Chapter 5, Carbohydrates Flashcards
What are the 3 elements that are most commonly found in carbohydrates
Hydrogen, Carbon, Oxygen
What is the general term for the monomers of carbohydrates
Monosaccharides
What is the general term for the polymers of carbohydrates
Polysaccharides (more than two monosaccharides)
What are the major functions of carbohydrates?
To serve as a short-term energy/fuel
Building materials (cellulose/cotton)
Cell identity markers
What is the stoichiometric formula for monosaccharides?
(CH2O)n, where n is equal to the number of carbons
What is the most common monosaccharide
Glucose
What functional groups and bonds do monosaccharides have?
CarbonYL groups, hydroxyl groups and carbon-hydrogen bonds
Since the two functional groups are polar, are carbohydrates polar
Yes, they are hydrophilic (Polar)
There are many types of monosaccharides, how do you classify/identify them?
Each has a unique structure and function
Classified by the position of the functional group and the number of carbons
There are also two subtypes of monosaccharides, aldose sugars and ketone sugars.
How does one determine the subtype of monosaccharides?
Aldose sugars have an aldehyde group, located at the end of the carbon chain.
Ketone sugars have a ketone group in the middle of the carbon chain, with NO ALDEHYDES attached.
What do you call isomers with the same chemical formula, but different shapes/connectivity?
Constitutional (structural) Isomers, such as C3H6O3,
They can be an aldose sugar or ketose sugar
Glucose and Galactose are both monosaccharides with the same chemical formula and connectivity. what is the difference?
Glucose and Galactose are Enantiomers. The 4’ Carbon is a chiral (asymmetric) carbon, in which the carbon can have 4 groups that can be attached and the groups can have alternative positions.
Glucose has an OH facing away from the plane as the CH2OH/Oxygen (ester) ring while Galactose has the OH on the same plane as the CH2OH/Oxygen (ester) ring on the 4’ Carbon.
What happens to the linear structure of sugars when in contact with water?
Sugars form a ring between the 5’ carbon containing an OH and the 1’ carbon
This is an ester bond between 5’ and 1’ carbon creating a ring.
What is the difference between α-glucose and β-glucose
Alpha-Glucose = OH group A-way from the plane of the oxygen or CH2-OH group on 1’ Carbon
Beta-Glucose= OH is B-eside from the plane of the oxygen or CH2OH group 1’ Carbon
Summary of α-glucose and β-glucose and Galactose
α-glucose and β-glucose have the 1’ carbon OH groups flipped one or the other
Galactose and Glucose have the 4’ carbon OH group flipped to one of the other.
BOTH α-glucose and β-glucose HAVE THE SAME 4’ carbon OH GROUP IN THE SAME ORIENTATION, while galactose has it flipped
List 4 four ways that monosaccharicdes can vary
of carbons
Enantiomers
Aldose sugars
Ketose Sugars
# of carbons
(both aldose and ketose are constitutional (structural) Isomers)
How do monosaccharides polymerize? What bond is created between the two monosaccharides?
Just like other polymers, they undergo dehydration synthesis or condensation reaction between the two hydroxyl group
The bond is a covalent bond, called a glycosidic bond (3 types)
What do you call two monosaccharides linked together?
a Disaccharide(s)
What are the 3 disaccharides?
Surcose (Glucose + Fructose)
Lactose (Galactose + Glucose)
Maltose (Glucose + Glucose)
Can glycosidic linkage form between any two hydroxyl groups? If so, what are the two most common linkages
Yes, they can. The two most common linkages are α-glycosidic linkage and β-glycosidic linkage
More specifically:
α-1,4-glycosidic linkage
β-1,4-glycosidic linkage
α -1,6-glycosidic linkage
What is the difference between these linkages and why is it important?
α-1,4-glycosidic linkage is more closely associated with energy storage.
β-1,4-glycosidic linkage is more closely associated with structure (cellulose)
α-1,4-glycosidic linkage allows for disaccharides to begin chaining horizontally, while α -1,6-glycosidic linkage allows for branching away from the centre of the chain (vertically)
How do plants store sugar vs how do animals store sugar?
Plants store sugar as starch
Animals store sugar as glycogen
Both have more energy than CO2, electrons in C-H and C-C bonds share more equally, thus have higher potential energy than electrons in C-O bonds
Which is better for storing energy, carbohydrates or fatty acids?
Fatty acids, as they contain more C-C and C-H bonds than carbohydrates. Better for long-term storage
What are the 3 structural polymers and what is the difference between them? What’s in common?
Cellulose is parallel strands of β-1,4-glycosidic linkage
- Forms a protective layer around plant cells called the cell wall
Chitin are found in the cell walls of fungi, and the exoskeletons of insects and crustaceans.
- Contain NHCOCH3 also known as Acetanilide replaces an OH group
Peptidoglycan is found in bacterial cell walls
- Contains both NHCOCH3 (Acetanilide) and peptide bonds from 4 amino acids chained together
All of these structural polymers can form long strands with bonds between adjacent strands, which can be organized into fibres or sheets.
What is important about structural polymers to the human diet?
Carbohydrates form dietary fibres which are important for digestive health
Are β-1,4-glycosidic linkage easily hydrolyzed?
NO, β-1,4-glycosidic linkage are not easy to hydrolyze
Most organisms lack enzymes to hydrolyze them, and these fibres exclude water making hydrolysis difficult.
How do carbohydrates play a role in the cell membrane?
They display information on the outer surface of the cell, carbohydrates indicate cell identity such as blood type.
What are glycoproteins and glycolipids (Also in chpt 6b-f)
Glycoproteins are carbohydrates attached to proteins.
Glycolipids are carbohydrates attached to lipids
