DNA and RNA Nitrogen Bases Quiz

DNA Structure and Bonds

• Nucleotides in DNA are linked by phosphodiester bonds.
• Adenine pairs with thymine through two hydrogen bonds.
• Guanine forms three hydrogen bonds with cytosine in DNA.
• At the 5’ end of a nucleic acid strand, a phosphate group is present.
• In the double helix structure of DNA, nucleotides are linked by covalent bonds between the sugar of one nucleotide and the phosphate of the next.

Griffith's Experiment

• Griffith concluded that a 'transforming principle' could convert nonpathogenic bacteria into pathogenic ones.
• Bacteria of the 'S' strain are pathogenic due to their ability to produce a protective capsule that prevents phagocytosis.
• The term 'transformation' in Griffith's experiment refers to the process by which nonpathogenic bacterial cells acquired virulence from heat-killed pathogenic cells.
• Some living cells of the nonpathogenic strain became pathogenic due to the uptake of genetic material from the heat-killed 'S' strain.

Evidence for DNA as Genetic Material

• Further supporting evidence for DNA as the genetic material came from the identification and experimentation of nucleic acids, establishing their role in heredity.
• Heat-killed cells served as a source of genetic material that transformed nonpathogenic cells during the experiment.

Base Pairing and DNA Structure

• Watson and Crick concluded that nitrogenous bases pair specifically, with adenine always pairing with thymine and guanine pairing with cytosine.
• According to Franklin's model, sugar-phosphate backbones in DNA run in opposite directions (antiparallel).
• A DNA base pair of adenine and thymine is held together by two hydrogen bonds.

Nitrogenous Bases

• Cytosine and guanine pair through three hydrogen bonds.
• Thymine is a pyrimidine nitrogenous base found only in DNA.
• Uracil is a nitrogenous base found in RNA but not in DNA.
• In DNA, deoxyribose sugar distinguishes it from ribose sugar in RNA.

RNA Functions

• RNA's primary function is to serve as a messenger carrying genetic information from DNA to the ribosomes.
• Messenger RNA (mRNA) is responsible for carrying genetic information from DNA to ribosomes for protein synthesis.
• Transfer RNA (tRNA) helps in protein synthesis by transporting specific amino acids to the ribosome.
• The anticodon on tRNA is significant as it complements the mRNA codon, ensuring the correct amino acid is added during translation.

Nucleotides and Nucleosides

• Nucleosides are named based on their nitrogen base, with a prefix indicating the type (e.g., adenosine for adenine).
• A nucleotide is defined as a nucleoside with an added phosphate group.
• Nucleotides are formed when a phosphate group is attached to the sugar of a nucleoside.