Chapter 7: Carbohydrates Flashcards
It is the most abundant class of bioorganic molecules on planet Earth
Carbohydrates
Abundance of Carbohydrates in human body
relatively low
carbohydrates constitute about _____ by mass of dry ______ _______
- 75%
- plant materials
Substance that do not contain carbon
Bioinorganic Substances
What Bioinorganic Substances are in the Human body?
Water (about 70%)
Inorganic salts (about 5%)
Substances that contain carbon
Bioorganic Substances
What Bioorganic Substances are in the Human body?
Proteins (about 15%)
Lipids (about 8%)
Carbohydrates (about 2%)
Nucleic acids (about 2%)
Two main uses for the carbohydrates in plants
- In the form of cellulose, carbohydrates serve as structural elements
- In the form of starch, they provide energy reserves for the plants
What is the major carbohydrate source for humans and animals?
Dietary intake of plant materials
Functions of Carbohydrates in Humans
- Carbohydrate oxidation provides energy
- Provides a short term energy reserve
- Supply carbon atoms for the synthesis of other biochemical substances
- Essential components in the mechanisms of genetic control of growth and development of living cells
- Carbohydrates linked to lipids are structural components of cell membranes
- Carbohydrates linked to proteins function in a variety of cell–cell and cell–molecule recognition processes
Biochemical substances
proteins, lipids, and nucleic acids
- lowest number of specific molecule
- the simplest whole number ratio of atoms present in a compound
Empirical formula
General formula of Carbohydrates
CnH2nOn which can be written as Cn(H2O)n
Cn(H2O)n — the basis for the term
carbohydrate (“hydrate of carbon”)
A carbohydrate is a ______ ________, a ________ _________, or a compound that yields polyhydroxy aldehydes or polyhydroxy ketones upon hydrolysis
polyhydroxy aldehyde
polyhydroxy ketone
CHO
Aldehyde group
C=O
Ketone group
Types of Carbohydrates
- Monosaccharide
- Disaccharide
- Oligosaccharide
- Polysaccharide
Carbohydrates are classified based on
molecular size
- a carbohydrate that contains a single polyhydroxy aldehyde or polyhydroxy ketone unit
- water-soluble, white, crystalline solids
Monosaccharide
Monosaccharide cannot be broken down into ____ ___ by _____ _____
- simpler units
- hydrolysis reaction
- a carbohydrate that contains two monosaccharide units covalently bonded to each other
- crystalline, water-soluble substances
Disaccharides
Example of Disaccharide carbohydrates
Sugar (table sugar)
Lactose (milk sugar)
Product of the Hydrolysis of a disaccharide
two monosaccharide units
a carbohydrate that contains 3-10 monosaccharide units covalently bonded to each other
Oligosaccharide
_____ oligosaccharides are seldom encountered in biochemical systems
Free
Products of complete hydrolysis of an oligosaccharide
- trisaccharide > 3 monosaccharide units
- hexasaccharide > 6 monosaccharide units
a polymeric carbohydrate that contains many monosaccharide units covalently bonded to each other
Polysaccharide
Number of monosaccharide units present in polysaccharide
a few hundred units to over 50,000 units
Functional group that is always present in a carbohydrate molecule
Hydroxyl group
What is the product of complete hydrolysis of a polysaccharide?
