This document provides information about nucleic acids and their structure. It discusses that nucleic acids are polymers made up of nucleotides that store and transmit genetic information. There are two main types of nucleic acids - DNA and RNA. A nucleotide consists of a nitrogenous base, a pentose sugar (ribose in RNA and deoxyribose in DNA), and a phosphate group. DNA forms a double-stranded helical structure with complementary base pairing between adenine and thymine and cytosine and guanine. RNA is typically single-stranded. The document also discusses nucleic acid function and provides examples.

1. AP Biology
Topic: Nucleic acid chemistry
By
Dr. Zablon Kerima
Lecturer
Dept. Biochemistry
Kampala International
University -Tanzania

2. AP Biology
 Nucleic acids are molecules that store information for
cellular growth and reproduction
 There are two types of nucleic acids:
- deoxyribonucleic acid (DNA) and ribonucleic acid
(RNA)
 These are polymers consisting of long chains of
monomers called nucleotides
 A nucleotide consists of a nitrogenous base, a pentose
sugar and a phosphate group:

3. AP Biology
Nucleic Acids
 Function:
 store & transmit genetic information
 Types:
 RNA (ribonucleic acid) (rRNA, mRNA, tRNA)
 DNA (deoxyribonucleic acid)
 Structure:
 monomers = nucleotides…..?
 Polymers = polynucleotides (DNA, RNA)

4. AP Biology
Nucleotides
Phosphate
Pentose
Sugar
Nitrogenous
Base

5. AP Biology

6. AP Biology
Nucleotides
 3 parts
 nitrogen base (C-N ring)
 pentose sugar (5C)
 ribose in RNA
 deoxyribose in DNA
 phosphate (PO4) group

7. AP Biology
Nucleotide structure 1 - Pentose Sugars
 There are two related pentose sugars:
- RNA contains ribose
- DNA contains deoxyribose
 The sugars have their carbon atoms numbered with
primes to distinguish them from the nitrogen bases

8. AP Biology
Sugars
O
HOCH2
5’
1’
4’
3’ 2’
O
HOCH2
OH
OH
OH
O
HOCH2
OH
H
OH
Ribose
Deoxyribose
Generic Ribose
Structure
N.B. Carbons are given numberings as a
prime

9. AP Biology
Based on McMurry, Organic Chemistry, Chapter
28, 6th edition, (c) 2003
9
Nucleotide Structure - 2
Bases: Purine and Pyrimidine
 Pyrimidine contains two pyridine-like nitrogens in a
six-membered aromatic ring (single ring)
 Purine has 4 N’s in a fused-ring structure. Three
are basic like pyridine-like and one is like that in
pyrrole (double rings)

10. AP Biology
Nitrogen Bases
 The nitrogen bases in nucleotides consist of two general
types:
- purines: adenine (A) and guanine (G)
- pyrimidines: cytosine (C), thymine (T) and Uracil (U)

11. AP Biology

12. AP Biology
Bases - Pyrimidines
N
N
5
6
1
2
3
4
Uracil
NH
N
O
U
O
H
Thymine is found ONLY in DNA.
In RNA, thymine is replaced by uracil
Uracil and Thymine are structurally similar

13. AP Biology
Nucleotide Structure - 3
Phosphate Groups
Phosphate groups are what makes a nucleoside a
nucleotide……???
Phosphate groups are essential for nucleotide
polymerization
P
O
O
O
O X
Basic structure:
Free = inorganic
phosphate (Pi)

14. AP Biology
Nucleotide : Base-Sugar-PO4
2-
P
O
O
O
O
N
N
5
6
1
2
3
4
O
C
5’
1’
4’
3’ 2’
OH
Monophosphate

15. AP Biology
Phosphate groups
are what makes a
nucleoside a
nucleotide

16. AP Biology
AMP, ADP and ATP
 Additional phosphate groups can be added to the
nucleoside 5’-monophosphates to form diphosphates
and triphosphates
 ATP is the major energy source for cellular activity

17. AP Biology
Nucleosides and Nucleotides
 A nucleoside consists of a nitrogen base linked by
a glycosidic bond to C1’ of a ribose or
deoxyribose
 Nucleosides are named by changing the nitrogen
base ending to -osine for purines and –idine for
pyrimidines
 A nucleotide is a nucleoside that forms a
phosphate ester with the C5’ OH group of ribose
or deoxyribose
 Nucleotides are named using the name of the
nucleoside followed by 5’-monophosphate

