Answer Questions 12 -15 completely 12. List the five types of additives in foods

Question

Answer Questions 12 -15 completely 12. List the five types of additives in foods and give one example for each type. In your examples, include a type of food to which it is added, and the effect that the additive has on the food. 13. Deoxyribonucleic acids (DNA) are a critical class of large molecules in living systems a. What is DNA made of? b. What does DNA do in the human body? c. Give an example of the types of disease or condition that can s rom DNA that is missing of performing its job incorrectly. 14. Many drugs have molecular structures that are very similar. a. Explain is the rationale for creating structurally-similar molecules. b. Name two structurally-similar drugs and discuss the advantages and disadvantages of structural similarity 15. Explain how the "nucleoside analog" type of AIDS antiviral medication works

Explanation / Answer

12. Food additives are chemicals added to foods to keep them fresh or to enhance their colour, flavour or texture. They may include food colourings (such as tartrazine or cochineal), flavour enhancers (such as MSG) or a range of preservatives. Some of them are:

13.

a) DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugargroup and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) andcytosine (C).

b) Genes are made up of DNA. Genes give your body instructions—much like a blueprint or a recipe—for everything it needs to do to grow, develop, and live. One example is that genes give your body instructions for making proteins.Proteins are the building blocks that do things, or perform functions, in the body. Different genes contain instructions to make different proteins, the same way that different recipes tell you how to make different dishes.

c) Any change in the DNA may change the protein’s shape. A protein’s shape is related to its function (what it does in the body). Thus, changes in your DNA can stop proteins from doing their job. This can cause conditions or diseases that affect your health.Sex-linked genetic diseases are those where the defective genes are carried on either the X or Y chromosomes. Cancer is also one of the most dangerous disease that can happen due to DNA disorder.

14.

a) Similar molecules exert similar biological activities.Bioisosteric replacements of atoms and groups pave the way from lead structures to therapeutically useful enzyme inhibitors, receptor agonists and antagonists, and other active principles. Several surprising structure-activity relationships demonstrate that chemically similar compounds may have significantly different biological actions and activities. Of course, even optical enantiomers most often have different biological activities. The principle of bioisosteric replacement of functional groups serves as a successful optimization strategy. Its systematic application has resulted in a broad variety of therapeutically used drugs, many of them finally having the desired combination of favorable properties.

b) Examples of two structurallly similar drugs are - Erybraedin C and Bitucarpin A. These drugs are employed as antitoxins, but display antifungal, antiviral and antibacterial properties as well. Erybraedin C and bitucarpin A are two new structurally related pterocarpans recently purified and characterized. Bitucarpin A differs from erybraedin C for the absence of a prenyl group in 5' position and the presence of a methoxylate hydroxyl group in 7, 4' positions. These compounds proved not to be clastogens in human lymphocytes per se but displayed anticlastogenic activity against mytomicin C and bleomycin C.erybraedin C may act as a potent growth inhibitory compound, at low and high cell density, comparable to other clinically important antineoplastic natural drugs including etoposide, on human colon adenocarcinoma cells. Bitucarpin A proved less active because it was conditioned by cell density effect, but this finding may represent a clinical advantage against early micrometastatic diseases.

15. Nucleoside analogs can be incorporated into DNA and block natural maturation processes. The first antiviral drug to be approved for treating HIV, zidovudine (AZT), is also a nucleoside analogue.AZT is a thymidine analogue. AZT works by selectively inhibiting HIV's reverse transcriptase, the enzyme that the virus uses to make a DNA copy of its RNA. Reverse transcription is necessary for production of HIV's double-stranded DNA, which would be subsequently integrated into the genetic material of the infected cell (where it is called a provirus).Cellular enzymes convert AZT into the effective 5'-triphosphate form. Studies have shown that the termination of HIV's forming DNA chains is the specific factor in the inhibitory effect.

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