Nucleic Acid Structure Quiz

Nucleic Acid Structure

• PowerPoints are supplementary material, not replacements for textbooks. Recommended textbooks are essential for complete understanding and exam preparation.
• Learning objectives for the lectures include: defining nucleosides, nucleotides, and nucleic acids; classifying and listing nitrogenous bases; describing DNA structure and properties; describing different types of RNA; and outlining DNA organization into a chromosome.
• Nucleic acids are polymers of nucleotides. DNA is a double-stranded helical polymer of deoxyribonucleotides. RNA is a single-stranded polymer of ribonucleotides. DNA forms a double helix.
• Nucleotides are composed of a nitrogenous base, a pentose sugar, and at least one phosphate group. A nucleotide includes a nitrogenous base, a pentose sugar (ribose/deoxyribose), and one or more phosphate groups. A nucleoside is a nitrogenous base and a pentose sugar.
• DNA and RNA differ in their nitrogenous bases and pentose sugars.
• Nitrogenous bases are of two types: Purines (Adenine (A) and Guanine (G) - 9 membered ring) and Pyrimidines (Thymine (T), Cytosine (C), and Uracil (U) - 6 membered ring)
• DNA contains Adenine, Thymine, Guanine, and Cytosine. RNA contains Adenine, Uracil, Guanine, and Cytosine.
• DNA's pentose sugar is deoxyribose, while RNA's is ribose.
• DNA is double-stranded, while RNA is single-stranded.
• DNA is a polymer of deoxyribonucleotides, while RNA is a polymer of ribonucleotides.
• The phosphate group (PO4) bridges the 3' and 5' positions of ribose sugar via a phosphodiester bond.
• The terminal nucleotide with a free 5' carbon is the 5' end. The terminal nucleotide with a free 3' carbon is the 3' end.
• The melting temperature (Tm) of DNA depends on the G-C content, as G-C bonds have three hydrogen bonds (stronger than A-T's two hydrogen bonds).
• DNA's structure was determined by Watson and Crick in 1953 and has a double helix structure
• Three types of DNA structures are A-DNA, B-DNA, and Z-DNA; B-DNA is the most common form.
• Watson-Crick DNA structure features two polynucleotide chains forming a double helix around a common axis. The strands are antiparallel and each is a right-handed helix. The nitrogenous bases are in the center and the sugar-phosphate chains on the sides. The helix has 10 base pairs per turn.
• Complementary base pairing occurs between the bases (A-T and G-C) through hydrogen bonds. (A=T; G=C)
• There are 3 dimensional structures for DNA.

Types of RNA

• mRNA (messenger RNA) is linear, derived from DNA by transcription, and carries the codon sequence for protein synthesis.
• rRNA (ribosomal RNA) is involved in protein synthesis (translation), ribosomes are protein synthesis sites and are composed of ribosomal RNA.
• tRNA (transfer RNA) is clover-leaf shaped and involved in protein synthesis (translation), transferring amino acids to the growing protein chain.

Chromosome Structure

• DNA is organised into chromosomes within the nucleus.
• DNA is wrapped around histones to form nucleosomes.
• Nucleosomes undergo further folding to form chromosomes.
• Histones are positively charged proteins rich in basic amino acids (arginine and lysine).

Test your knowledge on the structure and properties of nucleic acids, including DNA and RNA. Learn about nucleotides, nucleosides, and how these molecules function within chromosomes. This quiz will help reinforce your understanding of key concepts necessary for your studies in molecular biology.