Proteins Flashcards
Definitions of Proteins
Proteins are polymers; their monomers are amino acids
Definitions of dipeptide
Its formed when two amino acids are joined together
Definitions of Polypeptide
Its formed when more than two amino acids join together
Describe the structure of amino acids
They all have a carboxyl group (-COOH) and an amino group (-NH2) attached to a carbon group which is also attached to a variable group (-R) and a hydrogen atom (-H)
What are amino acids linked together by? & what reaction was it?
amino acids are linked together by peptide bonds to form dipeptides and polypeptides - its a condensation reaction
Definition of a peptide bond
peptide bond is a bond formed when two amino acids are joined together b a condensation reaction
Definition of Primary Structure
primary structure is the sequence of amino acids in a polypeptide chain
How does the primary structure affect the protein
the number and order of amino acid in a protein chain is important, as changing just one amino acid can alter the function of the protein.
Definition of secondary structure.
Secondary structure is the coiling or folding of an amino acid chain, which arises often as a result of hydrogen bond formation between the -NH and -CO groups of amino acids in the chain. This makes it automatically coil into a helix or fold into b pleated sheet
Definition of tertiary structure
Tertiary Structure is the overall three-dimensional shape of a protein molecule. Its shape arises due to interactions including Hydrogen bonding, Disulphide bridges, Ionic bonds and Hydrophobic interactions.
Definition of ionic bonds in protein
Ionic bonds are attractions between negatively-charged R groups and positively-chafed R groups on different parts of the molecules
Definition of Disulphide Bonds in protein
Whenever two molecules of the amino acid cysteine come close together, the sulfur atom in one cysteine bonds to the sulfur in the other cysteine, forming a disulphide bond.
Definition of Hydrophobic and hydrophilic interactions in protein
When hydrophobic (water-repelling) R groups are close together in the protein, they tend to clump together. This means that hydrophilic (water-attracting) R groups are more likely to be pushed to the outside, which affects how the protein folds up into its final structure.
Definition of Hydrogen bonds in protein
These weak bonds from between slightly positively-charged hydrogen atoms in some R groups and slightly negatively-charged atoms in other R groups on the polypeptide chain.
What do Hydrogen bonds do?
They are involved in keeping the tertiary and quaternary structure of the protein in the correct shape. The presence of H+ bonds can give protein molecules a lot of strenght .
Definition of quaternary structure
Quaternary structure is where a protein consists of more than one polypeptide chain e.g. insulin
Definition of globular protein
Globular protein has a relatively spherical shape, which are soluble in water, and often have metabolic roles within the organism.
Describe the structure of globular proteins
They are round and compact
What makes Globular Proteins soluble
In a globular protein, any hydrophobic R groups are turned inwards towards the centre of the molecule, while hydrophilic groups are on the outside. This makes the protein soluble as water molecules can bind to them, and now they’re easily transported in fluids. This is caused by the hydrophilic and hydrophobic interactions in the protein tertiary structure.
Give 3 examples of globular proteins
> Haemoglobin
Insulin
Amylase
Whats the job of haemoglobin and whats type of protein is it known as?
> Haemoglobin is a globular protein that carries oxygen around the body in red blood cells.
Its known as a conjugated protein . Each of four polypeptide chain in haemoglobin has a prosthetic called haem
Definition of conjugated protein
this means its a protein with a non protein group attached to it & the non protein group is called a prosthetic group
What does a haem group contain?
iron, which oxygen binds to
What is insulin and its role?
its a hormone secreted by the pancreas. It helps to regulate the blood glucose level
