Chapter 2 (Nucleic acids and Proteins)

• Protein:


  a biomacromolecule made of amino acid chains folded into a 3D shape
• Polypeptide:


  a long chain of amino acids. Proteins can be made of one or many polypeptides
• Proteome:


  all the proteins that are expressed by a cell or organism at a given time
• Enzymes:


  an organic molecule, typically a protein, that catalyses (speeds up) specific reactions
• Peptide hormone:


  a protein signalling molecule that regulates physiology or behaviour
• Antibody:


  a protein produced by plasma cells during the adaptive immune response that is specific to an antigen and combats pathogens in a variety of ways. Also known as immunoglobulin
• Carboxyl group:


  the functional group on amino acid molecules that contains a hydroxyl group (OH) and an oxygen doublebonded to a carbon atom
• Amino group:


  the functional group on amino acid molecules that is made up of one nitrogen and two hydrogens (NH2)
• R-group:


  the variable portion of an amino acid molecule. It can be one of twenty variations and determines the identity of the amino acid
• Hydrophobic:


  having a tendency to repel and be insoluble in water
• Hydrophilic:


  having a tendency to be attracted to and dissolve in water
• Monomer:


  a molecule that is the smallest building block of a polymer
• Polymer:


  a large molecule that is made up of small, repeated monomer subunits
• Condensation reactions:


  a reaction where two monomers join to form a larger molecule, producing water as a by-product
• Peptide bonds:


  the chemical bond linking two amino acids
• Protein primary structure:


  the first level of protein structure, which refers to the sequence of amino acids in a polypeptide chain
• Protein secondary structure:

  the level of protein structure where the amino acid chain forms either alpha-helices, beta-pleated sheets, or random coils
• Protein tertiary structure:


  the functional 3D shape of a polypeptide chain
• Protein quaternary structure:


  the level of protein structure where multiple polypeptide chains bond together, or other non-protein groups are added to form a fully functional protein
• Alpha helix:


  an organised coiled secondary structure of proteins
• Beta-pleated sheet:


  an organised folded secondary structure of proteins
• Random coils:


  an irregular secondary structure of proteins that is neither an alpha helix nor a beta-pleated sheet
• Disulphide bonds:


  a strong covalent bond occurring between two sulphur atoms
• Amino acid

  A) Amino group

  B) Carboxyl group

  C) Side chain

  D) Centeral carbon

  
• Nucleic acid:


  the class of macromolecule that includes DNA and RNA. All nucleic acids are polymers made out of nucleotide monomers
• Nucleotides:

  the monomer subunit of nucleic acids. Made up of a nitrogen-containing base, a fivecarbon sugar molecule (ribose in RNA and deoxyribose in DNA), and a phosphate group
• DNA (deoxyribosenucleic acid):


  a double-stranded nucleic acid chain made up of nucleotides. DNA carries the instructions for proteins which are required for cell and organism surviva
• RNA (ribonucleic acid):


  a singlestranded nucleic acid chain made up of nucleotides. Includes mRNA, rRNA, and tRNA
• Phosphodiester bond:


  a strong covalent bond linking a five-carbon sugar to a phosphate group
• Sugar-phosphate backbone:


  a strong covalently linked chain of five-carbon sugar molecules and phosphate groups in a nucleic acid chain
• Chromosome:


  a structure made of protein and nucleic acids that carries genetic information
• Gene:


  a section of DNA that carries the code to make a protein
• Genome:


  the complete set of DNA housed within an organism
• Antiparallel:


  a characteristic of DNA strands describing how each strand runs in an opposite direction to the other. One strand runs in a 3’ to 5’ direction and the other runs in a 5’ to 3’ direction
• Complementary base pairing:


  describes which nucleotides can form hydrogen bonds with each other. C pairs with G, A pairs with T (or U in RNA)
• Double helix:


  the structure of double-stranded DNA in the nucleus of eukaryotic cells, where each DNA strand wraps around a central axis
• Nuclear DNA:


  DNA that is located in the nucleus of a cell
• Messanger RNA (mRNA):


  RNA molecules that are produced during transcription and carry genetic information from the nucleus to the ribosomes
• Transfer RNA (tRNA):

  RNA that recognises specific codons on the mRNA strand and adds the corresponding amino acid to the polypeptide chain during protein synthesis
• Ribosomal RNA (rRNA):


  RNA that is a key structural component of ribosomes, which assemble proteins