Transcript Chapter 8-2: Cell Reproduction

Chapter 8-2: Cell
Reproduction
Cell Reproduction
 1 cell makes 2 identical cells
 Ex: make new skin cells when you get
cut
Chromosomes
 Contain DNA
 Carry out genetic material
 Chromatin—relaxed form of chromosomes
 Each chromosome 2 halves (sister
chromatids)
 Held together by a centromere
Chromosomes cont…
Cell Cycle
 Sequence of growth and division in the
cell
Interphase
 First phase of the cell cycle
 Busiest phase of the cell cycle
 G1=First part of interphase
 Cell grows
Interphase cont…
 S phase
 Second part of interphase
 Cell copies its chromosomes
 46 to 92
Interphase cont…
 G2 phase
 Third and last part of interphase
 Cell copies all the other organelles
Mitosis
 Last 4 phases of the cell cycle
 Dividing the nucleus of the cell
Prophase
 Second phase of the cell cycle
 First and longest phase of mitosis
Prophase cont…
 Chromatin becomes chromosomes
Prophase cont…
 Nuclear envelope and nucleolus
disappear
Prophase cont…
 Centrioles (found only in animals)
move to opposite ends of the cell
Prophase cont…
 Spindle fibers grow out of centrioles
 Looks like string/rope
Metaphase
 Phase 3 of the cell cycle
 Spindle fiber attaches to
chromosomes at centromere
 Chromosomes line up in the middle
of the cell
Anaphase
 Phase 4 of the cell cycle
 Centromeres break apart
 Chromatids (each half of the
chromosome) move to opposite
ends of the cell
 Pulled apart by centrioles and
spindle
Telophase
 Phase 5 of the cell cycle
 Chromatids unwind into chromatin
 Spindle fibers and centrioles disappear
 Nucleolus and nuclear envelope reappear
Cytokinesis
 Last step before cell divides
 Division of the cytoplasm
 1—2—4—8—16
 In Animals
 Plasma membrane pinches in to
form two new cells
Cytokinesis cont…
 In plants
 Cell plate forms between two cells
Levels of Organization
 Atoms
 Molecules
 Cells
 Tissues---group of cells that perform same
function (Ex: Smooth muscle)
 Organs—groups of tissues (Ex: Stomach)
 Organ systems—several organs that work
together (Ex: Digestive system)
 Organism—all the organ systems together
(Ex: Humans)