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Chapter 18 and GHW#8
Questions
Carbohydrates
Carbohydrates
Organic compounds containing many -OH groups
(polyhydroxy), and aldehydes or ketones functional
groups. They are called sugars.
Aldoses: Aldehyde sugars are called aldoses.
Ketoses: Ketone sugars are called ketoses.
Formula for Cabohydrates:
CnH2nOn or Cn(H2O)n (hydrates of C)
n= number of atoms
Monosaccharides
They consist of one sugar containing 3,4,5,6 and 7 carbon
atoms
Disaccharides
Polysaccharides
Drawing Sugar Molecules
Linear structure-Fischer projection
CHO
Aldehyde
H
HO
OH
H
CH2 OH
O
HO
Ketone
H
H
OH
H
OH
H
OH
H
OH
CH2 OH
Glucose
Polyhydroxy
aldehyde
CH2 OH
Fructose
Polyhydroxy
ketone
Types of sugars
Number fo carbon atoms
• Triose sugar units containing three carbon atoms
• Tetroses sugar units containing four carbon tomsa
• Pentoses sugar units containing five carbon atoms
• Hexoses sugar units containing six carbon atoms
Chirality: Handedness in Molecules
Most monosaccharaides exist in
two forms: a “left handed” and
“right handed” form due to chiral
carbon atoms
CHO
CHO
HO
H
H
OH
C
C
CH2OH
CH2OH
CHO
CHO
HO
H
CH2OH
H
OH
CH2OH
Chirality and Optical Activity
D
L
L isomers
D isomers
Polarimeter assigns D and L isomers
D-rotated to right
L-rotates to left
Cyclic anomeric forms: a- and b- forms
Fischer structure
Haworth structures
ALDEHYDE sugar or aldoses + alcohol --- hemiacetal (cyclic ring)
1) Give names of the following carbohydrates.
Identify the chiral carbon atoms with *
2) Circle the correct classifications that apply to
the following carbohydrates.
2) Circle the correct classifications that apply to
the following carbohydrates.
2) Complete the names, circle carbon atom numbers of
the OH group which is on the left and the structure for
following aldohexoses.
2) Complete the names, circle carbon atom numbers of
the OH group which is on the left and the structure for
following aldohexoses.
2) Complete the names, circle carbon atom numbers of
the OH group which is on the left and the structure for
following aldohexoses.
2) Complete the names, circle carbon atom
numbers of the OH group which is on the left and
the structure for following aldohexoses.
How you get cyclic hemiacetal form of
the ketohexose sugar Dfructofuranose with b-anomeric.
How you get cyclic hemiacetal form of the
ketohexose sugar D-glucopyranose with banomeric.
4)
a) Complete the following diagram to get the cyclic
hemiacetal form of the aldohexose sugar Dglucopyranose with b-anomeric configuration.
4)
b) Draw the structure of b-D-mannopyranose
4)
c) What is the difference between
pynanose and furanose types of sugars?
d) What is the difference between a and b
forms of cyclic hemiacetal forms of sugars?
5) Convert the hemiacetal cyclic structures
(Haworth Projections) for following
carbohydrates to Fischer Projections.
a) Use the procedure we used in problem 4
to get linear form of the hexoketose sugar
from cyclic D-fructofuranose with b-anomeric
5)
b) Use the procedure we used in problem 4
to get linear form of the hexoaldose sugar
from cyclic D-sugarpyranose with a-anomeric
Glycosidic bonds
• Glycosidic bond- covalent bond between a
hemiacetal or hemiketal and an alcohol.
6) What are the following? What is/are
glucosidic linkage found in them?
a) Starch:
b) Amylopectin:
c) Glycogen:
d) Cellulose
7) Answer following question about
glycosidic bond of the di-, oligo- and polysaccharides.
a) Name of the following glucoside
8)
b) Name of the following N-Glycoside
c) Name of the following glucoside.
8)
d) The following is a part of a cellulose
polymeric chain. What is the type of glucosidic
linkage?
Nucleic Acids
phosphate-group+pentose-sugar+Base
D-Ribos
D-deoxyribose
• Deoxysugar or D-deoxyribose: ribose-derivative
with an oxygen missing on C-2.
Nucleic Acids
Bases
Purines
pyrimidines
8)
e) What is DNA? Describe the components.
8)
f) What is RNA? Describe the components.