proteins

• how many different amino acids are there

  20
• what are proteins

  condensation products of amino acids
• draw the general structure of an amino acid

  label

  A) amine group

  B) carbon

  C) carboxylic acid group

  D) R-group which differs in each amino acid

  
• how does a condensation reaction form

  a H atom is removed from the amino group, which combines with the OH group removed from the carboxylic acid group of another
• what bond forms in an amino acid

  peptide bond
• what is a dipeptide

  2 amino acids bonded by a peptide bond, formed through a condensation reaction
• what is a polypeptide

  many amino acids bonded by peptide bonds, through a condensation reaction
• draw the forming of a dipeptide

  before and after

  A) water lost

  B) minus H2O condensation reaction

  C) peptide bond

  D) dipeptide

  
• what is the primary structure of a protein

  the sequence of amino acids in the polypeptide chain
• draw an example of the primary structure

  labels

  A) amino acid

  B) peptide bond

  C) carboxyl group

  D) amino group

  
• what is the secondary structure of a protein

  the folding of the primary structure, involving hydrogen bonds
• what are the 2 types of secondary structures of proteins

  alpha - helix and beta - pleated sheets
• describe the alpha - helix

  hydrogen bonds formed between amino acids occuring at regular intervals in the sequence in a spiral or helical shape
• describe beta - pleated sheets

  sections of the polypeptide chain, orientated in opposite directions, lying adjacent to eachother. more rigid and less flexible than aplha - helix
• where do the hydrogen bonds form in a proteins secondary structure

  between the C=O and NH groups
• draw an alpha helix an beta pleated sheet

  label which is which and where hydrogen bonds would form

  A) alpha - helix

  B) beta - pleated sheet

  C) hydrogen bond

  D) hydrogen bond

  E) hydrogen bond

  F) hydrogen bond

  
• what is the tertiary structure of a protein

  further folding of the secondary structure
• Hydrogen bonds:

  • Numerous but relatively weak and easily broken, especially by high temperatures
• Ionic bonds:

  • Quite strong but easily damaged by changes in pH
• Disulfide bonds/bridges:

  • Covalent bonds formed between R-groups of sulfur-containing proteins (i.e. cystoine) that are very strong and give strength to structural proteins
• Hydrophobic interactions:

  • Amino acids with hydrophobic R-groups tend to take up positions within the molecule surrounded by other parts of the polypeptide and further influence the tertiary structure
• draw the tertiary structure of a protein

  labels

  A) hydrogen bonds

  B) disulfide bridges

  C) hydrophobic interactions

  D) ionic bonds

  E) hydrophobic interactions

  F) disulfide bridges

  G) hydrogen bonds

  H) ionic bonds

  I) amino group

  J) amino acid

  K) peptide bonds

  
• what is the quaternary structure of a protein

  two or more polypeptides bonded together, mainly by disulfide bridges
• what is a prosthetic group

  a non - protein component that is integral in the function og a quaternary protein
• what is a conjugated protein

  a protein molecule to which a non - protein group is chemically combined
• give 3 examples of conjugated proteins

  myoglobin, haemoglobin, glycoprotein
• describe the structure of haemoglobin

  a conjugated protein that consists of 4 polypeptide chains - each chain is attached to an iron - rich haem group, which is an essential part of the molecule in the transport of oxygen
• draw the structure of a haemoglobin molecule

  labels

  A) alpha chain

  B) iron

  C) beta chain

  D) beta chain

  E) haem group

  F) alpha chain

  
• what do glycoproteins have attached to them

  a carbohydrate
• describe fibrous proteins

  consists of polypeptides arranged in chains that form fibres or sheets

  parallel chains linked by cross-bridges to form very strong and stable molecules
• what type of protein is collagen

  fibrous protein
• describe the structure and function of collagen

  each molecule consists of 3 identical polypeptides wound together in a parallel triple helix and held together by hydrogen bonds, which gives great tensile strength

  present in tendons which holds muscle to bone and it is very strong and shouldn't stretch
• describe globular proteins

  they have a metabolic role and a specific 3D shape

  enzymes and antibodies

  haemoglobin
• where are prions found and what do they do

  mammals

  nervous system for synaptic transmission
• what is the formula for a normal prion

  PrP or PrP^c
• what is the formula of the disease causing protein

  PrP^Sc
• what can cause the disease causing prion to form

  normal can spontaneously adopt diseased form

  DNA mutations

  eating contaminated food
• when one diseased prion forms how does it replicate

  the diseased form acts as a template for more of these proteins to form
• describe exactly how diseased prions replicate

  once one diseased prion present, this leads to a chain reaction for more disease causing proteins to form

  the prion protein present progressively become misfolded and changes from PrP to PrP^Sc

  over time, these reach a threshold level and causes neurodegenative disorders in the brain and other nervous tissues, leading to death
• how long is the degenerative period for a prion disease

  5-20 years