What Is Reverse Transcription
Reverse transcription is the process of transcribing a DNA molecule from an RNA molecule. This method of replication is utilized by retroviruses, such as HIV, and produces altered DNA, which can be incorporated directly into a host cell, allowing rapid reproduction. This is made possible by the reverse transcriptase enzyme. This can be seen in Figure 4.
Figure 4: The process of reverse transcription.
How Do You Read An Anticodon
Since codons in mRNA are read in the 5 3direction, anticodons are oriented in the 3 5 direction, as Figure 3-19 shows. Each tRNA is specific for only one amino acid and carries that amino acid attached at its free 3 end. Amino acids are added to the tRNA by enzymes called aminoacyl-tRNA synthetases.
Difference Between Transcription And Translation
Transcription and Translation Definition: The process of transcription is used to make an RNA copy of a gene sequence of the DNA. While the process of translation is used to translate the sequence of messenger RNA molecule to the amino acid sequence during the protein synthesis.
Both strategies of transcription and translation are used by a gene in order to build proteins. Transcription is the first strategy, used to rewritten the gene sequence of DNA in the RNA. While the translation is the second strategy, in which messenger RNA decodes information of gene sequence in DNA in order to build proteins, which contains a particular series of amino acids.
Explain the process of DNA Translation?
Also Check: Lesson 4.5 Practice B
Translation : Definition Steps Diagram
DNA is the genetic material of all known life from the simplest one-celled bacteria to the most magnificent five-ton elephant on the African plain. “Genetic material” refers to the molecules that contain two important sets of instructions: one for making proteins for the cell’s current needs, and the other for making copies of themselves, or replicating, so that the exact same genetic code can by used by future generations of cells.
Keeping the cell alive long enough to reproduce requires a great many of these protein products, which DNA orders via the mRNA it creates as an envoy to the ribosomes, where proteins are actually synthesized.
The encoding of genetic information by DNA into messenger RNA is called transcription, while the making of proteins on the basis of directions from mRNA is called translation.
Translation involves the cobbling together of proteins via peptide bonds to form long chains of amino acids or the monomers in this scheme. 20 different amino acids exist, and the human body needs some of each one of these to survive.
The protein synthesis in translation involves a coordinated meeting of mRNA, aminoacyl-tRNA complexes and a pair of ribosomal subunits, among other players.
The Genetic Code And Mutations
You may have already learned about mutations that involve large deletions or rearrangement of segments of DNA. These result in loss or gain of a gene and therefore, a function. What about mutations or changes in a single base pair of a codon? These are called point mutations. A classic example is a point mutation in a gene for beta globin chain.
A change in a single base pair in this gene changes the amino acid glutamine to valine. This results in a disease called sickle cell anaemia. There are other types of mutations too. Lets use the following statement with three-letter words like the genetic code, as an example:
TOM HAS BIG TOE
- Now, insert one letter in the middle TOM HAS OBI GTO E
- Now, insert two letters TOM HAS ONB IGT OE
In both the above cases, the frame of reading is shifted changing the meaning of the sentence. If similar insertions of one or two bases happen in the genetic code, the frame will shift and change the sequence of amino acids added. This is called a frameshift insertion.
- Now, delete the letter B from the above sentence TOM HAS IGT OE
- Now, delete I from the above sentence TOM HAS GTO E
Again, the frame has shifted changing the meaning of the sentence. But, this time letters were deleted, so this is a frameshift deletion. Inserting or deleting three letters adds or deletes one codon and therefore, one amino acid. This does not affect the reading frame. Lets use the above sentence as an example.
Don’t Miss: Who Are Paris Jackson’s Biological Parents
Ribosome Structure And Function
Ribosomes are macromolecular, multi-subunit structures containing RNA as well as protein and are the primary machines that drive protein synthesis. The structure of the ribosome derives primarily from it RNA component and base-pairing with mRNA and tRNA is crucial to its function.
The ribosome contains two subunits and translation is initiated when the smaller subunit binds to sequences upstream of the coding sequence on the mRNA. Prokaryotic translation begins with the rRNA directly binding to the mRNA, whereas eukaryotic translation involves other proteins called initiation factors. The smaller subunit, along with some other proteins recruit the larger subunit of the ribosome, and translation begins.
