Download Mitosis - Net Start Class

Asexual
Reproduction
3 Questions will be
Mitosis
asked
in 3 minutes.
Write a brief answer for
each one. Be
prepared to share your
answer.
1
1
Mitosis is the process in which the
nucleus divides to form two new
nuclei. How does mitosis differ in
plants and animals?
WHY DO CELLS DIVIDE?
Give me 2 reasons.
HOW will YOU
remember IPMAT?
How do little elephants
grow up to be BIG elephants?
The process of asexual reproduction
begins after a sperm fertilizes an egg.
You started as a cell smaller than
a period at the end of a sentence…
How did you
get from there
to here?
Skin cancer - the abnormal growth of
skin cells - most often develops on skin
exposed to the sun.
Cells that reproduce by asexual
reproduction reproduce constantly.
Use your book and define the following terms in
your notes. You have 5 minutes.
1) Page 244 CHROMOSOME (it is not in bold, so read
carefully)
CHROMATID
2)Draw a chromatid.
3) Page 245
CENTROMERE
4) Page 247 SPINDLE


Strands of DNA
Each human has 23 pair (diploid or 2n)
 One from your mother
 One from your father
DNA molecule with attached proteins
Sister chromatids
One from Mom
One from Dad
Chromosome number
• Every organism has its own specific number of
chromosomes
Examples: Human = 46 chromosomes or 23 pairs
Dog = 78 chromosomes or 39 pairs
Goldfish = 94 chromosomes or 47 pairs
Lettuce = 18 chromosomes or 9 pairs
a. G1
1. Interphase
b. S
c. G2
1. Prophase
2. Mitosis
a. Nuclear
division
2. Metaphase
b. Cytokinesis
4. Telophase
3. Anaphase
From the Virtual Cell Biology Classroom on ScienceProfOnline.com
Control of the Cell Cycle


Prior & After Mitosis
G1 period
 90% of cell life spent here
 Cell goes about it’s business

S period
 DNA is duplicated

G2 period
 Cell prepares to divide

Cannot see DNA- uncoiled as chromatin
Animated Mitosis Cycle
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase & Cytokinesis
•
•
•
Chromosomes are duplicated (# doubles)
Chromosomes appear as threadlike coils (chromatin)
at the start, but each chromosome and its copy(sister
chromosome) change to sister chromatids at end of
this phase
Cells are usually in interphase
Nucleus
CELL
MEMBRANE
Cytoplasm
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis begins (cell begins to divide)
Centrioles (or poles) appear and begin to move to
opposite end of the cell.
• Spindle fibers form between the poles.
• Chromosomes coil up and become visible, thicker,
and shorter
• Nuclear envelope disappears
•
•
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Spindle fibers
Centrioles
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
•
•
Metaphase = Middle
Chromosomes attach to the spindle fibers.
Chromosomes move to the middle of the cell.
Metaphase
2nd step in Mitosis
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
•
Chromosomes separate and begin to move to
opposite ends of the cell.
Spindle fibers pull chromosomes to opposite poles
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Chromosomes uncoil and appear as threads rather
than rods.
• Nuclear membrane reforms around chromosomes.
• Two new nuclei form.
• Spindle fibers disappear
• Mitosis ends.
•
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
•
Cell membrane moves inward to create two
daughter cells – each with its own nucleus with
identical chromosomes.
Cytoplasm divides.
• After mitosis and cytokinesis, the cell
returns to Interphase to continue to grow
and perform regular cell activities
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase

Prophase:





Chromosomes condense
Nuclear envelope disappears
centrosomes move to opposite sides of the cell
Spindle forms and attaches to centromeres on the chromosomes
Metaphase
 Chromosomes lined up on equator of spindle
 centrosomes at opposite ends of cell

Anaphase
 Centromeres divide: each 2-chromatid chromosome becomes two 1chromatid chromosomes
 Chromosomes pulled to opposite poles by the spindle

Telophase
 Chromosomes de-condense
 Nuclear envelope reappears
 Cytokinesis: the cytoplasm is divided into 2 cells
Phase
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Chromosome
Appearance & Location
Important Events
Phase
Interphase
Prophase
Chromosome
Appearance & Location
DNA copies itself;
chromatin
Chromosomes coil up
Important Events
DNA replication, cell
grows and replicates
organelles
Nuclear envelope
disappears, spindle
fibers form
Chromosomes line up in
the middle
Spindle fibers connect
to chromosomes
Anaphase
Chromosome copies
divide and move apart
Spindle fibers pull
chromosome copies
apart to opposite poles
Telophase
Chromosomes uncoil
back into chromatin
Nuclear envelopes reform,
2 new nuclei are formed,
spindle fibers disappear
Metaphase
Cytokinesis
Chromatin
Division of the rest of
the cell: cytoplasm and
organelles
43
COOL LINKS
http://www.youtube.com/watch?v=m73i1Zk8EA0&f
eature=youtube_gdata_player
http://www.youtube.com/watch?v=DD3IQknCEdc&
feature=youtube_gdata_player
http://www.youtube.com/watch?v=XSKhGLQn4E&feature=youtube_gdata_player
http://www.youtube.com/watch?v=eTvaGPcYNF8
&feature=youtube_gdata_player