BIO202 Final Term Current Paper 2023 by Maryam

WelcOme vularians….(◔‿◔) · Subjective 2023 🥴 · 1.characteristics of VLDLs · VLDLs (very low density lipo proteins) are assembled

in the liver.

• composed predominantly of TAGs synthesized in liver and

• contain some cholesterol and cholesteryl esters

• As VLDL pass through the circulation, TAG is degraded and taken up by

peripheral tissues in the form of fatty acids, causing the VLDL to decrease in

size and become denser, called VLDL remnant.

2.primary structure of DNA

The primary structure of a nucleic acid is its covalent structure and nucleotide sequence. • The back bone of the primary structure is the linear strand made by sugar phosphate residues, linked together, while the bases project laterally. This way a long, un-branched chain is formed. Primary structure is a huge linear polymer of dNTPs that are joined to each other by 5’- 3’ PDE bonds. • The resulting long, un-branched chain has polarity. • Both 5’-end and 3’-end are free. at 5’-end there is a free phosphate. at 3’-end there is a free OH that are not attached to other nucleotides. • Purines and pyrimidines project laterally from the backbone and forms a variable part. • The variable part is concerned with the expression of genetic information. By convention, the structure of a single strand of nucleic acid is always written with the 5´ end at the left and the 3´ end at the right • that is, in the 5´ to 3´ direction . • Some simpler representations of this penta deoxy ribonucleotide are • pA-C-G-T-A OH, • pApCpGpTpA, and finally 5´-ACGTA-3´.

174 Nucleotides and Nucleic Acids-DNA

3.how activation energy effect rate of reaction

Activation energies, G‡, • The activation energies, G‡, for the • S

→ P

and P → S reactions are indicated. • G′⁰ is the overall standard free-

energy change in the direction S → P

• The rate of a reaction reflects this activation energy: a higher activation energy corresponds to a slower reaction.

• Reaction rates can be increased by raising the temperature, thereby

increasing the number of molecules with sufficient energy to overcome the energy barrier. • Alternatively, the activation energy can be lowered by adding a catalyst.

• Catalysts enhance reaction rates by lowering activation energies

• The role of enzymes is to accelerate the interconversion of S and P. • i.e enzymes lower the energy of activation, Δ G‡, of a reaction.

• The enzyme is not used up in the process, and the equilibrium point

is unaffected.