Question

Describe the steps to transcribe an mRNA molecule and use the mRNA molecule to produce proteins.

Answer 1

Transcription and translation are the two main processes in protein synthesis. Transcription produces a complementary mRNA from the DNA template, and after processing, the mRNA is used in translation to form a protein. Protein synthesis involves initiation, elongation, and termination, followed by mRNA processing, translation, and folding of the polypeptide.

Step-by-step explanation:

Overview of Transcription and Protein Synthesis

Protein synthesis begins with the critical process of transcription, during which a segment of DNA is used to create a complementary mRNA molecule. This occurs in the following steps:

Initiation: Transcription factors and RNA polymerase bind to DNA at the promoter region of a gene, unwinding the DNA strand.

Elongation: RNA polymerase moves along the DNA template strand, adding complementary RNA nucleotides to grow the mRNA strand.

Termination: The RNA polymerase reaches a stop signal in the DNA sequence and releases the newly synthesized mRNA strand.

In eukaryotes, the new mRNA undergoes processing which may include splicing, editing, and polyadenylation.

The processed mRNA then travels out of the nucleus into the cytoplasm.

Once in the cytoplasm, translation takes place:

A ribosome attaches to the mRNA.

Transfer RNA (tRNA) molecules with attached amino acids recognize specific codons on the mRNA through their anticodons and bind to the mRNA, bringing the appropriate amino acids into place.

As the ribosome moves along the mRNA, amino acids are joined together forming a polypeptide chain.

The folding of the polypeptide into its functional three-dimensional structure results in the final protein.

Answer 2

Step-by-step explanation:

The genes in DNA encode protein molecules, which are the "workhorses" of the cell, carrying out all the functions necessary for life. For example, enzymes, including those that metabolize nutrients and synthesize new cellular constituents, as well as DNA polymerases and other enzymes that make copies of DNA during cell division, are all proteins.

In the simplest sense, expressing a gene means manufacturing its corresponding protein, and this multilayered process has two major steps. In the first step, the information in DNA is transferred to a messenger RNA (mRNA) molecule by way of a process called transcription. During transcription, the DNA of a gene serves as a template for complementary base-pairing, and an enzyme called RNA polymerase II catalyzes the formation of a pre-mRNA molecule, which is then processed to form mature mRNA (Figure 1). The resulting mRNA is a single-stranded copy of the gene, which next must be translated into a protein molecule.

During translation, which is the second major step in gene expression, the mRNA is "read" according to the genetic code, which relates the DNA sequence to the amino acid sequence in proteins (Figure 2). Each group of three bases in mRNA constitutes a codon, and each codon specifies a particular amino acid (hence, it is a triplet code). The mRNA sequence is thus used as a template to assemble—in order—the chain of amino acids that form a protein

But where does translation take place within a cell? What individual substeps are a part of this process? And does translation differ between prokaryotes and eukaryotes? The answers to questions such as these reveal a great deal about the essential similarities between all species.