When RNA needs to be made, an enzyme called RNA polymerase unzips the DNA and pairs a nucleotide with each strand of DNA. In RNA, the base Thymine is replaced with Uracil (U). This single stranded mRNA breaks off and travels through the cytoplasm to a ribosome. In the ribosome, the RNA is read three base pairs at a time. Each three bases codes for a codon and each codon represents an amino acid. The amino acids keep adding on to the polypeptide until a stop codon is reached.
A mutation is a change in the genome. Mutations can either be harmful, give benefits, or have no affect at all. A point mutation is a mutation that changes on or two bases. A substitution is swapping one base out for another. A frameshift mutation is a deletion or insertion of a base and changes every codon that comes after the mutation.
Another concept is gene regulation and expression. In any given cell, only a fraction of the DNA is used to express a phenotype. In prokaryotic cells, a repressor is attached to the operator that prevents the RNA polymerase from reading the DNA, but the repressor detaches when lactose is present allowing the gene to be expressed. However, this process is much more complex in human cells.
This unit was not to difficult, as I found the process of making a protein and mutations fairly straightforward. The concept of gene regulation was difficult to understand and it was very complex. This unit helped me understand the last two units better, as they were also about genetics. Making the study guide helped me learn, because if forced me to answer questions and told me what I knew and did not know. This unit has helped me grow as a student, because it made me have to try harder to learn things I did not understand. A question I have about this unit is how the mRNA travels through the cytoplasm to the ribosome without getting lost.
https://commons.wikimedia.org/wiki/File:0323_DNA_Replication.jpg
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