Exam 1 Flashcards
Identify the functions of carbohydrates in the
human body.
a. They provide energy during their oxidation and a short-term energy reserve.
b. They form part of the framework for nucleic acids and supply
carbon atoms for synthesis of other biomolecules.
c. When linked to proteins, they are involved in the cell–cell and cell–molecule recognition process, and they function asstructural components of cell membranes when linked to lipids.
d. All the above.
d. All of the above
Biochemistry, the study of the chemical
substances of living organisms, includes the study
of:
a. carbohydrates, lipids, proteins, and salts.
b. carbohydrates, lipids, proteins, and organic salts.
c. carbohydrates, lipids, proteins, and nucleic acids.
d. carbohydrates, lipids, and proteins.
C. carbohydrates, lipids, proteins, and nucleic acids.
Process in which plants produce carbohydrates
using carbon dioxide, water, and solar energy
Photosynthesis
It is estimated that more than __ of all organic
carbon atoms are found in the carbohydrate
materials of plants.
A. 50%
B. 25%
C. 100%
D.75%
A. 50%
What are some uses for for carbohydrates outside of food?
Carbohydrates in the form of cotton and linen are
used as clothing
Carbohydrates in the form of wood are used for
shelter and heating and in making paper
Most of the matter in plants, except water, is?
Carbohydrate Material.
what accounts for 75% of dry plant
material and are produced by photosynthesis?
Carbohydrates
What are 6 Functions of Carbohydrates in the Human Body?
Carbohydrate oxidation provides energy.
• Carbohydrate storage, in the form of glycogen,
provides a short-term energy reserve
• Carbohydrates supply carbon atoms for the
synthesis of other biochemical substances
(proteins, lipids, and nucleic acids)
• Carbohydrates form part of the structural
framework of DNA and RNA molecules
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
Empirical formula of simple carbohydrates -
CnH2nOn (n is the number of atoms)
Polyhydroxy aldehyde, ketone,
or a compound that produces such substances
upon hydrolysis
Carbohydrate
What contains single polyhydroxy aldehyde or ketone
unit
Monosaccharides
What cannot be broken down into simpler substances
by hydrolysis reactions
Monosaccharides
What contains 2 monosaccharide units covalently
bonded to each other
Disaccharides
Contains 3–7 C atoms
Monosaccharides
Upon hydrolysis, they produce 2
monosaccharide units
Disaccharides
5 and 6 carbon species are more common
Monosaccharides
What are Pure Monosaccharides
Water soluble white,
crystalline solids
Common Disaccharides
Table sugar (sucrose) and milk sugar (lactose)
Upon hydrolysis, they produce 2
monosaccharide units
Disaccharides
Contain three to ten monosaccharide units
covalently bonded to each other
Oligosaccharides
Free _____ are seldom encountered
in biochemical systems
Oligosaccharides
Usually found associated with proteins and lipids
in complex molecules
Oligosaccharides
Contain many monosaccharide units covalently
bonded
• Number of monosaccharide units varies from a
few 100 units to 50,000 units
Polysaccharides
Name 3 Examples of Polysaccharides
Cellulose - Paper, cotton, wood
– Starch - Bread, pasta, potatoes, rice, corn, beans,
and peas
Carbohydrates are classified as:
a. monosaccharides, disaccharides, oligosaccharides, and polysaccharides.
b. polyhydroxy aldehydes or ketones.
c. monosaccharides and disaccharides.
d. monosaccharides, oligosaccharides, polysaccharides, and polyhydroxy aldehydes or ketones.
a. monosaccharides, disaccharides, oligosaccharides, and polysaccharides
C atom attached to 4 different
groups
Chiral center
Bromochloroiodomethane is a ___ organic molecule
Chiral
A carbohydrate molecule whose mirror image is not superimposable is said to be a \_\_\_\_\_ molecule. a. achiral b. chiral c. nonidentical d. nonsuperimposable
b. chiral
Two Types of Stereoisomers
Enantiomers: Stereoisomers whose molecules are
non-superimposable mirror images of each other
• Molecules with chiral center
– Diastereomers: Stereoisomers whose molecules are
not mirror images of each other
• Example: Cis-trans isomers
What feature does a carbohydrate possess that
generates stereoisomerism?
a. Presence of a chiral center
b. Presence of structural rigidity
c. Presence of three or more carbon atoms
d. Presence of an achiral center
a. Presence of a chiral center
Two-dimensional structural notation for showing
the spatial arrangement of groups about chiral
centers in molecules
• According to this formula, a chiral center is
represented as the intersection of vertical and
horizontal lines
• Functional groups of high priority will be written
at the top
Fischer Project Formula (see slides 31-33)
• The four groups attached to the atom at the
chiral center assume a tetrahedral geometry
governed by the following conventions:
Tetrahedral Arrangements (See slide 30)
What formula is used to show the two-dimensional
structure of groups around chiral centers in a
molecule?
