Primary, secondary and tertiary structures of proteins

the role of any protein in an organism depends on…

the proteins shape, each protein has a precise chemical composition aka amino acid sequence leading it to have a unique three dimensional shape.

what is a proteins primary structure?

the number, type and sequence of amino acid units in a protein.

how is the primary structure of an amino acid displayed?

by the three letter abbreviations for the amino acid or by the structural formula of the protein.

what is the conventional order that amino acids are written in?

from the N-terminal amino acid to the C-termianal amino acid

what is the three dimensional shape of a protein determined by?

the precise order in which its amino acids are joined together. This is due to many interactions between nearby amino acids, leading to the folding of a protein chain

how many amino acids in insulin?

51

what is the secondary structure of a protein

is the coming and pleasing of a protein molecule to produce a secondary level of structure in a protein.

describe the peptide links in a secondary structure of protein?

hydrogen bonds between the polar -NH group in one peptide link and the polar -C=O group in another peptide link can form at regular intervals. (in short there is a hydrogen bond between the polar -NH group and polar -C=O group)

what is a alpha helix?

a secondary structure formed when regions in a molecule coils into a spiral shape due to excessive hydrogen bonding between the peptide links on the same polypeptide chain (four amino acid units along the chain)

why do the hydrogen bonds form in the secondary structures?

due to the attraction between the partial positive charge of the hydrogen on the -NH group and the partial negative charge on the oxygen of a -C=O. group

which amino acids are most likely to not form an alpha helx structure?

proline and glycine are unlikely to exist in. an alpha helix structure sue to its ring structure, prolines structure is too rigid to allow it to form part of a helix. and because glycine only has a hydrogen atom for its R group means it introduces too much flexibility and reduces the stability of the alpha helix structure.

alpha helixes form from the…

same polypeptide chain

what are beta pleated sheets?

hydrogen bonds form between peptide links to produce regions where two or more parts of the polypeptide chains line up parallel to eaccchother

what allows the hydrogen bonds from the beta pleated sheets to occur at regular intervals?

the repeating stucture of the backbone of the protein chain (-N-C-C-N-C-C-N-C-C-)

What stabilises the beta pleated sheets.?

the fact that the hydrogen bonds occur at regular intervals .

what amino acids make the most stable beta pleated sheets?

glycine and alanine and seriine. as every second R group is H. With only there small side groups, sections of the protein molecule can line up closely , enableling strong hydrogen bonds to form between the adjacent sections producing the alpha beta sheets.

the secondary sturcture of a protein results from…

hydrogen bonding between the partially negative O in the C=O group and partial positive N from the N-H groups in the peptide links along the protein backbone. This leads to the formation of alpha helixes and beta pleated sheets

the tertiary structure of a protein is the…

overall three dimensional structure adopted by a protein molecule.

how are tertiary structures produced?

is produced from the three dimensional folding of its secondary structures (the alpha helixes and beta pleated sheets) this protein can twist back over itself to create a unique shape, which is responsible for the proteins function

(think about tertiary structure) what influences the three dimensional shape of the molecule?

the side chains of the amino acid units making up the polypeptide chain. These side chains can interact with each other in a number of ways, causing the protein to fold into the three dimensional shape.

what happens to non- polar chains?

they tend to fold towards the interior of protein molecules, away from contact with the water molecules

what happens to polar functional groups?

they become charged depending of the pH of their surroundings

what ar the types of bonding that can occur in a tertiary structure?

hydrogen bonds, dipole dipole interactions, ionic interactions, covalent cross links, and dispersion forces.

what are the required components in side chains for hydrogen bonds to occur?

-O-H, -N-H, -C=O

what are the required components in a side chain for dipole- dipole interactions?

any polar group such as those containing -S-H, -O-H or -N-H

What are the required components of side chains fit ionic interactions?

the side chains must contain -NH+3 and another group that contains -COO-

what are the required components for covalent cross links?

only cysteine side chain groups react to form a disulphide bridge (-S-S-)

what are the required components of the side chain for dispersion forces to arise?

any non polar group

the bonding in the tertiary structure does what?

it links two parts of a polypeptide chain.

what are the different shapes of proteins?

some resemble flat sheets, some are long and helical and others are compact and globular.