P2. Carbohydrates Flashcards
provides energy
Carbohydrate oxidation
Carbohydrate storage, in the form of ____, provides a short-term energy reserve.
glycogen
- human and animal energy storage
- can be found in the liver
- supply carbon atoms for the synthesis of other biochemical substances (proteins, lipids, and nucleic acids)
- form part of the structural framework of DNA and RNA molecules.
Carbohydrates
Carbohydrates linked to lipids are structural components of?
cell membranes
Carbohydrates linked to proteins function in a variety of ____ recognition processes.
cell–cell and cell–molecule
- a compound that yields polyhydroxy aldehydes or polyhydroxy ketones upon hydrolysis.
carbohydrates
is a polyhydroxy aldehyde
carbohydrate glucose
is a polyhydroxy ketone.
carbohydrate fructose
Classifications of Carbohydrates:
monosaccharides
disaccharides
oligosaccharides
polysaccharides
- are classified as aldose or ketose on the basis of the type of carbonyl present.
Monosaccharides
glycosides formed from the linkage of two monosaccharides.
Disaccharides
Disaccharides is the most important Oligosaccharides.
carbohydrates that
contain three to ten monosaccharide units.
Oligosaccharides
- are polymers.
- are monomers.
- polysaccharides
- monosaccharides
- handedness in molecules
- objects & mirror images
Chirality
The 2 existant forms of monosaccharides:
- left handed form
- right handed form
- images that coincide at all points when the images are laid upon each other.
- same reflection
- an object and it’s mirror image are identical and can’t be distinguished
Superimposable mirror images
- are images where not all points coincide when the images are laid upon each other.
- an object and it’s mirror image are different and can be distinguished
Nonsuperimposable mirror images
- an atom in a molecule that has four different groups bonded to it in a tetrahedral orientation.
an atom that has four different groups bonded to it in such a manner that it has a nonsuperimposable mirror image.
chiral center
- molecule that contains a chiral center and it’s nonsuperimposable w/ features of handedness.
- molecule that doesn’t contain a chiral center and it’s superimposable w/o features of handedness.
- chiral
- achiral
molecule whose mirror images are not superimposable (meaning NONSUPERIMPOSABLE).
chiral molecule
it is the left & right handed form of chiral molecules
STEREOISOMERISM/ ISOMERS
**
- connected in the same way but are arranged differently in space.
- same formula but different in structures/space.
Stereoisomerism
Two types of Stereoisomerism:
- enantiomers
- diastereomers
- have structures that are nonsuperimposable mirror images of each other
Enantiomers
- have structures that are not nonsuperimposable mirror images of each other
Diastereomers
PROPERTIES OF ENANTIOMERS:
- constitutional isomers
- diastereomers
-differ in most chemical and physical properties.
have different boiling points and melting points.
Constitutional isomers
also differ in most chemical and physical properties. They also have different boiling points and freezingpoints
Diastereomers
nearly all the properties of a pair of enantiomers are the same.
Two differences:
- Their interaction with plane polarized light
- Their interaction with other chiral substances
Enantiomers are ____: Compounds that rotate ____.
- optically active
- plane polarized light
Two types of Enantiomers Plane Polarized Light:
- dextrorotary
- levorotary
- D-type
- present in our body
- RIGHT hydroxyl group
- towards the right light movement/ clockwise
- positive sign
dextrorotary
- L-type
- LEFT hydroxyl group
- towards the left light movement/ counterclockwise
- negative sign
L-sucrose and L-fructose are present in animals
levorotary
In D and L you need to look at the structure + and - are determined by using a ____.
polarimeter
is a two-dimensional structural notation for showing the spatial arrangement of groups about chiral centers in
molecules.
Fischer projection formula
usually the Chiral Center represents what element?
Carbon
In a Fischer projection formula a ____ is represented as the intersection of vertical and horizontal lines
Chiral Center (Carbon)
used to designate the handedness of glyceraldehyde enantiomers.
can be extended to other monosaccharides with more than one chiral center.
D and L system
- is numbered starting at the carbonyl group end of the molecule
- is used to determine D or L configuration.
- carbon chain
- highest-numbered chiral center
- are often classified by both their number of carbon atoms and their functional group.
- cannot be further hydrolyse to smaller compounds
Monosaccharides
- PENTOSE & HEXOSE are the most important monosaccharides base on human standards.
six-carbon monosaccharide with an aldehyde functional group is an
aldohexose
five-carbon monosaccharide with a ketone functional group is a
ketopentose
- the most abundant in nature
- the most important from a human nutritional standpoint.
D-glucose/ aldohexose
- biochemically the most important ketohexose
- also known as levulose and fruit sugar.
D-Fructose/ ketohexose
- Milk sugar
- Synthesize in human
- Used to differentiate between blood types
- Six membered cyclic form
D-Galactose/ Aldohexose
- Part of RNA
- Part ofATP
- Part of DNA
- Five membered cyclic form
D-Ribose/ Aldopentose
2 forms of D-glucose:
alpha-form
beta-form
C1: -OH
C5: CH2OH
(they are on opposite sides)
Alpha-form
C1: -OH
C5: CH2OH
(they are on the same sides)
Beta-form
a two-dimensional structural notation that specifies the three-dimensional structure of a cyclic form of a monosaccharides.
HAWORTH PROJECTION FORMULAS
determined by the position of the —OH group on C1 relative to the CH2OH group that determines D or L series.
- both of these groups point in the same direction
- the two groups point in opposite directions
Alpha or Beta configuration
- Beta configuration
- Alpha configuration
The specific identity of a monosaccharide is determined by the positioning of the other ____ in the ____.
