Lecture 4: Carbohydrates Flashcards
simplest carbohydrates are small, monomeric
molecules—
the monosaccharides
how many monosaccharides are in oligosaccharides
2-10
true or false: maltose is a disaccharide
true
what are polysaccharides
long polymers of monosaccharides
oligosaccharides and polysaccharides are also referred to as __
glycans
Carbohydrates are represented by a stoichiometric formula ____
(CH2O)n
Carbohydrates are named that way bc ___
chemists knew
only the stoichiometry of saccharides and thought of
them as “hydrated carbon.”
what is the major energy cycle of life
photosynthesis and respiration
write the photosynthesis and respiration equation
check notes
the term ____ is reserved for compounds with the (CH2O)n empirical
formula,
carbohydrate
the term ___ covers both these
compounds and all derivatives of carbohydrates
saccharide
The term ____ generally refers to underivatized
monosaccharides and small oligosaccharides
sugar
Sucrose is a disaccharide containing: ___ and __
glucose and fructose
List carbohydrates roles (7)
- energy storage and generation
- molecular recognition
- cellular protection
- cell signalling
- cell adhesion
- biological lubrication
- protein trafficking
How does carbohyadrate molecular recognition work?
*check ntbk notes
How does carbohyadrate Cellular protection work?
*check ntbk notes
How does carbohyadrate Cellular signalling work?
*check ntbk notes
How does carbohyadrate Cellular adhesion work?
*check ntbk notes
How does carbohyadrate biological lubrication work?
*check ntbk notes
How does carbohyadrate protein trafficking work?
*check ntbk notes
the smallest monosaccharide is ___ with n=3
triose
Monosaccharides are generally characterized by the presence
of _____ and one or more
hydroxyl groups.
one carbonyl group (aldehyde or ketone)
What are the two trioses? what are their difference? Whats the relationship between the two?
There are two trioses: glyceraldehyde and dihydroxyacetone;
one is an aldose, the other is a ketose. They are tautomers
Whats the other name for glyceraldehyde and dihydroxyacetone
aldotriose
and ketotriose,
what are enantiomers?
nonsuperimposable mirror images
The most compact way to represent enantiomers is to use a ___
Fischer
projection.
the terms d and l were meant to indicate the ______ of polarized light: d for __),
l for __).
direction of rotation
of the plane of polarization; dextro-right; levo-left
List the disadvantages of D-L writing system
- 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.
What is the other proposed convention for writing enantiomers?
R-S nomenclature ; Cahn-Ingold-Prelog System
What is the hierarchy for prioritization in R-S nomenclature
SH 7 OR 7 OH 7 NH2 7 CO2H 7 CHO 7 CH2OH 7
CH3 7 H. ;;7=>
R is when it is ___; S is when it is ___
clockwise; counterclockwise
What are diastereomers?
they have more than 1 chiral carbon
What are tetroses?
they with the empirical formula (CH2O)4, have two chiral carbons
in the aldose
In general, a molecule with n chiral centers
will have __ stereoisomers
2^n
The prefix d or l is used to designate the orientation about
the chiral carbon __ from the carbonyl group
farthest
What are the tetrose sugars?
erhythrose and threrose (aldose); erythrulose (ketose)
how many chiral centers does aldotetrose have
2
how many chiral centers does ketotetrose have
1
how many chiral centers does ketopentrose have
2
how many chiral centers does aldopentrose have
3
Draw all of the structures, from tetroses to hexoses. both aldose and ketose
check notes
___ is a 5 membered ring structure derived from the reaction of C-1 of D-ribose and C-4 hydroxyl
furanose
furanose is similar with ___
furan
__ is if C-1 reacts with the C-5 hydroxyl. it is a 6-membered ring
pyranose
pyranose is similar with ___
pyran
What influences for the monomers to form which type of ring?
- depends on the particular sugar structure,
- pH
- solvent
- temperature
- if incorporated w polysaccharides, it might be influenced
Cyclization has created a new asymmetric center at carbon __
1
What are anomers?
differing in configuration
only at the carbonyl carbon
What is the process that The monosaccharides
can undergo interconversion between the a and b forms, using the
open-chain structure as an intermediate.
mutarotation
What are conformational isomers?
interchange by a simple deformation of the molecule.
What are configurational isomers ?
can interconvert only through the breaking and re-formation of covalent bonds.
True or false: In general, hexoses prefer funarnose than pyranose
hexoses prefer the pyranose ring structure when in aqueous solution.
What are epimers?
only differs at one C atom
What C atom are glucose and mannose differ?
C2
What C atom are glucose and galactose differ?
C4
What is the role of that one heptose?
Sedoheptulose plays a major role in the fixation
of CO2 in photosynthesis
