LAB 5: DNA

• In gel electrophoresis, what directs and speeds up the movement of DNA through the gel?

  Electricity
• The lysis solution in Part I includes SDS (Sodium Dodecyl Sulphate), a detergent. According to the lab manual, what is a detergent?

  A detergent is a chemical that allows lipids (and similar non-polar compounds) to mix with water.
• What is sodium citrate?

  Sodium citrate helps to inactivate the enzymes that would break up DNA.
• What is sodium chloride (NaCl)?

  Sodium chloride is table salt. Proteins do not stay dissolved well in salt water.
• What is EDTA (Ethylene Diamine Tetraacetic Acid)?

  EDTA is a magnesium ion chelator. A chelator removes ions from a solution. Ions in solution help to stabilize phospholipid membranes, and also activate the enzymes that would break up DNA.
• The processes that allow a sequence of bases in DNA to specify a sequence of amino acids in a protein are referred to as transcription and translation.
• • In transcription, a sequence of bases in DNA is transcribed into a sequence of bases in RNA.
  • In translation, the sequences of bases in RNA is translated into a sequence of amino acids in a protein.
• What is the main molecule that accomplishes transcription?

  RNA polymerase
• Which enzyme can only bind to DNA at a specific sequence of bases on the DNA?

  A promoter
• What is a template strand?

  The DNA sequence that is used during transcription to produce RNA.
• • In DNA, adenine always pairs with thymine (A-T), and guanine always pairs with cytosine (G-C).
  • In RNA, adenine always pairs with uracil (A-U), and guanine always pairs with cytosine (G-C).
• What is a terminator sequence?

  DNA sequence that signals the end of transcription.
• What is the difference between a start codon and a stop codon?

  A start codon initiates protein synthesis, while a stop codon signals the end of protein synthesis.
• How many bases are in a codon?

  Three
• Why is SDS in the lysis solution?

  SDS is a chemical that allows lipids to mix with water.
• After exposure to the electric current, the gel is immersed in a warm stain solution. Why do we keep this solution warm?

  Warm water allows the stain to diffuse into the gel.
• In this drawing of DNA bands in a gel after electrophoresis, which lane (indicated by letter) includes the band with the smallest DNA fragments? Explain.

  C, smaller DNA fragments will travel a further distance.
• What are the four bases that are found in DNA?

  Adenine, thymine, cytosine, guanine
• A sample of DNA is 100,000 bases long. It is cut between bases 25,000 and 25,001, and between bases 50,000 and 50,001. This DNA is then loaded into a gel and exposed to an electric current (electrophoresis). How many bands of DNA would result?

  Two DNA bands