lecture 5

Question 1

what are the fundamental structural features of carbohydrates?

Answer 1

basic structure is the monosaccharide, with Oligo- meaning a few, usually 2 to 10 and Poly being polymers of the simple of the simple sugars. Sugars end in”-ose” and are in the D-config in our bodies, maintained by isomerase; keep in mind stereochemistry in the D,L configuration

Question 2

D/L designates what?

Answer 2

how the constituents are formed around the chiral carbon; when referring to sugars, especially the D config pay attention to the -OH group because these will be found on the right, on the fifth carbon marking it in the D config

Question 3

whats the difference between galactose and glucose?

Answer 3

the 4th carbon, the body uses glucose for glycolysis and galactose doesn’t because no enzymes

Question 4

what is significant about ketone?

Answer 4

dihydroxyacetone has no chirality, though it is important because it is a glycolytic intermediate, important for ketone bodies, mitochondria function

Question 5

whats the difference between glucose and fructose?

Answer 5

glucose is aldose and fructose is a ketose

Question 6

why can liner glucose molecules form a cyclical structure?

Answer 6

carbonyl group and OH group allow for covalent bonding to happen becoming a cyclic structure

Question 7

how do aldoses and ketoses generally present?

Answer 7

cyclical

Question 8

what is the common cyclic form of aldose?

Answer 8

pyranose preferred (ring strain), can also be a furanose

Question 9

what is the common cyclic form of ketoses?

Answer 9

furanose preferred (ring strain), can also be a pyranose

Question 10

what is the anomeric carbon for aldo-carbohydrate molecules?

Answer 10

carbon 1 because once the ring is formed depending on whether the -OH group from carbon 5 attacks will determine whether it is in the Beta or alpha form forming tetrahedral geometry

Question 11

what is meant when a carbohydrate adopts the alpha form?Beta form?

Answer 11

if -OH is bottom is down, alpha; -OH up is beta; these can always form and break and can do so as long as you have the -OH group

Question 12

keep in mind that when glucose undergoes metabolism we will glucose being phosphorylated in which position?for glycogen?

Answer 12

carbon 6; carbon 1

Question 13

what is the anomeric carbon for the linear structure of ketoses?

Answer 13

carbon 2, anomeric carbon in relation with carbohydrates starts with the carbonyl carbon; keep in mind same concept when determining alpha vs beta configurations

Question 14

sugar that have aldehydes are reactive, T/F?

Answer 14

true, because the oxygen attached to the carbonyl is drawing more electronegativity and so this means the hydrogen can be easily lost, so once lost the remaining electrons are going to want to react, so aldehyde is going to want to reduce

Question 15

what does reduce mean?

Answer 15

gain electrons and losing is oxidized

Question 16

what is a reducing sugar?

Answer 16

a sugar that is reducing means it can reduce something, i.e.- glucose test, take blood and use chemicals using copper based reaction in which glucose in aldehyde form could react with the copper which in turn could steal an electron, picking up an oxygen to make Cu2O, but in the process the sugar is oxidized and use it to compare to scale to determine blood glucose

Question 17

remember sugars are reducing in linear form, why?,

Answer 17

it can’t be cyclical because you need the aldehyde which provides the electron withdrawing power of the oxygen that causes the loss of the hydrogen; also in the cyclical form the electrons are tied up in covalent bonds

Question 18

ketones are reducing sugars, T/F? defend your answer

Answer 18

F, they ketone carbonyls but they are not aldehydes therefore they can’t participate in oxidation reduction reactions.

Question 19

recall that we said that we can form and reform between cyclical and linear glucose structures when is this not the case?

Answer 19

as long as you have the -OH you form and reform double bonds but as soon as you put any other atom on there besides the hydrogen you lose the ability to make the double bonded oxygen you develop a glycosidic bond. So when you replace the hydrogen bonded to the oxygen at the anomeric carbon formed from the attack of carbon 5 to carbon 1 methylation occurs and the structure becomes fixed

Question 20

if you have a phosphate on carbon 6, would this be a glycosidic bond?

