DNA Deoxyribonucleic Acid
Components of DNA
- There are FOUR nitrogen bases
- Adenine, Thymine, Guanine and Cytosine
- G=C (three hydrogen bonds)
Complementary Base Pairs
Pyrimidine vs. Purine
- If you were to stretch the DNA of one cell it would be 6 feet long.
- All of your DNA would reach the moon!
- DNA has a special mechanism of getting all that DNA into the cell
- It is called supercoiling.
- TRY THE ACTIVITY!!! (If time permits)
- chromatin – DNA strands populated with proteins; found in eukaryotes (humans)
- -prokaryotic DNA is commonly referred to as being “naked” (bacteria)
- histones – proteins that bind to eukaryotic DNA
- DNA backbone has a negative charge (phosphate group)
- histones bind to DNA due to a positive charge
200 bp 8 histones single histone DNA strand nucleosome
- approximately every ~200 bp of DNA is associated with a group of histones
- nucleosomes are organized in a stacked spiral structure
- the solenoid fibre is known as the 30 nm fibre
- supercoiling – twisting and compacting to form mitotic chromosomes