Fischer projection
- Vibrational Characteristics of Ordinary
Light and Plane-Polarized Light
See Slide 38
Name the properties of Ordinary light waves and Plane polarized light waves
Ordinary: Vibrate in all directions
Plane Polarized Light Waves: One direction
Dextrorotatory compound: Chiral compound
that rotates light towards ___
• Levorotatory compound: Chiral compound that
rotates light towards ___
Dextrorotatory: Right (Clockwise)
Levorotatory: Left (Counterclockwise)
Interactions Between Chiral Compounds
Check Slides 40 and 41
What is meant when it is said that carbohydrates
are optically active compounds?
a. A solution of carbohydrate when placed in a light beam
reflects the light back to the observer.
b. A solution of carbohydrate will rotate the plane of
polarized light.
c. A solution of carbohydrate will not rotate the plane of
polarized light.
d. Being optically active, they do not possess handedness.
b.A solution of carbohydrate will rotate the plane of
polarized light.
Triose
3 carbon atoms
Tetrose
4 carbon atoms
Pentoses
5 carbon atoms
Hexoses
6 carbon atoms
Aldoses:
Monosaccharides with one aldehyde
group
Ketoses:
Monosaccharides with one ketone group
Aldohexose
Monosaccharide with aldehyde group
and 6 C atom
Ketopentose
Monosaccharide with ketone group and
5 C atoms
What structural feature distinguishes an aldose
and a ketose?
a. An aldose possesses an aldehyde group, and a ketose
possesses a ketone group.
b. An aldose contains 5 carbon atoms, and a ketose
contains 6 carbon atoms.
c. An aldose possesses only –OH groups, and a ketose
possesses a carbonyl group.
d. An aldose possesses a ketone group, and a ketose
possesses an aldehyde group.
a. An aldose possesses an aldehyde group, and a ketose
possesses a ketone group.
4 Groups of Monosaccharides
Ketoses, Aldohexose, Ketopentose, Aldoses
Most abundant in nature
Most important source of human nutrition
D-Glucose
Other names for Glucose
– Dextrose
– Blood sugar
Glucose is a Six-membered cyclic form
see slide 50
Milk sugar • Synthesized in human beings • Also called brain sugar – Part of brain and nerve tissue • Used to differentiate between blood types
D-Galactose
D-Galactose is a Six-membered cyclic form
See Slide 51
Ketohexose • Sweetest tasting of all sugars – Found in many fruits and in honey • Good dietary sugar due to higher sweetness
D-Fructose
D-Fructose is a Five-membered cyclic form
See Slide 52
Part of a variety of complex molecules which include: – RNA – ATP – DNA
D-Ribose
D-Ribose is a Five-membered cyclic form
see slide 53
Which monosaccharide is the most important from
a human nutritional standpoint?
Glucose
Cyclic Hemiacetal Forms of D-Glucose
• Dominant forms of monosaccharides with 5 or
more C atoms
Cyclic structures are formed by
the reaction of
carbonyl group (C=O) with hydroxyl (–OH) group
on carbon 5
Cyclic monosaccharides that differ only in the
position of the substituents on the anomeric
carbon atom
Anomers (see slide 57, 58)
Cyclic monosaccharide containing a
five-atom ring
Furanose
Cyclic monosaccharide containing a
six-atom ring
Pyranose
Monosaccharides in nature have cyclic forms
because they can form:
a. internal acetals that are stable.
b. internal hemiacetals that are stable.
c. internal acetals that are rapidly converted to stable
hemiacetals.
d. internal hemiacetals that are rapidly converted to stable acetals.
b. internal hemiacetals that are stable.
Two-dimensional
structural notation that specifies the threedimensional structure of a cyclic form of a
monosaccharide
Haworth projection formula
α and β Configuration
Slide 64
–OH Group Position
Slide 65
Haworth projection formula for a monosaccharide
is a formula showing:
a. a line structure of a stable internal acetal.
b. a two-dimensional notation that specifies the three dimensional structure of a cyclic monosaccharide.
c. a line structure of a stable internal hemiacetal.
d. a two-dimensional notation that specifies the three dimensional structure of a stable cyclic acetal.
b. a two-dimensional notation that specifies the three dimensional structure of a cyclic monosaccharide.
