How does the changes in the DNA code from CTT to CAT in the beta chain of haemoglobin affect cell activity?
To understand how changes in the DNA code can affect cell activity, we need to delve into the process of protein synthesis. The DNA code contains instructions for producing proteins, which are essential for various cellular functions. In this case, we are specifically looking at the beta chain of hemoglobin, an important protein in red blood cells responsible for oxygen transport.
The DNA code is transcribed into a messenger RNA (mRNA) molecule, which then undergoes translation to synthesize the protein. During translation, each three-letter code, called a codon, in the mRNA is matched with a corresponding three-letter code, called an anticodon, on a transfer RNA (tRNA) molecule. Each tRNA molecule carries a specific amino acid.
In the case of the beta chain of hemoglobin, the original DNA code sequence is CTT. This corresponds to the mRNA codon GAA. During translation, the tRNA molecule with the anticodon CUU recognizes this codon and carries the amino acid leucine, adding it to the growing protein chain.
Now, let's consider the changes in the DNA sequence from CTT to CAT. This single point mutation alters the mRNA codon to GAU. During translation, the tRNA molecule with the anticodon CAU now recognizes this codon and carries the amino acid histidine, instead of leucine, to be added to the growing protein chain.
This change in the amino acid sequence can have significant consequences for the structure and function of the resulting protein, in this case, the beta chain of hemoglobin. Amino acids have different properties, and their arrangement determines the protein's overall shape and function.
Since histidine has different chemical properties compared to leucine, the alteration in the amino acid sequence may disrupt the normal folding of the beta chain of hemoglobin. This could potentially affect the protein's ability to bind and transport oxygen efficiently.
Furthermore, alterations in the beta chain of hemoglobin can lead to structural abnormalities, such as in sickle cell disease, where a single change in the amino acid sequence causes the hemoglobin to form abnormal shapes, resulting in red blood cell deformation and impaired oxygen transport.
In conclusion, changes in the DNA code, such as the mutation from CTT to CAT in the beta chain of hemoglobin, can affect cell activity by altering the amino acid sequence of the protein. This can impact the structure and function of the protein, potentially leading to significant consequences for cellular processes.