Answer 20

no, because a glycosidic bond is defined as being on the anomeric carbon, specific

Question 21

If you were asked a question about, say, the top left structure, the question would let you know that you were looking at a glucose molecule, and it might ask you if it is alpha or beta, or what number carbon has the phosphate, or what the name of the molecule would be (knowing the glucose part, you can say alpha-D-glucose 1 phosphate).

Answer 21

refer to word document

Question 22

what are UDP-Glucuronate and Glucuronides?

Answer 22

function to aid in the excretion of non polar substances; keep in mind that when a carbon goes from an -OH, to an aldehyde to carboxylic acid we become more oxidized. Lots of hydrophobic molecules in the body that need to be rid of and so the liver oxidizes glucose creating a glucuronate and attaches to the hydrophobic molecule (-OH containing compounds) to become water soluble and then excreted from the body

Question 23

the difference between -OH and -COOH with respect to being placed on sugars?

Answer 23

is that the carboxylic acid is more polar the more soluble it is

Question 24

name another example of how glucuronate functions?

Answer 24

bilirubin (breakdown product of heme) very non polar because of the carbons and when attach gluronate to produce glucronide you increase solubility of the molecule and can now be released. This is related to jaundice, when people have trouble clearing hemoglobin and the bilirubin accumulate

Question 25

A good example in talking about reduced sugars is sorbitol, explain how sorbitol is produced?

Answer 25

you reduce the aldehyde on glucose from a C=O double bond to -OH and because of this, you can no longer form the ing structure, the name of the molecule becomes sorbitol; because its not real glucose it isn’t readily used in glycolysis and so it becomes excreted

Question 26

what is the prime difference between glucose and galactose?

Answer 26

the position of the -OH on carbon number 4

Question 27

carbonyl group reacted with an amine produces?

Answer 27

amide, we see these when sugars like glucosamine and galactosamine are acetylated.

Question 28

why are acetylated amino sugars important?

Answer 28

adding additional atoms changing shape, polarity and geometry of the structure producing different sugars

Question 29

what do we need to know about the common amino sugar disaccharides, like chondroitin-4-sulfate, heparin, etc…

Answer 29

they are highly substituted and very polar; these are glycosaminoglycans using N-acetylated glucose and galactose sugars

Question 30

what are some common dietary disaccharides?

Answer 30

lactose, maltose, sucrose, cellobiose, isomaltose

Question 31

what comprises lactose?

Answer 31

galactose and glucose, beta 1,4

Question 32

what comprises sucrose?

Answer 32

glucose and fructose, alpha 1,2

Question 33

what comprises maltose?

Answer 33

2 glucose alpha 1,4

Question 34

what comprises cellobiose?

Answer 34

glucose and glucose, beta 1,4

Question 35

what comprises isomaltose?

Answer 35

2 glucose, alpha 1,6

Question 36

what happens when you have a diet heavy in monosaccharides?

Answer 36

bath cells in these sugars and sucked up rapidly and increasing BGL rapidly as oppose to ingesting disaccharides like fruits and vegetables

Question 37

what are starch and glycogen considered?

Answer 37

storage molecules

Question 38

starch is stored by?

Answer 38

plants

Question 39

glycogen is stored by?

Answer 39

animals

Question 40

what are two forms of starch stored by plants?

Answer 40

amylose (linear, 10-30%) and amylopectin (branched 70-90%)

Question 41

where can you find glycogen reserves?

Answer 41

liver(10%) and muscle(1-2%), similar to amylopectin

Question 42

what is cellulose?

Answer 42

most abundant polymer on earth and support of trees and plants connect by a beta 1,4 linkages not alpha like in glucose; strands form extended ribbons (zigzag like and not spiral like in glycogen) and we cannot break these down because we do not have the enzymes to break them down