EduNinjaThe table shows some essential and non-essential amino acids.
What is a valid conclusion for an amino acid in the table?
Lysine is synthesized by the human body.
Alanine can only be obtained from food.
Glycine is not used in the human body.
Valine must be supplied in the diet.
Which row correctly matches the level of structure of a protein molecule with the bonds that stabilize it?
Level of structure
Bonds
primary
peptide and hydrogen bonds between amine and
carboxyl groups
secondary
hydrogen bonds between R-groups of amino acids
tertiary
disulfide, hydrogen and ionic bonds between R-groups
of amino acids
quaternary
covalent bonds between hydrophobic and hydrophilic
regions on the polypeptide subunits
Myoglobin is a globular protein in which nearly all the non-polar R-groups point towards the inside of the molecule. The outside surface contains all the polar R-groups. What can be deduced from this?
Disulfide bonds occur on the inside.
Hydrogen bonds form with water on the outside.
Ionic bonds form with water on the outside.
Covalent bonds occur on the inside.
Diagrams of three different proteins, X, Y and Z , are shown.
Which row describes the structure of each protein shown?
X
Y
z
quaternary
globular
secondary
conjugated
fibrous
globular
tertiary
quaternary
primary
globular
secondary
fibrous
This diagram shows the amino acids present in a molecule of insulin, using three-letter abbreviations.
What describes the structure of insulin?
Insulin is a fibrous protein, since the amino acids are arranged in a linear pattern.
Insulin consists of a single continuous polypeptide chain with one free amino terminal and one free acid terminal.
Insulin has three disulphide bridges giving it tertiary structure and two polypeptide chains giving it quaternary structure.
Insulin has primary and secondary structure only, as there is no evidence of a three-dimensional shape in the diagram.
The diagram shows the structure of the protein CXCL12.
Which chemical group is found at X ?
NOH
COH
COOH
The image shows the structure of the protein hemoglobin.
What level of protein structure bonds the and chains together?
Primary
Secondary
Tertiary
Quaternary
Which organic molecules may contain the element sulphur?
Proteins
Carbohydrates
Phospholipids
Nucleic acids
Which element is most common in proteins?
Sodium
Nitrogen
Phosphorus
Iron
Which protein has the highest tensile strength (ability to resist breaking when stretched)?
Cellulose
Actin
Spider silk
Albumin