How the DNA structure forms the genetic code, and how that genetic code comes to be expressed as a phenotype.
Get broad question.
Since this is not my area of expertise, I searched Google under the key words "DNA and genetic code" to get these possible sources:
https://www.google.com/search?client=safari&rls=en&q=DNA+and+genetic+code&ie=UTF-8&oe=UTF-8
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.
http://www.hackcollege.com/blog/2011/11/23/infographic-get-more-out-of-google.html
Don't just copy the material. Express the ideas in your own words. Although this will take more time and effort, you will learn more.
The DNA structure plays a critical role in the formation of the genetic code, which ultimately determines how the genetic information is expressed as phenotypes (observable characteristics).
The DNA molecule consists of two strands that are twisted together in a double helix shape. Each strand is made up of smaller units called nucleotides, which are composed of a sugar molecule, a phosphate group, and one of four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G). The DNA strands are held together by hydrogen bonds between complementary base pairs - A with T, and C with G.
The genetic code is essentially the sequence of these nitrogenous bases along the DNA molecule. It is this sequence that encodes the instructions for building and functioning of living organisms. The genetic code is read in groups of three consecutive bases, called codons. Each codon corresponds to a specific amino acid or a start/stop signal.
Here's how the DNA sequence is translated into a phenotype:
1. Transcription: The first step is transcription, where a specific region of DNA, typically a gene, is copied or transcribed into a molecule called messenger RNA (mRNA). This process involves an enzyme called RNA polymerase that builds a complementary mRNA strand using one of the DNA strands as a template. However, during transcription, adenine (A) in DNA is replaced by uracil (U) in mRNA.
2. mRNA Processing: Before the mRNA can be used as a template for protein synthesis, it undergoes additional processing. This includes the removal of non-coding regions called introns and the splicing together of coding regions called exons.
3. Translation: The next step is translation, which takes place on ribosomes in the cell. Transfer RNA (tRNA) molecules bring amino acids to the ribosome, guided by the codons on the mRNA. The order of codons on the mRNA determines the order in which amino acids are brought and joined together to form a polypeptide chain, the building block of proteins.
4. Protein Folding and Function: Once the polypeptide chain is synthesized, it undergoes a process called protein folding, where it takes on a specific three-dimensional structure. The folded protein's shape determines its function, such as an enzyme catalyzing a chemical reaction or a structural protein providing support for cells or tissues.
Ultimately, the combination of different proteins and their interactions leads to the development of specific phenotypes, such as eye color, hair texture, or susceptibility to certain diseases. The complex network of gene expression and interactions between proteins determine how an organism develops and functions.