18. AP Biology
Names of Nucleosides and Nucleotides

19. AP Biology

20. AP Biology
RNA & DNA
 RNA
 single nucleotide chain
 DNA
 double nucleotide chain
 N bases bond in pairs
across chains
 spiraled in a double helix

21. AP Biology
Building the polymer

22. AP Biology
Nucleic polymer
 Backbone
 sugar to PO4 bond
 new base added to sugar of previous base
 polymer grows in one direction
 N bases hang off the
sugar-phosphate backbone
Dangling bases?
Why is this important?

23. AP Biology
Nucleic acids
 Structure / monomer
 nucleotide
 Function
 information storage
& transfer
 Examples
 DNA, RNA

24. AP Biology
DNA molecule
 Double helix
 H bonds between bases join
the 2 strands
 Adenine:: Thymine
 (A-T)
 Cytosine:: Guanine
 (C-G)
 RNA
oA-U (Uracil)
oG-C

25. AP Biology
Information polymer
 Function
 series of bases encodes information
 like the letters of a book
 stored information is passed
from parent to offspring
 need to copy accurately
 stored information = genes
 genetic information
Passing on information?
Why is this important?

26. AP Biology
A
A
A
A
T
C
G
C
G
T
G
C
T

27. AP Biology
ATP
 Adenosine triphosphate
 Adenosine
 Composed of adenine and ribose
 Triphosphate
 3 phosphate groups attached to
each other and the ribose
 ATP = High energy molecule
-supplies energy for muscle contraction and
nerve impulses
 ADP = Lower energy molecule (diphosphate)
+
+

28. AP Biology
What are the complementary
base pairs for DNA?
A. A-T and G-U
B. A-T and G-C
C. A-U and G-C
D. A-T and C-U
A
-
T
a
n
d
G
-
U
A
-
T
a
n
d
G
-
C
A
-
U
a
n
d
G
-
C
A
-
T
a
n
d
C
-
U
0%
10%
5%
86%

29. AP Biology
What is one difference between
DNA and RNA?
A. DNA has uracil and
RNA does not
B. RNA is single
stranded and DNA
is double stranded
C. DNA has 4 bases
and RNA has 5
D. DNA has a ribose
sugar and RNA
does not
D
N
A
h
a
s
u
r
a
c
i
l
a
n
d
R
N
A
.
.
.
R
N
A
i
s
s
i
n
g
l
e
s
t
r
a
n
d
e
d
a
.
.
D
N
A
h
a
s
4
b
a
s
e
s
a
n
d
R
N
.
.
.
D
N
A
h
a
s
a
r
i
b
o
s
e
s
u
g
a
r
a
.
.
5% 5%
10%
81%

30. AP Biology
What are the 3 parts of a
nucleotide?
A. 5 C sugar, carbon base,
carboxyl group
B. 3 C sugar, nitrogen base,
phosphate group
C. 5 C sugar, nitrogen base,
phosphate group
D. 5 C sugar, nitrogen base,
hydroxyl group
5
C
s
u
g
a
r
,
c
a
r
b
o
n
b
a
s
e
,
.
.
.
3
C
s
u
g
a
r
,
n
i
t
r
o
g
e
n
b
a
s
e
.
.
.
5
C
s
u
g
a
r
,
n
i
t
r
o
g
e
n
b
a
s
e
.
.
.
5
C
s
u
g
a
r
,
n
i
t
r
o
g
e
n
b
a
s
e
,
.
.
.
10%
5%
80%
5%

31. AP Biology
Which of the following supplies cellular
energy for muscle contractions and nerve
impulses?
A. DNA
B. RNA
C. ATP
D. ABC
D
N
A
R
N
A
A
T
P
A
B
C
0% 0%
95%
5%

32. AP Biology
Proteins
 Structure / monomer
 amino acids
 levels of structure
 Primary
 Secondary
 Tertiery
 Quaternary
 Function
 enzymes u defense
 transport u structure
 signals u receptors
 Examples
 digestive enzymes, membrane channels, insulin
hormone, actin and myosin, antibodies, collagen
peptide bond