Module 08: Carbohydrates (Stoker) Flashcards
This is the study of the chemical substances found in living organisms and the chemical interactions of these substances with each other
Biochemistry
This is a chemical substance found within a living organism
biochemical substance
This form of biochemical substance are comprised of water and inorganic salts.
Bioinorganic substances
This form of biochemical substance are comprised of carbohydrates, lipids, proteins, and nucleic acids
Bioorganic substances
How many percentage of dry plant material is produced by photosynthesis?
75%
This is the structural element of carbohydrates?
Cellulose
This is the energy reservoir of the body and is present in small amounts.
Starch/glycogen
The average human diet contains how many carbohydrates?
2/3 of carbohydrates
Carbohydrates are also known as what
Saccharides (is perceived as the most abundant bioorganic molecules on Earth)
How are carbohydrates produced?
Produced by photosynthesis
What is the general formula of carbohydrates?
(CH2O)n (n≥3)
What are the functions of carbohydrates?
(1) Carbohydrate oxidation - provides energy
(2) Carbohydrate storage, in the form of glycogen, provides a short-term energy reserve
(3) Carbohydrates supply carbon atoms for the synthesis of other biochemical substances (proteins, lipids, and nucleic acids)
(4) Carbohydrates form part of the structural framework of DNA and RNA molecules
(5) Carbohydrates linked to lipids (Chapter 19) are structural components of cell membranes
(7) Carbohydrates linked to proteins (Chapter 20) function in a variety of cell–cell and cell–molecule recognition processes
When integrated with lipids, carbohydrates act as “_________________-“
structural components of cell membranes
When integrated with proteins, carbohydrates act as “_________________-“
function in a variety of cell–cell and cell–molecule recognition processes
What is the simpler formula of carbohydrates?
CnH2nOn or Cn(H2O)n (hydrates of C), where n pertains to the number of atoms
In plants, these serve as structural elements in the cell wall of plants
Cellulose
in plants, these serve as energy reserve for plants
Starch
Carbohydrates are classified as either what?
polyhydroxy aldehydes or ketones
How do some carbohydrates produce such substances?
Hydrolysis
These contain single polyhydroxy aldehyde or ketone unit. They cannot be broken down into simpler substances by hydrolysis (reaction with water) reactions
Monosaccharide
How many carbon atoms do Monosaccharides contain?
Contains 3 to 7 C atoms, where 5 and 6 carbon species are more common
How are Monosaccharides classified?
They are water-soluble white crystalline solids
What are examples of Monosaccharides?
Glucose and Fructose
These contain 2 monosaccharide units and are classified to be more common and are also crystalline water soluble substances.
Disaccharides
What do Disaccharides form when hydrolyzed?
2 monosaccharide units
These are generic examples of Disaccharides?
Table sugar (sucrose) and milk sugar (lactose)
In the human body, Disaccharides function as what?
In human body, Disaccharides are associated with proteins and lipids for structural and regulatory functions
These contains 2 to 10 monosaccharide units that are covalently bonded to each other
Oligosaccharides
These contains many monosaccharide units that are covalently bonded.
Polysaccharides
These Polysaccharides may contain 100s of 1000s of monosaccharide units.
Polymers
These are generic examples of Polysaccharides?
Cellulose and Starch
Most monosaccharides exist in two forms:
(1) Left-handed
(2) Right-handed
These types of objects are defined as images that coincide at all points when the images are laid upon each other
Superimposible on their mirror images (achiral)
These types of objects are characterized to be Chiral (handedness).
Non-superimposable on their mirror images
How do you define a chiral center?
C atom attached to 4 different groups (A molecule with chiral center is a chiral molecule )
How do you classify chirality?
(1) Best way to visualize - look at all C atoms and see if there are at least two H atoms then that can’t be a chiral center
(2) C atoms with less than one H atoms are worth looking at for their chirality
(3) similarity and difference of groups
Why is 3-bromopentane achiral?
C has two CH2-CH3 groups – so it is achiral
What are the responses of Left and Right Handed Forms of a Molecule in a Human Body?
