- Secondary. The secondary structure is locally folded and is the repeated
twisting of the polypeptide chain that links together the amino acids. There
are two types of secondary structures. These are a helix and a pleated sheet.
The alpha-helixis a clockwise spiral structure. The pleated sheetforms the
parallel portion of the polypeptide chain. - Te rtiary. The tertiary structure is the three-dimensional active structure of
the polypeptide chain. Tertiary structure is the minimal level of structure
for biological activity. - Quarternary. Is where the proteins, in order to be functional, contain sub-
units of polypeptide chains. An example would be DNA polymerase.
Proteins have many roles in a living organism. They are found in bone colla-
gen and connective tissue and provide protection in the form of immunoglobins,
which are antibodies. Some of the other important proteins are:- Myosin. Muscle contraction.
- Actin. Muscle contraction.
- Hemoglobintransports oxygen (O 2 ) and carbon dioxide (CO 2 ) in blood.
- Enzymes. An enzyme that is a biological catalyst that increases the rate of
chemical reactions in cells by reducing the energy required to begin the
reaction. The reaction does not change the enzyme. The name of an
enzyme typically ends with “-ase.” - Flagellin. Protein in flagella.
The Blueprint of Protein Synthesis
Proteins play a critical role in chemical reactions of microorganisms and other
kinds of organisms. Information needed to direct the synthesis of a protein is
contained in DNA (Deoxyribonucleic Acid). This information is transferred
through generations from parent to child microorganisms. Nucleotides also store
energy in high-energy bonds and form together to make nucleic acids.
There are three parts to a nucleotide:- A nitrogen base, such as adenine.
- A five-carbon sugar, such as ribose.
- One or more phosphate groups.
(^42) CHAPTER 2 Chemical Elements of Microorganisms