Transcript Mitosis and Meiosis/ Genetics

Mitosis and Meiosis/ Genetics
Announcements
* next week is the Embryology lab.
* There is a quiz next week and as usual cover
materials from this lab and the upcoming one.
*home assignment for today will be posted on my
web-page late today
Today
*Mitosis
*difference between animal and plant cells
*Meiosis
Mitosis
*it serves as a means of growths and repair in
multicellular eukaryotes
*it a common feature of a lot of tissues in the
human body
e.g. skin wounds heals by mitosis
e.g. bone fractures heals by mitosis
e.g. Liver tissue can regenerate
? Brain cells
? Heart muscle cells(fibers)
*uncontrolled cell division…benign or malignant
tumors
Mitosis
* Cell cycle
*G1, S, and G2 are
termed Interphase
Chromosomes
Karyotype
is numbers, forms
and types of
chromosomes
in a cell
Mitotic phase
1-Prophase
Chromatin in the nucleus condense.
The nucleolus disappears.
Centrioles begin moving to opposite ends
of the cell and fibers extend from the
centromeres.
2-Metaphase
Spindle fibers align the chromosomes
along the middle of the cell nucleus.
This line is referred to as the metaphase
plateor equator
Mitotic phase
3-Anaphase
The paired chromosomes separate at the
kinetochores and move to opposite sides
of the cell.
4-Telophase
Chromatids arrive at opposite poles of
cell, and new membranes form around
the daughter nuclei. The chromosomes
disperse and are no longer visible under
the light microscope.
Animal vs Plant cells
*karyokinesis is the same
*cytokinesis (cytoplasm division)
-in animal cells, it is a function of the actin filaments
of the spindle fiber.
-in plant cells, it is a function of the cell wall
Mitosis
* In brief,
-one round of cell division per round of DNA
synthesis.
-one cell end with two cells of the same genetic
content(2N)
Meiosis
*it serves as a means of reproduction
*two rounds of cell division per one round of
DNA synthesis.
*one cell with 2N content end with 4 cells of
1N content.
*2 stages, Meiosis 1 and 2
*homologous recombination (synapse) occur
between homologous pair of chromosomes.
*in anaphase of meiosis one, the two sister
chromatids remain attached and the whole
chromosome is pulled toward one end
I got the picture
*examine demo
-Onion root tip mitosis
-chiasmata(recombination or crossing-over) in
meiotic cells of grasshopper
*simulating mitosis and meiosis
The genetic disease project
*group project
*I will demonstrate how to use library resources
*two weeks from today you will present for the class
-PowerPoint presentation (15-20m’)
-all the group members must share in the oral
presenatation and written report