Primarily, the ribosome contains three important regions the P site, the A site and the E site formed by the three-dimensional shape of the rRNA. The P site binds to the growing polypeptide, the A site anchors an incoming charged tRNA and after peptide bond formation, the tRNA binds briefly to the E site before leaving the ribosome.
Examples Of Disorders Related To Mrna Processing
Over 200 diseases are associated with defects in the processing of pre-mRNA to mRNA. Mutations in DNA or splicing machinery majorly affect pre-mRNA splicing accuracy. For example, an abnormal DNA sequence can eliminate, weaken or activate hidden splice sites in pre-mRNA. Likewise if the splicing machinery is not working properly, the spliceosome may cut the pre-mRNA incorrectly regardless of the sequence. These mutations result in the processing of pre-mMRA to mRNAs that will go on to encode malfunctioning proteins. The abnormal mRNAs themselves are also sometimes the targets for nonsense-mediated mRNA decay as well as co-transcriptional degradation of nascent pre-mRNAs. Cells derived from patients with a variety of diseases including progeria, breast cancer and cystic fibrosis display RNA splicing defects, with cancer and neuropathological diseases being the most common.
You May Like: Unit 1 Test Study Guide Geometry Basics
Wrapping Up Translation Vs Transcription
For as powerful as it is, DNA is as good as its products. It is for this very reason that the processes of transcription and translation are so important. For a smooth operation of cell processes both the DNA sequences and the products thereof must work according to plan. This is where transcription and translation come into play and fulfill a vital purpose in the DNA function.
What Are Codon Codes
A codon is a trinucleotide sequence of DNA or RNA that corresponds to a specific amino acid. The genetic code describes the relationship between the sequence of DNA bases in a gene and the corresponding protein sequence that it encodes. The cell reads the sequence of the gene in groups of three bases.
Recommended Reading: Does Mj Have Any Biological Kids
Solved Example For You
Q1: Use the genetic code checkerboard to list the amino acid sequence resulting from the following mRNA sequence: 5-A U A G C A G G A C U U-3.
Sol: The answer is 5- isoleucine-alanine-glycine-leucine -3. If you use the checkerboard, you can see that AUA codes for isoleucine, GCA codes for alanine, GGA codes for glycine and CUU codes for leucine.
Modification Of Mrna In Eukaryotic Cells
Creating a completed mRNA molecule isnt quite as simple in eukaryotic cells. Like prokaryotic cells, the end of a transcription unit is signalled by a certain sequence of nucleotides. Unlike prokaryotic cells, however, RNA polymerase continues to add nucleotides after transcribing the terminator sequence.
Proteins are required to release the RNA polymerase from the template DNA strand and the RNA molecule is modified to remove the extra nucleotides along with certain unwanted sections of the RNA strand. The remaining sections are spliced together and the final mRNA strand is ready for translation.
In eukaryotic cells, transcription of a DNA strand must be complete before translation can begin. The two processes are separated by the membrane of the nucleus so they cannot be performed on the same strand at the same time as they are in prokaryotic cells.
Don’t Miss: Angle Addition Postulate Worksheet Answer Key
Other Differences Between Dna And Rna
At a more macro level, DNA is double-stranded while RNA is single-stranded. Specifically, DNA takes the form of a double helix, which is like a ladder twisted in different directions at both ends.
The strands are bonded at each nucleotide by their respective nitrogenous bases. This means that an “A”-bearing nucleotide can only have a “T”-bearing nucleotide on its “partner” nucleotide. This means that in sum, the two DNA strands are complementary to each other.
DNA molecules can be thousands of bases long. In fact, a human chromosome is nothing more than a single very long strand of DNA coupled with a good deal of protein. RNA molecules of all types, on the other hand, tend to be comparatively small.
Also, DNA is found primarily in the nuclei of eukaryotes but also in mitochondria and chloroplasts. Most RNA, on the other hand, is found in the nucleus and the cytoplasm. Also, as you’ll soon see, RNA comes in various types.
