Chapter 7, Problem 13WIO

Refer to the figure to answer these questions:

a. Add labels for mRNA (including the 5' and 3' ends) and tRNA. In addition, draw in the RNA polymerase enzyme and the ribosomes, including arrows indicating the direction of movement for each.

b. What are the next three amino acids to be added to polypeptide b?

c. Fill in the nucleotides in the mRNA complementary to the template DNA strand.

d. What is the sequence of the DNA complementary to the template strand (as much as can be determined from the figure)?

e. Does this figure show the entire polypeptide that this gene encodes? How can you tell?

f. What might happen to polypeptide b after its re lease from the ribosome?

g. Does this figure depict a prokaryotic or a eukaryotic cell? How can you tell?

Summary Introduction

To add:

The labels for $\text{m-RNA}$(including $5^{\prime }$ and $3^{\prime }$ ends) and $\text{t-RNA}$. In addition, draw in the RNA polymerase enzyme and the ribosome including arrows indicating the direction of movement of each.

Concept introduction:

A polypeptide chain is formed during the process of translation. In this process, the $\text{m-RNA}$ sequence is decoded into ribosome that helps in the joining amino acids together and initiates the process of formation of polypeptide chain and protein synthesis. The $\text{m-RNA}$ sequence is obtained from the transcription process.

Explanation of Solution

Pictorial representation: Fig.1: The nucleotide sequence

Fig.1: The nucleotide sequence.

Explanation:

The $\text{m-RNA}$ sequence which is copied from template DNA is from $5^{\prime }\to 3^{\prime }$ and during the process of transcription the RNA polymerase binds at the promoter region and initiates the formation of $\text{m-RNA}$. The transfer RNA is bind with the anticodon. It carries amino acid that is coded by codon. For example: In the given figure, $\text{UGA}$ is transfer RNA. Whereas, the $\text{m-RNA}$ is decoded into ribosome and it helps to bind amino acid together to form a polypeptide chain.

Summary Introduction

To determine:

What are next three amino acids to be added in polypeptide b.

Concept introduction:

A polypeptide chain is formed during the process of translation. In this process, the $\text{m-RNA}$ sequence is decoded into ribosome that helps in the joining amino acids together and initiates the process of formation of polypeptide chain and protein synthesis. The $\text{m-RNA}$ sequence is obtained from the transcription process.

Explanation of Solution

Pictorial representation: Fig.1: The nucleotide sequence

Fig.1: The nucleotide sequence.

Explanation:

Amino acid is an organic compound which serves as the basic building block of protein. It binds together with peptide bond to form protein, which performs specific function in body. It codes for amino acid methionine, serine and valine.

Summary Introduction

To fill:

The nucleotide in the $\text{m-RNA}$ complementary to the template DNA strand.

Concept introduction:

A polypeptide chain is formed during the process of translation. In this process, the $\text{m-RNA}$ sequence is decoded into ribosome that helps in the joining amino acids together and initiates the process of formation of polypeptide chain and protein synthesis. The $\text{m-RNA}$ sequence is obtained from the transcription process.

Explanation of Solution

Pictorial representation: Fig.1: The nucleotide sequence

Fig.1: The nucleotide sequence.

Explanation:

The $\text{m-RNA}$ is formed by a template strand during the process of transcription and is always complementary to each other. In the above mentioned figure, the template strand is $3^{\prime }\to 5^{\prime }$ and the complementary $\text{m-RNA}$ formed is $5^{\prime }\to 3^{\prime }$. The nucleotide sequence for $\text{m-RNA}$ is $\text{GUUAGGACACC}$.

Summary Introduction

To determine:

What is the sequence of DNA, which is complementary to the template strand.

Concept introduction:

A polypeptide chain is formed during the process of translation. In this process, the $\text{m-RNA}$ sequence is decoded into ribosome that helps in the joining amino acids together and initiates the process of formation of polypeptide chain and protein synthesis. The $\text{m-RNA}$ sequence is obtained from the transcription process.

Explanation of Solution

Pictorial representation: Fig.1: The nucleotide sequence

Fig.1: The nucleotide sequence.

Explanation:

The template DNA strand is $\text{GAATCCTGTGG}$ and its complementary DNA sequence is $\text{CTTAGGACACC}$. The template strand is $3^{\prime }\to 5^{\prime }$ and complementary DNA strand is $5^{\prime }\to 3^{\prime }$.

Summary Introduction

To determine:

Does this figure show the entire polypeptide that this gene encodes. How can you tell this.

Concept introduction:

A polypeptide chain is formed during the process of translation. In this process, the $\text{m-RNA}$ sequence is decoded into ribosome that helps in the joining amino acids together and initiates the process of formation of polypeptide chain and protein synthesis. The $\text{m-RNA}$ sequence is obtained from the transcription process.

Explanation of Solution

Pictorial representation: Fig.1: The nucleotide sequence

Fig.1: The nucleotide sequence.

Explanation:

No, this is not the entire polypeptide chain that is coded by gene because this chain only contains initiation codon such as $\text{AUG}$ that codes for amino acid methionine, but there is no such stop codon present in the polypeptide chain. Hence, the polypeptide chain will extend till the stop codon terminating the protein synthesis.

Summary Introduction

To determine:

What might happen to polypeptide b after it releases from ribosome.

Concept introduction:

A polypeptide chain is formed during the process of translation. In this process, the $\text{m-RNA}$ sequence is decoded into ribosome that helps in the joining amino acids together and initiates the process of formation of polypeptide chain and protein synthesis. The $\text{m-RNA}$ sequence is obtained from the transcription process.

Explanation of Solution

Pictorial representation: Fig.1: The nucleotide sequence

Fig.1: The nucleotide sequence.

Explanation:

When polypeptide b is released from ribosome, the process of protein synthesis is terminated and complete protein is synthesized and ready for gene expression. Ribosome helps in binding amino acids together to form a polypeptide chain.

Summary Introduction

To determine:

Does this figure depict the prokaryotic or eukaryotic cell. How can you tell.

Concept introduction:

A polypeptide chain is formed during the process of translation. In this process, the $\text{m-RNA}$ sequence is decoded into ribosome that helps in the joining amino acids together and initiates the process of formation of polypeptide chain and protein synthesis. The $\text{m-RNA}$ sequence is obtained from the transcription process.

Explanation of Solution

Pictorial representation: Fig.1: The nucleotide sequence

Fig.1: The nucleotide sequence.

Explanation:

This figure represents the prokaryotic cell because in prokaryotic cell, both the transcription and translation process occur simultaneously, while in eukaryotic cell, the transcription and translation processes occur at different space and time.