Problem 12 - Biology: Concepts and Applications

Question

Each amino acid is specified by a set of _____ bases in an mRNA transcript. a. 3 b. 20 c. 64 d. 120

Step-by-Step Solution

Answer

Each amino acid is specified by a set of 3 bases in an mRNA transcript, corresponding to option a.

Step 1: Understanding the Relationship

To determine how many bases in an mRNA transcript specify an amino acid, it is important to remember the concept of codons. In genetics, a codon is a set of three nucleotide bases in mRNA that corresponds to a specific amino acid in the protein synthesis process.

Step 2: Reviewing the Answer Choices

Look at the options provided: a. 3, b. 20, c. 64, and d. 120. From your understanding, you know that each codon is made up of three bases, corresponding to option a.

Step 3: Confirming through the Genetic Code

The genetic code shows that there are 64 possible codons (combinations of the four RNA bases: adenine (A), uracil (U), cytosine (C), and guanine (G)), but each codon is indeed made up of 3 bases.

Step 4: Selecting the Correct Answer

Based on the understanding that a codon consists of 3 bases and specifies one amino acid, the correct answer is option a. 3, as it directly corresponds to the number of bases forming a single codon.

Key Concepts

mRNA transcript

The process of transcription is a vital step in converting the genetic information coded within DNA into a format that can be read and translated into proteins. This is where messenger RNA, or mRNA, comes into play. During transcription, the DNA sequence of a gene is copied into mRNA. This mRNA transcript is essentially a single-stranded copy containing the genetic instructions that will be used to build proteins.
Here's how it works:

• DNA serves as the template, and enzymes called RNA polymerases read this template to synthesize a complementary strand of mRNA.
• The mRNA strand is complementary to the DNA sequence, but instead of thymine (T), it contains uracil (U).
• Once formed, the mRNA transcript leaves the nucleus and travels to the ribosome, where protein synthesis occurs.

mRNA is crucial because it bridges the gap between the DNA in the nucleus and the protein construction sites in the cytoplasm. It's like a "bluprint" that conveys the instructions of the genetic code directly to the areas where proteins are assembled.

genetic code

The genetic code is often compared to a universal language, conveying information essential for life. It is the set of rules by which the information encoded in mRNA is decoded into proteins. Each three-base sequence on the mRNA, known as a codon, specifies a particular amino acid or a stop signal in protein synthesis.

Key features of the genetic code include:

• It consists of 64 codons representing the 20 amino acids, along with start and stop signals.
• Each amino acid can be encoded by more than one codon, making the code redundant but ensuring that errors (mutations) often don't affect protein formation.
• The code is almost universal across all organisms, meaning the same codon tends to encode the same amino acid in all living beings.
• It is both "unambiguous", as each codon specifies only one amino acid, and "degenerate", since multiple codons can specify the same amino acid.

The genetic code provides the instructions for building proteins, which are crucial for cell structure and function. Without it, cells wouldn't be able to produce the enzymes and structural components necessary for life.

nucleotide bases

Nucleotide bases are the building blocks of mRNA and indeed all nucleic acids, including DNA. There are four types of nucleotide bases in RNA: adenine (A), uracil (U), cytosine (C), and guanine (G). These bases pair with each other in specific ways to form the rungs of the nucleic acid structure.

Understanding nucleotide bases is vital for grasping how genetic information is encoded:

• In DNA, adenine pairs with thymine (T) and cytosine with guanine. In RNA, uracil replaces thymine.
• The sequence of these bases stores vast amounts of genetic information, and the particular sequence of nucleotides in mRNA will dictate the protein synthesized.
• The order of nucleotide bases in a triplet, or codon, determines which amino acid is added next during protein synthesis.

Nucleotide bases are the letters in the genetic alphabet, forming the words (codons) and sentences that dictate how proteins are made. This makes them fundamental to genetics, molecular biology, and life processes as a whole.