Chapter 8 Spark Page Bobby Kiaer

Watson and Crick - in the 1950s they suspected that DNA was a helix. They officially discovered DNA to be a double helix structure on February 28th, 1953. Watson and Crick worked tirelessly on finding out the structure of DNA. Their discovery revolutionized the study of biology.

Watson and Crick

Chargaff Rule - this was founded by Erwin Chargaff in 1950. Chargaff made two discoveries about DNA and made those discoveries into rules. The first rule was that the amounts of thymine and adenine are equal, and the amounts of cytosine and guanine are also equal and identical. The second rule stated that the DNA of different species differs in its proportions of adenine and guanine.

The Chargaff Rule

How do the base pairs bind? Base pairs bind because the stands of DNA match and are complementary. The base of each nucleotide on one strand pairs with a capable partner asked on the other one. The base pairing patterns are A to T and G to C and these are the same in all molecules that have DNA.

Base pairs bonding

What is a chromosome? A chromosome is a structure that consists of DNA and any associated proteins. Chromosomes usually consist of one DNA molecule and each species has a characteristic chromosome number.

A chromosome explained

What is a karyotype? A karyotype is an image of an individual’s diploid set of chromosomes. It is the number of chromosomes in a given species.

A karyotype

How does DNA replicate? DNA replication is known as the process in which a cell copies its DNA. DNA replicates by a double helix being unwound and every strand acts as a template and model for the following strand. The DNA is then replicated when the bases are synthesized to new partner strands. DNA replication makes the chromosome have have two DNA molecules. The main way the DNA replicates is because the a cell copies it chromosomes. The process starts with an enzyme breaking the hydrogen bonds that hold the double helix structure together and two DNA strands break apart and separate. Then the enzyme creates primers and they work as attachment points for the DNA.

The process of DNA replication

What damages DNA? DNA is damaged by several things like ionizing radiation from x rays, gamma rays, and UV light. These things break DNA, cause covalent bonds to form between opposite strands, it causes adjacent nucleotide dimers to form, and it fatally changes nucleotide bases.

DNA being damaged in many ways

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