Synthesis Processing And Function
The brief existence of an mRNA molecule begins with transcription, and ultimately ends in degradation. During its life, an mRNA molecule may also be processed, edited, and transported prior to translation. Eukaryotic mRNA molecules often require extensive processing and transport, while prokaryotic mRNA molecules do not. A molecule of eukaryotic mRNA and the proteins surrounding it are together called a messenger RNP.
Also Check: Geometry Segment Addition Postulate Worksheet
Translation: Making Protein Synthesis Possible
- B.A., Biology, Emory University
- A.S., Nursing, Chattahoochee Technical College
Protein synthesis is accomplished through a process called translation. After DNA is transcribed into a messenger RNA molecule during transcription, the mRNA must be translated to produce a protein. In translation, mRNA along with transfer RNA and ribosomes work together to produce proteins.
Nucleotide Bases Are Translated Into 20 Different Amino Acids
RNA molecules only contain four different types of nitrogenous bases but there are 20 different amino acids that are used to build proteins. In order to turn four into 20, a combination of three nitrogenous bases provides the information for one amino acid.
Each three-base word is called a codon and the series of codons holds the information for the production of the polypeptide chain. There are a total of 64 different codons and more than one codon translates into each amino acid.
A strand of mRNA obviously has multiple codons which provide the information for multiple amino acids. A tRNA molecule reads along one codon of the mRNA strand and collects the necessary amino acid from the cytoplasm.
The tRNA returns to the ribosome with the amino acid, binds to the complementary bases of the mRNA codon, and the amino acid is added to the end of polypeptide chain as the RNA molecules move through the ribosome.
Also Check: Is Ap Physics C Hard
Translation Occurs In Ribosomes
Ribosomes are small cellular machines that control the production of proteins in cells. They are made from proteins and RNA molecules and provide a platform for mRNA molecules to couple with complimentary transfer RNA molecules.
Each tRNA molecule is bound to an amino acid and delivers the necessary amino acid to the ribosome. The tRNA molecules bind to the complementary bases of the mRNA molecule.
The bonded mRNA and tRNA are fed through the ribosome and the amino acid attached to the tRNA molecule is added to the growing polypeptide chain as it moves through the ribosome.
What Are The Stages Of Translation In Biology
Translation is a process by which the genetic code contained within a messenger RNA molecule is decoded to produce a specific sequence of amino acids in a polypeptide chain. It occurs in the cytoplasm following transcription and, like transcription, has three stages: initiation, elongation and termination.
Also Check: Ccl4 Shape
What Happens After Translation
The process of translation creates a polypeptide chain that still needs to be modified before it can work properly as a new protein. The primary structure of a protein, its amino acid sequence, represents only a small part of its eventual function.
The protein is modified after translation by folding it into specific shapes, a process that often occurs spontaneously owing to electrostatic interactions between amino acids in non-neighboring spots along the polypeptide chain.
Translation: Rna To Protein
Translation is the process by which mRNA is decoded and translated to produce a polypeptide sequence, otherwise known as a protein. This method of synthesizing proteins is directed by the mRNA and accomplished with the help of a ribosome, a large complex of ribosomal RNAs and proteins. In translation, a cell decodes the mRNAs genetic message and assembles the brand-new polypeptide chain. Transfer RNA, or tRNA, translates the sequence of codons on the mRNA strand. The main function of tRNA is to transfer a free amino acid from the cytoplasm to a ribosome, where it is attached to the growing polypeptide chain. tRNAs continue to add amino acids to the growing end of the polypeptide chain until they reach a stop codon on the mRNA. The ribosome then releases the completed protein into the cell.
DNA to protein: This interactive shows the process of DNA code being translated to a protein from start to finish!
Read Also: Molecular Shape For Ccl4
Basic Differences Between Dna And Rna
At the molecular level, DNA differs from RNA in two ways. One is that the sugar in DNA is deoxyribose, whereas in RNA it is ribose . Deoxyribose differs from ribose in that, instead of having a hydroxyl group at the number-2 carbon position, it has a hydrogen atom . Thus deoxyribose is one oxygen atom short of ribose, hence “deoxy.”