(1) Both may be active, one may be more active or one may be active and other non-active
Example: Right handed hormone epinephrine is 20 times more active than left handed form
(2) Almost all monosaccharides are right handed
(3) Amino acids are almost always left handed
Where are Monosaccharides derived from?
Derived from CO2 and H2O by photosynthesis
How are Monosaccharides classified?
(A( their carbonyl group: aldehydes (aldose) or ketones (ketose)
(B) the number of C (trioses, tetroses, pentoses, hexoses, heptose)
(C) According to configuration – D or L sugar
This is known as the smallest aldose.
Glyceraldehyde
This is known as the smallest ketose
Dihydroxy-acetone
How many chiral carbons does aldohexose d-glucose have?
four (4) chiral carbons
These have the same absolute configuration at the asymmetric center farthest away from their carbonyl group as does D-glyceraldehyde (i.e., C5 in D glucose).
D sugars
How many asymmetric center does Glyceraldehyde have?
one asymmetric center
How did Emil Fischer propose spatial isomers (Stereoisomers)?
In 1892, Emil Fisher proposed that the spatial isomers (stereoisomers), of glyceraldehyde be designated D- and L-glyceraldehyde. Fisher assigned the D and L to the above structures of glyceraldehyde, but it was not until 1949 that experiments confirmed that his guess was correct.
What do D-isomers denote?
D indicates rotation to the right
What do L-isomers denote?
L indicates rotation of polarized light to the left. The L sugars are the mirror images of their D counterparts
This pertains to the monosaccharide with an aldehyde group on C1
Aldose
This pertains to the monosaccharide with a keto group on C2
Ketose
These are isomers that have the same molecular and structural formulas but differ in the orientation of atoms in space.
Stereoisomers
These are stereoisomers whose molecules are nonsuperimposable mirror images of each other. Molecules with chiral center.
Enantiomers
These are stereoisomers whose molecules are not mirror images of each other.
Diastereomers
This is a method for giving molecular chirality specifications in two dimensions
Fischer projection formulas
How are Fischer projection formulas characterized?
This is a two-dimensional structural notation for showing the spatial arrangement of groups about chiral centers in molecules.
In a Fischer projection formula, how is a chiral center (Carbon) represented?
as the intersection of vertical and horizontal lines
In a Fischer projection formula, D and L system are used to what
D and L system used to designate the handedness of glyceraldehyde enantiomers can be extended to other monosaccharides with more than one chiral center
These has four groups attached to the atom at the chiral center
tetrahedral geometry (Tetrahedral Arrangements)
In Tetrahedral Arrangements, what do vertical arrangements represent?
represent bonds to groups directed into the printed page.
In Tetrahedral Arrangements, what do horizontal arrangements represent?
represent bonds to groups directed out of the printed page
Where should one start numbering a carbon chain?
starting at the carbonyl group end of the molecule
What is used to determine D or L configuration?
highest-numbered chiral center
These are diastereomers whose molecules differ only in the configuration at one chiral center
Epimers
How do Constitutional isomers and Diastereomers differ?
in most chemical and physical properties.(boiling points and melting points)
How are enantiomers different?
(1) Their interaction with plane polarized light
(2) Their interaction with other chiral substances
In this property of light, these form light move in all directions
Ordinary (unpolarized) Light
In this property of light, these form light move in same (comparable) and in one direction.
Plane polarized Light
How is a Plane polarized Light rotated?
Plane polarized light is rotated clockwise (to right) or counterclockwise (to left) when passed through enantiomers (Direction and extent of rotation will
depend upon the enantiomer)
How do same concentration of two enantiomers rotate?
rotate light to same extent but in opposite direction (optically active)
This is a chiral compound that rotates light towards right (clockwise; +)
Dextrorotatory
This is a chiral compound that rotates light towards left (counterclockwise; -)
Levorotatory
How are D and L as well as + and - determined, respectively?
Structure and by using a polarimeter
How is the solubility of achiral solvents enantiomeric pairs characterized?
Enantiomeric pairs have same solubility in achiral solvents like ethanol
How is the solubility of chiral solvents enantiomeric pairs characterized?
