Homework SourseProtein synthesis is vital for cell growth and metabolism De
Solution
Transcription: The ultimate function of a DNA strand is to produce proteins, for that; the DNA has to convert into RNA. In transcription, a part of the double-stranded DNA template helps for producing single-stranded RNA molecule. Only one strand of DNA serves as a template for transcription at any given time. This template strand names as the noncoding strand. The other strand refers as the coding strand because its sequence will be the identical as that of the novel RNA molecule. Transcripton helps in rises of many RNA molecusles like ribosomal RNA, non-coding RNA, transfer RNA and ribozymes. In most organisms, within the same chromosome, the strand of DNA that works as the template for one gene may be the nontemplate strand for another gene. It has following steps:
Initiation: After choosing a strand, an enzyme RNA polymerase starts to make RNA by binding to the promoter sequence of DNA strand. This is called as initiation. In this step, the enzyme needs various transcriptonsal factors for recognizing and starting the process. The enzyme moves forward in the direction 3’ to5’ by skipping the promoter when all factors bind to the strand.
Elongation: In this step, RNA polymerase codes RNA from the strand.
Termination: the termination process needs to stop the unnecessary production of RNA.
Translation: the process to produce proteins, translation is the step to make polypeptide chain(s) for protein. This step requires mRNA for template of coding sequences, a site for synthesis which is ribosome and tRNAs for every type of amino acid. The process includes following steps:
Initiation: During initiation, ribosomal units cover the mRNA for creating a complete ribosome. Now, a tRNA which has anticode of AUG for the amino acid methionine, binds to ribosome.
Elongation: it is the step of continuing the polypeotide synthesis.
Termination: this step requires stopping the synthesis. The process is regulating by stop codons, when a stop codon appears the synthesis stops.
Similarities between transcription and translation:
Both require RNA
Both processes have common procedure which follows initiation Elongation and termination.
Difference between transcription and translation:
Transcription
Translation
It synthesizes RNA
It synthesizes polypeptide chain
The RNA is as a product
It requires mRNA as a template
The template is DNA strand for transcription process
RNA is as a template
The process needs enzyme over DNA strand
No enzyme is present over RNA
Transcription factors requires for the synthesis
No factors needed.
Enzyme binds to promoter region of DNA
tRNA binds to start codon of RNA
The structural changes after translation:
Primary protein or it also calls as nascent protein. This protein form when a messenger RNA converts into polypeptide chain. Polypeptide chain is made of twenty different amino acids; these acids combine by peptide bonds. Each polypeptide chain has either N or C terminal which defines as the free amide and carboxyl group respectively.
Secondary structures: These are two types, helix and sheets. The polypeptide chain undergoes conformational changes by the connection of hydrogen bonds between peptide bonds. The -helix is formed by the H-bonding between the C=O and NH2 group at every 3 to 4 residues. This is right-handed coiled structure. The sheets formed by the H-bond attachment between residues at continuous series but this extend up to 10 amino acids. Minimum 3 amino acids are needed to form this structure. This sheet is parallel sheet when the hydrogen bonds do not form adjacent to each other. The anti-parallel forms when hydrogen bonds are present adjacent to each other.
Tertiary structure: this structure forms when the hydrophobic amino acids of polypeptide chains are fold together to form a globular structure. That names as the three-dimensional structure of protein. The structure also involves the disulfide binding. The interactions among hydrophobic amino acids call as hydrophobic interaction. This process is very important to achieve the highest stability for a particular protein.
Quaternary Structure: The protein can be monomeric or polymeric; means how many polypeptide chains are intact together. The study of Quaternary Structure reveals that how the monomers of protein interact together to form protein structure. These monomers may different or same to each other. The each monomer interact together after folded by many process; tertiary structure. These interaction forms larger proteins.
| Transcription | Translation |
| It synthesizes RNA | It synthesizes polypeptide chain |
| The RNA is as a product | It requires mRNA as a template |
| The template is DNA strand for transcription process | RNA is as a template |
| The process needs enzyme over DNA strand | No enzyme is present over RNA |
| Transcription factors requires for the synthesis | No factors needed. |
| Enzyme binds to promoter region of DNA | tRNA binds to start codon of RNA |
