Proteins

• What is the general structure of an amino acid

  a central carbon, an amine group, a carboxyl group and a hydrogen atom
• What does the R group determine

  whether an amino acid is acidic, basic, polar (hydrophilic) or non-polar (hydrophobic)
• Why is cysteine important

  because of its unique R group containing a sulfur atom
• What can Cysteine form

  very strong disulphide bonds (a compound containing a R-SS-R functional group)
• What are proteins and polypeptides made of 


  long chains of amino acids
• What are these amino acid monomers joined together by

  A condensation reaction
• How does a peptide bond form

  Between the amine group and the carboxyl group of 2 amino acids molecules to make a dipeptide
• If a protein consists of one or more polypeptide chains it is folded into a...

  3D shape
• Describe the primary structure of a protein

  a sequence of amino acids

  determined by the gene base sequence

  peptide bonds form between adjacent amino acids
• Describe the structure of a secondary protein

  Alpha helices and Beta pleated sheets

  Formed by coiling/folding and held by hydrogen bonds between the non-R group portions of amino acids
• Describe the structure of a tertiary protein

  folding which forms the 3D shape of the protein

  Held in place by hydrophilic/ phobic interactions, hydrogen bonds, ionic bonds and disulphide bonds between the R group

  The interaction between R groups creates the complex 3D structure of the protein
• Describe the quaternary structure of a protein

  Multiple polypeptide chains (subunits) with bonds/interactions between
• Describe the bonds in the tertiary structure of a protein

  Hydrogen bonds are weak

  Hydrophilic/hydrophobic interactions- between non-polar sections of the protein

  strong ionic bonds occurring between positively and negatively charged R-groups

  Disulphide bridges- one of the strongest and most important type of bond in proteins occurs between 2 cysteine amino acids
• What are the factors affecting the function of a protein

  Changes in temperature, pH or salt concentration
• What type of protein are collagen keratin and elastin


  Fibrous protein
• Where is collagen usually found in the body?


  skin

  bones

  tendons
• Describe the structure of collagen


  Three polypeptide chains wound in a triple helix

  has a high proportion of glycine which is small and allows the three chains to lie closely together

  strong rope-like structure
• Where is keratin usually found in?


  hair, hooves, horns and fingernails
• Describe the structure of keratin


  a large proportion of amino acids are cysteine resulting in many strong disulfide bridges
• Where is elastin usually found in?


  walls of blood vessels, alveoli and bladder
• Describe the structure of elastin


  made of many tropoelastin molecules crosslinked together

  able ti stretch and recoil

  crosslinked covenant bonds are formed between lysine amino acids
• Explain why insulin is soluble in blood


  hydrophilic amino acids are folded on the protein surface
• Name the bond formed between 2 amino acids

  peptide bond
• state the bonds involved in the tertiary structure of a protein 


  ionic

  covenant

  disulfide bridges

  hydrogen bonding

  hydrophobic/phillic interactions
• What is the tertiary structure of a protein 


  folding into a 3D shape
• State the bond involved in the secondary structure of a protein


  hydrogen bond
• What are the three different types of proteins 


  globular conjugated and fibrous
• Give an example of a conjugated protein


  haemoglobin, catalase
• What are prosthetic proteins


  non-protein component in a conjugated protein
• Explain why keratin is relatively strong, inflexible and insoluble 


  many strong disulphide bonds
• what are the components that make up an amino acid


  central carbon + H atom + amine group + carboxyl group
• Collagen is a fibrous protein which is flexible but does NOT stretch
• Insulin is a globular protein with a specific and fixed shape
• Elastin is a fibrous protein that recoils after being deformed
• Haemoglobin is a globular protein which can change shape
• What are prosthetic groups 


  non-protein component in a conjugated protein
• What is the structure of globular proteins 


  have a compact, spherical structure
• Where are the hydrophobic r groups on a globular protein


  point into the centre away from aqueous surroundinds
• Where are the hydrophilic r groups on a globular protein


  on the outside of a molecule which can form hydrogen bonds with water molecule making them soluble
• Where are globular proteins usually found in 


  may be found in cells, tissue fluid or in fluids being transported