1. If the following RNA fragment AUG-CGU-AAA-GAG-GGA-CAA-UAA has been derived from the DNA sequence:

This RNA fragment has been formed from DNA strand by the process of transcription. In this process, DNA is transcribed or copied to messenger RNA (mRNA). The process of conversion from DNA to RNA takes place in two steps and is based on Watson-Crick base pairing principle. The first step is the formation of pre-messenger RNA with the help of RNA polymerase enzyme. Then, a single-stranded RNA is formed which is the reverse compliment of the original DNA sequence. The introns present in pre-messenger RNA are not needed during protein synthesis. So, these introns are removed from the pre-messenger RNA by editing it so that mRNA molecule can be produced. This is the second step in transcription process and is called as RNA splicing (Davidson 2009). The RNA sequence is formed from DNA sequence by replacing thymine (T) with the base uracil (U).

RNA is then transformed into the protein through the process of translation. The process of translation involves three important steps of Initiation, Elongation and Termination. Basically, the mRNA which is formed in the transcription process is then moved out of the nucleus and reaches to the ribosome in the cytoplasm. Ribosome is the factory for the synthesis of protein in the cell (Morris & Mattick 2014). The presence of transfer RNA (tRNA) is required for the process of translation to take place. Each codon is a three-base stretch or triplet of messenger RNA. The interaction of each codon takes place with the anticodon of tRNA molecule by the Watson crick base pairing principle. The amino acid which is present at the 3’- terminus of the tRNA molecule is then incorporated into the elongating and growing chain of protein molecule. The uncharged tRNA molecule leaves the ribosome, thus, helps in the synthesis of proteins (Hori, Tomikawa, Hirata, Toh, Tomita, Ueda & Watanabe 2014).

2. Part 1: The work of Austrian Monk Gregor Mendel includes-

Gregor Johann Mendel was the famous biologist (father of genetics) and who had made tremendous contributions in the field of genetics specifically in hereditary. He was the first to explain the transmission of genetic traits by performing the experiments on the breeding of pea plant. He presented the results of breeding experiments in the form of Punnett square. On the basis of his experimentation, Mendel proposed the three rules of Mendelian Inheritance. These are Law of segregation (each gamete carries only one allele for a gene), Law of Independent assortment (genes segregate independently) and Law of Dominance (an organism with atleast one dominant allele displays the effect of dominant allele) (Mendelian Genetics 2000).

Part 2, 3 and 4:

Let R represent the people with tongue roller; r represent the people who are non-tongue roller; T represent the people who can taste phenylthiocarbamate (PTC) and t represent the people who cannot taste PTC. Suppose a woman who is a non-PTC taster and a homozygous tongue roller gets married with a man who is a PTC taster and heterozygous tongue roller. They have three children who are a homozygous tongue roller and a PTC taster, a heterozygous tongue roller and a PTC taster, and a non PTC taster and also heterozygous tongue roller. If they had 16 in all, then a man with Rr and Tt trait would be RrTt and could produce gametes with either R or r and either T or t. So, R or r are the two options for first trait which as well as T or t are the two options for the second trait. Therefore, the total number of gametes which may be produced are 2*2=4.

3. The chemical structure of carbohydrates, proteins and lipids can be described as:

Carbohydrates are the simple sugars. These are polyhydoxy aldehydes or ketones, or these are the substances which on hydrolysis produces such compounds. (CH2O)n is the empirical formula for most of the carbohydrates and some carbohydrates also contain sulphur, phosphorous or nitrogen. The monosaccharides, oligosaccharides and polysaccharides are the three major classes of carbohydrates. Monosaccharides consist of a single ketone unit or polyhydroxy aldehyde, for example, D-glucose which is also called as dextrose is the sugar consisting of six carbons and is the most abundant monosaccharide. Oligosaccharides consist of two or more monosaccharide units joined together by glycosidic linkages or bonds, for example, sucrose or cane sugar is the most abundant disaccharide which consists of D-fructose and D-glucose. The carbohydrates that contain more than 20 monosaccharide units are called as polysaccharides. These can have linear as well as branched structure like for example, cellulose and glycogen. The monosaccharide unit in both is D-glucose and they only differ from each other in terms of glycosidic linkage (Cummings & Stephen 2007).

Proteins are the most abundant biological large molecules in living systems. These are also known as polypeptides. Proteins are composed of amino acids which are joined together with the help of peptide bonds. An amino acid consists of a central carbon atom which is named as alpha carbon atom and is linked to an amino group, hydrogen atom, carboxylic acid group and a side chain or R group (Hoffman & Falvo 2004).

Lipids are hydrophobic in nature. These are soluble in chloroform, methanol and in other organic solvents. These include fatty acids, phospholipids, fats and oils and steroids. The tail of a lipid molecule is hydrophobic while the head or central part is a carboxyl group and is hydrophilic (Prescher & Bertozzi 2005).

4. Enzymes are the proteins or biomolecules that catalyzes or increases the rate of chemical reactions and are involved in all biological reactions. Thus, the enzymes are also known as biological catalysts. They have an optimum temperature and works at optimum pH (Peterson, Daniel, Danson & Eisentha 2007). Enzymes are specific in their action meaning one enzyme can act on only one kind of substrate and can thereby control only one type of reaction, thus converting that particular substrate into the product. Enzymes can be classified into six classes, namely, Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases and Ligases according to the type of reaction catalyzed by them. Proteases, lipases and amylases are the three main types of enzymes in human body (Fernandes 2010).

