Chapter 7: Carbohydrates Flashcards
are the most abundant class of bioorganic molecules on planet Earth.
Carbohydrates
Carbohydrates’ A abundance in the human body is relatively ___
Low
2 biochemical substances
Bioinorganic substances
Bioorganic substances
Substances that do not contain carbon
Bioinorganic substances
Substances that contain carbon
Bioorganic susbtances
carbohydrates
constitute about ___ by mass of ___ ___ materials.
-75%
- dry plant
Composition of bioinorganic substances
Water (70%)
Inorganic salts (5%)
Composition of Bioorganic susbtances
Proteins (about 15%)
Lipids (about 8%)
Carbohydrates (about 2%)
Nucleic acids (about 2%)
How do green (chlorophyll-containing) plants produce carbohydrates?
Via photosynthesis
Two main uses for the carbohydrates in
plants:
- In the form of cellulose
- In the form of starch
carbohydrates serve as structural elements
Cellulose
they provide energy reserves for the plants
Starch
Dietary ___ of plant materials is the major ____ source for ___
and ____.
- intake
- carbohydrate
- humans
-animals
The average human diet should ideally be about _____ carbohydrate
by mass.
- two-thirds
Functions of carbohydrates in humans:
- Carbohydrate oxidation provides energy
- (Glycogen) provides a short-term energy reserve
- Carbohydrates 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 (ribose,deoxyribose)
- 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.
Carbohydrate storage, in the form of ____, provides a short-term energy reserve.
glycogen
structural components of cell membranes.
(carbohydrates linked to) lipids
function in a variety of cell–cell and cell–molecule recognition processes.
(Carbohydrates linked to) Proteins
General formula of most simple carbohydrates
CnH2nOn
the basis for the term carbohydrate (“hydrate of carbon”)
Cn(H2O)n
A carbohydrate is a ____ ____, a ____ ____, or a compound
that ___ polyhydroxy aldehydes or polyhydroxy ketones upon ____.
-polyhydroxy aldehyde
-polyhydroxy ketone
-yields
-hydrolysis
Carbohydrates are classified on the ___ _ _____ __.
basis of molecular size
Types of carbohydrates
- Monosaccharide
- Disaccharide
- Oligosaccharide
- Polysaccharide
a carbohydrate that contains a single polyhydroxy aldehyde or
polyhydroxy ketone unit.
Monosaccharide
Monosaccharide;
- cannot be broken down into ____ ___ by _____ reactions.
- _________, white, _____ ____
-simpler units
-hydrolysis
- water-soluble, white, crystalline solids
is a carbohydrate that contains two monosaccharide units covalently bonded to each other
Disaccharide
properties of dissaccharides
Like monosaccharides, disaccharides are crystalline, water-soluble substances.
examples of disaccharides
Sucrose (table sugar)
Lactose (milk sugar)
Hydrolysis of a disaccharide produces
two monosaccharides units
a carbohydrate that contains 3-10 monosaccharide units covalently bonded to each other.
Oligosaccharide
are seldom encountered in biochemical systems.
“free” oligosaccharides
“free” oligosaccharide are usually found associated with ____ and ____ in complex molecules that have both ____ and _____ functions.
- proteins
- lipids
- structural and regulatory
Complete hydrolysis of an oligosaccharide produces
several monosaccharide
molecules
-a trisaccharide produces
-a hexassacharide produces
-3 monosaccharide
-6 monosaccharides
a polymeric carbohydrate that contains many monosaccharide units covalently bonded to each other
polysaccharide
The number of monosaccharide units present in a polysaccharide varies from a ____ ____ ___ to over ____ units.
few hundred units to over 50,000
By definition, each member of a pair of stereoisomers must have
- the same molecular formula and
- same bonding pattern
D- and L- differ in the ____ ____ of atoms in the molecule
- spatial arrangements
two possible isomeric forms
stereoisomers
The prefixes ___ and ___found in the complete name of a monosaccharide
D- and L-
carbon atom that has four different groups bonded to it
Chiral carbon
are images that coincide at all points when the images are laid upon each other.
Superimposible mirror images
are images where not all points coincide when the images are laid upon each other.
Nonsuperimposable mirror images
The Importance of Chirality
- Sometimes both forms are biologically active, each form giving a different response;
- Sometimes both elicit the same response, but one form’s response is many times greater than that of the other; and
- Sometimes only one of the two forms is biochemically active.
a compound that has n chiral centers may exist in a maximum of __ ______ ____.
- 2^n stereoisomeric forms
types of constitutional isomers
-Skeletal isomers
- Positional isomers
- functional isomers
Types of stereoisomers
enantiomers and diastereomers
stereoisomers that are not mirror images of each other
Diastereomers
types of diastereomers
Cis-trans isomers
is a compound that rotates the plane of polarized light.
optically active compound
is a chiral compound that rotates the plane of polarized light in a clockwise direction.
dextrorotatory compound
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
1. Aldose
2. Ketose
Biochemically important monosaccharides
- D-Glucose
- D-Galactose
- D-Fructose
- D-Ribose
- Found in high amounts
in ripe fruits - Blood sugar
D-Glucose
D-Glucose is also called
Dextrose
- seldom encountered as a
free monosaccharide - Synthesized from glucose in the body for the production of lactose
D-Galactose
a disaccharide of
glucose and galactose
Lactose