Download Asexual Reproduction – Mitosis NOTES

SCIENCE 9
~~Asexual Reproduction – Mitosis NOTES~~
NAME: ______________
DATE:_______________
CLASS: 90__
Asexual Reproduction
• Asexual reproduction requires _________________
• The offspring produced are _________ to the parent.
• Asexual reproduction occurs in our ___________cells.
This means all of our cells except for sperm cells in males and egg cells in females.
We need asexual reproduction for three reasons:
• __________
We grow from one initial cell to an adult.
• __________
When we injure ourselves, our cells must reproduce asexually to replace this.
• __________
Our cells are constantly being replaced. Most of our cells have a very short life
span.
Why do our cells need to be replaced?
Our cells don’t live for ever!
Some are programmed to die (PCD-Programmed
Cell Death).
Some cells die when they are
_________________________.
Some cells die when they don’t receive enough
___________________.
These cells need to be replaced for our bodies
to continue to function!
_____________ cells die every minute in your body!!!
Our cells have varying life spans.
Why do we age?
• Asexual Reproduction/Mitosis!
• As we just stated-our cells are ____________________.
As we age, they are either ______________, or are replaced _____________.
When our cells stop replacing themselves at a fast pace, our skin wrinkles, our bones
become weak, and we our immune system is weakened.
Cancer-Mitosis gone bad!
• Our cells are ____________________ when something
goes wrong, but cancerous cells cannot do this.
• When cells divide at an uncontrollably fast rate, cancer is
created.
• The cancerous cells _____________, and _________ the
good cells of oxygen and food.
•
The risk of cancer is increased by tobacco, radioactivity, UV
radiation, etc
The First Cell
• The first cell of a new organism is called the zygote.
• It is created by the fusion of the __________________________.
• This cell will divide into two, these two cells will each divide into two more (four total
cells) and so on to create the new organism.
• Each of these cells must contain ____________________.
Maintaining Identical DNA:
• If cells simply divided into two, there would be only a fraction of the original nucleus (and
therefore original DNA) in each cell.
• To ensure that each cell has an entire set of chromosomes, each of our cells goes through
what is called “_________________” each time they divide.
The Cell Cycle
The Cell cycle allows the cell time to under go the process
of______________________ (mitosis + cytokinesis), and
_____________________
The majority of a cells life is spent in the ___________ and
growth portions of its cycle.
Before we begin, some terminology…
• Genetic material, called DNA, is found on the ________________
located in the nucleus of a cell.
• The genetic material that makes up chromosomes is called
______________.
• When the chromatid is duplicated, the two ___________________
are attached in the middle by a ________________.
Getting Ready – ________________
• The period _______________ is called interphase.
• During this period, the cell grows and the genetic material (called chromatid) duplicates
The duplicated sister chromatids attach in the middle by a _______________ to
create a double stranded chromosome.
• This process ensures that the same genetic information is
passed on to each of the two new daughter cells.
Mitosis
Phase #1- _____________
During prophase:
• The double-stranded chromosomes _____________ (shorten
and thicken)
• The _________________ (the membrane surrounding the nucleus) dissolves.
• The ______________ move to opposite poles of the cell
• The ________________ begin to form from the centrioles
• Spindle fibers attach to opposite ends of the ________________
Phase #2- ___________
During metaphase:
• The spindle fibers tug on opposite sides of the ___________
• This tugging action causes the double-stranded chromosomes to
form a _________________ at the ___________ of the cell.
This “equator” is called the _____________.
Phase #3-____________
During Anaphase:
• The spindle fibers ___________________.
• This causes the _____________ to split in two.
• One _______________ moves towards each pole of the cell.
• If this process is successful, each daughter cell will have a
complete set of identical genetic information.
Phase #4- _____________
During Telophase:
• The spindle fibers continue to shorten, pulling the sister
chromatids all the way to _____________________.
• The spindle fibers begin to _____________.
• The _________________ form around each set of
single-stranded chromosomes.
• The chromosomes begin to uncoil into thin strands of
chromatid.
Wrapping up - Cytokinesis:
• Cytokinesis happens after mitosis.
During cytokinesis:
• Animal cells: The ____________ pinches off near the middle of the cell, dividing the
_______________ into two new cells.
• Plant cells: A ______________ develops across the centre of the cells, forming a new
______________ and two new cells.