starter 1. what is the purpose of cell division? 2. what are the 3 major steps and what happens in...
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Curious? Asexual reproducers Archea Bacteria Protists Starfish Sexual reproducers (pregnancy length) Birds Humans (9 months) Insects Rabbit (33 Days) Alpine Salamander (38 months) Elephant (22 months)TRANSCRIPT
Starter1. What is the purpose of cell division?2. What are the 3 major steps and what
happens in each of the cell cycle?3. Why must DNA replication happen
before mitosis and cytokinesis?4. What are the phases of mitosis?5. With a pencil, label your drawings with
the stages of the cell cycle, the phases of mitosis and cytokinesis.
Where we have been. Cells
Organelles Nucleus
DNA Replication
Chromosomes
Curious? Asexual
reproducers Archea Bacteria Protists Starfish
Sexual reproducers (pregnancy length) Birds Humans (9 months) Insects Rabbit (33 Days) Alpine Salamander
(38 months) Elephant (22
months)
Starter Using 9.1 complete the reproduction
venn diagram on the front table
Asexual Vs. Sexual Reproduction Reproduction – 2 types
Asexual One Parent Offspring genetically identical to the ONE parent Quick Many offspring
Sexual Two Parents Offspring share genetic information from BOTH parents Creates variation (offspring genetically different) Slower Few offspring
Chromosomes Chromosomes
DNA condensed, wrapped around proteins, called histones Nucleus Only visible during cell division Each organism has its own number
Corn – 20, fruit fly 8, horsetail – 216, Chimp – 48, Dog – 78, humans? Somatic cells? Sex Cells?
Haploid-half set of chromosomes 23 in our nucleus
Diploid – Full Set of chromosomes 46 in our nucleus
Chromosomes Sister Chromatids
The 2 halves of a replicated chromosome Centromere
The place where sister chromatids are connected
CELL DIVISION
Cell Division Why?
Replace lost cells Repair Growth and development Reproduction
Cell Cycle “ALL CELLS COME FROM CELLS” The “life cycle” of a cell from the
beginning of one division to the beginning of the next division.
Cell division 1 cell becomes 2
The 2 new cells are called Daughter Cells
The Cell Cycle Interphase
G1 – primary growth S – DNA replication G2 – Cell carries out
everyday functions, prepares for division
Mitosis M – Cell divides
Cytokinesis Cytoplasm divides
MITOSISThe Break Down
The Phases Prophase Metaphase Anaphase Telophase Cytokinesis
Prophase
Nucleus disappears Chromatin condenses forming
chromosomes (visible) Centrioles move to opposite sides of the
nucleus Spindle fibers form between them – some
of which attach to centromeres on each side of the chromosome
Metaphase Chromosomes line up in the middle of
the cell
Anaphase Sister chromatids split at centromeres to
make separate chromosomes Chromosomes move to opposite ends of
the cell
Telophase Chromosomes begin to uncoil back into
chromatin Nuclear membranes develop around the
bundles of chromatin at opposite ends of the cell
Spindle fibers disappear Nucleolus reappear in each new,
daughter cell
Cytokinesis When the cytoplasm divides, cell division
is complete.
Not always the same! Animals
Cell membrane pinches, forming 2 identical daughter cells
Complete cells that are identical
Plants Cell Plate forms
halfway between the 2 nuclei
Materials for new cell walls and membranes gather and fuse in the middle between the 2 nuclei. Material gradually divides to create 2 cells.