Question

What determines the base sequence of all types of RNA?

Short answer

The base sequence of all types of RNA is determined by the base sequence of DNA through the process of transcription.

Step-by-step solution

- Understand RNA basics

RNA (ribonucleic acid) is a nucleic acid similar to DNA. It plays a crucial role in coding, decoding, regulation, and expression of genes. The base sequence of RNA is composed of adenine (A), cytosine (C), guanine (G), and uracil (U).

- Identify the source of the RNA sequence

The base sequence of RNA is determined by the base sequence of DNA. During a process known as transcription, a segment of DNA is used as a template to produce an RNA sequence. This RNA sequence is complementary to the DNA template strand.

- Learn the transcription process

Transcription begins when RNA polymerase binds to a specific segment of the DNA called the promoter. RNA polymerase then unwinds the DNA and synthesizes an RNA strand that is complementary to the DNA template strand by matching RNA nucleotides (A, C, G, U) with their complementary DNA bases (T, G, C, A respectively, replacing thymine (T) with uracil (U)).

- Complementary base pairing rules

The pairing rules for transcription are: Adenine (A) pairs with Uracil (U), and Cytosine (C) pairs with Guanine (G). Knowing these rules helps to understand the sequence of the RNA that is formed.

Key concepts

RNA structure

RNA, or ribonucleic acid, is an essential molecule in the cells of all living organisms. Just like DNA, RNA is made up of nucleotides, but there are some key differences:

• RNA is single-stranded, whereas DNA is double-stranded.
• RNA contains the sugar ribose, while DNA contains deoxyribose.
• Instead of thymine (T), RNA nucleotides include uracil (U).

The structure of RNA allows it to perform a variety of functions, such as coding for proteins, acting as a messenger, and even catalyzing biochemical reactions. There are different types of RNA within the cell, including mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA), each serving a unique purpose in the gene expression process.

transcription process

Transcription is the process through which an RNA strand is synthesized from a DNA template. This critical process occurs within the cell nucleus and involves several key steps:
First, RNA polymerase enzyme binds to a specific DNA sequence called the promoter. The promoter signals the beginning of a gene.
Once bound, RNA polymerase begins to unwind the DNA helix, exposing the template strand.
As transcription progresses, RNA polymerase matches RNA nucleotides to the DNA bases on the template strand, forming a strand of RNA that is complementary to the DNA.
The RNA strand elongates until RNA polymerase reaches a terminator sequence, signaling the end of the gene.
The newly synthesized RNA strand then detaches from the DNA template, completing the transcription process.
This RNA strand can now carry genetic information from the DNA to the ribosome, where it will be translated into a protein.

complementary base pairing

Complementary base pairing is a fundamental principle in both DNA and RNA synthesis. The bases in nucleic acids pair in a specific manner to ensure accurate genetic information transfer.
In DNA, the bases pair as follows:

• Adenine (A) pairs with Thymine (T)
• Cytosine (C) pairs with Guanine (G)

In RNA, the pairing rules are similar but with a key difference:

• Adenine (A) pairs with Uracil (U)
• Cytosine (C) pairs with Guanine (G)

During transcription, the RNA sequence formed is complementary to the DNA template strand. For example, if the DNA template sequence is 5'-ATCG-3', the RNA sequence will be 3'-UAGC-5'.
This specific pairing ensures that the genetic code is accurately transcribed from DNA to RNA, maintaining the integrity of genetic information through cellular processes.