Proteins Flashcards
U1L6 (23 cards)
What’s a single unit that makes up protein called?
An Amino Acid.
It contains a Carboxyl group and an Amino group.
What is the structure of an Amino Acid?
It has a central carbon with Carboxylic Acid group, an Amino group and a variable R group (a side chain).
The side chain is what determines the shape and function of an Amino Acid.
What does Amphiprotic mean?
Amphiprotic means it contains both acidic and basic functional groups.
The acidic group can donate the H+ to the basic group.
How many Amino acids are there?
20 Amino Acids, which are all determined by the side chain.
8 are essential to the human body and must be consumed via food.
What are the four groups Amino Acids are classified under?
Non Polar, Polar, Basic and Acidic
How are polypeptides formed?
They are formed through numerous condensation reactions which bond them together.
After the H2O is extracted, it forms a Peptide Linkage.
It requires an Amine group and a Carboxyl group/
What determines the function of a protein?
The shape of a protein determines it’s function.
Amino acid order determines the shape
(conformation) of a protein.
Function depends on its ability to recognize
and bind a molecule.
Amino acids 🡪 conformation 🡪 function 🡪 binding
What are some examples of protein binding in the body?
Antibodies: binds to a particular foreign substance that fit their binding sights
Enzymes: recognize and bind to their substrates, causing a chemical reaction to occur.
Neurotransmitters: passes signals from one cell to another by binding to receptor sights on proteins in the receiving cell.
What are the 4 levels of protein structure?
Primary
Secondary
Tertiary
Quaternary
The first three organize folding within a single polypeptide.
The fourth organize interactions between two
or more polypeptides that
make a protein.
What about the Primary structure?
The primary structure is a unique sequence of Amino acids.
The sequence is determined by DNA.
A slight change in the primary structure can affect a protein’s conformation and ability to function properly.
What’s an example of a Primary protein structure?
Sickle Cell Anemia.
When one Amino Acid is substituted with another, it causes the hemoglobin to crystalize. This crystallization causes the blood cells to have a deformed shape, which could lead to increase chances of blood clots and the whatnot.
What about the secondary structure?
The secondary structure of proteins result from hydrogen bonds at regular intervals along the polypeptide backbone..
Typical shapes include the Alpha Helix (coil) and the Beta pleated sheets (flat).
This is NOT found in all proteins.
What about the Tertiary structure?
The tertiary structure involves interactions between R groups and R groups (or sidechains).
It also has interactions between sidechains and the backbone.
What other types of interactions occur in the tertiary structure?
Some interactions that occur in tertiary structures include Hydrogen bonds, Ionic bonds, Hydrophobic interactions (often in interior of the protein) and covalent bonds.
Disulfide bridges is also another interaction that could occur. It essentially formed between the sulfhydryl groups
(SH) of cysteine amino acids.
What’s a Proline kink?
A Proline is the only amino acid in which the R group is attached to the amino group.
This forms a natural kink in the polypeptide.
It helps to shape its tertiary structure.
What about a Quaternary structure?
It is an aggregation of two or more polypeptide subunits.
It forms two types of proteins: globular and fibrous.
This is NOT found in all proteins.
What’s an example of a globular protein structure?
A Hemoglobin.
Globular proteins are water soluble and compact/spherical.
Example of a Quaternary Fibrous structure?
Collagen.
Fibrous proteins are water insoluble and threadlike in nature.
It is essentially 3 polypeptides supercoiled like a rope.
provides structural strength for role in connective tissue.
What is protein folding?
Protein folding is a process that occurs spontaneously.
It is aided by Chaperone proteins (called ‘Chaperonin’).
It provides the polypeptides an ideal environment for folding.
What’s conformational change?
It is when a protein changes shape.
Conformational changes are reversible.
It does not disrupt a proteins function, rather it defines what the protein’s function is.
Change occurs in response to physical and chemical conditions.
What’s denaturation?
Denaturation is when a change in the shape of a protein disrupts the function of a protein.
Alterations in the environment (pH, salt concentration, temperature, etc) disrupts bonds and forces of attraction.
What’s renaturation?
Renaturation is when SOME proteins can return to their original shape and function after being denatured, though its uncommon and only occurs with some proteins (such as hemoglobin).
The cell is crowded which also makes renaturation difficult/impossible with certain proteins.
An example of denaturation?
An example of denaturation is when you cook an egg. When the egg is boiling, the proteins in the Egg white get broken down and denatured. This causes the Egg white to solidify. You cannot return a solid egg white to it’s original liquid state > it cannot renature.
This is an example of permanent denaturation.
