Polar R groups of closely positioned amino acids often enter into with each other, which helps give a protein its three-dimensional shape. Polar R groups of closely positioned amino acids often enter into with each other, which helps give a protein its three-dimensional shape.

Polar R groups of closely positioned amino acids often enter into "HYDROGEN BONDING".

Explanation: hydrogen bonding which is a partial intermolecular bonding interaction, is a type of bonding between a lone pair on an electron rich donor atom.

An amino acids is an organic acid, which has an amino group, carboxy group, and an organic R group. This R group can be polar or non polar. When it is polar it goes into hydrogen bonding with each other. The polar side chain which is the R chain makes an amino acids to be able to dissolve in water.

Amino acid with a Non polar R chain does not form hydrogen bond with each other.

See picture to understand the structure of an amino acid. You will see the carboxylic chain, the amino chain, and the R side chain.

the aksumite empire was an ancient kingdom located in what is now northern ethiopia from the period of 100 ad to 940 ad. its capital was the city of aksum. the kingdom established itself as one of the 4 great powers at its time, along with persia, rome, and china.

the kingdom was rich in goods like gold, iron, and salt. it established strong commercial ties with the regions governed by rome, egypt, and persia (arabia). aksum was a key location in this commercial network. trade was also facilitated with the introduction of the aksumite currency.