describe the processes of transcription and translation and correctly identify the anticodon for the following DNA template strand ACG TGG GCA TGA ACG TGG
The processes of transcription and translation are key steps in the central dogma of molecular biology, which describes the flow of genetic information within a cell.
Transcription is the process by which the DNA sequence is copied into an RNA molecule. It occurs in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells. Here's how transcription works:
1. Initiation: An enzyme called RNA polymerase binds to a specific region of DNA called the promoter, which marks the beginning of a gene. The DNA strands unwind, exposing the template strand.
2. Elongation: RNA polymerase moves along the DNA template strand, synthesizing an RNA molecule by adding complementary RNA nucleotides. The RNA molecule is built in the 5' to 3' direction, using RNA nucleotides (adenine, uracil, cytosine, and guanine) that are complementary to the DNA nucleotides (thymine, adenine, cytosine, and guanine) on the template strand. For example, if the template strand has an adenine, a uracil will be added to the growing RNA molecule.
3. Termination: Transcription continues until the RNA polymerase reaches a specific DNA sequence called the terminator. At this point, the RNA polymerase detaches from the DNA, and the newly synthesized RNA molecule is released.
Translation is the process by which the RNA molecule produced during transcription is converted into a protein. It takes place in the cytoplasm of the cell, specifically on ribosomes. Here's how translation works:
1. Initiation: The ribosome binds to the start codon (AUG) on the mRNA molecule. The start codon codes for the amino acid methionine, which serves as the initiator amino acid.
2. Elongation: Ribosomes move along the mRNA molecule in a process called elongation. Transfer RNA (tRNA) molecules, which carry specific amino acids, bind to the corresponding codons on the mRNA molecule by complementary base pairing.
3. Termination: Translation continues until a stop codon (UAA, UAG, or UGA) is reached. Stop codons do not code for any amino acids but indicate the end of the protein-coding sequence. At this point, the ribosome releases the newly synthesized protein, and the translation process is complete.
Now, let's identify the anticodon for the given DNA template strand ACG TGG GCA TGA ACG TGG. During translation, tRNA molecules carry specific amino acids to the ribosome. Each tRNA molecule has an anticodon that is complementary to the codon on the mRNA. To determine the anticodon, we need to transcribe the DNA template strand into an RNA molecule and then identify the codons.
DNA template strand: ACG TGG GCA TGA ACG TGG
Transcribed RNA strand: UGC ACC CGU ACG UGC ACC
The codons can be identified by looking at the mRNA strand:
UGU - Cys (cysteine)
ACC - Thr (threonine)
CGU - Arg (arginine)
ACG - Thr (threonine)
UGC - Cys (cysteine)
ACC - Thr (threonine)
Therefore, the anticodon for the given DNA template strand is CUG (complementary to the codon AUG), which corresponds to the amino acid Methionine, serving as the initiator codon.