Monosaccharides
D-
Dextro means right
L-
Levo means left
D- and L- differ in the ____ _______ of _____ in the molecule
spatial arrangements of atoms
A carbon atom that has four different groups bonded to it
Chiral carbon
Images that coincide at all points when the images are laid upon each other
Superimposable mirror images
Images where not all points coincide when the images are laid upon each other
Nonsuperimposable mirror images
The Importance of Chirality
- both forms are biologically active, giving a different response
- both elicit the same response, but giving different number of response
- Sometimes only one of the two forms is biochemically active
A compound that has _ ____ _____ may exist in a _______ of ___ ______ _____
- n chiral centers
- maximum of 2n stereoisomeric forms
It is a compound that rotates the plane of polarized light
Optically active compound
It is a chiral compound that rotates the plane of polarized light in a clockwise direction
Dextrorotatory compound
It is a chiral compound that rotates the plane of polarized light in a counterclockwise direction
Levorotatory compound
Classification of Monosaccharides based on the type of carbonyl group
- Aldose
- Ketose
- it is a monosaccharide that contains an aldehyde functional group
- are polyhydroxy aldehydes
Aldose
- it is a monosaccharide that contains a ketone functional group
- are polyhydroxy ketones
Ketose
Monosaccharides are often classified by both their ____ of ____ ____ and their ________ _____
- number of carbon atoms
- functional group
An aldose with 3 carbons
Aldotriose
A ketose with 6 carbons
Ketohexose
Biochemically Important Monosaccharides
- D-Glyceraldehyde and Dihydroxyacetone
- D-Glucose
- D-Galactose
- D-Fructose
- D-Ribose
- simplest monosaccharide
- these triose are important intermediates in the process of glycolysis
D-Glyceraldehyde and Dihydroxyacetone
- found in high amounts in ripe fruits
- blood sugar
- also called dextrose
D-Glucose
- seldom encountered as a free monosaccharide
- Synthesized from glucose in the body for the production of lactose
- called brain sugar
D-Galactose
It is a disaccharide of glucose and galactose
Lactose
Why is the D-Galactose called brain sugar?
because it is a component of glycoproteins found in brain and nerve tissue
D-Galactose is present in the ______ _______ that distinguish various types of blood (A, B, AB, and O)
chemical markers
- biochemically the most important ketohexose
- also known as levulose and fruit sugar
- sweetest-tasting of all sugar
D-Fructose
D-Fructose is found in
- found in many fruits
- present ni honey in equal amounts with glucose
Use of D-Fructose
Used as a dietary sugar because less is needed for the same amount of sweetness
- 5-carbon sugar (pentose)
- component of ribonucleic acids (RNAs) and energy-rich compounds such as adenosine triphosphate (ATP)
D-Ribose
It can oxidize both ends of a monosaccharide at the same time
Strong oxidizing agents
Strong oxidizing agents can oxidize both ends of a monosaccharide at the same time to produce a
dicarboxylic acid
Such polyhydroxy dicarboxylic acids are known as _____ _____
aldaric acids
It is an acetal formed from a cyclic monosaccharide by replacement of the hemiacetal carbon -OH group with an -OR group
Glycoside
A glycoside produced from glucose
Glucoside
A glycoside produced from galactose
Galactoside
Monosaccharide Derivatives
Acidic Sugars
Sugar Alcohols
Glycosides
Phosphate Esters
Amino Sugars
It is obtained by oxidation
Acidic Sugars
It is obtained by reduction
Sugar Alcohols
A reaction with alcohol
Glycosides
Classes of Acidic Sugars
Aldonic acid
Alduronic acid
Aldaric acid
A true sugar alcohol
Alditol
Acid group in Aldonic acid
Top
Acid group in Alduronic acid
Bottom
Acid groups in Aldaric acid
Top and Bottom
Alcohol groups in Alditol
Both top and bottom
What are the 4 Monosaccharides
D-Glucose
D-Galactose
D-Fructose
D-Ribose
What joined the two monosaccharides that consist the disaccharides?
Oxygen bridge
It is the bond between two monosaccharides resulting from the reaction between the hemiacetal carbon atom -OH group of one monosaccharide and an -OH group on the other monosaccharide
Glycosidic bond/linkage
What are the particular disaccharides we commonly see?
