DNA and RNA Composition Quiz

Composition and Structure of DNA and RNA

• DNA and RNA are nucleic acids, biopolymers composed of nucleotides
• Nucleotides are the building blocks of DNA and RNA
• DNA is typically double-stranded, forming a double helix
• RNA is typically single-stranded
• Both DNA and RNA have a sugar-phosphate backbone
• DNA's sugar is deoxyribose, RNA's sugar is ribose
• DNA has the bases adenine (A), thymine (T), guanine (G), and cytosine (C).
• RNA has the bases adenine (A), uracil (U), guanine (G), and cytosine (C).
• Watson and Crick determined the three-dimensional structure of DNA in 1953
• DNA replication follows a semi-conservative mechanism
• In prokaryotic cells, DNA is smaller, circular and located in the cytoplasm
• In eukaryotic cells, DNA is larger, arranged in chromosomes, and located in nucleus

Objectives

• Understand the definition and history of DNA
• Explain the chemical structure of DNA
• Differentiate between DNA and RNA
• Compare and contrast DNA and RNA

DNA Structure

• DNA is a double helix, with two strands running antiparallel (5' to 3' and 3' to 5').
• The strands are connected by hydrogen bonds between complementary bases: A with T, and G with C.
• A sugar-phosphate backbone forms the exterior of the double helix.
• Nucleotides are joined by phosphodiester bonds
• DNA has a double helix structure
• The bases from opposite strands pair through hydrogen bonds.
• DNA shape can be a double helix
• DNA has an antiparallel structure
• DNA uses hydrogen bonds

History of DNA

• Gregor Mendel's plant experiments advanced the study of genetics in 1857
• Friedrich Miescher discovered DNA in 1869
• Further research on DNA has led to many advancements in genetics since those early discoveries

DNA as a Double Stranded Helix

• James Watson and Francis Crick determined the three-dimensional structure of DNA, based on work by Rosalind Franklin
• This structure is a double-stranded helix

DNA & RNA

• Nucleic acids are biopolymers made up of nucleotides.
• DNA is deoxyribonucleic acid
• RNA is ribonucleic acid
• DNA has deoxyribose sugar
• RNA has ribose sugar
• DNA bases are A, T, G, C
• RNA bases are A, U, G, C

DNA vs RNA

Types of RNA

• Messenger RNA (mRNA) carries the genetic code for protein synthesis.
• Ribosomal RNA (rRNA) forms the ribosome structure and catalyzes protein synthesis.
• Transfer RNA (tRNA) transports amino acids to ribosomes for protein synthesis.
• Small nuclear RNAs (snRNAs) and small nucleolar RNAs (snoRNAs) play roles in various nuclear processes, including mRNA splicing and rRNA processing .
• MicroRNAs (miRNAs) and small interfering RNAs (siRNAs) regulate gene expression.
• Piwi-interacting RNAs (piRNAs) protect the germ line from transposable elements.
• Long noncoding RNAs (lncRNAs) serve as scaffolds and regulate diverse cell processes

Denaturation, Renaturation, and Hybridization of DNA

• Denaturation: Alkali or heat separates DNA strands by disrupting hydrogen bonds
• Renaturation: If separated DNA strands are slowly cooled under appropriate conditions, complementary base pairs reform.
• Hybridization: A single strand of DNA or RNA can pair with a complementary base sequence on another DNA or RNA strand.

Mitochondrial DNA

• Mitochondrial DNA is a double-stranded circular DNA molecule found in mitochondria.
• The genetic code for mitochondria is slightly different than that of genomic DNA
• Mitochondria possess their own genome containing genes for essential components of the electron transport chain
• Mitochondria are maternally inherited

How Chemical Bonds Hold DNA Together

• Covalent bonds hold sugar-phosphate backbones together.
• Hydrogen bonds connect complementary bases

DNA in prokaryotes and eukaryotes

• Prokaryotic DNA is smaller, circular, and located in the cytoplasm.
• Eukaryotic DNA is larger, arranged into chromosomes, and located in the nucleus.