Submitted By Juliiabroown
Words: 641
Pages: 3


By Julia BRown


The DNA molecule is a long polymer / chain of repeating units. The units are called monomers nucleotides that make up DNA. In the nucleotides there’s phosphate, sugar and a base. There are 4 types of bases in DNA which are the thymine, adenine, cytosine, and guanine. DNA is genetic material that identical molecules could not carry different instructions across all organisms. The same 4 bases are found in the DNA of all organisms but the proportion differs from organism to organism. In the DNA of each organism there’s an equal amount of adenine (a) to thymine (t) and equal amount of cytosine (c) to guanine (g). The structure of some proteins is shaped like a spiral or helix, so it was hypothesized that DNA might also be in the shape of a helix. DNA is shaped as an X surrounded by a circle consisting of 2 strands that are regular with a consistent width apart. Sugar phosphate are the backbones on the outside and the bases are on the inside. The DNA nucleotides of a single strand are joined together by covalent bonds that connect the sugar of one nucleotide to the phosphate of the next nucleotide. The alternating sugars and phosphates from the sides of a double helix, appearing as a twisted ladder. The double helix is held together by hydrogen bonds between bases in the middle. The hydrogen bonds are weak but together they maintain a strong DNA structure.


Replication starts when a DNA molecule unzips in both directions as nucleotide base pairs seperate then replication begins on both strands of the molecule at the same time. Now each existing strand of the DNA molecule is a template for a new strand. Nucleotides free­floating pair up with exposed bases on each template strand. DNA polymerases join the nucleotides together to make new strands. In the end two identical double­stranded DNA molecules result from replication. Each DNA molecule contains one original strand and one new strand.
Replication takes places for when a cells DNA is copied two complete and identical sets of genetic information are made.


There are few differences between RNA and DNA. RNA differs from DNA in 3 ways. First, the sugar in RNA is ribose which has one extra oxygen atom not present in DNA’s sugar
(deoxyribose). Second, RNA has the base uracil in place of thymine. Third difference between
RNA and DNA is that RNA is a single strand of nucleotides, in contrast to the double stranded…