1. Describe the structure of DNA. DNA stands for Deoxyribonucleic acid and looks like a spiral. The spiral is also known as a double helix. The strands are made up of our genetic information, composed of genes and chromosomes. There are four bases divided among purines and pyrimidines. On the purines there are Adenine (A) and Guanine (G). On the pyrimidines there are Cytosine (C) and Thymine (T). The base pairs are Adenine and Thymine (A-T) and Cytosine and Guanine (C-G). DNA is found in the nucleus of every human cell. Humans have 46 chromosomes. When a cell reproduces, the chromosomes get copied and distributed to each offspring.
2. How does an organism’s genotype determine its phenotype? The genes are transcribed to produce mRNA. The mRNA is translated to produce proteins. The proteins are more often than not enzymes,that catalyze reactions that would otherwise take forever to happen. These reactions involve the formation of products that are functioning in the cell for various things such as structural support, fibers, cytoskeleton, channels on membrane, enzymes that metabolize food molecules like glucose, energy production, transport, signal systems, pigmentation, attachment to other cells and more.
These together, work in an orchestrated manner to produce characters that we can physically see. For example, there is a gene that produces protein involved in the production of melanin (skin pigment). When this gene is mutated or non-functional, the enzyme is not produced. Hence, the pathway of melanin production is shut down and that person does not produce any melanin pigment. This is what we see and call as albinism, the people without any pigment in their skin, hair and eyes
3. Describe each stage of the flow of information starting with DNA and ending with a trait.
DNA molecules store the necessary instructions for building a protein macromolecule. These instructions are copied from the DNA molecule into the form of an RNA molecule. One or many copies can be made of these instructions. Each of these m RNA copies move away from the DNA templates and enter the cytoplasm of the cell, where they encounter the machinery that will convert the biological information into the correct linear sequence of amino acids that will become a functioning protein.
Once the protein has been assembled and folded it can go to work. In the example of the red-color trait, this protein is in the form of an enzyme catalyst that enhances and speeds up the chemical reaction producing the red pigment. As the protein goes to work the trait is produced. In this example, the trait is the red color seen in the petals of the flower.
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