Transcript Unit 11 Cell Division

Unit 11
Cell Division
Cell Cycle
• Interphase consists of G1, S and G2
phases
• Cell spends about 90% of its time in
interphase
• Cell cycle consists of interphase and
mitosis (division of nucleus)
Interphase
• G1
– Increased metabolic activity
– Replication of organelles
• S (synthesis)
– DNA is duplicated
– Each unduplicated chromosome becomes duplicated
• G2
– Second growth phase
– Preparation for division
Chromosome structure
• Duplicated chromosome
– Duplicated during S phase of interphase
• 2 sister chromatids joined by a centromere
– Sister chromatids should be identical
• Kinetochore on either side of centromere
– Binds to microtubules during mitosis and
directs the separation of sister chromatids
Cytokinesis
• Division of the cytoplasm
• Occurs after mitosis
Mitosis Ex. 11.1
• Answer questions
• Watch video for help with answers
Exercise 11.2
• Observe mitosis in whitefish blastula cells
• Try to identify cells in each phase of
mitosis.
Exercise 11.3
• Observe mitosis in Allium (onion) cells.
• Draw an example of each phase.
• Compare mitosis in animal and plant cells.
Meiosis
• Purpose- production of gametes
– Sperm and egg
– Occurs in gonads
• Meiosis occurs in animals and plants but is
more complex in plants
• Two cell divisions
– Meiosis I
– Meiosis II
Homologous chromosomes
• In a diploid cell, chromosomes exist in
pairs that have corresponding but not
identical genetic information.
• One member of pair from mother, one
from father.
• Meiosis I
– Separates homologous chromosomes
• Meiosis II
– Separates sister chromatids
• At the end of Meiosis
– 4 haploid gamete cells produced
Exercise 11.5
• Simulate meiosis using pop-beads
Cell Models
• Pay attention to the cell models showing
mitosis and meiosis which are displayed
around the room.
Unit 11 HW
• Due next week
• Reinforces concepts learned today