Maltose
Lactose
Sucrose
Maltose, Lactose, or Sucrose are produced in cells because the reactions are ______ by _____
catalyzed by enzymes
- often called malt sugar
- produced whenever the polysaccharide starch breaks down
- made up of two D-glucose units, one of which must be α-D-glucose
- α(1→4) linkage
Maltose
malt
germinated barley that has been baked and ground; contains this disaccharide
Maltose is produced whenever the polysaccharide _____ breaks down
starch
- the enzyme that breaks the glucose–glucose α(1→4) linkage present in maltose
- found both in the human body and in yeast
Maltase
Consequently, maltose is _______ easily by humans and is readily _______ by yeast
- digested
- fermented
- an intermediate in the hydrolysis of the polysaccharide cellulose
- contains two D-glucose monosaccharide units
- a D-glucose units function as a hemiacetal that has a β configuration
- β(1→4) linkage
Cellobiose
Reason why cellubiose cannot be digested by humans and fermented by yeast
Since both human body and yeast lack enzyme cellobiose, it cannot break the glucose-glucose β(1→4) linkage of cellobiose
- major sugar found in milk
- made up of a β-D-galactose unit and a D-glucose unit joined by a β(1→4) linkage glycosidic linkage
Lactose
Formation of Lactose
when galactose bonds to glucose
Lactose can be hydrolyzed by acid or by the enzyme _______, forming an ________ ______ of galactose and glucose
- lactase
- equimolar mixture
It is a condition in which people lack the enzyme lactase
Lactose Intolerance
___ of adults (the majority) are lactose intolerant
60%
What happens when lactose molecules remain in the intestine undigested?
They attract water to themselves, causing fullness, discomfort, cramping, nausea, and diarrhea
- common table sugar
- is the most abundant of all disaccharides and occurs throughout the plant kingdom
- α-D-glucose and β-F-fructose in an α,β(1→2) glycosidic linkage
- a nonreducing sugar
- exists in only one form
Sucrose
What oligosaccharides are found in onions, cabbage, broccoli, brussel sprouts, whole wheat?
Two naturally occuring oligosaccharides
What oligosaccharides are found in all types of beans?
trisaccharide raffinose and tetrasaccharide stachyose
What do you call the toxin that is produced by the potato plant?
Solanine
What is the use of Solanine in a potato plant?
A defense against insects and predators
Solanine amounts in potatoes _______ when potatoes ______ and when they are _______ to _______
- increase
- sprout
- exposed to sunlight
Green coloration in the skin of potatoes
It denotes the presence of chlorophyll, and the toxin solanine. Such potatoes need to be deeply peeled before use
Blood Type that is Universal donor
Type O
Blood Type that is Universal acceptor
Type AB
An alternate name for a polysaccharide
Glycan
Important parameters that distinguish various polysaccharides from each other
- The identity of the monosaccharide repeating unit(s) in the polymer chain
- The length of the polymer chain
- As with disaccharides, the type of glycosidic linkage between monomer units
- The degree of branching of the polymer chain
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
A polysaccharide that is a storage form for monosaccharides
Storage polysaccharide
Use of storage polysaccharide
an energy source in cells
- has a structure similar to that of amylopectin
- both (1→4) and (1→6) linkages are present
- an ideal storage form for glucose
Glycogen
Difference of Glycogen and Amylopectin
- number of glucose units between branches
- total number of glucose units
Starch:
Source of Amylose
Plant
Starch:
Source of Amylopectin
Plant
Starch:
Subunit of Amylose
α-glucose
Starch:
Subunit of Amylopectin
α-glucose
Starch:
Bond of Amylose
1→4
Starch:
Bond of Amylopectin
1→6
Starch:
Branch of Amylose
No (Linear)
Starch:
Branch of Amylopectin
Yes (~per 20 subunits)
Source of Glycogen
Animal
Subunit of Glycogen
α-glucose
Bonds in Glycogen
1→4 and 1→6
Branches of Glycogen
Yes (~per 10 subunits)
- the structural component of plant cell walls
- most abundant naturally occurring polysaccharide
