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6 (a) Describe how a section of DNA determines the structure of a protein - Edexcel - GCSE Biology - Question 6 - 2013 - Paper 1
Question 6
6 (a) Describe how a section of DNA determines the structure of a protein. (b) Describe the structure of DNA, including the roles of the scientists involved in its... show full transcript
Worked Solution & Example Answer:6 (a) Describe how a section of DNA determines the structure of a protein - Edexcel - GCSE Biology - Question 6 - 2013 - Paper 1
Step 1
Describe how a section of DNA determines the structure of a protein.
Answer
A section of DNA, known as a gene, contains the instructions for synthesizing a protein. These instructions are encoded in the sequence of nucleotides, which are the building blocks of DNA.
Each nucleotide is made up of a sugar, a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine). The sequence of these nitrogenous bases is what determines the specific sequence of amino acids in a protein during the process of translation.
The process occurs as follows:
- Transcription: The gene is transcribed into messenger RNA (mRNA) in the nucleus. This mRNA carries the genetic information from the DNA.
- Translation: The mRNA travels to the ribosome, where it is read in sets of three bases called codons. Each codon corresponds to a specific amino acid.
- Amino Acids to Protein: The sequence of amino acids forms a polypeptide chain that folds into a functional protein, determining its structure and function.
Step 2
Describe the structure of DNA, including the roles of the scientists involved in its discovery.
Answer
The structure of DNA is a double helix, which consists of two long strands formed by nucleotides spiraling around each other. Each nucleotide consists of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine).
The paired bases, adenine with thymine and cytosine with guanine, form the rungs of the helix, while the sugar and phosphate form the sides. This structure was elucidated through the work of several key scientists:
- James Watson and Francis Crick: They are credited with the discovery of the double helix structure of DNA in 1953, using a model-building approach and integrating available experimental data.
- Rosalind Franklin: Her X-ray diffraction images of DNA, particularly Photo 51, were crucial in revealing the double helix structure.
- Maurice Wilkins: He collaborated with Franklin and was instrumental in sharing her results, contributing to the understanding of DNA structure.
Together, their research laid the foundation for molecular biology and genetics.