(6) Write the molecule or class of molecules described by each clue. If the clue

Question

(6) Write the molecule or class of molecules described by each clue. If the clue describes more than one (type of) molecule, give an example of a molecule or class of molecules described by the clue (1 point each)

(A) Molecule that “stores” genetic information, i.e. the molecule that genes are made of

(B) A non-reducing sugar (provide one example of a compound in this category)

(C) Nucleic acid base (nucleobase) present in DNA instead of uracil due to uracil’s tendency to tautomerize

(D) An amino acid residue likely to be found at the edge of a membrane spanning helix as well as to be involved in binding with galactose residues in oligosaccharides

(E) Aldohexose: in its ?-pyranose form, all of the heavy atom substituents on the ring are equatorial

(F) Keto-hexose that, having the same configurations at carbons 3-5 as glucose, can be produced from glucose via an enediol intermediate

(G) Hetero-polysaccharide whose high negative charge density increases the affinity of anti-thrombin (which it binds) to the positively charged thrombin molecule

(H) Extended (non-substituted) poly-saccharide chain with structure reminiscent of a protein ?-strand; as in fibrous proteins like silk fibroin, the strands form rolled sheets

(I) An amino acid residue likely to be found at the edge of a membrane spanning helix as well as to be phosphorylated by an activated insulin receptor

(J) A molecule (e.g. provide an example of such a molecule) that reacts with Benedict’s reagent to form a red precipitate

Explanation / Answer

A) The molecule that store genetic information is Deoxyribonucleic acid(DNA). It is present in chromosomes which are in nucleosus of cell

B) A sugar that cannot donate electrons to other molecules and therefore cannot act as a reducing agent. Sucrose is the most common nonreducing sugar.Other examples are trehalose, raffinose, stachyose and verbascose.

C) It is Thymine. Thymine has greater resistance to photochemical mutation, making the genetic message more stable.

E) An aldohexose is a hexose with an aldehyde group on one end. The aldohexoses have four chiral centres for a total of 16 possiblealdohexose stereoisomers.  Commonly occur in nature: D-glucose, D-galactose, and D-mannose.

G) If the polysaccharides molecules are formed by different kinds of monosaccharides, they are considered heteropolysaccharides. Hyaluronic acid, formed by thousands of alternative units of N-acetyl glucosamine and glucuronic acid, is an example of heteropolysaccharide.  

F) A ketohexose is a ketone-containing hexose (a six-carbon monosaccharide). The most common ketohexoses, each of which represents a pair of enantiomers (D- and L-isomers), Examples are psicose, fructose, sorbose, and tagatose.

H) Polysaccharides have several roles. Polysaccharides such as starch, glycogen, and dextrans are all stored in the liver and muscles to be converted to energy for later use. Amylose and Amylopectin are polysaccharides of starchUnbranched polysaccharides contain only alpha 1,4 linkages. However, there exists branched polysaccharides which are branched by virtue of certain molecules being linked to a molecule via alpha 1,4 and another via alpha 1,6 glycosidic bonds.

I) It is Tyrosine.  the insulin receptor plays a key role in the regulation of glucose homeostasis, a functional process that under degenerate conditions may result in a range of clinical manifestations including diabetes and cancer

J) Benedict's test detects the presence of aldehydes and alpha-hydroxy-ketones. Examples are glucose, fructose.

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