Carbs and Lipid Structure

Question 1

aldoses

Answer 1

carb with an aldehyde group (a carbonyl group attached to an H and R group). aldose sugars have suffix “-ose” ie. glucose

Question 2

ketoses

Answer 2

carb with a ketone group (a carbonyl group bonded to two other carbon atoms). ketoses have the suffix “-ulose” (fructose is an exception since it is actually a ketose)

Question 3

example of a pentose (5 carbon) sugar

Answer 3

ribose

Question 4

Stereoisomers

Answer 4

Have the same chemical formula (ie C6H12O6) but differ in position of the hydroxyl group on one or more of their asymmetric carbons. (different in every other perspective ie different chemical characteristics and recognized by different enzymes). (ie fructose, glucose, mannose and galactose are stereoisomers)

Question 5

Epimers

Answer 5

stereoisomers that differ in the position of the hydroxyl group at only one specific C (ie glucose and galactose are C-4 epimers)

Question 6

What is a significance in epimers?

Answer 6

C4-epimerase is able to change glucose into galactose and back forth. if you have a person with a genetic disorder that does not permit this person to ingest galactose, you don’t have to worry about galactose deficiency, because this person has that enzyme.

Question 7

Which sugars are C4 epimers?

Answer 7

Glucose and galactose

Question 8

Which sugars are C2 epimers?

Answer 8

glucose and mannose

Question 9

enantiomers

Answer 9

mirror images of each other. most sugars in human tissues are in D form.

Question 10

anomeric carbon

Answer 10

is term C1, which is counting down for the non-ring carbon. this is where cyclic sugars mutarotate.

Question 11

glycation

Answer 11

the addition of a single glucose (linear form) to protein via a non-enzymatic reaction in a non-specific manner, which mainly occurs in plasma and interstitial fluids. (clinical note: in chronic hyperglycemia seen in poorly controlled diabietes results in increased levels of glycation on vascular tissues.)

Question 12

Glycosylation

Answer 12

defined as the addition of a polysaccharide or an oligosaccharide (2-10 component sugars), to proteins, lipids, or other organic molecules in an enzymatic related manner. (ie glycolipids and glycoproteins. Glycosylation is a form of co-translational and post-translational modification which occurs in ER and golgi. glycosylations very important in cell-cell recognition.

Question 13

glycation v. glycosylation

Answer 13

gycosylation:
chemical reaction: enzymatic, regulated
sugar unit: glycan (oligo or polysachharides)
location of reaction: ER & Golgi (part of co/post-translational modification.)
Impact on molecule: resulting in functionality.
glacation: non-specific & non-enzymatic, SINGLE LINEAR GLUCOSE, various places where glucose is present, typically reduces the physiological fn

Question 14

oxidation is a loss or gain of elections?

Answer 14

“OIL RIG” oxidation is loss of electrons, reduction is gain of electrons. oxidation is gain O2 and loss H2, and reduction is loss O2 and gain H2

Question 15

oxidize forms of glucose

Answer 15

D-gluconate (anomeric carbon is oxidized)

beta-D-glucoronate (C6 carbon oxidized)

Question 16

what is the significance of oxidized sugars?

Answer 16

Glucuronic acid/glucuronate is commonly conjugated/added onto hydrophobic molecules
in the liver in order to make the molecule more hydrophilic/polar, thus more soluble and
excretable from the body. This conjugation step is called the second phase of drug
metabolism.

Question 17

what are two important biological sugars?

Answer 17

Important biologic acidic sugars include glucuronic

acid (from glucose) and iduronic acid (from galactose). They are negatively charged in physiological pH.

Question 18

reduced sugars

Answer 18

If the aldehyde of a sugar is reduced, all of the carbon atoms contain alcohol (hydroxyl) groups, and the sugar is a polyol (e.g. sorbitol from glucose or galactitol from galactose). If one of the hydroxyl groups is reduced so that the carbon contains only hydrogen, the sugar is a deoxysugar, such as the deoxyribose in DNA.

Question 19

alcohol -> aldehyde = oxidation or reduction?

Answer 19

alcohol -> aldehyde -> acid = oxidation

reverse is reduction

Question 20

Amino and N-acetylated amino sugars

Answer 20

Amino and N-Acetylated amino sugars contain an
amino group substitutes for one of the hydroxyls; an example is glucosamine. The amino group may also be acetylated; an example is N-acetylglucosamine.
• Biological Significance: these amino sugars are
essential components of glycosaminoglycans,
glycolipids and glycoproteins.

Question 21

glucosaminoglycans

Answer 21

linear polymers of repeating disaccharides (50-150 repeats) that form ground substance of extracellular matrix. They are negatively charged at physiologic pH, and give glycosaminoglycans their strongly negative nature and water adsorption. Chondroitin sulfate is an example of glycosaminoglycan. disaccharide unit = [acidic sugar + N-acylated amino sugar]n (n=50-150 units)

Question 22

glycans (and “gly” v. “glu”)

Answer 22

glycans: immediately think oligo or polysaccharides

gly means sugar but not glucose, glu means glucose

Question 23

Disaccharides v. oligosaccharides v. polysaccharides

Answer 23

Disaccharides (2), oligosaccharides (3-12) and polysaccharides (>12)

Question 24

glycosides

Answer 24

glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond.

