2.7 Proteins Flashcards
(20 cards)
what is the function of proteins (3)?
-they are structural building blocks
-help cellular functions such as immune defence, cell-to-cell transport, oxygen transport
-genetic operations such as growth, repair, and protection
what is the subunit of a protein?
amino acid
what is the structure of an amino acid?
an organic molecule that has a central carbon atom attached to an amino group, a carboxyl group, a hydrogen atom and a side chain
why are amino acids amphoteric?
amino acids are amphoteric because they can act both as an acid and a base
how can you tell if an amino acid is nonpolar?
-electronegativity is less than 0.4
-is sulphur or nitrogen is present within the structure not at the bottom
how can you tell if an amino acid is polar?
- the R group contains sulfur, nitrogen, and/or oxygen at the bottom because these electrons have a higher electronegativity so they draw atoms toward them a.k.a the SNO rule
how can you tell if an amino acid is electrically charged and acidic?
there is a negative charge in the R groups because acids donate H+ ions to solutions
how can you tell if an amino acid is electrically charged and basic?
the R group has a positive charge because it accepts H+ ions from solutions
how many amino acids are essential?
9
what does the protein’s primary structure look like?
a chain of 50 amino acids linked by peptide bonds
types of amino acids present and the sequence varies from one protein molecule to the next
what chemical bond is involved in the primary protein structure?
an amide linkage forms between the miano group from one amino acid and the carboxyl group from an adjacent amino acid
what does the protein’s secondary structure look like?
one or more polypeptide chains individually coiled into an alpha helix or a non-helical structure called a beta pleated sheet.
how is the chemical bond formed in the alpha helix in the secondary structure?
bonds form between the carboxyl group of one amide linkage and the hydrogen of one amino group, four amide linkages away
how are the chemical bonds formed in the beta-pleated sheets in the secondary structure?
two parts of the polypeptide chain lie parallel and hydrogen bonds form between the oxygen from a carbonyl and a hydrogen atom from an amino group
what does the protein’s tertiary structure look like?
a further folded version of the coiled alpha helices and beta pleated sheets
what are the chemical bonds involved in the tertiary protein structure?
d, h, i, p, v
- Disulfide bridges between two cysteine
- hydrogen bonds form between two polar groups
- ionic bonds form between a positive and negative side chain
- Proline kink swirls
- van der wall forces form between two non-polar groups
what does the protein’s quaternary structure look like?
the assembly of two or more tertiary, sub-units
what bonds are involved in the quaternary structure?
the same types of bonds in the tertiary structure
the highly specific bonds that are established during protein formation can be disrupted by a variety of environmental changes such as
-temperature (particularly high temperature)
-ph
-ion (salt) concentration
what is protein denature caused by?
denature which is the unravelling of a protein structure due to the disruption of H-bonds, ionic bonds, disulfide bridges, and hydrophobic interactions
