Amino acid

Definition

Amino acids are organic compounds that serve as the building blocks of proteins, consisting of an amino group, a carboxyl group, and a unique side chain. These side chains determine the specific properties and functions of each amino acid, influencing how proteins fold and interact within biological systems, thereby linking them to the genetic code and tRNA which play vital roles in protein synthesis.

5 Must Know Facts For Your Next Test

1. There are 20 standard amino acids that combine in various sequences to form proteins, each with unique properties due to their side chains.
2. The sequence of amino acids in a protein is determined by the genetic code, which is transcribed into mRNA and translated into protein by ribosomes.
3. tRNA molecules are crucial in bringing the correct amino acids to the ribosome based on the codon sequence present in the mRNA.
4. Amino acids can be classified as essential or non-essential; essential amino acids must be obtained through diet while non-essential can be synthesized by the body.
5. The folding and function of proteins are largely dependent on the interactions between amino acids, including hydrogen bonding, ionic interactions, and hydrophobic effects.

Review Questions

• How do amino acids link together to form proteins, and what role does tRNA play in this process?
  • Amino acids link together to form proteins through peptide bonds, which are formed during dehydration reactions. tRNA plays a crucial role in this process by carrying specific amino acids to the ribosome, where it matches its anticodon with the corresponding codon on the mRNA. This ensures that the correct amino acids are added in the proper sequence, leading to the formation of functional proteins.
• Discuss how the genetic code dictates the sequence of amino acids in a protein and its significance in protein function.
  • The genetic code is a set of rules that defines how sequences of nucleotides in DNA and RNA correspond to specific amino acids. Each codon, composed of three nucleotides, specifies one particular amino acid. This precise sequencing is crucial because even small changes can significantly affect protein folding and function, potentially leading to diseases or disorders.
• Evaluate how variations in amino acid sequences can lead to different protein structures and functions, providing examples from known proteins.
  • Variations in amino acid sequences can drastically alter protein structures and functions due to changes in interactions between side chains. For example, sickle cell hemoglobin has a single amino acid substitution (valine instead of glutamic acid), leading to a change in its structure that causes red blood cells to become misshapen. Such changes can affect oxygen transport efficiency and result in various health issues. Similarly, enzymes like lactase have specific sequences that allow them to catalyze reactions effectively; any alteration might result in reduced enzyme activity or specificity.

Related terms

peptide bond: A covalent bond formed between two amino acids during a dehydration reaction, linking them together in a polypeptide chain.

codon: A sequence of three nucleotides in mRNA that corresponds to a specific amino acid or signals termination during protein synthesis.

tRNA (transfer RNA): A type of RNA that carries amino acids to the ribosome during protein synthesis, matching the codons in mRNA with the correct amino acids.