Lecture 4: Carbohydrates

Question 1

simplest carbohydrates are small, monomeric

molecules—

Answer 1

the monosaccharides

Question 2

how many monosaccharides are in oligosaccharides

Answer 2

2-10

Question 3

true or false: maltose is a disaccharide

Answer 3

true

Question 4

what are polysaccharides

Answer 4

long polymers of monosaccharides

Question 5

oligosaccharides and polysaccharides are also referred to as __

Answer 5

glycans

Question 6

Carbohydrates are represented by a stoichiometric formula ____

Answer 6

(CH2O)n

Question 7

Carbohydrates are named that way bc ___

Answer 7

chemists knew
only the stoichiometry of saccharides and thought of
them as “hydrated carbon.”

Question 8

what is the major energy cycle of life

Answer 8

photosynthesis and respiration

Question 9

write the photosynthesis and respiration equation

Answer 9

check notes

Question 10

the term ____ is reserved for compounds with the (CH2O)n empirical
formula,

Answer 10

carbohydrate

Question 11

the term ___ covers both these

compounds and all derivatives of carbohydrates

Answer 11

saccharide

Question 12

The term ____ generally refers to underivatized

monosaccharides and small oligosaccharides

Answer 12

sugar

Question 13

Sucrose is a disaccharide containing: ___ and __

Answer 13

glucose and fructose

Question 14

List carbohydrates roles (7)

Answer 14

• energy storage and generation
• molecular recognition
• cellular protection
• cell signalling
• cell adhesion
• biological lubrication
• protein trafficking

Question 15

How does carbohyadrate molecular recognition work?

Answer 15

*check ntbk notes

Question 16

How does carbohyadrate Cellular protection work?

Answer 16

*check ntbk notes

Question 17

How does carbohyadrate Cellular signalling work?

Answer 17

*check ntbk notes

Question 18

How does carbohyadrate Cellular adhesion work?

Answer 18

*check ntbk notes

Question 19

How does carbohyadrate biological lubrication work?

Answer 19

*check ntbk notes

Question 20

How does carbohyadrate protein trafficking work?

Answer 20

*check ntbk notes

Question 21

the smallest monosaccharide is ___ with n=3

Answer 21

triose

Question 22

Monosaccharides are generally characterized by the presence
of _____ and one or more
hydroxyl groups.

Answer 22

one carbonyl group (aldehyde or ketone)

Question 23

What are the two trioses? what are their difference? Whats the relationship between the two?

Answer 23

There are two trioses: glyceraldehyde and dihydroxyacetone;

one is an aldose, the other is a ketose. They are tautomers

Question 24

Whats the other name for glyceraldehyde and dihydroxyacetone

Answer 24

aldotriose

and ketotriose,

Question 25

what are enantiomers?

Answer 25

nonsuperimposable mirror images

Question 26

The most compact way to represent enantiomers is to use a ___

Answer 26

Fischer | projection.

Question 27

the terms d and l were meant to indicate the ______ of polarized light: d for __), l for __).

Answer 27

direction of rotation | of the plane of polarization; dextro-right; levo-left

Question 28

List the disadvantages of D-L writing system

Answer 28

- this correspondence does not always hold because the magnitude and even the direction of optical rotation are a complicated function of the electronic structure surrounding the chiral center - it is not absolute; the designation is always with respect to some reference compound.

Question 29

What is the other proposed convention for writing enantiomers?

Answer 29

R-S nomenclature ; Cahn-Ingold-Prelog System

Question 30

What is the hierarchy for prioritization in R-S nomenclature

Answer 30

SH 7 OR 7 OH 7 NH2 7 CO2H 7 CHO 7 CH2OH 7 | CH3 7 H. ;;7=>

Question 31

R is when it is ___; S is when it is ___

Answer 31

clockwise; counterclockwise

Question 32

What are diastereomers?

Answer 32

they have more than 1 chiral carbon

Question 33

What are tetroses?

Answer 33

they with the empirical formula (CH2O)4, have two chiral carbons in the aldose

Question 34

In general, a molecule with n chiral centers | will have __ stereoisomers

Answer 34

2^n

Question 35

The prefix d or l is used to designate the orientation about | the chiral carbon __ from the carbonyl group

Answer 35

farthest

Question 36

What are the tetrose sugars?

Answer 36

erhythrose and threrose (aldose); erythrulose (ketose)

Question 37

how many chiral centers does aldotetrose have

Answer 37

2

Question 38

how many chiral centers does ketotetrose have

Answer 38

1

Question 39

how many chiral centers does ketopentrose have

Answer 39

2

Question 40

how many chiral centers does aldopentrose have

Answer 40

3

Question 41

Draw all of the structures, from tetroses to hexoses. both aldose and ketose

Answer 41

check notes

Question 42

___ is a 5 membered ring structure derived from the reaction of C-1 of D-ribose and C-4 hydroxyl

Answer 42

furanose

Question 43

furanose is similar with ___

Answer 43

furan

Question 44

__ is if C-1 reacts with the C-5 hydroxyl. it is a 6-membered ring

Answer 44

pyranose

Question 45

pyranose is similar with ___

Answer 45

pyran

Question 46

What influences for the monomers to form which type of ring?

Answer 46

- depends on the particular sugar structure, - pH - solvent - temperature - if incorporated w polysaccharides, it might be influenced

Question 47

Cyclization has created a new asymmetric center at carbon __

Answer 47

1

Question 48

What are anomers?

Answer 48

differing in configuration | only at the carbonyl carbon

Question 49

What is the process that The monosaccharides can undergo interconversion between the a and b forms, using the open-chain structure as an intermediate.

Answer 49

mutarotation

Question 50

What are conformational isomers?

Answer 50

interchange by a simple deformation of the molecule.

Question 51

What are configurational isomers ?

Answer 51

can interconvert only through the breaking and re-formation of covalent bonds.

Question 52

True or false: In general, hexoses prefer funarnose than pyranose

Answer 52

hexoses prefer the pyranose ring structure when in aqueous solution.

Question 53

What are epimers?

Answer 53

only differs at one C atom

Question 54

What C atom are glucose and mannose differ?

Answer 54

C2

Question 55

What C atom are glucose and galactose differ?

Answer 55

C4

Question 56

What is the role of that one heptose?

Answer 56

Sedoheptulose plays a major role in the fixation | of CO2 in photosynthesis