DNA(Deoxyribonucleic Acid) :DNA(Deoxyribonucleic Acid)


Genetic material of cells… :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


DNA Nucleotide :DNA Nucleotide


A HISTORY OF DNA :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)


Watson & Crick proposed… :Watson & Crick proposed… DNA had specific pairing between the nitrogen bases: ADENINE – THYMINE CYTOSINE - GUANINE DNA was made of 2 long stands of nucleotides arranged in a specific way called the “Complementary Rule”


DNA Double Helix :DNA Double Helix


DNA Double Helix :DNA Double Helix


Nitrogenous Bases :Nitrogenous Bases PURINES 1. Adenine (A) 2. Guanine (G) PYRIMIDINES 3. Thymine (T) 4. Cytosine (C)


Chargaff’s Rule :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.


BASE-PAIRINGS :BASE-PAIRINGS


Genetic Diversity… :Genetic Diversity… Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.


The Code of Life… :The Code of Life… The “code” of the chromosome is the SPECIFIC ORDER that bases occur. A T C G T A T G C G G…


DNA Replication :DNA Replication DNA must be copied The DNA molecule produces 2 IDENTICAL new complementary strands following the rules of base pairing: A-T, G-C Each strand of the original DNA serves as a template for the new strand


Slide 14:1. Why is replication necessary? 2. When does replication occur? 3. Describe how replication works. Use the complementary rule to create the complementary strand: A---? G---? C---? T---? A---? G---? A---? G---? C---? A---? G---? T---? Replication Quiz


Slide 15:1. Why is replication necessary? So both new cells will have the correct DNA 2. When does replication occur? During interphase (S phase). 3. Describe how replication works. Enzymes unzip DNA and complementary nucleotides join each original strand. 4. Use the complementary rule to create the complementary strand: A---T G---C C---G T---A A---T G---C A---T G---C C---G A---T G---C T---A Replication Quiz


(1961) Watson & Crick proposed… :(1961) Watson & Crick proposed… …DNA controlled cell function by serving as a template for PROTEIN structure. 3 Nucleotides = a triplet or CODON (which code for a specific AMINO ACID) AMINO ACIDS are the building blocks of proteins.


AMAZING DNA FACTS… :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)