Which of the monosaccharides glucose, fructose,
galactose, and ribose has each of the following
structural characteristics? (There may be more than
one correct answer for a given characteristic)
a. It is a pentose.
b. It is a ketose.
c. Its cyclic form has a 6-membered ring.
d. Its cyclic form has two carbon atoms outside the ring.
a. It is a pentose: Ribose
b. It is a ketose: Fructose
c. Its cyclic form has a 6-membered ring: Glucose,
and galactose
d. Its cyclic form has two carbon atoms outside the ring:
Fructose
Five important reactions of monosaccharides:
Oxidation to acidic sugars – Reduction to sugar alcohols – Glycoside formation – Phosphate ester formation – Amino sugar formation
- Formed when weak oxidizing agents
such as Tollens and Benedict’s solutions oxidize the
aldehyde end
Aldonic acid
Carbohydrate that gives a positive
test with Tollens and Benedict’s solutions
Reducing Sugar
Sorbitol
Used as a moisturizing agent in foods and
cosmetics and as a sweetening agent in chewing
gum
Acetal formed from a cyclic
monosaccharide by replacement of the
hemiacetal carbon –OH group with an –OR
group
Glycoside
Glycoside produced from glucose
Glucoside
Glycoside produced from galactose
Galactoside
Hydroxyl groups of a monosaccharide can react
with inorganic oxyacids to form inorganic esters
• Phosphate esters of various monosaccharides
are stable in aqueous solution and play
important roles in the metabolism of
carbohydrates
Phosphate Ester Formation
- Formed when one of the hydroxyl
groups of a monosaccharide is replaced with an
amino group
Amino sugar
Which of the following sugars can be oxidized by Tollens and Benedict’s reagents in basic conditions? a. D-glucose, an aldohexose b. D-fructose, a ketohexose c. D-mannose, an aldohexose d. All the above
d. All the above
Maltose (Malt Sugar)
See Slide 80
Cellobiose
See Slide 81
Lactose
See Slide 82
a condition in which
people lack the enzyme lactase needed to
hydrolyze lactose to galactose and glucose
Lactose intolerance
see slide 84 for more information on what happens
The most abundant of all disaccharides and
found in plants
• Produced commercially from the juice of sugar
cane and sugar beets
Sucrose (Table Sugar)
What is the linkage that is formed when two
monosaccharides react to form a disaccharide
called?
a. Alcohol group linkage
b. Glycosidic linkage
c. Hemiacetal linkage
d. Acetal linkage
b. Glycosidic linkage
Which disaccharide is a nonreducing sugar? a. Maltose b. Lactose c. Cellobiose d .Sucrose
d. Sucrose
Which of these disaccharides, i.e., maltose, cellobiose,
lactose, and sucrose, have the following structural or
reaction characteristics? (There may be more than one
correct answer for a given characteristic)
a. Two different monosaccharide units are present.
b. Hydrolysis produces only monosaccharides.
c. Its glycosidic linkage is a “head-to-head” linkage.
d. It is not a reducing sugar
a. Two different monosaccharide units are present.
Lactose, sucrose
b. Hydrolysis produces only monosaccharides.
Maltose, cellobiose, lactose, sucrose
c. Its glycosidic linkage is a “head-to-head” linkage.
Sucrose
d.It is not a reducing sugar.
Sucrose
Carbohydrates that contain 3–10
monosaccharide units bonded to each other via
glycosidic linkages
Oligosaccharides
Blood Types and Oligosaccharides
See Slide 93 and 94
Which of the following is a toxin produced by potato plants? a. Raffinose b. Stachyose c. Solanine d. None of the above
c. Solanine
Polymers of many
monosaccharide units bonded with glycosidic
linkages
Polysaccharides
Two types of Polysaccharides
– Homopolysaccharide
– Heteropolysaccharide
Not sweet and do not show
positive tests with Tollen’s and Benedict’s
solutions, whereas monosaccharides are sweet
and show positive tests
• Limited water solubility
• Polysaccharides
A _____ is a polysaccharide in which only one
type of monosaccharide monomer is present.