Enantiomeric pairs have different solubility in chiral solvent like D-2-butanol
The comparable (similar) boing points melting points, and densities of enantiomers are dependent on what
intermolecular forces and chirality doesn’t depend on them
This classification of monosaccharides contains three carbon atoms.
Triose
This classification of monosaccharides contains four carbon atoms.
Tetrose
This classification of monosaccharides contains five carbon atoms.
Pentoses
This classification of monosaccharides contains six carbon atoms.
Hexoses
This is a monosaccharide with aldehyde group and 6 C atoms
D-Glucose (Aldohexose)
This is a monosaccharide with ketone group and 6 C atoms
D-Fructose (Ketohexose)
This is an optimal source of glucose.
Grape fruit, grape sugar, dextrose, and blood sugar (70 - 100 mg/100 mL of blood)
This is the most abundant in nature and is nutritionally most important
Glucose
How much glucose can be obtained from grapefruit?
20-30% by mass
Glucose is characterized as a What?
Six membered cyclic form )Aldohexose)
This is the sweetest tasting of all sugars, found in many fruits and in honey is also perceived as a good dietary sugar due to higher sweetness
Fructose
fructose is characterized as a What?
Six membered cyclic form Ketohexose)
This is known as the milk sugar and is synthesized by humans. It is also utilized to differentiate between blood types.
Galactose
Galactose is also known as “__________-“
brain sugar (part of the brain and nerve tissue)
Galactose is characterized as a What?
Six membered cyclic form )Aldohexose)
Ribose is a part of what?
(1) ATP
(2) DNA
(3) RNA
Ribose is characterized as a What?
Five membered cyclic form (Aldopentose)
This is the dominant form of monosaccharides with 5 or more C atoms.
Cyclic Hemiacetal Forms of D-Glucose
How are cyclic forms in equilibrium?
cyclic forms are in equilibrium with open chain form
How are cyclic forms formed (generated)?
Cyclic forms are formed by the reaction of carbonyl group (C=O) with hydroxyl (-OH) group on carbon 5
What is the alpha form of d-glucose?
Alpha-form: -OH of C1 and CH2OH of C5 are on opposite sides
What is the beta form of d-glucose?
OH of C1 and CH2OH of C5 are on same sides
What kind of isomerism is observed in aldose and ketose pair?
Functional isomers-
What are some examples of epimers?
glucose and mannose, glucose and galactose
How does D-glucose and D-Mannose differ?
epimer at C2
How does D-Glucose and D-Galactose?
epimer at C4
All aldoses with five or more carbon atoms establish similar equilibria, but with different percentages of the _______________.
alpha, beta, and open-chain forms.
This pertains to a cyclic monosaccharide containing a six-atom ring
Pyranose
This pertains to a cyclic monosaccharide containing a five-atom ring
Furanose
This is a two-dimensional structural notation that specifies the three-dimensional structure of a cyclic form of a monosaccharide
Haworth projection formula
How is alpha and beta configuration determined?
Alpha or Beta configuration is determined by the position of the —OH group on C1 relative to the CH2OH group that determines D or L series.
How are the positions of the OH group on C1 relative to the CH2OH group in the Beta Configuration?
both of these groups point in the same direction
How are the positions of the OH group on C1 relative to the CH2OH group in the Alpha Configuration?
the two groups point in opposite directions.
How is the specific identity of a monosaccharides determined?
by the positioning of the other —OH groups in the Haworth projection formula.
How is the OH group at a chiral center that is to the right in a Fischer projection formula pointed in the Haworth projection?
Down
How is the OH group at a chiral center that is to the left in a Fischer projection formula pointed in the Haworth projection?
Up
What are the five most important reactions of monosaccharides?
Oxidation to acidic sugars
Reduction to sugar alcohols
Glycoside formation
Phosphate ester formation
Amino sugar formation
What are examples of aldonic acids?
