Proteins Flashcards
What sort of molecule is made when two amino acids join together
Dipeptide
What sort of molecule is formed when more than two amino acids bond together
Polypeptide
What is made up by one or more polypeptides
A protein
What is the general structure of an amino acid
A carboxyl group (-COOH), an amino group (-H2N), a hydrogen (-H) and a variable group (-“R”) all attached to a carbon atom (C)
What part of the amino acid determines its characteristics and makes it different from others
The variable group
What chemical elements do all amino acids contain
Carbon, oxygen, hydrogen and nitrogen
What element do only some amino acids contain
Sulphur
What bonds link amino acids to form di/polypeptides
Peptide bonds
What sort of reaction is amino acid synthesis
Condensation
What sort of reaction is breaking a peptide bond
Hydrolysis
What is the primary structure of a protein
The sequence of amino acids in the polypeptide chain (one different amino acid here can change the structure of the entire protein)
What is the secondary structure of a protein
The chain of the primary structure doesn’t remain straight. In the secondary structure hydrogen bonds form between nearby amino acids to make it coil into an alpha helix or fold into a beta pleated sheet
What are the monomers of proteins
Amino acids
What is the tertiary structure of a protein
The coiled/folded chAin is often coiled/folded even further. More bonds form between different parts of the polypeptide Chain. For proteins made from a single polypeptide chain the tertiary structure is their final structure
What is the quaternary structure of a protein
Some proteins are made of several different polypeptide chains all Joined together by bonds, the quaternary structure is the way these are assembled together (eg haemoglobin is 4 polypeptide chains bonded together)
What is computer modelling
A method of creating 3D interactive images of proteins (handy for investigating different levels of structure)
What are the bonds in the primary structure
Peptide bonds between amino acids
What are the bonds in the secondary structure
Hydrogen bonds between points (amino acids) on the polypeptide chain
What are the bonds in the tertiary structure
Ionic interactions
Weak interactions between negative r groups and positive r groups on different parts of the molecule
Disulphide bonds
Whenever two molecules of the same amino acid cysteine come close together the sulphur atom in one cysteine bonds to the sulphur in the other
Hydrophobic/hydrophilic interactions
When hydrophobic r groups are close together they tend to clump together in the protein. This means hydrophilic r groups are more likely to be on the outside which affects the way the proteins folds up into its final structure
Hydrogen bonds
Weak bonds that form in many places between slightly positive hydrogen atoms and slightly negative charged atoms in other r groups on the polypeptide chain
What are the bonds in the quaternary structure
Tends to be determined by the tertiary structure of the individual polpeptide chains being bonded together (therefore influenced by all the bonds in previous structures)
Where are the hydrophilic r groups in a globular proteins? What properties does this give them? Why is this useful?
Pushed to the outside
Makes them soluble
Therefore easily transported in fluids
What type of protein is haemoglobin and what does it do
Globular
Carries oxygen around the body in red blood cells
WhatS a conjugated protein? Give an example
A protein with a non protein group attached called a prosthetic group. Haemoglobin has 4 called haem groups (they contain iron that the oxygen binds to)
What type of protein is insulin and what does it do?
Globular protein
A hormone secreted by the pancreas that helps to regulate blood glucose levels
Solubility is important to be transported to areas that it acts in
It consists of two polypeptide chains that are bonded by disulphide bonds
What type of protein is amylase and what does it do
Globular protein
An enzyme that catalyses the breakdown of starch in the digestive system
Made of a single chain of amino acids
Secondary structure is made of BOTH an alpha helix and a beta pleated sheet
Main features of fibrous proteins
Insoluble
Strong
Fairly unreactive
What are the three proteins (we need to know) and what do they do
Collagen- found in connective tissues such as bone, skin and muscle
Very strong
Minerals can bind to it to increase its rigidity (eg in bone)
Keratin- found in many external structures (hair skin nails feathers horns)
Can either be flexible (skin) or hard and tough (nails)
Elastin- found in elastic connective tissues such as skin large blood vessels and some ligaments
Elastic so allows tissue to return to original shape after being stretched
