Steps in Protein Synthesis
1. A. Transcription
- Transcription is the first part of the central dogma of molecular biology: DNA → RNA. It is the transfer of genetic instructions in DNA to mRNA. During transcription, a strand of mRNA is made to complement a strand of DNA.
Steps of Transcription
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Transcription takes place in three steps: initiation, elongation, and termination.
a.) Initiation is the beginning of transcription. It occurs when the enzyme RNA polymerase binds to a region of a gene called the promoter. This signals the DNA to unwind so the enzyme can “read” the bases in one of the DNA strands. The enzyme is ready to make a strand of mRNA with a complementary sequence of bases.
b.) Elongation is the addition of nucleotides to the mRNA strand.
c.) Termination is the ending of transcription. The mRNA strand is complete, and it detaches from DNA.
2. E. mRNA links to ribosome
- After mRNA leaves the nucleus, it moves to a ribosome, which consists of rRNA and proteins. The ribosome reads the sequence of codons in mRNA,
3. B. tRNA amino acids units links to mRNA
- Molecules of tRNA bring amino acids to the ribosome in the correct sequence.
4. C. amino acid separate from tRNA
- While bound to mRNA, tRNA gives up its amino acid.
5. D.Polypeptide chain assembled
- With the help of rRNA, bonds form between the amino acids as they are brought one by one to the ribosome, creating a polypeptide chain.
6. F. Stop codon encountered in mRNA
- The chain of amino acids keeps growing until a stop codon is reached.
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What is Protein Synthesis?
Protein synthesis is the process in which cells make proteins. It occurs in two stages: transcription and translation.
Transcription- is the process during which a DNA sequence of a gene is copied to make an RNA molecule. It includes three steps: initiation, elongation, and termination.
Translation- is the process during which an mRNA molecule is used to assemble amino acids into polypeptide chains.
For additional information about this process, just click this link: What is the function of RNA polymerase in protein synthesis? https://brainly.ph/question/2123385
Processing mRNA
- Splicing- removes introns from mRNA. Introns are regions that do not code for the protein. The remaining mRNA consists only of regions called exons that do code for the protein.
- Editing- changes some of the nucleotides in mRNA. For example, a human protein called APOB, which helps transport lipids in the blood, has two different forms because of editing. One form is smaller than the other because editing adds an earlier stop signal in mRNA.
- Polyadenylation- adds a “tail” to the mRNA. The tail consists of a string of As (adenine bases). It signals the end of mRNA. It is also involved in exporting mRNA from the nucleus, and it protects mRNA from enzymes that might break it down.
Key terms
RNA (ribonucleic acid)- Single-stranded nucleic acid that carries out the instructions coded in DNA
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Central dogma of biology-The process by which the information in genes flows into proteins: DNA → RNA → protein
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Polypeptide-A chain of amino acids
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Codon- A sequence of three nucleotides that corresponds with a specific amino acid or start/stop signal during translation.
Messenger RNA (mRNA)- Carries information from DNA in the nucleus to ribosomes in the cytoplasm
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Ribosomal RNA (rRNA)- Structural component of ribosomes
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Transfer RNA (tRNA)- Carries amino acids to the ribosome during translation to help build an amino acid chain
DNA or deoxyribonucleic acid- is a long molecule that contains our unique genetic code.
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