bio class

The structure of DNA and its discovery.

Erwin Chargaff discovered that the amount of adenine was almost equal to the amountof thymine, and that the amount of guanine was almost equal to the amount of cytosin. Rosalind Franklin discovered that the structure contained rungs like a ladder. The strands were side by side, forming and "X". This means it has a double helix shape. The biology pair of Watson and Crick paired thymine with guanine, and cytosine to be a uniform structure. Each side is a complete compliment.

Words worth knowing :

Biology :a natural science concerned with the study of life and living organisms.

Nucleotide : The building blocks of nucleic acids, such as DNA and Rna. They are an organic compound made up of nitrogen base,

sugar, and phosphate group.

Base Pairs : The linking between two nitrogen bases. Links in the DNA chain.

Double Helix : The structure shape of DNA; a spiral staircase.

DNA : a type of macromolecule known as nucleic acid.

Transcription : The making of a copy of genetic info stored in DNA strands.

Translation : A step in protein biosynthesis where the genetic codes carried by mRNA is decoded.

Genes : The fundamental, physical, and functional unit of heredity.

Chromosomes : A structure within the cell that bears the genetic material.

DNA is made of four types of nucleotides, which are linked covalently into a polynucleotide chain (a DNA strand) with a sugar-phosphate backbone from which the bases (A, C, G, and T) extend. A DNA molecule is composed of two DNA strands held together by hydrogen bonds between the paired bases. The arrowheads at the ends of the DNA strands indicate the polarities of the two strands, which run antiparallel to each other in the DNA molecule. In the diagram at the bottom left of the figure, the DNA molecule is shown straightened out; in reality, it is twisted into a double helix, as shown on the right.