this ppt describe the structure of DNA and RNA. it is best for those who are basic to cell biology and molecular biology. especially for first year students in life sciences.

1. 1
Lecture: 5
Cell biology
Instructor: Shahid Zadran

2. Two types of Nucleic Acids
• 1) De-oxy Ribonucleic acid
• 2) Ribonucleic Acid
2

3. 3
DNA
• It is linear polymer ‫خطی‬ ‫پلیمر‬
.
• Mad up 4 specific
Nucleotides (
‫از‬
۴
‫نوکلوتاید‬ ‫نوع‬
‫هستند‬ ‫خاص‬
)
• DNA is macromolecule which
contain information (
‫اطالعات‬
)
for protein synthesis and cell
structure of living organism

4. 4
Monomer of Nucleic Acids
‫اسیدها‬ ‫نوکلیک‬ ‫منومرهای‬
• The monomer of DNA
and RNA are called
Nucleotide ‫نوکلیوتاید‬.
• Nucleotide have three
parts:
• 1. nitrogenous base
• 2. Pentose sugar
• 3. phosphate group

5. 5
Sugar in DNA and RNA
‫قند‬
(
‫ای‬ ‫این‬ ‫دی‬
)
‫و‬
(
‫ای‬ ‫این‬ ‫ار‬
)
• DNA have
deoxyribose
sugar
• RNA have
Ribose
Sugar

6. 6
Nitrogenous Bases
• Nitrogenous bases occur in two
shapes:
• 1) purine: have two rings (
‫حلقه‬ ‫دو‬
)
structure (Adenine,Guanin)
• 2) pyrimidine: have single ring
structure
(thymine,cytosine,uracil)

7. 7
Nitrogenous Bases

8. 8
nitrogenous bases
• Cytosine C
• Thymine T
• Adenine A
• Guanine G
DNA has four different bases:

9. Nucleoside
• Sugar + Nitrogenous base is called
Nucleoside.
9

10. 10
Chargaff’s Rule:
• Adenine and Thymine
always join together
A T
• Cytosine and Guanine
always join together
C G
The Number of Adenine always
equal to thymine and guanine
always equal to cytosine in a

11. Bonds in Nucleotide
11

12. Primary Structure of DNA
. (
‫ای‬ ‫این‬ ‫دی‬ ‫در‬ ‫اولیه‬ ‫ساختار‬
)
12

13. Primary structure of Nucleic
acid
• Nucleotides of DNA and RNA are
linked through a covalent bond called
phosphodiester bond.
• This make a long chain of
polynucleotides and are called primary
structure of DNA or RNA
• POLYMERIZATION occur in 5c 3c
direction.
13

14. 14

15. Secondary structure of DNA
‫ای‬ ‫این‬ ‫دی‬ ‫در‬ ‫دوم‬ ‫ساختار‬
• Proposed by Watson and Crick in 1953
• Called DNA double helix
structure (
‫ای‬ ‫دوګانه‬ ‫پیچ‬ ‫مار‬ ‫ساختار‬
)
• Nitrogenous bases are towards
center
• Purine will always bind with pyrimidine
through hydrogen bonds.
• Purine with purine or pyrimidine with
pyrimidine can not bind with each 15

16. Secondary structure
• A=T have two hydrogen bonds
• G---C have three hydrogen bonds
• The two chains in double helix will be
anti-parallel.
• It means one strand will be (5-3)
from top to bottom, and the other
will be from (5-3) from bottom to
top.
16

17. 17

18. Minor and Major Groove
‫بزرګ‬ ‫دهانه‬ ‫و‬ ‫کوچک‬ ‫دهانه‬
• Double helix of DNA form two groove
called minor and major grove.
18

19. DNA Packaging
‫ای‬ ‫این‬ ‫دی‬ ‫بندی‬ ‫بسته‬
19

20. 20

21. Nucleosome
21