Chapter 8 Spark Page By Joe O'Leary

Watson and Crick were two scientists that were the first people to describe what the double helix of DNA was. So they were basically trying to see what DNA really looked like and why it does what it does. They did this using X-ray diffraction and mathematics about helixes to find out what it looked like and what it was. They wrote an article called the pearl and it contained answers to some questions about living organisms. This allowed people to discover how and why hereditary diseases happened Watson had two degrees in zoology and became interested in genetics after that, which led to him studying chemistry later on in life. After discovering this Watson and Crick both went separate pathways on their careers.

Chargaffs rule stated that DNA from any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases as well as the amount of guanine is equal to cytosine. The rule also states that the amount of adenine is equal to thymine. The rule is trying to state that base amounts should be equal in order for DNA to function properly. Chargaff also had a rule saying the DNA is composed differently in species. This helps explain why there are different species and why everything doesn't look the same.

A base pair is a unit that contains two nucleobases that bond together due to hydrogen bonds. Base pairs are known as building blocks to the DNA's double helix and are reasons for the folded nature of DNA and RNA. Due to specific hydrogen bonding, base pairs allow DNA helix to maintain a regular structure that is reliant on its nucleotide sequence. Base pairs bond due to hydrogen bonding. However hydrogen bonds don't make the base pairs very stable, as base pairs become stable due to stacking reactions. In the reaction the larger nucleobases are called purines and the smaller ones are called pyrimidines and they pair with each other to form the bond.

A chromosome is a small thread-like structure that DNA is packaged into. Every chromosome is made of tightly wrapped DNA that is wrapped around proteins that support a chromosomes structure. Chromosomes are only visible during cell division when it becomes more tightly packed. Every chromosome has a point called the centromere that divides the chromosome into two sections. That allows the chromosome to take its characteristic shape and is helped used to describe the location of genes.

A karyotype is a map of a persons chromosomes. They are used usually when a chromosome genetic disorder is found in people. A karyotype shows the homologous pairs of a persons cells and since every single cell in that persons body has the same DNA, it has the same number of chromosomes so the analysis of one is more than enough.

DNA replication is a biological process of making two identical forms of DNA from the original molecule. This occurs in every single living organism and is the reason for biological inheritance. During this process the double helix of two complementary strands are separated. This then serves as the template for for the production of the replica, this is a process called semiconservative replication. Then cellular proof reading and error Checking make sure there is perfect fidelity for the new DNA. The process of the replication begins in the genome. The unwinding of DNA and the beginning of making the new strands results in replication folks. Then proteins help continue the process. Then the strands are made by DNA polymerase adding nucleotides. Then DNA replication finally occurs in the S-stage.

There are many things that can damage DNA. One of which is oxidative stress, which has many terrible effects but the worst is believed to be damage to DNA. This could then lead to numerous types of cancer. Also ultraviolet and many other types of radiation can damage DNA. This would break the strands of DNA and that would affect the expressions of a couple of genes. Hydrocarbon exposure also would lead to deterioration of DNA.

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