Translation process Explained || Protein synthesis class 12 biology || Bioscholar — Transcript

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1. 0:00You probably already know that proteins
2. 0:02are the building blocks of life. They
3. 0:04shape our muscles, strengthen our nails
4. 0:07and hair, and take part in vital tasks
5. 0:10like carrying oxygen, fighting
6. 0:12infections, and much more. But did you
7. 0:15know where do these proteins actually
8. 0:17come from? How does your body make them?
9. 0:20To answer that, we need to dive into one
10. 0:22of biologyy's most fascinating
11. 0:24processes, translation. the molecular
12. 0:27workshop where proteins are built.
13. 0:32Translation is the biological process in
14. 0:34which the sequence of nucleotides in
15. 0:36messenger RNA is decoded to assemble a
16. 0:39chain of amino acids forming a specific
17. 0:42protein. In simpler words, it's the step
18. 0:45where the genetic code written in mRNA
19. 0:48is translated into a functional protein.
20. 0:51It is the second step of the central
21. 0:53dogma and takes place in the cytoplasm.
22. 0:56Just to recap, the central dogma
23. 0:59describes how genetic information flows.
24. 1:01DNA is transcribed into mRNA and that
25. 1:05mRNA is then translated into protein.
26. 1:08For translation to happen, the cell
27. 1:10requires mRNA carrying the genetic
28. 1:14message from the nucleus. ribosomal
29. 1:17subunits, the protein building machines,
30. 1:20tRNA molecules, which bring in the right
31. 1:23amino acids and the amino acids
32. 1:25themselves, the raw material of
33. 1:27proteins. It's actually a simple yet
34. 1:30fascinating process, almost like a
35. 1:32well-coordinated game. And this game
36. 1:35unfolds in three main stages:
37. 1:38initiation, elongation, and termination.
38. 1:42Initiation is the starting point of
39. 1:44protein synthesis. Here's how it
40. 1:46unfolds. The small ribosomal subunit
41. 1:49attaches to the mRNA strand at a
42. 1:52specific site close to the start codon.
43. 1:55A codon is simply a group of three
44. 1:57nucleotides that codes for one amino
45. 1:59acid. In this case, Aug is the universal
46. 2:03start signal. A transfer RNA carrying
47. 2:06the amino acid methionine. The universal
48. 2:09start amino acid recognizes the aug
49. 2:12codon and pairs with it using its
50. 2:14anticodonin region. An anticodonin is a
51. 2:17set of three bases on the transfer RNA
52. 2:20complmentary to the codon on the mRNA.
53. 2:24This ensures accuracy because each codon
54. 2:26in the mRNA has a matching anticodon on
55. 2:29a specific tRNA and every tRNA carries
56. 2:32only its designated amino acid. The
57. 2:35large ribosomal subunit then joins the
58. 2:38complex forming a complete ribosome.
59. 2:41This structure now has three important
60. 2:43sites that control the flow of
61. 2:45translation.
62. 2:46First, a site or aminoasile site, the
63. 2:50entry point where each new transfer RNA
64. 2:52carrying an amino acid arrives. Second,
65. 2:56P site or peptidal site, the spot where
66. 2:59the growing polyeptide chain is held and
67. 3:01new bonds are formed. and the third E
68. 3:04site or exit site, the exit door where
69. 3:07empty transfer RNA molecules leave after
70. 3:10delivering their amino acid. With the
71. 3:12ribosome fully assembled and the first
72. 3:15amino acid in place at the P site, the
73. 3:17protein building machinery is ready to
74. 3:19move on to the next stage, elongation,
75. 3:22where the chain starts growing one amino
76. 3:24acid at a time. Once the initiation
77. 3:27complex is ready, the ribosome begins
78. 3:30the actual process of building the
79. 3:31protein chain. Here's how elongation
80. 3:34works step by step. After the start
81. 3:37codon is set at the P site, the ribosome
82. 3:40reads the next codon on the mRNA. A tRNA
83. 3:44carrying the corresponding amino acid
84. 3:46enters the A site and pairs its
85. 3:48anticodin with the codon on the mRNA.
86. 3:52The amino acid at the P site that is
87. 3:54methionine is joined to the new amino
88. 3:56acid at the A site by a peptide bond.