Benedict’s, Fehling’s, Barfoeds and Tollens reagent
This form of oxidation to sugar acids involve enzymes/
alduronic acid
This form of oxidation to sugar acids involve a strong oxidizing agent (HNO3)-
aldaric acid
The redox chemistry of monosaccharides in terms of the oxidation of acidic sugar is closely linked to what? .
the alcohol and aldehyde functional groups present in them
Weak oxidizing agents such as Tollens and Benedict’s solutions oxidize what?
oxidize the aldehyde end to give an aldonic acid.
This is a carbohydrate that gives a positive test with Tollens and Benedict’s solutions.
reducing sugar
What can a reducing sugar do?
A reducing sugar reduces the oxidizing agent and is oxidized to an acid.
How can Monosaccharides be oxidized>
Monosaccharides can be oxidized by weak oxidizing agents such as Cu2+ ions.
What kind of acid is d-gluconate?
aldonic acid
What is oxidized by strong oxidizing agents?
Strong oxidizing agents like concentrated nitric acid can oxidize both ends of a monosaccharide at the same time (the carbonyl group and the terminal primary alcohol group)
What is produced upon oxidizing both ends of a monosaccharide at the same time (the carbonyl group and the terminal primary alcohol group)?
dicarboxylic acid:
Aldaric acids are known as “_______________”
polyhydroxy dicarboxylic acids
How is alduronic acid produced
In biochemical systems enzymes can oxidize the primary alcohol end of an aldose such as glucose, without oxidation of the aldehyde group, to produce an alduronic acid.
How are sugars reduced?
The carbonyl group in a monosaccharide (either an aldose or a ketose) is reduced to a hydroxyl group using hydrogen as the reducing agent.
What is the product of the reduction to sugar alcohols?
The product is the corresponding polyhydroxy alcohol
This is used as moisturizing agents in foods and cosmetics and as a sweetening agent in chewing gum
Sorbitol
Cyclic forms of monosaccharides are called “___________”
hemiacetals (they react with alcohols to form acetals)
Monosaccharide acetals are called “______________”
glycoside
How are glycosides formed?
A glycoside is an acetal formed from a cyclic monosaccharide by replacement of the hemiacetal carbon —OH group with an —OR group:
For example:
A glycoside produced from glucose - glucoside
A glycoside produced from galactose – galactosidase
What are the four blood types?
A, B, AB, and O:
What happens when the wrong blood is transfused?
A transfusion of wrong blood type can cause the blood cells to form clumps - a potentially fatal reaction.
They are universal donors.
People with type O blood
They are universal recipients.
People with type AB blood
What are the most common blood types in the United States?
In the United States type O blood is the most common and type A the second most common.
What is the biochemical basis for various blood types?
The biochemical basis for the various blood types involves monosaccharides present on plasma membranes of red blood cells.
What is the importance of monosaccharides in blood groups?
The monosaccharides responsible for blood groups are D-galactose and its derivatives.
What is formed when the hydroxyl groups of a monosaccharide react with inorganic oxyacids to form inorganic esters?
Phosphate ester
When are Phosphate ester stable?
When they are in aqueous solution and play important roles in the metabolism of carbohydrates.
These are important building blocks of polysaccharides such as chitin
Amino sugars and their N-acetyl derivatives
One monosaccharide can act as what?
hemiacetal and other as alcohol
This is produced as an intermediate in the hydrolysis of the polysaccharide cellulose:
Cellobiose
Cellobiose contains what?
two b - D-glucose monosaccharide units linked through a b (1—4) glycosidic linkage.
Why can’t cellobiose be digested properly?
Because humans do not have enzymes that can break (1-4) linkages of cellobiose
This is digested easily by humans because we have enzymes that can break a (1-4) linkages
Maltose
Lactose is made up of what?
b-D-galactose unit and a b-D-glucose unit joined by a b(1-4) glycosidic linkage
This is the principal carbohydrate in milk.
Lactose
How much lactose constitutes humans?
7%–8% lactose
How much lactose constitutes cow’s milk?
- 4%–5% lactose
This is a condition in which people lack the enzyme lactase needed to hydrolyze lactose to galactose and glucose.
Lactose intolerance
This hydrolyzes b(1-4) glycosidic linkages.
Lactase
What causes the Deficiency of lactase?