The enzymes contain an active site and have a surface with a distinctive shape and area. This allows only certain kind of substrate to bind to the active site of an enzyme. A substrate is a molecule that binds to the active site and is then acted upon by the enzyme. This enzyme catalyzed reaction is characterized by the formation of a complex between enzyme and substrate when the substrate molecules bind to the enzyme molecules and the complex formed is called as enzyme-substrate complex or ES complex.

E + S       ES        EP       E + P

The formation of this ES complex produces certain conformational changes in the enzyme and thus, lowers the activation energy of a reaction. It also enhances the rate of the reaction. The substrate is then converted into the product and the enzymes play their role by accelerating the conversion of substrates into the products. The product formed leaves the active site of enzyme and the product is released when the reaction is complete. The enzyme is unchanged and remains unaffected in this process and move on to combine with more substrate molecules (Schiffer 2013).

Therefore, enzymes played the role in metabolism by accelerating the chemical reactions, lowering the activation energy and acting on specific substrates.

5. The two main pathways involved in the production of energy within cell are Glycolysis and Tri-carboxylic acid (TCA) cycle. Glycolysis is the first metabolic pathway and is a universal central pathway of glucose metabolism. The breakdown of glucose is the sole source of metabolic energy in some cells and tissues. The TCA cycle is also called as Citric acid cycle and Krebs cycle. This pathway acts as a central point in metabolism as it allows degradative pathways to lead in and anabolic pathways to lead out and also this pathway is closely regulated in coordination with other pathways (Jose, Bellance & Rossignol 2011).

Adenosine triphosphate (ATP) is the main compound which acts as a carrier of chemical energy in most cells. Fats, proteins and carbohydrates are the three main types of molecules that provide the energy which is required for the synthesis of ATP molecules. Also, the main site for ATP synthesis is mitochondria and the site of cytoplasm also contributes for the synthesis of some ATP molecules. Carbohydrates are broken down into glucose, lipids into fatty acids and proteins are broken down into amino acids which are degraded into several intermediate compounds by the series of oxidation-reduction reactions in mitochondria. These intermediates then enter the TCA cycle. The role of electron transport chain system then comes into the play resulting in the synthesis of ATP molecules. The metabolism of glucose and other sugars by glycolysis yields pyruvate along with the two molecules of ATP per molecule of glucose is also generated. This pyruvate is then oxidized to acetyl-CoA and CO2 by a cluster of enzymes called as Pyruvate Dehydrogenase (PDH) complex. This enzyme complex is located in the mitochondria of eukaryotes and in cytosol of prokaryotes. The complete oxidation of one molecule of fatty acid results in the synthesis of hundred ATP molecules. In this way, these two pathways are linked with each other (Fernie, Cerrari & Sweetlove 2004).

REFERENCES

Cummings, JH & Stephen, AM 2007, Carbohydrate terminology and classification, European Journal of Clinical Nutrition, vol. 61, pp. 5-18.

Davidson, C 2009, Transcription: Imperatives for Qualitative Research, International Journal of Qualitative Methods, vol. 8, no. 2, pp. 36-52.

Fernandes, P 2010, Enzymes in Food processing: A Condensed overview on Strategies for better biocatalysts, Enzyme Research, vol. 2010, pp. 1-19.

Fernie, AR, Cerrari, F & Sweetlove, LJ 2004, Respiratory metabolism: glycolysis, the TCA cycle and mitochondrial electron transport, Current Opinion in Plant Biology, vol. 6, 254-261.

Hoffman, JR & Falvo, MJ 2004, Protein-Which is Best?, Journal of Sports Science and Medicine, vol. 3, pp. 118-130.

Hori, H, Tomikawa, C, Hirata, A, Toh, Y, Tomita, K, Ueda, T & Watanabe, K 2014, Transfer RNA Synthesis and Regulation, Encyclopedia of Life Sciences.

Jose, C, Bellance, N & Rossignol, R 2011, Choosing between glycolysis and oxidative phosphorylation: A tumor’s dilemma?, Biochimica et Biophysica Acta (BBA)-Bioenergetics, vol. 1807, no. 6, pp. 552-561.

Mendelian Genetics 2000, Mendel’s First Law of Genetics, accessed on 4 August, 2015 from https://www.ndsu.edu/pubweb/~mcclean/plsc431/mendel/mendel1.htm

Morris, KV & Mattick, JS 2014, The rise of regulatory RNA, Nature Reviews Genetics, vol. 15, pp. 423-437.

Peterson, ME, Daniel, RM, Danson, MJ & Eisentha, R 2007, The dependence of enzyme activity on temperature: determination and validation of parameters, Biochemical Journal, vol. 402, pp. 331-337.

Prescher, JA & Bertozzi, CR, 2005, Chemistry in living systems, Nature Chemical Biology, vol. 1, pp. 13-21.

Schiffer, SH 2013, Catalytic efficiency of enzymes: A theoretical analysis, Biochemistry, vol. 52, no. 12, pp. 1-19.