Genetic Material Components Quiz

DNA Structure

• DNA is a group of molecules responsible for carrying and transmitting genetic instructions from parents to offspring.
• DNA is used by eukaryotes and prokaryotes to synthesize proteins and enzymes essential for cell survival.

Basic Building Blocks of DNA

• Nucleotides are the basic building blocks of DNA, composed of a sugar group, a phosphate group, and a nitrogen base.
• Nucleotides are connected by a phosphodiester bond between the 3rd carbon of one sugar and the 5th carbon of the second sugar.

Nitrogenous Bases

• There are two types of nitrogenous bases: pyrimidines and purines.
• Pyrimidines have a single carbon-nitrogen ring and contain two nitrogen atoms in their structure.
• Purines have two carbon-nitrogen rings fused together and contain four nitrogen atoms in their structure.
• Nitrogenous bases in DNA: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T).
• Nitrogenous bases in RNA: Adenine (A), Guanine (G), Cytosine (C), and Uracil (U).

Base Pairing

• A pairs with T (DNA) or U (RNA) and G pairs with C.
• C pairs with G and T (DNA) or U (RNA) pairs with A.

Pentose Sugars

• Two types of pentose sugars are present in nucleic acids: ribose and deoxyribose.
• Ribose is present in RNA, and deoxyribose is present in DNA.
• Deoxyribose is missing one hydroxyl group at the carbon 2nd position compared to ribose.

Phosphate Group

• The phosphate group is bonded to the 5th atom of the sugar.
• The phosphate group has a negative charge, making DNA highly charged and polar.

The Watson-Crick Model

• The model has a single DNA molecule consisting of two individual nucleic acid chains that are coiled around a central axis.
• The two chains are antiparallel, with the backbone of the nucleic acid (sugar-phosphate) on the exterior and the nitrogenous base on the inside.
• Each complete turn of the helix is 10 bases per turn.
• The nitrogenous bases of opposite chains are electrostatically attracted to one another, forming hydrogen bonds.

Stability Factors for the DNA Helix

• Positive forces: hydrogen bonds, stacking interactions, and the negative charge of the phosphate group.
• Hydrogen bonds: A-T forms two hydrogen bonds, and G-C forms three hydrogen bonds.
• Stacking interactions: the arrangement of sugars and bases along the axis, with hydrophobic bases stacked on the inside and hydrophilic sugar phosphate backbone on the outside.

Chargaff's Rule

• The number of nitrogenous bases in DNA is present in equal quantities.
• The amount of A is equal to T, and the amount of C is equal to G.

The Structure of RNA

• RNA has ribose sugar instead of deoxyribose in DNA.
• RNA has uracil instead of thymine in DNA.
• Most RNA is a single-stranded polynucleotide chain, while DNA is a double helical structure.
• Some animal viruses have RNA as their genetic material, which is double-stranded helix.