Question

Which of the following statements is an accurate description of proteins? Which of the following statements is an accurate description of proteins?
A. The primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the DNA of a gene.
B. The 20 amino acids found in proteins differ in the composition of their R groups, which may be either polar or charged. Secondary structures, which include the alpha helix or beta pleated sheet, are held together by interactions between R groups.
C. Tertiary structure is the overall shape of a polypeptide, which may be stabilized by hydrophobic interactions, hydrogen bonds, ionic bonds, and peptide bonds.
D. Quaternary structure is only found in proteins that have four identical polypeptide subunits.

Answer 1

Answer:

The right answer is A)The primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the DNA of a gene.

Explanation:

Proteins are aminoacids´s polymers. There are 20 different aminoacids that differs only in their R groups. There are four kind of protein structures:

1) Primary structure: it refers to tha secuence of aminoacids in the protein and is defined by DNA.

2) Secondary structure: it describes the situation in which we can identify repeated segments along the polypeptid chain. There are two secondary structures: alpha helix and beta pleated. This two conformation are held together by interactions between peptidic groups. R groups can interact only if they are small.

3) Tertiary structure: is the three-dimentional conformation of the polypeptid and it is stabilized by   hydrogen bonds, electrostatic interactions, hydrophobic interactions and disulphide bonds. Stabilizing bonds can be between peptidic groups (peptide bond).

4)Quaternary structure: it applies for that proteins conformed by different subunits. It describes the conformation and interaction between these subunits in the polypeptid.