
How do cells make proteins?
Answer
479.7k+ views
Hint: Proteins are the building block of an organism. They are made up of long chains of amino acid residues connected through peptide bonds. Their synthesis occurs in the ribosomes of cells.
Complete answer:
A cell is the basic unit of life that contains all the fundamental molecules in our body. It contains organs that perform all the basic functions of our body.
Proteins are large macromolecules that are polymers of amino acid residues. They can be classified into 4 types based on their protein structure- primary, secondary, tertiary, and quaternary. They perform various functions like- growth and maintenance of the body tissues, carrying out many biochemical reactions, hormonal proteins acting as messengers, provides stiffness and rigidity to the cells and tissues, maintains the pH of our body, transportation, and storage of nutrients, etc.
The synthesis of protein occurs through the coding or sequencing of the DNA molecule present in the nucleus of the cell. DNA codes for proteins through an intermediate messenger called mRNA by the process of transcription. The template or the sense strand of the DNA is transcripted into an RNA sequence. This occurs in three steps- Initiation, elongation, and termination.
1)Initiation- The DNA sequence has a promoter region consisting of recognition sites for the binding of RNA polymerase. The binding of RNA polymerase results in the separation of the double-stranded DNA. As a result, a template of ssDNA is obtained for transcription.
2)Elongation- The RNA polymerase reads the bases one by one on the template strand and creates a complementary RNA sequence of nucleotides. This RNA sequence completely resembles the non-template strand of DNA, except at the thymine position. RNA has the nitrogenous base uracil in the place of thymine.
3)Termination- The terminator molecules terminate the process of RNA transcription by sending signals and releasing the transcript from the RNA polymerase.
The mRNA molecule is further translated to code for amino acids that build up to form protein molecules. Translation, the second step of gene expression, occurs in three steps- Initiation, elongation, and termination.
Initiation- An initiation complex is formed by the initiator tRNA and a ribosome that binds to the 5’ end of the mRNA. The initiator tRNA carries the amino acid Methionine, which binds to the start codon on mRNA sequence, hence starting the translation process.
Elongation- The ribosome moves to the other codon molecule, which is bound by the specific amino acid brought by the tRNA molecule. This step leads to the elongation of the amino acid chain.
Termination- The translation process is stopped when the ribosome binds to the stop codon sequence on the mRNA chain. The stop codons do not code for any amino acids and thus leads to the release of the polypeptide chain from the mRNA sequence. This polypeptide chain or the amino acid chain is folded in various structures to form proteins.
Note: The flow of information from DNA to proteins occurs through a messenger RNA because the coding of DNA directly into proteins would lead to the loss of genetic material due to the insufficient coding amino acids. The flow of information from DNA to RNA is a reversible process, where the reverse step is called reverse transcription. The translation is the flow of information from RNA molecules to proteins and is a non-reversible step.
Complete answer:
A cell is the basic unit of life that contains all the fundamental molecules in our body. It contains organs that perform all the basic functions of our body.
Proteins are large macromolecules that are polymers of amino acid residues. They can be classified into 4 types based on their protein structure- primary, secondary, tertiary, and quaternary. They perform various functions like- growth and maintenance of the body tissues, carrying out many biochemical reactions, hormonal proteins acting as messengers, provides stiffness and rigidity to the cells and tissues, maintains the pH of our body, transportation, and storage of nutrients, etc.
The synthesis of protein occurs through the coding or sequencing of the DNA molecule present in the nucleus of the cell. DNA codes for proteins through an intermediate messenger called mRNA by the process of transcription. The template or the sense strand of the DNA is transcripted into an RNA sequence. This occurs in three steps- Initiation, elongation, and termination.
1)Initiation- The DNA sequence has a promoter region consisting of recognition sites for the binding of RNA polymerase. The binding of RNA polymerase results in the separation of the double-stranded DNA. As a result, a template of ssDNA is obtained for transcription.
2)Elongation- The RNA polymerase reads the bases one by one on the template strand and creates a complementary RNA sequence of nucleotides. This RNA sequence completely resembles the non-template strand of DNA, except at the thymine position. RNA has the nitrogenous base uracil in the place of thymine.
3)Termination- The terminator molecules terminate the process of RNA transcription by sending signals and releasing the transcript from the RNA polymerase.
The mRNA molecule is further translated to code for amino acids that build up to form protein molecules. Translation, the second step of gene expression, occurs in three steps- Initiation, elongation, and termination.
Initiation- An initiation complex is formed by the initiator tRNA and a ribosome that binds to the 5’ end of the mRNA. The initiator tRNA carries the amino acid Methionine, which binds to the start codon on mRNA sequence, hence starting the translation process.
Elongation- The ribosome moves to the other codon molecule, which is bound by the specific amino acid brought by the tRNA molecule. This step leads to the elongation of the amino acid chain.
Termination- The translation process is stopped when the ribosome binds to the stop codon sequence on the mRNA chain. The stop codons do not code for any amino acids and thus leads to the release of the polypeptide chain from the mRNA sequence. This polypeptide chain or the amino acid chain is folded in various structures to form proteins.
Note: The flow of information from DNA to proteins occurs through a messenger RNA because the coding of DNA directly into proteins would lead to the loss of genetic material due to the insufficient coding amino acids. The flow of information from DNA to RNA is a reversible process, where the reverse step is called reverse transcription. The translation is the flow of information from RNA molecules to proteins and is a non-reversible step.
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