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🦠microbiology review

Glycine

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Glycine is the smallest and simplest amino acid, consisting of a single hydrogen atom attached to a central carbon atom. It is a nonessential amino acid, meaning the body can synthesize it, and it plays crucial roles in protein structure, neurotransmission, and various metabolic processes.

5 Must Know Facts For Your Next Test

  1. Glycine is the most abundant amino acid in collagen, a protein that provides structural support and strength to connective tissues like skin, bone, and cartilage.
  2. Glycine is a key component of the cell membrane, where it helps maintain the integrity and fluidity of the lipid bilayer.
  3. In the central nervous system, glycine acts as an inhibitory neurotransmitter, helping to regulate neuronal excitability and muscle tone.
  4. Glycine is involved in the synthesis of various important molecules, including creatine, heme, and purines (components of DNA and RNA).
  5. Disruptions in glycine metabolism have been linked to certain neurological disorders, such as non-ketotic hyperglycinemia, a rare genetic condition that can lead to seizures and developmental delays.

Review Questions

  • Explain the role of glycine in protein structure and function.
    • Glycine is a critical amino acid for protein structure due to its small size and lack of a side chain. Its small size allows it to fit into tight spaces within protein structures, and it is often found in turns and bends of the protein backbone. Glycine's flexibility and lack of steric hindrance enables it to adopt conformations that would be sterically unfavorable for larger amino acids. This makes glycine an important contributor to the secondary and tertiary structures of proteins, which are essential for their proper folding and biological functions.
  • Describe the significance of glycine as an inhibitory neurotransmitter in the central nervous system.
    • In the central nervous system, glycine acts as an inhibitory neurotransmitter, helping to regulate neuronal excitability and muscle tone. Glycine binds to specific receptors on postsynaptic neurons, causing the opening of chloride channels and the hyperpolarization of the cell membrane. This inhibits the generation of action potentials, reducing the likelihood of the neuron firing and transmitting a signal. The inhibitory effects of glycine are particularly important in the spinal cord and brainstem, where it plays a role in controlling reflexes and muscle coordination. Disruptions in glycine neurotransmission have been linked to neurological disorders, such as non-ketotic hyperglycinemia, highlighting the critical function of glycine in the proper functioning of the nervous system.
  • Analyze the broader metabolic roles of glycine beyond its functions in protein structure and neurotransmission.
    • In addition to its roles in protein structure and neurotransmission, glycine is involved in a variety of other metabolic processes that are essential for overall health and homeostasis. Glycine is a precursor for the synthesis of important molecules such as creatine, heme, and purines, which are components of DNA and RNA. Creatine plays a crucial role in energy production and muscle function, while heme is a vital component of hemoglobin and various enzymes. The synthesis of purines is necessary for the production of genetic material and the regulation of cellular processes. Furthermore, glycine helps maintain the integrity of cell membranes and contributes to the regulation of acid-base balance in the body. Disruptions in glycine metabolism can therefore have far-reaching consequences, affecting multiple physiological systems and leading to various pathological conditions.