Answer:
Carboxyl group and amino group.
Explanation:
Amino acids have three parts which are the carboxyl group, amino group and the side chain. When forming a peptide bond, the carboxyl group of one amino acid forms bonds with the amino group of the other one to form the peptide bonds between them.
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Eukaryotic cells use three major processes to transform the energy held in the chemical bonds of food molecules into more readily usable forms — often energy-rich carrier molecules. Adenosine 5'-triphosphate, or ATP, is the most abundant energy carrier molecule in cells.
Demonstrative pronoun is the answer.