Question

Compare the codons with a purine, either \(A\) or \(G\), as the second base. Do the majority of the amino acids specified by these codons have hydrophilic or hydrophobic side chains?

Short answer

Answer: The majority of amino acids specified by codons with a purine at the second base have hydrophilic side chains.

Step-by-step solution

Identify the codons with a purine as the second base

In this step, we will list down all the possible codons with a purine (either Adenine (A) or Guanine (G)) as the second base. Codons with A in the second position: NAY, NAG Codons with G in the second position: NGY, NGG *Note: N represents any of the 4 nucleotides (A, U, G, C)

Look up the genetic code table

We will consult a genetic code table to determine which amino acids are specified by the codons we identified in step 1. Codons with A in the second position: - NAY: Asn (Asparagine) or Tyr (Tyrosine), depending on the first and third nucleotides - NAG: Gln (Glutamine) or Lys (Lysine), depending on the first and third nucleotides Codons with G in the second position: - NGY: Ser (Serine) or Cys (Cysteine), depending on the first and third nucleotides - NGG: Arg (Arginine), variable third nucleotide

Classify amino acids based on their side chain properties

We will classify the amino acids specified by the codons with a purine in the second position as either hydrophilic or hydrophobic based on their side chain properties. Hydrophilic amino acids: - Asn (Asparagine) - Tyr (Tyrosine) - Gln (Glutamine) - Lys (Lysine) - Ser (Serine) - Arg (Arginine) Hydrophobic amino acid: - Cys (Cysteine)

Answer the question

Comparing the number of hydrophilic and hydrophobic amino acids specified by codons with a purine in the second base: Hydrophilic: 6 Hydrophobic: 1 We can conclude that the majority of amino acids specified by these codons have hydrophilic side chains.

Key concepts

Codons with Purine Bases

Understanding the significance of purine bases within codons is key to deciphering the genetic code. Each codon consists of three nucleotides and serves as a template for synthesizing a specific amino acid.

When we look closely at codons with a purine, adenine (A) or guanine (G), as the second base, we embark on a journey through the intricacies of genetic language. The possibilities for the codons are variant, with the 'N' representing any nucleotide (A, U, G, or C), resulting in codons such as NAY and NAG for adenine, and NGY and NGG for guanine as the second base.

These codons with purine bases play a pivotal role in the syntheses of proteins. The genetic code table, an essential tool in molecular biology, reveals which amino acids correspond to these codons. It's fascinating to see how the specific placement of purine bases influences amino acid selection and thus, the protein's properties.

Hydrophilic and Hydrophobic Amino Acids

Peering into the world of amino acids, one can classify them based on the nature of their side chains into hydrophilic (water-loving) and hydrophobic (water-fearing). These characteristics determine how amino acids interact with the aqueous environment within cells.

Understanding Hydrophilicity

Hydrophilic amino acids like asparagine (Asn), tyrosine (Tyr), glutamine (Gln), lysine (Lys), serine (Ser), and arginine (Arg) possess side chains that can form hydrogen bonds with water molecules, making them soluble in water. These amino acids are attracted to the aqueous environment and tend to be located on the exterior of proteins, interacting with the cell's watery milieu.

Understanding Hydrophobicity

On the other hand, hydrophobic amino acids such as cysteine (Cys) have side chains that repel water, preferring to associate with each other within the protein core. These amino acids are integral to maintaining the structural integrity of proteins. They enable the complex folding required to create functional and biologically active proteins.

Nucleotide Base Pairing

Nucleotide base pairing is the foundation of the DNA double helix structure and is crucial for the stability of the genetic code. These pairings follow specific rules where adenine (A) always pairs with thymine (T), and guanine (G) pairs with cytosine (C) in DNA.In the context of RNA, which plays a critical role during protein synthesis, adenine pairs with uracil (U) instead of thymine.

Role in Genetic Code

The precise pairing ensures accurate replication and transcription processes, allowing genetic information to be reliably passed from DNA to RNA. During translation, the mRNA codons are read by the ribosome, aligning with their complementary anticodons on the tRNA, which brings the corresponding amino acids for protein synthesis. This orderly operation ultimately leads to the accurate expression of proteins, dictating everything from physical traits to enzyme functions within an organism.