Download Mitosis Notes

Chapter 8 Notes
Mitosis
 Cells must divide:
1.to keep the surface to volume ratio
manageable
2.because if cells get too large, they
can not eliminate wastes and bring
in proper nutrition.
Diploid – 2 sets of chromosomes
(ex. 46 in human body cells) – 2n
Haploid – 1 set of chromosomes
(ex. 23 in human sex cells) - n
Chromatin and Chromosomes
 Chromatin is the thin, threadlike DNA
found when the cell is not dividing.
 Chromosomes are the thick coiled
visible form of DNA found during cell
division.
 Chromosome
DNA
 In prokaryotic cells, the circular
chromosome (DNA) floats in the
cytoplasm.
 In eukaryotic cells, sets of
chromosomes in different
lengths (DNA) are found in the
nucleus of the cell.
Cell Cycle
 During the cell cycle, a cell
grows, replicates (copies) all of
its DNA, and divides into two
daughter cells, which each
receives an exact copy of the
parent cell’s DNA.
 In humans, parent cells have 46
chromosomes, so each daughter cell
will have 46 chromosomes.
Cell Cycle
 There are 2 main parts of the cell
cycle:
 1. interphase
 2. cell division (mitosis and
cytokinesis
 Interphase is the part of the cell
cycle in which the cell is growing and
carrying out its function. This is
when the cell is doing its job
Cell Cycle
 There are 2 main parts of the cell
cycle:
 1. interphase
 2. cell division (mitosis and
cytokinesis
 Mitosis is the division of the
nucleus
 Cytokinesis is the division of the
cytoplasm.
Interphase
 3 phases of interphase:
 1. G1 – Cell growth
 2. S – DNA replication
 3. G2 – preparation for mitosis;
organelles are produced
 G1- S G2M C
End part 1
Mitosis - Prophase
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PROPHASE:
Chromatin condenses into chromosomes
Nuclear membrane is broken down
Spindle fibers form
Mitosis - Metaphase
 METAPHASE:
 Chromosomes line up in the MIDDLE of
the cell.
Mitosis - Anaphase
 ANAPHASE:
 The sister chromatids separate and move
APART toward the opposite sides of the
cell.
Mitosis - Telophase
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TELOPHASE:
Chromosomes uncoil into chromatin.
Two new nuclear membranes form.
Opposite of prophase.
Cytokinesis
 CYTOKINESIS:
 The cell membrane and cytoplasm divide
 In plant cells, a cell plate is formed, which
turns into a new cell wall.
 Animal cells pinch in half.
 Result of mitosis: 2 daughter cells that
are exactly like the parent cell
A karyotype shows the number of
chromosomes and whether it is a
boy or girl.
Gamete – sex (reproductive) cell –
egg or sperm (or pollen) – haploid
Somatic cell – body cell - diploid
In meiosis, crossing over takes
place when homologous
chromosomes exchange segments
of DNA.