The second structural difference between the nucleic acids lies in the composition of their nitrogenous bases. DNA and RNA both contain the two purine bases adenine and guanine as well as the pyrimidine base cytosine . But while the second pyrimidine base in DNA is thymine in RNA this base is uracil .
As it happens, in nucleic acids, A binds to and only to T , and C binds to and only to G. This specific and unique complementary base pairing arrangement is required for the proper transmission of DNA information to mRNA information in transcription and mRNA information to tRNA information during translation.
What Happens After Translation In Protein Synthesis
In the process of translation, the mRNA attaches to a ribosome. Next, tRNA molecules shuttle the appropriate amino acids to the ribosome, one-by-one, coded by sequential triplet codons on the mRNA, until the protein is fully synthesized. When completed, the mRNA detaches from the ribosome, and the protein is released.
You May Like: Geometry Segment Addition Postulate Worksheet
Before Translation: Creating An Mrna Template
The oft-quoted “central dogma” of molecular biology is DNA to RNA to protein. Phrased even more succinctly, it might be put transcription to translation. Transcription is the first definitive step toward protein synthesis and is one of the ongoing necessities of any cell.
This process begins with the unwinding of the DNA molecule into single strands so that the enzymes and nucleotides participating in transcription have room to move to the scene.
Then, along one of the DNA strands, a strand of mRNA is assembled with the help of the enzyme RNA polymerase. This mRNA strand has a base sequence complementary to that of the template strand, save for the fact that U appears wherever T would appear in DNA.
- For example, if the DNA sequence undergoing transcription is ATTCGCGGTATGTC, then the resulting strand of mRNA would feature the sequence UAAGCGCCAUACAG.
When an mRNA strand is being synthesized, certain lengths of DNA, called introns, are eventually spliced out of the mRNA sequence because they do not code for any protein products. Only the portions of the DNA strand that actually code for something, called exons, contribute to the final mRNA molecule.
A Overview Of Translation
Like any polymerization in a cell, translation occurs in three steps: initiation brings a ribosome, mRNA and an initiator tRNA together to form an initiation complex. Elongation is the successive addition of amino acids to a growing polypeptide. Termination is signaled by sequences in the mRNA and protein termination factors that interrupt elongation and release a finished polypeptide. The events of translation occur at specific A, P and E sites on the ribosome .
Monocistronic Versus Polycistronic Mrna
An mRNA molecule is said to be monocistronic when it contains the genetic information to translate only a single protein chain . This is the case for most of the eukaryotic mRNAs. On the other hand, polycistronic mRNA carries several open reading frames , each of which is translated into a polypeptide. These polypeptides usually have a related function and their coding sequence is grouped and regulated together in a regulatory region, containing a promoter and an operator. Most of the mRNA found in bacteria and archaea is polycistronic, as is the human mitochondrial genome. Dicistronic or bicistronic mRNA encodes only two proteins.
What Is Transcription And Translation
Transcription and translation take the information in DNA and use it to produce proteins. Transcription uses a strand of DNA as a template to build a molecule called RNA. During translation, the RNA molecule created in the transcription process delivers information from the DNA to the protein-building machines.
Don’t Miss: Who Are Paris Jackson’s Biological Parents
Trna Structure And Function
Transfer RNA act as adapter molecules between mRNA and amino acids, bringing the appropriate amino acid to the ribosome based on mRNA codons. tRNAs contain a three-base anticodon that can recognize and bind with mRNA as well as act as a signal for the correct amino acid. The anticodon sequence is complementary to the mRNA codon, and runs in an antiparallel direction, allowing the two molecules to base pair with each other.
A group of enzymes called aminoacyl tRNA synthetases attach the appropriate amino acid to tRNA molecules based on their anticodon. There is one aminoacyl tRNA synthetase for each of the 20 amino acids and the enzyme can recognize all the anticodons that represent that particular amino acid. These enzymes use the energy from ATP to attach the amino acid to the last nucleotide on the 3 end of tRNA. The tRNA is now considered to be charged and can participate in the protein synthesizing reactions on the ribosome.