89. 3:59This reaction is catalyzed by the
90. 4:01ribosomes enzyatic activity.
91. 4:04Specifically, the peptide l transferase
92. 4:06function. This is how a peptide bond
93. 4:09forms. One amino acid has a caroxile
94. 4:12group and the next amino acid has an
95. 4:14amino group. During the reaction, the
96. 4:17hydroxal group from the caroxile end of
97. 4:20one amino acid and a hydrogen atom from
98. 4:22the amino group of the next amino acid
99. 4:25are removed. Together they form a
100. 4:27molecule of water. What's left behind is
101. 4:30a new bond between the carbon of the
102. 4:32caroxile group and the nitrogen of the
103. 4:34amino group. This bond is called a
104. 4:36peptide bond. In short, peptide bond
105. 4:40formation is a dehydration reaction that
106. 4:42links amino acids into a growing
107. 4:44polyeptide chain.
108. 4:47Now the ribosome shifts one codon
109. 4:49forward along the mRNA.
110. 4:52The tRNA that was in the P site now
111. 4:54moves to the E site and exits. The tRNA
112. 4:58that was in the A site with the growing
113. 5:00peptide chain shifts into the P site.
114. 5:03The A site is now empty, ready for the
115. 5:06next incoming tRNA.
116. 5:09This cycle, codon recognition, peptide
117. 5:12bond formation, and transllocation
118. 5:14repeats over and over, causing the
119. 5:16polyeptide chain to grow longer with
120. 5:19each round.
121. 5:25Termination is the stage where protein
122. 5:28synthesis comes to an end. Here's how it
123. 5:31happens. As the ribosome moves along the
124. 5:33mRNA, eventually it reaches a stop
125. 5:36codon. A stopcodon may be one of the
126. 5:39three. Unlike other codons, these do not
127. 5:42code for any amino acid. Instead, they
128. 5:45signal the ribosome that the protein is
129. 5:47complete. A special protein called the
130. 5:50release factor binds to the stop codon
131. 5:52in the A site of the ribosome. This
132. 5:55triggers the ribosome to cut the bond
133. 5:57between the polyeptide chain and the
134. 5:59final tRNA in the P site.
135. 6:02The newly made polyeptide chain is
136. 6:05released into the cytoplasm, ready to
137. 6:07fold into its unique 3D structure.
138. 6:11The ribosomal subunits tRNA and mRNA
139. 6:15then separate and can be recycled for
140. 6:18another round of translation. And that's
141. 6:20the complete journey of protein
142. 6:22synthesis, initiation, elongation, and
143. 6:25termination. From a simple sequence of
144. 6:28nucleotides in mRNA, the cell constructs
145. 6:31a full polyeptide chain, the foundation
146. 6:34of proteins. Later this chain undergoes
147. 6:38folding and post-transational
148. 6:39modifications transforming into a
149. 6:42functional protein that carries out
150. 6:44essential tasks in the body. But our
151. 6:46story doesn't end here. The product of
152. 6:49translation is a polyeptide chain and on
153. 6:52its own it's not yet functional. To
154. 6:54become a true protein, this chain folds
155. 6:57into a specific 3D shape guided by
156. 7:00various chemical interactions and bonds
157. 7:02such as hydrogen bonds, ionic bonds, and
158. 7:05dulfide bridges. It's this precise
159. 7:08folding that gives every protein its
160. 7:11unique shape and ultimately its unique
161. 7:13function. Once properly folded, the
162. 7:16protein may stay inside the cell to
163. 7:18perform its role or it may be
164. 7:20transported out of the cell to work
165. 7:22elsewhere in the body like enzymes in
166. 7:24digestion, antibodies in immunity or
167. 7:27hormones in signaling. And so the
168. 7:30journey of translation closes, a process
169. 7:33where molecular precision turns genetic
170. 7:35information into the very proteins that
171. 7:37power life. Each protein crafted is
172. 7:40unique, purposeful, and vital. Silently
173. 7:43shaping everything from the strength of
174. 7:45our muscles to the sharpness of our
175. 7:47thoughts. It's a reminder that even the
176. 7:50tiniest processes inside our cells carry
177. 7:52the blueprint of life's complexity and
178. 7:54beauty.