Chapter 8: DNA, RNA, and the Flow of Genetic Information

• What type of mutation causes sickle cell anemia?

  Point mutation in hemoglobin gene
• On which chromosome is the gene for hemoglobin located?

  Chromosome 11
• What happens to the amino acid at position #6 in sickle cell anemia?

  It is replaced by another amino acid
• What is the Central Dogma of Biochemistry?

  • Information in DNA is transcribed to RNA
  • RNA is translated into protein

  
• What are the two main kinds of nucleic acids?

  DNA and RNA

  
• What are nucleic acids made of?

  Long linear polymers of nucleotides
• What do nucleic acids carry?

  Genetic information passed between generations
• What are the three main components of a nucleotide?

  1. carbon sugar, phosphate group, base

  
• What sugar is found in RNA?

  Ribose
• What sugar is found in DNA?

  Deoxyribose

  
• What is a nucleoside?

  Sugar + base
• What is a nucleotide?

  Sugar + base + phosphate

  
• How is a nucleic acid polymer formed?

  By linking nucleotides together

  
• How are nucleosides named when the base is a purine?

  Remove “-ine” and add “-osine”
• How are nucleosides named when the base is a pyrimidine?

  Take the first part of the base name and add “-idine”
• What is the relationship between nucleosides of adenine and adenosine?

  Adenosine is the nucleoside of adenine
• What is the relationship between nucleosides of cytosine and cytidine?

  Cytidine is the nucleoside of cytosine
• What is the structure of a nucleotide?

  Nucleoside + phosphate

  
• Where is the phosphate group connected in nucleotides?

  To the 5'-C of the monomers
• What types of nucleotides can exist?

  Monophosphates, diphosphates, triphosphates

  
• How are nucleotides named based on their base?

  Remove “-ine” and add “-ylate” for purines
• How are nucleotides named for pyrimidines?

  Take the first part of the base name and add “-idylate”
• How can nucleotides indicate the number of phosphate groups?

  Named as nucleoside derivatives
• What is the process of phosphodiester bond formation?

  Nucleophilic attack of 3'-OH on phosphate
• What is the structure of double-helical DNA?

  • Two DNA polymer chains coiled around an axis
  • Right-handed helix
  • Antiparallel chains
  • Sugar-phosphate backbone on exterior
  • Bases toward the interior

  
• How many bases are there per turn in DNA?

  About 10 bases
• What is the angle of rotation for each base in DNA?

  36 degrees from the one below
• How are bases oriented in the DNA helix?

  Nearly perpendicular to the helix axis
• What maintains the constant diameter of the DNA double helix?

  Specific base pairing
• Which bases pair together in DNA?

  Adenine with Thymine, Guanine with Cytosine

  
• How many hydrogen bonds form between Adenine and Thymine?

  2 hydrogen bonds

  
• How many hydrogen bonds form between Guanine and Cytosine?

  3 hydrogen bonds
• What are the characteristics of A-DNA, B-DNA, and Z-DNA?

  • A-DNA: Right-handed, wider, shorter, tilted base pairs
  • B-DNA: Right-handed, 10.4 bases/turn
  • Z-DNA: Left-handed, narrow, alternating purines and pyrimidines

  
• What does the double helical model suggest about DNA replication?

  It suggests a mechanism for genetic material replication

  
• What was the purpose of the Meselson & Stahl experiment?

  To determine the mechanism of DNA replication

  
• What type of DNA was used in the Meselson & Stahl experiment?

  15N-labeled DNA

  
• How did Meselson & Stahl test for the presence of 14N?

  By determining the density of replicated DNA

  
• What does a mixture of 15N and 14N DNA indicate?

  Density between 15N-DNA and 14N-DNA
• What must happen for DNA to replicate in a semiconservative manner?

  The two strands must separate

  
• What causes DNA strands to separate?

  Breaking of hydrogen bonds between bases