proteins mock

• what are proteins made of and how many different ones are there

  20 different amino acids
• what elements do proteins contain

  carbon, hydrogen, oxygen, nitrogen and some contain sulfur
• draw and label an amino acid

  
• What are the bonds between amino acids called?

  peptide bonds
• how are the bonds between amino acids made

  condensation reaction - the water molecule is fromed by combining an OH from the carboxyl group from one amino acid and a H from the amino group of another amino acid
• Which parts of amino acids are involved in a peptide bond?

  the C of the carboxyl group and the N of the amino group of the other amino acid
• what affects the shape of a polypeptide

  the types of bonding between the amino acids in the chain
• what shape do polypeptides have and why

  a precise 3D shape which is vital for the function e.g. enzymes
• what are the 4 types of bonds that affect the shape of a polypeptide

  - hydrogen (weakest)

  - ionic

  - hydrophobic/hydrophilic interactions

  - disulfide
• how do ionic bonds form

  between positively and negatively charged R groups
• how do hydrophobic/hydrophillic interactions form in proteins

  interactions between hydrophobic non-polar R groups and a hydrophilic polar R group. the polar group folds out to face polar water. the non-polar will fold in to avoid polar water --> helps protein to fold
• How do disulfide bonds form?

  between the sulfur-containing groups of two cysteine (an amino acid) molecules. they could be in the same chain (intrachain) or between different chains (interchain). this is a strong covalent bond
• What is the primary structure of a protein?

  sequence of amino acids in a polypeptide chain --> different sequences = different proteins
• What is the secondary structure of a protein?

  the start of protein folding, they form alpha helix (within the chain) or beta pleated sheets (between parallel chains), both are held by hydrogen bonds
• What is the tertiary structure of a protein?

  the way in which a protein coils to form a precise 3D shape - made up of one amino acid chain - disulfide, hydrophobic/phillic, ionic and hydrogen bonding help to maintain the shape (intra-disulfide)
• What is the quaternary structure of a protein?

  two or more polypeptide chains (subunits) joined together held together by the 4 types of bonds
• what are the 3 types of quaternary structure proteins

  globular, fibrous, conjugated
• what are globular proteins

  spherical, water soluble proteins
• How do globular proteins form?

  the hydrophobic R groups fold away from the water and on the inside of the protein and the hydrophilic R groups fold outwards to face the water
• Why are globular proteins soluble and why do they need to be

  the hydrophilic R groups are on the outside of the protein so they can travel in the blood
• what are some types of globular proteins and an example

  enzymes e.g. amylase and hormones e.g. insulin which regulates blood glucose concentration
• what are conjugated proteins

  Globular proteins that contain a non-protein component called a prosthetic group that is attached by either hydrogen, covalent or ionic bonds
• give an example of a conjugated proteins

  haemoglobin
• what is haemoglobin

  the red, oxygen-carrying pigment found in red blood cells
• what is the structure of the protein part of haemoglobin

  globular: 4 polypeptides: two alpha and two beta subunits
• How does haemoglobin carry oxygen?

  each polypeptide chain has a prosthetic group called a haem group. each haem group has an iron ion Fe2+, which can join with an oxygen molecule so it can carry 4 oxygens at one time

  
• What are fibrous proteins?

  proteins formed from long, insoluble molecules
• what is the structure of fibrous

  they are made up of small number of repeating amino acids and a high proportion of cysteine molecules to form disulfide bridges or bonds
• properties of fibrous proteins

  insoluble and strong but have important structural roles
• examples of fibrous proteins

  keratin, elastin and collagen
• Where is keratin found?

  external structures like skin, hair, nails --> can be flexible e.g. in skin or hard and tough e.g. in nails
• where is elastin found

  in elastic connective tissue such as skin, larger blood vessels and in alveoli in lungs so they can stretch and recoil
• where is collagen found

  connective tissues that need mechanical strength e.g. bone, skin and muscle
• what is a dipeptide?

  two amino acids joined together
• why do some proteins not have a quaternary structure?

  they only contain one polypeptide chain
• what are the types of bonds in each of the levels of protein structure?

  primary: peptide bonds

  secondary: hydrogen bonds and peptide bonds

  tertiary: ionic, disulfide, hydrogen and hydrophobic and hydrophilic interactions

  quaternary: same as tertiary