Chapter 27, Problem 1P

(a)

Summary Introduction

To predict: The amino acid sequences of peptides formed by ribosomes in response to the given $\text{mRNA}$ sequences GGUCAGUCGCUCCUGAUU.

Introduction:

The biosynthesis of protein is done with the help of messenger RNA (mRNA). The proteins are encoded by the genetic codons. The ribosomes are present in biological decoding machinery. These ribosomes link specific amino acids in a sequence which is specified by codons.

Explanation of Solution

Explanation:

The amino acids specify by $\text{mRNA}$ sequences are as follow:

GGU CAG UCG CUC CUG AUU

Gly–Gln–Ser–Leu–Leu–Ile

Here, the codon GGU specifies the glycine amino acid, CAG specifies glutamine, UCG specifies serine, CUC and CUG both specify amino acid leucine. The amino acid Isoleucine is specified by the codon AUU. Thus, the amino acids which specify the mRNA sequence are glycine, glutamine, leucine, serine and isoleucine.

(b)

Summary Introduction

To determine: The amino acid sequences of peptides formed by ribosomes in response to the given $\text{mRNA}$ sequences UUG GAU GCG CCA UAA UUU GCU.

Introduction:

Biological decoding machinery consists of the ribosomes. The similar types of genetic codes are present in all living organisms. The total numbers of codons present in individuals are 64 in number which includes the 20 amino acids

Explanation of Solution

Explanation:

The amino acids specified by the mRNA sequences are as follow:

UUG GAU GCG CCA UAA UUU GCU

Leu – Asp – Ala – Pro – stop (UAA is a stop codon)

The codon UUG specifies theleucine amino acid, GAU specifies aspartic acid, GCG specifies alanine, CCA specify amino acid proline and UAA act stop codon which also stops the further protein synthesis. Thus, the amino acids which are specified by codons are leucine, aspartic acid, alanine and proline. The codon UAA is the stop codon which stops the synthesis of protein.

(c)

Summary Introduction

To determine: The amino acid sequences of peptides formed by ribosomes in response to the given mRNA sequences CAUGAUGCCUGUUGCUAC. 

Introduction:

There are some amino acids which are encoded by more than one codon. All the living organisms consist of similar type of genetic codes. The proteins are synthesized by the genetic codons.

Explanation of Solution

Explanation:

The amino acids specify by mRNA sequences are as follow:

CAU GAU GCC UGU UGC UAC

His–Asp–Ala–Cys–Cys–Tyr

The codon CAU specifies the histidine amino acid, GAU specifies aspartic acid, GCC specifies alanine, both UGC codons specify amino acid cysteine and UAC specifies tyrosine. Thus, the mRNA sequence specifies the amino acid histidine, aspartic acid, alanine, cysteine and tyrosine.

(d)

Summary Introduction

To determine: The amino acid sequences of peptides formed by ribosomes in response to the given mRNA sequences AUG GAC GAA..

Introduction:

These ribosomes link specific amino acids in a sequence which is specified by codons. Individuals consists of total numbers of 64 codons are which includes the 20 amino acids. This is because there are some amino acids which are coded by more than one codon.  

Explanation of Solution

Explanation:

The amino acids specify by mRNA sequences are as follow:

AUG GAC GAA

Met–Asp–Glu in eukaryotes and fMet–Asp–Glu in prokaryotes

AUG specifies the methionine amino acid, GAC specifies aspartic acid, GAA specifies glutamate. In prokaryotes, AUG specifies methyl methionine. Thus, the amino acids methionine, aspartic acid and glutamate are coded by the codons present in mRNA sequence.