DNA Structure and Function Chapter 8

Before the thought of a double-helix, scientists have started the puzzle and completed all of it except for one piece till 1963, when James Watson and Francis Crick revolutionized the thought of DNA. Watson and Crick suspected DNA to be in the shape of a double-helix and unknowingly, completed the puzzle of DNA. Their original model has been changed, but the model has ultimately remained the same.

Watson and Crick, February 28, 1953

Before the double-helix would be thought of, before the puzzle of DNA would be completed, one man helped change the thought of DNA for years to come. Erwin Chargaff found two very important rules about DNA. Rule I: the amounts of thymine and adenine are identical, as are the amounts of cytosine and guanine (T = A & C = G)

Erwin Chargaff
Chargaff's Rule

The bonds of DNA are two sugar-phosphate chains, the bonds between the sugar and the phosphate form the backbone of the DNA. Hydrogen bonds between the strands hold them together., while only two kinds of base pairing can bond, A to T and G to C.

Diagram of base pairs bond

A chromosome is a structure that is made of DNA and proteins, which carries part or all of the cells genetics. Each chromosome during one cell life had one DNA molecule, and when the cell divides, the chromosome duplicates. After replication, the chromosome consists of two molecules. The human body has 23 sets of chromosomes, and 46 chromosomes.

Diagram of chromosome

A karyotype is an image of one's diploid chromosomes.

Diagram of karyotype

Before division, all cells copy their chromosomes, forming two sets, it's called DNA replication. During DNA replication, enzymes break the hydrogen bonds that hold the DNA together, causing them to unwind and separate. Different enzymes then form primers, which then attach to points of the DNA, and reassembles the strand of DNA. The new establishment of forming new base pairings is called Nucleic Acid Hybridization.

Replication cannot occur when a DNA strand is damage. DNA can become damaged from ionizing radiation from x-ray waves, UV light, and gamma rays.

Diagram of DNA Damage
Created By
Miles Ventura
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