2. DNA - Deoxyribonucleic Acid
•Found in nucleoid of prokaryotic cells
•Found in the nucleus of all eukaryotic cells
•In mitochondria (mtDNA)
•In chloroplasts (ctDNA)
•Different segments along the DNA are
genes
• Genes - determine body function and
physical characteristics
• Genes are located on chromosomes.
• Chromosomes are made of DNA & proteins
7. STRUCTURE OF DNA
• Double stranded
– helix (twisted, curved)
– Right-handed twist
8. DNA - Double Helix Structure
1) Sides of the ladder are made up
of sugar and phosphates
2) Nitrogen bases stick out from the
sides of the ladder (rungs)
3) When the two sides (chains) of the
ladder are connected, it’s a complete
DNA molecule
9. DNA - Double Helix
4) Adenine bonds with Thymine*
5) Guanine bonds with Cytosine*
6) Hydrogen bonds connect the bases
*see next slide
10. Edwin Chargaff – 1947
Studied DNA in various species
Nitrogen bases are proportionate within a species
Ratio of bases are various between species
•Adenine and Thymine were found in proportionate amounts
•Cytosine and Guanine were found in proportionate amounts
Chargaff’s Rules