a. heteropolysaccharide
b. homopolysaccharide
c. heteromonosaccharide
d. homomonosaccharide
b. homopolysaccharide
Polysaccharide that is
a storage form for monosaccharides and used
as an energy source in cells
Storage polysaccharide
Glucose is the monomeric unit
– Storage polysaccharide in plants
Starch
Types of Polysaccharides Isolated From Starch
Amylose, • Amylopectin
Glucose storage polysaccharide in humans and animals • Contains only glucose units • Branched chain polymer with α(1->4) glycosidic bonds in straight chains and α(1->6) in branches • Three times more highly branched than amylopectin in starch • Contains up to 1,000,000 glucose units
Glycogen
Excess glucose in blood is stored in the form of:
Glycogen
In starch, two different glucose-containing
polysaccharides can be isolated. They are _____
and _____
a. glycogen; amylose
b. amylose; amylopectin
c. amylose; cellulose
d. glycogen; cellulose
b. amylose; amylopectin
Linear homopolysaccharide with β(14) glycosidic bond • Contains up to 5000 glucose units with molecular mass of 900,000 amu It serves as dietary fiber in food and readily absorbs water resulting in softer stools
Cellulose
Similar to cellulose structurally and functionally
• Linear polymer with all β(1->4) glycosidic
linkages
– It has an N-acetyl amino derivative of glucose
• Function is to give rigidity to the exoskeletons of
crabs, lobsters, shrimp, insects, and other
arthropods
Chitin
What is the structural component of plant cell walls? a. Starch b. Glycogen c. Chitin d. Cellulose
d. Cellulose
The Structure of Chitin
slide 112
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
• They are heteropolysaccharides, i.e., different
monosaccharides exist in an altering pattern
Acidic polysaccharides
Examples of Acidic polysaccharides
Hyaluronic acid
Heparin
Alternating residues of N-acetyl- β-Dglucosamine and D-glucuronate
• Highly viscous and serve as lubricants in the
fluid of joints as well as vitreous humor of the
eye
Hyaluronic Acid
Polysaccharide with 15–90 disaccharide
residues per chain
• Blood anticoagulant
Heparin
Heparin, a well known acidic polysaccharide, is
best known for its biochemical function as a(n)
_____.
a. coagulant
b. anticoagulant
c. exoskeleton
d. dietary fiber
b. anticoagulant
Dietary
monosaccharides or disaccharides
Sweet to taste and commonly referred to as sugars
Simple carbohydrates
Dietary
polysaccharides
– Include starch and cellulose, which are normally not
sweet to taste
Complex carbohydrates
Dietary carbohydrates constitute \_\_\_\_\_ of the diet of most people. a.10% b.25% c.35% d.50%
d. 50%
Lipid molecule that has one or more
carbohydrate (or carbohydrate derivative) units
covalently bonded to it
Glycolipid
Protein molecule that has one or
more carbohydrate (or carbohydrate derivative)
units covalently bonded to it
Glycoprotein
A protein molecule that has one or more carbohydrate units covalently bonded to it is known as a(n) \_\_\_\_\_. a. glycolipid b. glucoprotein c. glycoprotein d. oligosaccharide protein
b. glucoprotein
D-glucose consists of six carbon atoms. When drawn using the Fischer projection formula, how do you determine that it is the D isomer? How many chiral carbon centers does it have and how many stereoisomers are possible?
a. The –OH on the chiral carbon farthest from the carbonyl group points to the
right. There are five chiral centers providing 32 stereoisomers.
b. The –OH on the chiral carbon farthest from the carbonyl group points to the
right. There are four chiral centers providing 16 stereoisomers.
c. The –OH on the chiral carbon farthest from the carbonyl group points to the
left. There are five chiral centers providing 32 stereoisomers.
d. The –OH on the chiral carbon farthest from the carbonyl group points to the
left. There are four chiral centers providing 16 stereoisomers.
b. The –OH on the chiral carbon farthest from the carbonyl group points to the
right. There are four chiral centers providing 16 stereoisomers.
Prior to a marathon run, an athlete consumes large amounts of complex carbohydrates to do what is known as “carbohydrate loading.”
What happens in the body to the glucose molecules present in these complex carbohydrates and why is carbohydrate loading important?
a. The complex carbohydrates are broken down to glucose and any excess glucose, not
used for immediate energy, is stored in the form of glycogen, which can be used later as
a source of stored energy.
b. The complex carbohydrates are broken down to glucose and any excess glucose, not
used for immediate energy, is stored in the form of starch, which can be used later as a
source of stored energy.
c. The complex carbohydrates are broken down to galactose and any excess galactose,
not used for immediate energy, is stored in the form of glycogen, which can be used later
as a source of stored energy.
d. The complex carbohydrates are broken down to glucose and any excess glucose, not
used for immediate energy, is stored in the form of glycogen, which can be used later to
produce muscle tissue needed to complete the marathon.
a. The complex carbohydrates are broken down to glucose and any excess glucose, not
used for immediate energy, is stored in the form of glycogen, which can be used later as
a source of stored energy.
