Table of Contents
Learning Objective
By the end of this lecture you should be able to describe the process of translation and the types of RNA involved in translation. Remember, you are to go nowhere if you are not able to score upto 70% in the quiz.
Introduction
The ribosome is the site of this action.
Before we delve into the processes involved in Translation, I would like you to watch this video from Professor Dave. It perfectly explains Translation in a way that you will get to understand this post better.
Are you done?
Now let's delve into Translation.
Remember in the last lecture we discussed Transcription and how the mRNA is formed.
After mRNA has been formed, it moves into the cytoplasm of the cell (out through the nuclear pores) where it is quickly captured by a small Ribosome subunit.
The Ribosome then starts taking the mRNA in groups of three. We are talking about three bases here (don't forget we have four: adenine, uracil, cytosine, guanine).
When three bases have been taken up, tRNA molecules (transfer RNA) come to attach these three bases (don't also forget, they're still following the general rule of base-pairs, i.e, adenine to uracil, cytosine to guanine...).
When three bases pairs have been matched, the Ribosome moves onto the next three section of the mRNA and the former section shift sideways (outwards).
The same thing happens to the tRNA who lose their amino acids molecules to the ribosome during this process.
In summary, The Ribosome takes the mRNA in groups of three and attaches them to their specific tRNA unit (that has the exact three bases that will complement the bases in the mRNA) and as a result, amino acids are gotten from the tRNA and they are arranged as the polypeptide chain on the outside.
This occur until the Ribosome reaches one of the "stop" codes (a group of three nucleotides that signal the termination of translation). Then the ribosome releases both the polypeptide and the mRNA.
This polypeptide will then reform and begin to act as a protein in the cell's metabolism.
The steps in translation
Translation occur in three steps:
Initiation
Elongation
Termination
Initiation
- The Ribosome attaches to mRNA at a specific area.
- tRNA attaches to the start codon of the mRNA transcript.
- The start signal for translation is the codon AUG, which codes for methionine (or isoleucine). Not every protein necessarily starts with methionine, however, in so many occasions this first amino acid will be removed in later processing of the protein.
Elongation
- The ribosome starts matching tRNA anticodon sequences(three base nucleotides that is going to be paired with the ones on the mRNA) to the mRNA codon sequence (three base nucleotides on the mRNA).
- Each time a new tRNA comes into the ribosome, the amino acid that it was carrying gets added to the elongating polypeptide chain.
Termination
- The matching and pairing continues in the Ribosome until it hits a stop sequence (a group of three nucleotides that signal the termination of translation), here, it releases the formed polypeptide and the mRNA.
- The Polypeptide goes through reformation and starts acting as a functional protein in the cell.
Types of RNA
mRNA
mRNA fully known as Messenger RNA is a copy of a gene from the DNA of a cell.
It acts like a photocopy of a gene since it has a sequence complementary to one strand and identical to the other strand in the DNA.
The mRNA is essentially a messenger boy that carries information stored in the DNA to the cytoplasm where the Ribosomes can make it into protein.
tRNA
tRNA fully known as Transfer RNA is a type of RNA that has structures such that it can bind to an amino acid on one end and mRNA on the other end.
It acts as an adaptor to carry the amino acid elements of a protein to the appropriate place as coded for by the mRNA.
rRNA
rRNA fully known as Ribosomal RNA is one of the structural components of the ribosome. Its sequence is such that it complements regions in the mRNA so that the ribosome can match with and bind to an mRNA.
A ribosome has three binding sites for RNA:
A site
P site
E site
The A (aminoacyl) site [also known as entry site] is where aminoacyl-tRNA docks.
The P (peptidyl) site [also known as reaction site] is where peptidyl-tRNA binds.
The E (exit) site is where the tRNA leaves the ribosome.
Summary
☑️Translation is the process where mRNA is used to synthesize proteins.
☑️Translation occurs in the ribosome.
☑️mRNA from the nucleus is captured by the mRNA.
☑️tRNA molecules carrying amino acid molecules come to attach to each three group of nucleotides on the mRNA, releasing the amino acid molecules.
☑️Thus, protein is gotten and released from the ribosome.
Test Questions
TEST: MRNA TRANSLATION
please fill above required data
TEST: MRNA TRANSLATION
Total Questions: 20
you'll have 30 second to answer each question.
Quiz Result
Total Questions:
Attempt:
Correct:
Wrong:
Percentage:
Quiz Answers
1. A ribosome is made up of _ units
2
2. In translation...
RNA pass information from DNA for protein synthesis
3. Translation take place in which cell organelle?
Ribosome
4. tRNA is also called
Transfer RNA
5. The start codon for translation is
AUG
6. The matching and pairing of codons and anti-codons continue in ribosome until it hits _ that signal the termination of translation
Stop sequence
7. The mRNA is directly converted into proteins in the Ribosome
False
8. rRNA is fully known as
Ribosomal RNA
9. _ carries amino acids into the ribosome
tRNA
10. mRNA is captured by the _ unit of ribosome
Small
11. What happens to mRNA after translation is complete
It is degraded
12. Which comes first?
Transcription
13. Codon refers to the set of _ adjacent nucleotides in mRNA
Three
14. Anticodon refers to the sequence of 3 adjacent nucleotides located on ...
tRNA
15. The chemical bond that joins amino acids is...
Peptide bond
16. In what site of the Ribosome does tRNA enter?
A site
17. In what site of the ribosome does tRNA binds with mRNA
P site
18. In what site of the ribosome does tRNA leaves the ribosome
E site
19. The start signal during translation forms which protein?
Methionine
20. One of these is not a type of amino acid
Boline
![GENERAL QUESTIONS ON ANP 101 [MEDIUM]](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3Jdd42xekrYhc5OIwQ7vWl-_Qy9jM6WrMuuU8dhKeBulL5_YFhTnSfYfV1e6sTp2-TKsqVDbs4IJGIg1MgmOLSLqP5VfTbZ37VWa2cvRFXzezWRXRJkNnLuMpNDBKDBLbVjOG-F7uq8d-Yst4T4tZ8_fEvLG2bLenjuL0NuEbtrQuiJ_nznG3eDu0XQ/w74-h74-p-k-no-nu/20220704_063500.png)
