BIOMOLECULES PROTEINS скачать в хорошем качестве

BIOMOLECULES PROTEINS

Amino Acids: The monomeric units of proteins. There are 20 standard amino acids used by living organisms to build protein chains. Elemental Makeup: Proteins primarily consist of carbon, hydrogen, oxygen, and nitrogen; many also contain sulfur (found in amino acids like cysteine). Peptide Bonds: Amino acids are linked together in a specific sequence by covalent peptide bonds to form long chains called polypeptides. Directionality: Every protein chain has an N-terminus (free amino group) and a C-terminus (free carboxyl group). 2. Hierarchical Structure A protein’s function is entirely dependent on its three-dimensional shape, which is organized into four levels: Primary Structure: The unique, linear sequence of amino acids dictated by genetic code. Secondary Structure: Local folding into patterns like alpha-helices and beta-pleated sheets, stabilized by hydrogen bonds. Tertiary Structure: The complete 3D folding of a single polypeptide chain, driven by interactions between amino acid side chains (R-groups). Quaternary Structure: The arrangement of multiple polypeptide chains (subunits) working together as a single functional unit, such as in hemoglobin. 3. Vital Biological Functions Function Description Examples Enzymes Biological catalysts that speed up chemical reactions. DNA polymerase, Lactase Structural Provide support and mechanical strength to cells and tissues. Collagen, Keratin, Actin Transport Bind and carry atoms or small molecules throughout the body. Hemoglobin, Ferritin Signaling Transmit signals to coordinate biological processes. Insulin, Growth hormone Defense Protect the body by binding to foreign particles like viruses. Antibodies (IgG) 4. Synthesis and Stability Biosynthesis: Proteins are synthesized in the ribosomes through processes called transcription (DNA to mRNA) and translation (mRNA to protein). Denaturation: Changes in environmental conditions (like high temperature or extreme pH) can cause a protein to lose its 3D shape and become non-functional.