BIOCHEM 1.6

• What is the primary function of chromosomes?

  Chromosomes carry genetic information copied and passed on to daughter cells.
• What are chromosomes composed of?

  Chromosomes are made of long sections of DNA, proteins, and a small amount of RNA.
• What happens to each DNA molecule before cell division?

  Each DNA molecule makes a copy of itself before cell division.
• How many chromosomes do humans have?

  Humans have 46 chromosomes.
• What are homologous pairs?

  Homologous pairs are matching pairs of chromosomes found in cells.
• What is the diploid number?

  The diploid number is the total number of chromosomes in a cell.
• What is the haploid number in human gametes?

  The haploid number in human gametes is 23 chromosomes.
• What are the four stages of mitosis?

  • Prophase
  • Metaphase
  • Anaphase
  • Telophase

  
• What processes occur during interphase?

  • Replication of DNA
  • Replication of organelles with DNA
  • Making new organelles
  • Synthesis of ribosomal material
  • Synthesis of ATP
  • Synthesis of proteins
  • Increase in cell size
• What is the longest part of the cell cycle?

  Interphase is the longest part of the cell cycle.

  
• Where does mitosis occur in plants?

  Mitosis occurs in the meristems of plants.
• What occurs during metaphase?

  During metaphase, chromosomes align at the center of the spindle and attach to spindle fibers at the centromere.

  
• What is cytokinesis?

  Cytokinesis is the process of cytoplasm splitting to form two daughter cells.
• What is the mitotic index?

  The mitotic index is the percentage of cells in mitosis in a sample.
• How is the mitotic index calculated?

  The mitotic index is calculated as: $\text{Mitotic index} =$$\frac{\text{No of cells in prophase + metaphase + anaphase + telophase}}{\text{Total number of cells}} \times 100$.
• What are chiasmata?

  Chiasmata are points where chromatids are joined and may exchange genetic material during crossing over.
• What is crossing over?

  Crossing over is the swapping of pieces of chromosomes between homologous chromatids.

  
• What occurs during metaphase I of meiosis?

  During metaphase I, homologous chromosomes arrange randomly on the equator of the spindle.

  
• What happens during anaphase I of meiosis?

  During anaphase I, the chromosomes in each bivalent separate and are pulled to opposite poles.
• What happens during metaphase II of meiosis?

  During metaphase II, chromosomes line up separately on the spindle at the equator.

  
• What happens during telophase II of meiosis?

  During telophase II, chromatids lengthen, the spindle disappears, and the nuclear membrane reforms.