This document discusses DNA and its structure and function. It notes that DNA stores genetic information to build and maintain living organisms, and copies itself. James Watson and Francis Crick determined DNA's three-dimensional double helix structure in 1953, a seminal discovery that won them the Nobel Prize. DNA is composed of nucleotides containing deoxyribose, phosphate groups, and nitrogenous bases that pair up in a specific way between strands.

1. Made by; kush sehgal…
class xi science
r.no. 29

2. Stores genetic
information to build
and maintain a living
organism
Copies itself
2

3. Determined the three-dimensional
structure of
DNA
One of the greatest
discoveries in the history of
science
Nobel prize in 1962
3

4. 4
Deoxyribose
Phosphate
Base =

5. 5
Deoxyribose
Phosphate
Base

6. 6

7. Adenine pairs with
Thymine
Guanine pairs with
Cytosine
7

8. Total length of DNA in each
cell is about 6 feet
Wraps around proteins
called histones
Over 3 billion nucleotide
pairs in human DNA!
8

9. 9
DNA strands separate
DNA
nucleotides
attach to
each strand

10. 10

11. 11

12. 12

13. 13

14. 14

15. Replication is not 100% accurate
Errors occur when copying DNA
DNA damaged
Ultraviolet light
X-rays
Cigarette smoke
Nitrates (smoked meat)
Pesticides & Herbicides
15

16. 16