Revision exercises

Ex.1. Answer the following questions:

1. What is protein? What does the Greek work proteios mean? 2. How many amino acids occur naturally in proteins? 3. Can animals and humans synthesize all of the amino acids essential for life? What must they obtain proteins from? 4. What do enzymes allow the organism to do? 5. What organic substances perform important regulatory functions in human’s organism? 6. What do biochemists often refer to? 7. Haw many classes can proteins be informally divided into? 8. What are the most important physicochemical properties of proteins? 9. What classification of proteins is today widely used? 10. What are peptides?

Ex.2. Match the words with their definitions:

1. organ-specific	a. The change of folding structure of a protein (thus of physical properties) caused by heating, changes in pH, or exposure to certain chemicals;
2. species-specific	b. produced by the injection of the cells of a certain organ or tissue;
3. liver	c. a number of things arranged in a line or row;
4. string, alignment	d. the largest glandular organ in vertebrate animals, located in the upper or anterior part of the abdomen: it secretes bile, has an important function in the storage and metabolism of carbohydrates, fats, and proteins, and helps detoxify many poisonous substances that may be ingested;
5. provide	e. to let go, to set free;
6. legume	f. Limited to or found only in one species;
7. denaturation	g. the pod or seed of some members of this order, used for food;
8. release	h. to supply or make available.

Ex.3. Say whether the following statements are true or false:

1. Proteins of similar function differ gratly in amino acid composition and sequence. 2. Protein molecules are produced in cells and are allowed to be put into circulation within the organism only after synthesis is complete. 3. Enzymes are crucial for accomplishing all metabolic reactions. 4. The tercial structure controls the basic function of the protein. 5. Fibrous (structural) proteins serve regulatory, maintenance and catalytic roles in living organisms. 6. Ultracentrifugation is often used to determine the molecular weight of proteins. 7. A prefix shows how many amino-acid molecules present in a peptide.

Ex.4. Insert the necessary word:

1. Hemoglobin is … in the blood of many animals and humans that … oxygen to the tissues. 2. Hemoglobin forms an unstable, … with oxygen. 3. In the oxygenated state it is called oxyhemoglobin and is … ; in the reduced state it is … . 4. Each hemoglobin molecule is … of four heme groups surrounding a globin group, forming a tetrahedral structure. 5. There are four iron atoms in each molecule of hemoglobin, which accordingly can … four atoms of oxygen. (made up, an iron-containing protein, bright red, transports, bind, purplish blue, reversible bond)