מבנה הדנ"א DNA Deoxyribonucleic Acid

DNA:carries genetic information:smallest viruses = 4.5 genes, E. coli = 4000 genes, human = 30,000 genes

DNA Structure DNA is made of repeating subunits called nucleotides. Nucleotides have three parts: –Simple sugar –Phosphate group –Nitrogen base

Sugar O C C C C C 1’ 2’ 3’ 4’ 5’ The simple sugar is called: ribose and deoxyribose.

nucleoside = base + sugar

nucleotides = base + sugar + phosphate

H2OH2O Condensation reaction

A and T: 2 hydrogen bonds. G and C: 3 hydrogen bonds. Remember: The nitrogen bases are held together by hydrogen bonds

Watson and Crick First people to propose that DNA is made of two chains of nucleotides joined together by the nitrogen bases They believed that the two strands are joined by complimentary bases A-T C-G They also proposed that DNA is put together like a zipper that is twisted. When something is twisted like a spring, it is called a helix. Because DNA has two strands it is called a Double Helix.

הדנ"א מולקולה הכי יפה בעולם

הדנ"א מולקולה הכי יפה בעולם DNA is arranged in an anti-parallel configuration.

In English - E-A-R-T-H Is different than H-E-A-R-T For instance – T-A-A-G-C-A Is different than – A-G-C-A-A-G Because of the pairing- if you have one strand, it is easy to predict the replicated strand. T-A-G-C-C-G-T Would be replicated by matching T, with A, G with C A-T-C-G-G-C-A

DNA is arranged in an anti-parallel configuration.

Chargaff’s rule b “the amount of adenine present always equals the amount of thymine, and the amount of guanine always equals the amount of cytosine.” b A = T b C = G

הדנ"א מולקולה הכי יפה בעולם