Deficiency of lactase can be caused by a genetic defect, physiological decline with age, or by injuries to intestinal mucosa.
What happens when lactase is not digested properly?
it attracts water causing fullness, discomfort, cramping, nausea, and diarrhea. Bacterial fermentation of the lactose further along the intestinal tract produces acid (lactic acid) and gas, adding to the discomfort
This is the most abundant of all disaccharides and found in plants. It is produced commercially from the juice of sugar cane and sugar beets.
Sucrose (table sugar):
How much sucrose does sugar cane contain?
20% by mass
How much sucrose does sugar beet contain?
17% by mass sucrose
These are formed from monosaccharide units bonded with glycosidic linkages
Polymers
What are the two types of polymer chain?
Linear and branched, homo- and hetero-polysaccharides
Why don’t Polysaccharides show positive tests with Tollen’s and Benedict’s solutions?
They are not sweet and they have limited water solubility.
What are some examples of Polysaccharides?
Cellulose, starch in plants
Glycogen in animals
Chitin in arthropods
Glucaric acid is characterized as what “____________-“
water soluble
Galactaric acid is characterized as what “____________-“
nonpolar due to symmetry (water insoluble).
What is the basis of mucic acid test used to differentiate glucose from galactose.
polarity and solubility
This sugar acid is related to the Oxidation of the aldehyde group of aldoses
Aldonic acids
This sugar acid is related to the Oxidation of the primary alcohol group of aldoses
alduronic acids
This sugar acid is related to the Oxidation of both with concentrated HNO3
aldaric acid
what kind of acid is d-gluconic acid?
Aldonic acids
What kind of acid is d-glucuronic acid?
Alduronic acid
What kind of acids are glucaric and Galactaric acid
Aldaric acid
These are known as sugar alcohols. These are known as sweeteners in chewing gum and accumulates in the lens of diabetics resulting to cataracts
Glucitols
How can an aldehyde group or keto group be reduced?
The aldehyde group or keto group can be reduced to a 1o alcohol or 2o alcohol using H2 as reducing agent.
What occur predominantly as a cyclic structures?
aldotetroses and all monosaccharides with n ≥ 5
How are cyclic hemiacetals and cyclic hemiketals formed?
Alcohol groups can react with the aldehydes or ketones (The hydroxyl and either the aldehyde or the ketone of monosaccharides can react intramolecularly to form cyclic hemiacetals and hemiketals)
what are intramolecular hemiacetal formation?
Sugars with ≥ 5 C mostly exist in their cyclic form (Since C1 becomes a chiral center, there are two new possible stereoisomers that are named a and b)
These isomeric forms that differ only in their configuration about the hemiacetal or hemiketal carbon atom. ⇒ a, b anomers
Anomers
This is the hemiacetal carbon atom or the new chiral C.
anomeric carbon
How is the anomeric carbon formed?
Cyclic sugars have 2 anomeric forms. During cyclization, the carbonyl carbon becomes a chiral center and is called, the anomeric carbon with two possible configurations.
How do Disaccharides arise?
They arise through the formation of O-glycosidic bonds: condensation of anomeric carbon hydroxyl group with an alcohol.
How is lactose formed
condensation of a molecule of β-D galactopyranose with a molecule of D-glucose (a or b) through β-I,4- glycosidic linkage.
How is sucrose formed?
the condensation of a molecule of a-D-glucopyranose with a molecule of β-D-fructofuranose through α-1,2-glycosidic bond
What is the monomer and linkage of maltose respectively?
Two a-D-GLUCOSE and a-1,4-GLYCOSIDIC
What is the monomer and linkage of lactose respectively?
B-D GALACTOSE and a-D-GLUCOSE and b-1,4-GLYCOSIDIC
What is the monomer and linkage of sucrose respectively?
a-D-FRUCTOSE and a-D-GLUCOSE and b-1,2-GLYCOSIDIC
What is the monomer and linkage of cellobiose respectively?
Two b-D-GLUCOSE and b-1,4-GLYCOSIDIC
What is the monomer and linkage of isomaltose respectively?
Two a-D-GLUCOSE and a-1,6-GLYCOSIDIC
