Chapter 7 Flashcards
Describe Fischer vs Haworth projections. draw one of each
Fischer projections are particularly useful when dealing with linear structures (i.e., sugars in their open-chain form).
Haworth projections are commonly used to represent the cyclic form of monosaccharides (sugars) that are in solution
- Right side of fisher= bottom of Haworth!!
Describe Aldose vs Ketose
An aldose is a monosaccharide that contains an aldehyde group (-CHO) as its functional group. The aldehyde group is located at the end of the carbon chain.
A ketose is a monosaccharide that contains a ketone group (C=O) as its functional group. The ketone group is located at an internal carbon (not at the end of the molecule), specifically on carbon 2 in the open-chain form.
draw the 5 and 6 carbons sugars on slide 9 of the chapter 7 power point
CHECK ON SLIDES
Define anomeric carbon
The anomeric carbon is a specific carbon atom in a cyclic monosaccharide that is involved in the formation of a cyclic hemiacetal (in aldoses) or hemiketal (in ketoses). It is the carbon that was originally part of the carbonyl group (aldehyde or ketone) in the open-chain form of the sugar, and it becomes a new chiral center upon cyclization.
Describe a reducing vs nonreducing carbon
refer to whether a sugar (or a part of a sugar molecule) can participate in a redox reaction (reduction/oxidation). This property is largely determined by the presence of a free aldehyde group (in aldoses) or a free ketone group (in ketoses), which can be oxidized
A reducing sugar is a sugar that has a free aldehyde group (or sometimes a free ketone group) in its open-chain form
A nonreducing sugar is a sugar that does not have a free aldehyde or ketone group available for oxidation because the anomeric carbon is involved in a glycosidic bond with another sugar
Describe the steps of Extrapolating Fischer projections to circular structures: Haworth perspective formula
1) Draw the six membered ring (5 carbons and one oxygen in upper right corner)
2) Number the carbons in a clockwise direction beginning with the anomeric carbon
3) Then place the hydroxyl (OH) group. If it’s to the right in the Fischer projection then it is pointing down (i.e. below the plane of the ring), if left, it’s pointing upward. Once placed, if it’s on the same side of the ring as C-6 then its beta; if opposite then it’s alpha
4) The –CH2OH group projects upward for the D enantiomer, downward for the L enantiomer
What does oxidation of carbonyl carbon in aldoses produce
Aldonic acids
What does Oxidation of the C-6 carbon lead to
Production of the corresponding uronic acid.
What does Oxidation to produce aldonic acids depend on?
The linear form, can’t linearize if involved in glycosidic bond
How are disaccharides formed?
Through O-glycosidic bonds
What are the most important storage polysaccharides for plant cells?
starch
What are the most important storage polysaccharides for animal cells?
glycogen
Why would we not store glucose in its monomeric form?
The polysaccharide form allows you to break the bonds to access energy more effectively. It also has branched form, so you can strat cleavage in multiple locations.
What defines the
difference on whether the
glucose polysaccharide gets
used for energy storage or
structural aspects?
Energy storage polysaccharides like glycogen and starch are highly branched to allow rapid mobilization of glucose when energy is needed.
The branches increase the surface area, making it easier for enzymes to access and break down the polymer.
In contrast, structural polysaccharides like cellulose have linear or slightly branched chains that stack together in an organized manner, creating strong and rigid fibers. This provides mechanical strength and resistance to degradation, suitable for structural support in cell walls and exoskeletons.
Polysaccharides also form
________ with other
macromolecules
conjugates
Aside from being energy storage or structural components, they provide and “transmit” information
What are the ways glycoconjugates are formed?
N-linked glycosylation is when a
glycan is attached to a protein
via recognition of a motif. The
motif is Asparagine-X-Serine/Threonine where X is any
amino acid except proline. The
glycan is specifically connected
to the nitrogen atom of the
asparagine in this motif.
O linked glycosolation of a
protein occurs when the sugar is
attached to the oxygen molecule
of serine or threonine
What is a glycoconjugate?
A glycoconjugate is a molecule that consists of a carbohydrate (sugar) covalently attached to another biomolecule, such as protein, lipid, or nucleic acid. The carbohydrate component in a glycoconjugate typically plays a key role in the molecule’s function, such as in cell recognition, signaling, and immune responses.
What are the types of glycoconjugates
- Glycoproteins:
Proteins that have one or more carbohydrate chains (oligosaccharides) covalently attached to their amino acid side chains. - Glycolipids:
Lipids that have one or more carbohydrate chains attached to a lipid molecule. - Glycoaminoglycans (GAGS):
Long, unbranched polysaccharide chains composed of repeating disaccharide units, often containing amino sugars and uronic acid. They are often attached to proteins to form proteoglycans, which are important components of the extracellular matrix.
How does bond type affect whether something is used for storage vs structure.
α-1,4-Glycosidic Bond:
α-1,6-Glycosidic Bond
Storage Polysaccharides. The α-1,4-glycosidic bonds form helical structures, which allow the polysaccharides to be compact and easy to store, while α-1,6-glycosidic bonds create branches that increase the surface area for enzymatic attack
β-1,4-Glycosidic Bond:
tructural polysaccharides provide rigidity and support in cell walls and other structures. β-1,4-glycosidic bonds form straight, linear chains that can hydrogen bond with other chains to form strong fibers.
Draw the structures of:
- D-glyceraldehyde
- D-erythrose
- D-Ribose
- D-arabinose
- D-xylose
- D-Galactose
- D-Mannose
- D-Glucose
look on slides