- an unbranched glucose polymer
- β(1→4)
Cellulose
High concentrations of cellulose can be found
“woody” portions of plants—stems, stalks, and trunks
It is almost pure cellulose
Cotton (95%)
It is about 50% cellulose
Wood
- second most abundant naturally occurring polysaccharide
- gives rigidity to the exoskeletons of crabs, lobsters, shrimp, insects, and other arthropods, in the cell walls of fungi
- Polymer of the amino sugar N-acetyl-D-glucosamine (NAG)
Chitin
A monosaccharide found in blood type oligosaccharide
N-acetyl-D-glucosamine (NAG)
α(1→4) linkages
Maltose
Amylose
α(1→4) and α(1→6) linkages
Amylopectin
Glycogen
β(1→4) linkages
Lactose
Cellobiose
Cellulose
α,β(1→2) linkages
Sucrose
- a polysaccharide with a disaccharide repeating unit
- heteropolysaccharides
Acidic polysaccharide
One of the disaccharide components
amino acid
One or both of the disaccharide components
has a negative charge due to a sulfate group or a carboxyl group
Two different monosaccharides are present in an alternating pattern
heteropolysaccharides
Two of the most well-known acidic polysaccharides
hyaluronic acid and heparin
Bonds of hyaluronic acid and heparin
unbranched-chain structures
- contains alternating residues of N acetyl-β-D-glucosamine and D- glucuronate
- highly viscous
- have a glass-like appearance (solution)
Hyaluronic acid
Hyaluronic acid serves as a
lubricants in the fluid of joints
Hyaluronic acid is associated with
the jelly-like consistency of the vitreous humor of the eye
Greek word “hyalos” means
glass
- a blood anticoagulant
- naturally present in mast cells
- released at the site of tissue injury
Heparin
Function of Heparin
Prevents the formation of clots in the blood and retards the growth of existing clots within the blood
Applied as an anticoagulant to the interior/exterior surface of external objects that come in contact with blood to prevent the blood from clotting
Pharmaceutical-grade heparin
Source of pharmaceutical heparin
intestinal or lung tissue of slaughter-house animals (pigs and cows)
A dietary monosaccharide or dietary disaccharide
Simple carbohydrate
are usually sweet to the taste and are commonly referred to as sugars
dietary monosaccharide or dietary disaccharide
Two types of simple carbohydrate
Natural sugar
Refined sugar
A sugar naturally present in whole foods
Natural Sugar
A sugar that has been separated from its plant source
Refined Sugar
Two important sources of natural sugars
Milk and Fresh fruit
Major sources of refined sugars
Sugar beets and Sugar cane
Refined sugars are often said to provide _____ ______ because they provide energy but few other nutrients
empty calories
Natural sugars, on the other hand, are accompanied by ______
nutrients
Wide range of biochemical functions of mono-, di-. and oligosaccharide attached through glycosidic linkages to lipid molecules (glycolipids) and protein molecules (glycoproteins)
- allowing cells to interact with invading bacteria and viruses
- enabling cells of differing function to recognize each other
A lipid molecule that has one or more carbohydrate (or carbohydrate derivative) units covalently bonded to it
Glycolipid
A protein molecule that has one or more carbohydrate (or carbohydrate derivative) units covalently bonded to it
Glycoprotein
Glycolipids called __________ and ________ occur extensively in ____ ______
- cerebrosides and gangliosides
- brain tissue
A glycoproteins that are key components of the body’s immune system response to invading foreign material
Immunoglobins
are Y-shaped proteins that recognize unique markers (antigen) on pathogens
Antibodies or Immunoglobuins
Five types of Antibodies
IgA
IgD
IgE
IgG
IgM
- secreted into mucous, saliva, tears, colustrum
- tags pathogens for destruction
IgA
- B-cell receptor
- stimulates release of IgM
IgD
- binds to mast cells and basophils
- allergy and antiparasitic activity
IgE
- binds to phagocytes
- main blood antibody for secondary responses
- crosses placenta
IgG
- fixes complement
- main antibody of primary responses
- B-cell receptor
- immune system memory
IgM