is this ?

Answer 76

it relieves the ring strain caused by the 5 atoms being in the same plane . By having C3 . out the plan it reduces the strain

Question 77

are the ribose rings furanoses or pyransoes

Answer 77

furanoses