05-02-2013, 01:01 PM
DNA(Deoxyribonucleic Acid)
DNA.ppt (Size: 3.67 MB / Downloads: 37)
Genetic material of cells…
GENES – units of genetic material that CODES FOR A SPECIFIC TRAIT
Called NUCLEIC ACIDS
DNA is made up of repeating molecules called NUCLEOTIDES
A HISTORY OF DNA
Discovery of the DNA double helix
A. Frederick Griffith – Discovers that a factor in diseased bacteria can transform harmless bacteria into deadly bacteria (1928)
B. Rosalind Franklin - X-ray photo of DNA.
(1952)
C. Watson and Crick - described the DNA molecule from Franklin’s X-ray.
(1953)
Chargaff’s Rule
Adenine must pair with Thymine
Guanine must pair with Cytosine
Their amounts in a given DNA molecule will be about the same.
Genetic Diversity…
Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.
DNA Replication
Semiconservative Model:
1. Watson and Crick showed: the two strands of the parental molecule separate, and each functions as a template for synthesis of a new complementary strand.
AMAZING DNA FACTS…
DNA from a single human cell extends in a single thread for almost 2 meters long!!!
It contains information equal to some 600,000 printed pages of 500 words each!!!
(a library of about 1,000 books)