Amino Acids

• what four elements are used to make amino acids?

  • carbon
  • oxygen
  • hydrogen
  • nitrogen
• what are amino acids used to make?

  proteins
• what uses are there of proteins in the body?

  • structural functions (e.g. keratin, collagen)
  • almost all enzymes (e.g. amylase, lipase, protease)
  • cytoskeleton component
  • muscle filaments
  • components of histones
  • membrane transport proteins
  • some hormones (e.g. insulin)
  • antibodies
• what does the structure of an amino acid contain?

  • an amine group
  • a single covalent bond between amine group and carbon
  • R-group (variable) bonded to carbon
  • a carboxylic acid group (with a oxygen bonded with a double covalent bond)
• how many different amino acids are there?

  20 - each has a different R-group
• what is a buffer?

  • substances that can help to stabilise the pH by maintaining a relatively constant H+ concentration
• what does the word 'amphoteric' mean?

  amino acids which have both acidic and alkaline properties allowing it to act as a buffer
• explain how amino acids act as buffers

  • if pH rises - in an alkaline medium amino acids act as an acid and release H+ to neutralise pH
  • if pH falls - in an acidic medium, amino acids act as a base and absorbs H+ to neutralise pH
• how many different amino acids are coded for in the human genome?

  20
• how are he different amino acids represented?

  either a one-letter or three-letter code
• what are hydrophilic R-groups?

  polar R-groups with O or N atoms or with a positive or negative charge
• what are hydrophobic R-groups?

  Non-polar R-groups with C or H or S atoms only and no charges
• define amino acids

  • biological monomers of polypeptides (that join to form macromolecules known as proteins)
• define a dipeptide

  • a molecules formed by a condensation of two amino acids
• define a polypeptide/protein

  • a chain of more than 20 and less than 50 amino acids bound together via a covalent peptide bond
• what is the difference between a dipeptide and a polypeptide?

  • a dipeptide is two amino acids joined together
  • a polypeptide is more than two amino acids joined together
• what is released during the formation of a peptide bond and what is this reaction called?

  • water is released - in a condensation reaction
• why is breaking a peptide bond called hydrolysis?

  • water is needed to break the bond - hydro = water, lysis = breaking
• what is the role of plants in the origin of amino acids?

  • they combine nitrate ions with sugars to make amino acids
• what are essential amino acids?

  amino acids that we can't make in our body, but we need, so we get them from consuming them through our diet (eating plants that make the amino acids or eating animals that have consumed those plants)
• what are non-essential amino acids?

  amino acids that the human body can synthesize in sufficient amounts so we don't need to obtain them through our diet
• what do animals do with excess amino acids?

  • amino acids are toxic and as they can't be stored, they must be excreted from the body in the process called deamination
  • in the liver, amino acids are converted to urea and passed out in the urine
• what are the effects of amino acid deficiency in plants?

  • stunted growth and chlorosis
  • poor muscle growth
• what type of enzymes break down proteins?

  protease
• why is protease necessary?

  • proteins won't be broken down into amino acids - amino acid deficiency
  • DNA replication and transcription won't occur correctly
  • important for proper digestion, making sure you get the nutrients and energy the body needs to survive