Warm-up 12/11:
• Define the term Homologous?
• What is a Haploid? Diploid?
• Your somatic cells have 46 Chromosomes and
are diploid cells,
– How many chromosomes are in your haploid
Gametes?
• What do you call a photograph of all the
chromosomes?
Cell Cycle and Mitosis
Cell Cycle
• 3 major phases
• Interphase: time
between cell divisions
- G phases: growth
- S phase: copying of
DNA
• M phase (mitosis):
division of the nucleus
• Cytokinesis: division of
the cytoplasm
Mitosis (M phase)
•
•
•
•
2n  4n chromatids  2 (2n)
Continuous process starts with interphase
Need to separate the doubled chromosomes
Four phases
prophase  metaphase  anaphase  telophase
• PMAT
Prophase
•
•
•
•
•
Can see chromosomes
Chromatids stay connected by centromeres
Nucleolus and nuclear membrane break down
Centrosomes and centrioles appear
Early mitotic spindle forms
Metaphase
• Two types of fibers (mitotic spindle)
kinetechore fibers: attach to centromere of
chromosome
polar fibers: extend centrosome to centrosome, push
cell apart
• Fibers line up the chromosomes in middle
Anaphase
• Chromatids of each chromosomes are pulled apart
by fibers
• Move towards opposite poles of dividing cells
Telophase
•
•
•
•
•
Chromosomes in opposite ends
Spindle fibers break down
Nuclear envelope reforms
Nucleolus in each cell
Cytokinesis
MOVIE
Homework
• Chromosome Structure Due Monday
• Observing Mitosis Due Tuesday
• PQRST 154-159 Due Wednesday