How to Fill in the Codons That Represent Transcriptional and Translational Alignments

Within genetics, it is required to know how to crack the genetic code, or in other words, determining the amino acid sequence by going through the steps of DNA to mRNA [transcription] and then tRNA to proteins [translation]. Here is an easy step by step

Within genetics, it is required to know how to crack the genetic code, or in other words, determining the amino acid sequence by going through the steps of DNA to  mRNA [transcription] and then tRNA to proteins [translation]. Here is an easy step by step process of learning how to fill in the table to determine the sequences, allowing for the determination of the amino acids in the proteins.

1.) Suppose we have this table:

C

DNA DOUBLE HELIX

T

G

A

TEMPLATE STRAND

C

A

G

mRNA TRANSCRIBED

G

C

A

tRNA ANTICODON

TRP

TRP

AMINO ACIDS IN PROTEIN

2.) We want to complete this table by first filling in the boxes that are complementary to the given boxes. Let’s start with the Template Strand row. We know that the Template Strand is complementary to the DNA Double Helix Strand so for every C there is a G as it’s complement and vice versa and for every A there is a T to complement it and vice versa. Knowing this allows us to add in:

C

A

C

T

DNA DOUBLE HELIX

G

T

G

A

TEMPLATE STRAND

C

A

G

mRNA TRANSCRIBED

G

C

A

tRNA ANTICODON

TRP

TRP

AMINO ACIDS IN

PROTEIN

3.) After filling in these additions, the next step would be to look at the mRNA transcribed to help further fill in the empty boxes. We know that the mRNA strand in the complement of the DNA Double Helix Strand but instead of an A matching with a T, an A matches with a U and vice versa. Note: a C still matches with a G. Knowing this allows us to add in:

C

G

T

C

A

C

T

DNA DOUBLE HELIX

G

T

G

A

TEMPLATE STRAND

G

C

A

G

U

G

A

mRNA TRANSCRIBED

G

C

A

tRNA ANTICODON

TRP

TRP

AMINO ACIDS IN

PROTEIN

4.) This then allows us to fill in the Template Strand boxes that are open:

C

G

T

C

A

C

T

DNA DOUBLE HELIX

G

C

A

G

T

G

A

TEMPLATE STRAND

G

C

A

G

U

G

A

mRNA TRANSCRIBED

G

C

A

tRNA ANTICODON

TRP

TRP

AMINO ACIDS IN

PROTEIN

5.) The next step would be to look at the tRNA anticodon row. This row is the complement to the mRNA Transcribed Strand. Knowing this we can now fillin both of these rows. Note: A matches with U and C matches with G and vice versa, resulting in:

C

G

T

C

A

C

T

DNA DOUBLE HELIX

G

C

A

G

T

G

A

TEMPLATE STRAND

G

C

A

G

U

G

A

C

G

U

mRNA TRANSCRIBED

C

G

U

C

A

C

U

G

C

A

tRNA ANTICODON

TRP

TRP

AMINO ACIDS IN

PROTEIN

6.) These allows more boxes to then be filled in. now that we found some missing links in the mRNA transcribed row, we can now fill in the DNA Double Helix row and template strand of those last three columns:

C

G

T

C

A

C

T

G

C

A

DNA DOUBLE HELIX

G

C

A

G

T

G

A

C

G

T

TEMPLATE STRAND

G

C

A

G

U

G

A

C

G

U

mRNA TRANSCRIBED

C

G

U

C

A

C

U

G

C

A

tRNA ANTICODON

TRP

TRP

AMINO ACIDS IN

PROTEIN

7.) The next step to help us complete this table is to look at the last row which has the TRP [tryptophan] hints written in. This clue was given by a codon dictionary as seen here:

8.) By looking at this table to find TRP, it tells us that the genetic code for TRP is UGG. UGG can then be added into the mRNA Transcribed row:

C

G

T

C

A

C

T

G

C

A

DNA DOUBLE HELIX

G

C

A

G

T

G

A

C

G

T

TEMPLATE STRAND

G

C

A

U

G

G

U

G

A

C

G

U

mRNA TRANSCRIBED

C

G

U

C

A

C

U

G

C

A

tRNA ANTICODON

TRP

TRP

TRP

AMINO ACIDS IN

PROTEIN

9.) Step 8 shows that for every three columns, it indicates a genetic code that when looking at the codon dictionary will in turn tell you the amino acid that correlates with that code and vice versa. Knowing this, we are now able to fill in the rest of the bottom row. So for the first three columns [GCA] we would find this sequence on the codon dictionary to determine the amino acid that correlates to this codon. This can be continued for the next three, which we already know to be TRP and so on down the columns. Now the final row can be filled as indicated here:

C

G

T

C

A

C

T

G

C

A

DNA DOUBLE HELIX

G

C

A

G

T

G

A

C

G

T

TEMPLATE STRAND

G

C

A

U

G

G

U

G

A

C

G

U

mRNA TRANSCRIBED

C

G

U

C

A

C

U

G

C

A

tRNA ANTICODON

ALA

ALA

ALA

TRP

TRP

TRP

STOP

STOP

STOP

----

----

----

AMINO ACIDS IN

PROTEIN

10.) As a reminder that once a stop codon [UAA or UGA or UAG] has been reached, nothing is to come after it. Now the last step is to fill in the boxes in the third and forth column. These are skills we previously learned so this ending step should be review! The final, completed box is shown here:

C

G

T

A

C

C

A

C

T

G

C

A

DNA DOUBLE HELIX

G

C

A

T

G

G

T

G

A

C

G

T

TEMPLATE STRAND

G

C

A

U

G

G

U

G

A

C

G

U

mRNA TRANSCRIBED

C

G

U

A

C

C

A

C

U

G

C

A

tRNA ANTICODON

ALA

ALA

ALA

TRP

TRP

TRP

STOP

STOP

STOP

----

----

----

AMINO ACIDS IN

PROTEIN

CONGRATULATIONS! You have completed the steps within transcription and translation to reach the amino acid sequences by using what you know about the processes of starting with a DNA Strand, making a Template Strand, which then allows for the creation of the mRNA Strand and resulting in the tRNA Anticodon. With the help of a codon dictionary, we were able to determine the particular amino acid sequences of this entire sequence. 

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