- —OH groups
- Haworth projection formula
- any -OH group to the right of the FISCHER PROJECTION FORMULA points ____ to the HAWORTH PROJECTION FORMULA.
- any -OH group to the left of the FISCHER PROJECTION FORMULA points ____ to the HAWORTH PROJECTION FORMULA.
- DOWN
- UP
Five important reactions
monosaccharides:
- OXIDATION to acidic sugars
- REDUCTION to sugar alcohols
- Glycoside formation
- Phosphate ester formation
- Amino Sugar formation
- redox chemistry of monosaccharides is closely linked to the alcohol and aldehyde functional groups present in them.
- can yield three different types of acidic sugars depending on the type of oxidizing agent used
agents used?
Oxidation
Tollen’s and Benedict’s [weak]
Nitric Acid [strong]
carbonyl group in a monosaccharide (either an aldose or a ketose) is reduced to a hydroxyl group using hydrogen as the reducing agent.
Sugar Alcohols
general name for monosaccharide acetals is
glycoside
glucose acetals?
galactose acetals?
glucoside
galactoside
an acetal formed from a cyclic monosaccharide by replacement of the hemiacetal carbon -OH group with an -OR group.
Glycoside
Human blood is classified
into four types:
A, B, AB, & O
The biochemical basis for the various blood types involves ____ present on ____ .
- monosaccharides
- plasma membranes of red blood cells
monosaccharides responsible for blood groups:
D-galactose & its derivatives
hydroxyl groups of a monosaccharide can react with inorganic oxyacids to form inorganic esters.
Phosphate Ester Formation
are stable in aqueous solution and play important roles in the metabolism of carbohydrates.
Phosphate esters of various monosaccharides
one of the hydroxyl groups of a monosaccharide is replaced with an amino group
Amino Sugar (Formation)
important building blocks of polysaccharides:
AMINO SUGARS & their N-acetyl derivatives
- the reaction of 2 monosaccharides forms?
disaccharides
bond that links the two monosaccharides of a disaccharide (glycoside) together
glycosidic linkage
- is produced as an intermediate in the hydrolysis of the polysaccharide cellulose.
- cannot be digested by humans
Cellobiose
Cellobiose contains two ____ units linked through a ____ linkage.
- b - D-glucose monosaccharide
- b (1—4) glycosidic
- often called MALT SUGAR
- produced whenever the polysaccharide starch breaks down
as happens in plants when seeds germinate and in human beings during starch digestion.
Maltose
Structurally, maltose is made up of ____, one of which must be ____.
- two D-glucose units
- a-D-glucose
the major sugar found in milk
Lactose
Lactose is made up of ____ unit and a ____ unit joined by a ____.
- b-D-galactose
- b-D-glucose
- b (1-4) glycosidic linkage
a condition in which people lack the enzyme lactase needed to hydrolyze lactose to galactose and glucose
Lactose intolerance
hydrolyzes b (1-4) glycosidic linkages
Lactase
Deficiency of lactase can be caused by a genetic defect, physiological decline with age, or by injuries to intestinal mucosa.
- table sugar
- most abundant of all disaccharides & found in plants
- produced commercially from the juice of sugar cane and sugar be
- nonreducing sugars
Sucrose
a polymer that contains many monosaccharide units bonded to each other by glycosidic linkages.
polysaccharide
a polysaccharide in which only one type of monosaccharide monomer is present.
homopolysaccharide
a polysaccharide in which more than one (usually two) type of monosaccharide monomer is present.
heteropolysaccharide
is a polysaccharide that is a storage form for monosaccharides and is used as an energy source in cells
storage polysaccharide
- a homopolysaccharide containing only glucose monosaccharide units.
- the energy-storage polysaccharide in plants
- All of the glycosidic linkages (both amylose and amylopectin) are of the a type
they are constantly hydrolyze by ALPHA-AMYLASE
Starch
amylose & amylopectin
the other polysaccharide in starch, has a high degree of branching in its polyglucose structure.
Amylopectin
- like starch, is a polysaccharide containing only glucose units
- Liver cells and muscle cells are the storage sites
- an ideal storage form for glucose
Glycogen
- Linear homopolysaccharide with b (1-4) glycosidic bond [humans don’t have these enzymes that is why they can’t digest this]
- It serves as dietary fiber in food– readily absorbs water and results in softer stools.
animals also do not have that enzyme but they can digest it because of their bacteria in the gut.
Cellulose
- Similar to cellulose in both function and structure
- Linear polymer with all b (1-4) glycosidic linkages it has a N-acetyl amino derivative of glucose
Chitin
polysaccharides with a repeating disaccharide unit containing an amino sugar and a sugar with a negative charge due to a sulfate or a carboxyl group
Acidic polysaccharides
Structural polysaccharide present in ____ associated with joints, cartilage, synovial fluids in animals and humans
Examples:
* Hyaluronic acid
* Heparin
connective tissue
- Highly viscous - serve as lubricants in the fluid of joints and part vitreous humor of the eye.
Hyaluronic acid
Alternating residues of Hyaluronic Acid:
- N-acetyl-b-D-glucosamine
- D-glucoronic acid
An anticoagulant-prevents blood clots
Heparin
is a lipid molecule that has one or more carbohydrate (or carbohydrate derivative) units covalently bonded to it.
Glycolipids
is a protein molecule that has one or more carbohydrate (or carbohydrate derivative) units covalently bonded to it.
Glycoproteins