proteins Flashcards
(74 cards)
enzymatic proteins
catalysts in cellular reactions
hormonal proteins
Coordinate organism’s activities by triggering responses
immunological proteins
Protect against disease by recognising foreign bodies and microbes and activating immune cells
contractile and motor proteins
Aid muscle contractions and motor proteins are responsible for the movement of cilia and flagella
structural proteins
Provide support by forming structural components and assist in contractile functions
transport proteins
Act as protein channels or carrier proteins
receptor proteins
Assist the cell in responding to a chemical stimuli
storage proteins
Storage of metal ions and amino acids
what is a proteome?
proteome: the complex and complete set of proteins expressed by the genome of an individual cell or organism.
Varies between cell type, developmental stage and environmental conditions.
A cell has the entire genome but only some genes are switched on making sure it produces the right proteins.
what is proteomics?
Large scale study of the structure, function and interactions of proteins.
Might examine the proteins produced by cells in different conditions.
Important in the production of medications and early detection of diseases using protein biomarkers.
how does the synthesis of proteins work?
Proteins are made of amino acids, joined by peptide bonds.
Then coiled into proteins.
what is the amino acid structure? how to the amino acids change?
An amine group (NH2)
A carboxyl group (COOH)
A variable R group (or side chain)
There are 20 different standard (or canonical) amino acids, each with a different R group.
The varies of the R group (polar, non-polar, charged, non-changed etc.) determine the protein made
what is condensation polymerisation? how does it work?
Amino acids are joined by peptide bonds in a condensation polymerisation reaction which involves the removal of water (dehydration)
The hydrogen and oxygen from the carboxyl group of one amino acid join with the hydrogen atom of the amine group of another amino acid and produce water and a dipeptide (two amino acids linked) is synthesised with a peptide bond holding the amino acids together.
The backbone of a peptide chain is repeated amine and carboxyl groups.
The R groups are off the side
With folding and modification, a protein is formed.
primary structure? length and differences? what info do they form? how can we learn from them?
Linear sequence of amino acids in a polypeptide chain
Unique to each protein
Shorter than 50 amino acid sequences are called peptides
Length varies
Provides information on how the protein will fold
Functional and non-functional sequences are compared to see what causes a lack of function
Can be compared between proteins to see the evolutionary history
secondary structure? three types?
The folding or the coiling of the polypeptide chain.
Folding occurs due to the formation of hydrogen bonds between amine and carboxyl groups that are close together.
This results in the secondary structures: alpha helix, beta-pleated sheets and random coil
Alpha helix: hydrogen bonds form between adjacent amine and carboxyl groups, forming a helical shape
Beta-pleated sheets: hydrogen bonds form between amine and carboxyl groups in different parts of adjacent chains, causing the chains to fold back on each other
Random coil: it looks random, but eg. All insulin proteins will have the same random coils.
tertiary structures?
The further folding to form more stable, globular or fibrous 3D shapes
Usually the combination of alpha helices and beta-pleated sheets along with other folded areas.
Occurs due to different types of bonds, such as the disulphide bridge and the hydrogen bridge between the R groups.
3D structure is essential to functioning
Small chains fold due to chemical environment but more complex ones need specialised proteins to fold them and to refold them if the unravel or denature
This can be the final stage for some proteins
quaternary structure?
Two or more polypeptide chains or prosthetic groups (inorganic compound that is involved in protein structure or function) join together to make a single functional protein.
The polypeptides may be identical or different.
A protein with a prosthetic group is known as a conjugated protein.
chaperonins? how do they work?
Protein molecules that aid in the folding of other proteins.
It provides a sheltered space away from influences of the environment for a protein to fold.
It also stops newly synthesised polypeptide chains and submits form becoming non-non-functional due to high heat.
two types of proteins classification?
Fibrous proteins Elongated Insoluble Little or no tertiary folding eg. Collegen
Globular porteins Compactly folded Have tertiary or quaternary structures Usually Soluble Core is hydrophobic Outer hydrophilic region Most enzymes and hormones
what are the factors that affect proteins?
Temperature
pH
Concentration of ions or molecules that act as cofactors
denaturation and renaturation
Denatured when the bonds that cause its tertiary structure are broken and the protein changes shape
It is inactive
If it is partially affected, it may be able to renature if there are appropriate conditions
temp on proteins
At high temperatures they denature (40 degrees hydrogen bonds break)
At below 35 degrees the bonds are not flexible enough to allow the conformational changes
Optimal temperatures
pH on proteins
They have differing optimum pHs
They may denature if the pH gets too high or too low
effect of cofactors on protein function?
Some proteins need non-protein chemical compounds (cofactors) to function.
The presence and concentration of salts, specific elements or organic molecules has a significant role in the folding and function.