Question 25

O-linked v. N-linked glycosidic bonds

Answer 25

O-linked: Mostly found in sugar-sugar or sugar-protein attachment e.g. di-, oligo- and polysaccharides, etc.
N-linked: Mostly found in nucleosides and nucleotides e.g. Adenosine triphosphate (ATP)

Question 26

disaccharides

Answer 26

sucrose (glucose - fructose)
lactose (galactose - glucose)
maltose (glucose - glucose)

Question 27

monosaccharides (& disaccharides)

Answer 27

glucose, fructose and galactose

maltose, sucrose and lactose

Question 28

reducing sugar

Answer 28

concept that is related to anomeric carbon. If the –OH group on the anomeric carbon of a sugar
is not attached to any other structure, that sugar is a reducing sugar. Both lactose and maltose are reducing sugars, but sucrose is not. All monosaccharide hexoses are reducing sugars.

Question 29

polysaccharides

Answer 29

common polysaccharides include glycogen (animal origin), starch (plant origin) and cellulose (plant origin). All of which are made of D-glucose only.

Question 30

starch

Answer 30

glucose monomers are linked with each other in two forms: amylose (linear polymer) and amylopectin (branched polymer).

Question 31

amylose

Answer 31

Amylose is an unbranched, single-chain polymer of 500-2000 glucose subunits with
only a-1,4-glycosidic bonds.

Question 32

amylopectin

Answer 32

Amylopectin consists of the linear a-1,4-glucose polymers, as well as branched
a-1,6- ones. In starch, branches occur about every 25 linear residues.

Question 33

cellulose

Answer 33

Cellulose is the most abundant carbohydrate on earth and provides structural integrity for
plants. It is also made of glucose with b(1->4) polymers of glucose. Humans cannot
digest cellulose.

Question 34

glycogen

Answer 34

(an amylopectin only) is more densely branched (every 10-12 residues) compared to a starch amylopectin. One gram of glycogen adsorbs 3 grams of water.

Question 35

physiological functions of carbohydrates

Answer 35

Storage: examples include starch in plants and glycogen in animals
Structure: examples include cellulose and exoskeleton of many insects
Cell recognition: examples include glycocalyx/cell coat, glycoprotiens and glycolipids.

Question 36

non-membrane lipids

Answer 36

fatty acids, triacylglycerols, steroids and cholesterol

Question 37

nomenclature of fatty acids

Answer 37

This naming system consists of the number of carbon atoms followed (after a colon) by the
number of double bonds and the position of the double bond(s). The carboxyl carbon is
number 1. For example, oleic acid has 18 carbons and one double bond, which is located
between positions 9 and 10. Oleic acid is denoted as 18:1(delta)9 or 18:1(9) without the .

Question 38

Omega numbering system of fatty acids

Answer 38

The omega (w) numbering system: fatty acids are also classified by the distance of the
double bond closest to the (omega) end (the methyl group end). For example, oleic acid is an omega-9
fatty acid, linolenic acid is an omega-3 fatty acid, and arachidonic acid is an omega-6 fatty acid

Question 39

dietary essential fatty acids

Answer 39

gamma-linoleic (omega-6) and alpha-linolenic acids (omega-3). We must ingest them because humans can’t synthesize double bonds on fatty acids past
C9 position.

Question 40

gamma-linoleic omega-6 fatty acids

Answer 40

Linoleic (omega-6) is a precursor for
arachidonic acid (C20:4), which is a
major precursor for eicosanoids
synthesis.

Question 41

alpha-linolenic omega-3 fatty acids

Answer 41

Linolenic acid (omega-3) is a precursor of
other omega-3 fatty acids that are important
for growth and development.

Question 42

arachidonic acid

Answer 42

arachidonic acid (C20:4) is a major precursor for eicosanoids (linoleic [omega-6] fatty acid [a dietary essential fatty acid] is the precursor to arachidonic acid)

Question 43

branched fatty acids

Answer 43

example: pytanic acid, contains methyl group on the third carbon (b). Due to the methyl group,
it has to go through alpha-oxidation by a-
hydroxylase.

Question 44

Refsum disease

Answer 44

Refsum disease is caused
by a deficiency in alpha-hydroxylase. This
results in the accumulation of phytanic acid
in the plasma and tissues, causing neuronal damage. (a toe looks like its been moved up)

Question 45

trans fatty acids

Answer 45

Trans fatty acids are formed during the
partial hydrogenation of vegetable oils used in
margarine, Crisco, peanut butter, etc.
-Trans fatty acids are structurally similar to
saturated fatty acids, i.e. they are straight
even though they have a double bond.
-Epidemiological studies (e.g., Nurse’s Health
Study) show a correlation between trans
fatty acids and heart diseases.

Question 46

Triacylglycerols

Answer 46

Triacylglycerols (TAGs), the storage form of fatty acids, are formed by attaching three
fatty acids (as fatty acyl CoA, activated form of fatty acids) to a glycerol backbone. They
are hydrophobic and non-polar.

Question 47

steroids and cholesterol esters

Answer 47

Steroids and Cholesterol esters:
-Steroids (animal and plant origins) have a tetracyclic ring structure. Animal steroids are
derived from cholesterol.
-When the polar group of cholesterol is esterified to a fatty acid, it is referred to as a
cholesterol ester. Cholesterol ester is a nonpolar molecule.

Question 48

cholesterol esters

Answer 48

-When the polar group of cholesterol is esterified to a fatty acid, it is referred to as a
cholesterol ester. Cholesterol ester is an extremely nonpolar molecule. This is a storage form of cholesterol.