Chapter 2

• What makes bacteria different from archaea and eukaryotes?

  Has no histones
• In what stage of the cell cycle does the cell duplicate its DNA?

  S phase
• Eukaryotic cells that contain one set of genetic information are referred to as

  haploid
• Eukaryotic cells that contain two sets of genetic information are referred to as

  diploid
• Eukaryotic cells that contain more than two sets of genetic information are referred to as

  polyploid
• What is the function of the telomere?


  To protect the end of a DNA molecule
• What is the constricted region of the chromosome where the kinetochore forms?

  centromere
• Which stage of mitosis involves sister chromatids separating and moving toward opposite poles?

  anaphase
• In order to pass the G2/M checkpoint, the cell must do what?

  Have its DNA completely replicated and undamaged
• Assume that a cell has six chromosomes while it is in the G1 stage of the cell cycle. How many chromosomes and how many DNA molecules will it have in the G2 stage?

  6 chromosomes and 12 DNA molecules
• In what stage of meiosis does the separation of homologous chromosomes occur?

  Anaphase I
• What causes genetic variation in meiosis?

  crossing over and random distribution of maternal and paternal chromosomes
• Which molecule holds sister chromatids together during mitosis and meiosis?

  Cohesin
• How many ova (plural ovum) can be produced from two primary oocytes through meiosis?

  2
• What is the function of the G1/S checkpoint?

  Maintains cell until necessary enzymes for replication are synthesized
• What is the function of the G2/M checkpoint?

  Detection of DNA damage after replication
• What is the function of the spindle-assembly checkpoint?

  Ensures that each chromosome is attached to spindle fibers from opposite poles
• Which process of division is used for body cells?

  Mitosis
• Which process of division is used for gametes?

  Meiosis
• Crossing over is the exchange of genetic material between homologous chromosomes during meiosis
• Crossing over between non-sister chromatids causes genes on the same chromosomes to get shuffled
• Shugoshin prevents the sister chromatids from separating in Anaphase 1 of meiosis
• If shugoshin is mutated, premature separation of chromosomes will happen causing unequal numbers of chromatids/chromosomes to end up in the gametes
• The spindle microtubule attach the chromosome at the centromere
• Random alignment of chromosomes during metaphase I of meiosis causes genes on different chromosomes to shuffle
• Which phase do sister chromatids separate?

  Anaphase
• There is no reduction in chromosome number in mitosis
• In meiosis, the chromosome number halves.
• In mitosis, the individual chromosomes line up on top of each other.
• In meiosis, homologous pairs line up in metaphase I.
• A dividing eukaryotic cell is treated with a drug that inhibits the molecular motors associated with kinetochores. At which cell cycle stage would it stop?

  Metaphase
• Oogenesis begins before birth and a baby is born with the primary oocytes where meiosis is stalled at the Prophase I stage
• Describe double fertilization

  One sperm cell fertilizes the egg in the embryo sac making a diploid embryo (2n). The other sperm nucleus fertilizes the polar nuclei that has two haploid nucleus from the maternal side to produce 3n endosperm.
• Microspore is haploid
• Primary spermatocyte is diploid
• Microsporocyte is diploid
• First polar body is haploid
• Oogonium is diploid
• Spermatid is haploid
• Secondary oocyte is haploid