Question

What would be the sequence of the strand of DNA that is made from the following template: \(5^{\prime}\) -GATATCGAT-3'? (Your answer must be written \(5^{\prime} \rightarrow 3^{\prime} .\) ) How would the sequence be different if RNA were made from this DNA template?

Short answer

The complementary DNA sequence is \(5^{\prime}\) - ATAGCTATA - \(3^{\prime}\), and the RNA sequence made from the DNA template strand would be \(5^{\prime}\) - AUAGCUAUA - \(3^{\prime}\).

Step-by-step solution

Find the complementary DNA sequence

In DNA, the bases pair with each other following the base pairing rule: A pairs with T, and C pairs with G. So, we can find the complementary DNA sequence by pairing the template strand bases with their complementary bases following this rule. The template strand is \(5^{\prime}\) - GATATCGAT - \(3^{\prime}\). By pairing each base with its complementary DNA base, we obtain the complementary sequence: \(3^{\prime}\) - C T A T A G C T A - \(5^{\prime}\) Now, reverse the sequence to make it from \(5^{\prime} \rightarrow 3^{\prime}\): \(5^{\prime}\) - ATAGCTATA - \(3^{\prime}\)

Find the RNA sequence from DNA template

In RNA, the bases pair with DNA bases following a similar rule to the DNA base pairing, except that RNA contains uracil (U) instead of thymine (T). So, the rule for RNA-DNA base pairing is A pairs with U, and C pairs with G. Pair the template strand bases with their complementary RNA bases following this rule. The template strand is \(5^{\prime}\) - GATATCGAT - \(3^{\prime}\). By pairing each base with its complementary RNA base, we obtain the complementary RNA sequence: \(3^{\prime}\) - C U A U A G C U A - \(5^{\prime}\) Now, reverse the sequence to make it from \(5^{\prime} \rightarrow 3^{\prime}\): \(5^{\prime}\) - AUAGCUAUA - \(3^{\prime}\) The complementary DNA sequence is \(5^{\prime}\) - ATAGCTATA - \(3^{\prime}\), and the RNA sequence made from the DNA template strand would be \(5^{\prime}\) - AUAGCUAUA - \(3^{\prime}\).

Key concepts

Complementary DNA Sequence

Understanding the complementary DNA sequence is crucial for comprehending how genetic information is accurately replicated and transcribed. In DNA, the strands are antiparallel, meaning one strand runs in the 5' to 3' direction, and the other runs in the 3' to 5' direction. The complementary sequence is formed by the base pairing rule, where adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).

Consider the original DNA template strand, 5′ - GATATCGAT - 3′. To find the complementary strand, we create pairs such that G pairs with C, A with T, and so on. This results in 3′ - CTATAGCTA - 5′. Reversing this sequence, as the DNA polymerase operates in a 5' to 3' manner, yields 5′ - ATAGCTATA - 3′, which is ready for further biological processes such as replication and transcription. This complementary strand guides cell processes to ensure genetic information is maintained accurately.

RNA Base Pairing

When it comes to RNA base pairing, the process is similar to DNA but with a key difference: in RNA, uracil (U) takes the place of thymine (T). As such, when RNA is synthesized from a DNA template strand during transcription, adenine (A) pairs with uracil (U) instead of thymine (T), while cytosine (C) still pairs with guanine (G).

Starting again with the DNA template strand 5′ - GATATCGAT - 3′, the RNA base pairing would occur as follows: G pairs with C, A pairs with U (not T), and so on. This results in an RNA strand 3′ - CUATAGCUA - 5′. Flipping this sequence to align with the 5' to 3' direction gives us 5′ - AUAGCUAUA - 3′, which would be the mRNA transcript used for protein synthesis. This process is vital for translating the genetic code into functional proteins within the cell.

DNA Template Strand

The DNA template strand, also known as the antisense strand, serves as the pattern for creating a complementary RNA molecule during transcription. It is essential to note that only one of the two DNA strands is used as the template for transcription, and this strand is read in the 3' to 5' direction by RNA polymerase enzymes. The strand that is not used for the template is known as the coding strand or sense strand, and it has the same nucleotide sequence as the mRNA except that it contains thymine instead of uracil.

For instance, given the template strand 5′ - GATATCGAT - 3′, RNA polymerase reads this sequence in reverse (3' to 5') to generate a complementary RNA strand. Transcription factors and RNA polymerase work together to bind to specific sequences on the DNA template strand to initiate transcription, proceeding to unwind the DNA and assemble RNA nucleotides complementary to the DNA template, which results in mRNA that carries the genetic message out of the nucleus and into the cytoplasm for protein synthesis. This entire process is fundamental to gene expression and the flow of genetic information within cells.