DNA and Protein synthesis
Explain the double-stranded, complementary nature of DNA as related to its function in the cell.
Explain how DNA and RNA code for proteins and determine traits.
Explain how mutations in DNA that result from interactions with the environment (i.e. radiation and chemicals) or new combinations in existing genes lead to changes in function and phenotype.
DNA ( deoxyribonucleic acid ) is a double helix structure, with a Sugar and Phosphate Backbone, and made up of Nitrogen Bases (Nucleotides): Adenine, Thymine, Cytosine and Guanine. It is found in the Nucleus of the Cell. All of the 200 +cells in your body get their instructions on what do to from DNA. Each cell holds 32 DNA strands.
Mutations occur during DNA Replication due to environmental influences, such as radiation therapy, or can occur by chance. There are three different types of mutations.
1. Deletion: One nitrogen base is removed, and this causes a change in the entire sequence.
2. Addition: An extra nitrogen base is copied into the sequence.
3. Substitution: Wrong nitrogen base is copied into the sequence.
Some environmental influences like smoking and exposure to radiation can cause a mutation in the DNA. Some examples of Genetic Diseases due to Mutations are: Down Syndrome, Heart Disease and Phenylketonuria, along with various types of cancers.
Protein Synthesis involves both RNA and DNA, and begins in the Nucleus and later occurs in the ribosomes located throughout the cell. A cell functioning properly is able to create hundreds of protein a second.
Enzymes are used to help unzip the DNA strand, so that RNA can be created. RNA is made as a direct copy of the needed sequence of DNA, and this RNA is sent to different parts of the cell to gather amino acids to synthesize the proteins. Now called mRNA, it moves out of the nucleus into the Cytoplasm, where transfer RNA (tRNA) and ribosomes help add Amino Acids to the RNA. Once the chain has grown long enough, it folds into a 3 Dimensional Shape and is now able to function as a protein.
Even the most simplest change in a sequence can result in a very different phenotype or genotype. A phenotype is a physical trait (eye color) while a Genotype is seen in a person's Genetic Code.
DNA determines your traits through the alleles, found on every gene. Everyone has two alleles for each trait, one from their mother and one from their father. Whether or not a trait is recessive or dominant will determine what trait you have (Ex: Blue eyes are dominant, brown eyes recessive).
Punet Squares are a useful way to determine traits.