Download 01. Reproduction of Cells

Cell Reproduction
Curriculum outcomes to be
covered in the unit





Compare and contrast the reproduction and
development of representative organisms (313)
Describe in detail mitosis and meiosis (313-2)
Analyze and describe the structure and function
of female and male mammalian reproductive
systems (313-3)
Explain current reproductive technologies for
plant and animals (313-5)
Evaluate the use of reproductive technologies
for humans (313-6)


Before we begin, we must understand that
plants and animals grow by mitotic cell
division and form gametes (sex cells) by
meiosis.
We are going to look at both of these
processes in length.
Reproduction of the Cell (Humans)


The human body is composed of more than one
hundred trillion cells. These cells are continually
dying and new cells are continually being
formed, not to mention the fact that we came
from one cell.
An identical copy of your hereditary material is
found in the nucleus of every somatic cell (does
not include reproductive cells)




The hereditary material , also called the genetic
blueprint is organized into 46 parts known as
chromosomes (DNA molecules are found in
chromosomes).
Every time a cell reproduces, or divides, each
chromosome must be copied and distributed so
that each new cell gets a complete and accurate
set of information.
This process happens in the cell cycle.
The making of new cells is called cell division.
The Cell Cycle


The cell cycle is a continuous process that
does not pause after each cycle
Two divisions occur during
cell division – nuclear
division (mitosis)
and cytoplasmic division
(cytokinesis)
Interphase






Interphase is the time interval between
nuclear division (not a stage of mitosis)
In this stage:
Cells grow rapidly
Cells make structural proteins that repair
damaged parts
Cells transport nutrients
Eliminate wastes
Prepare for mitosis by building proteins
(most important are reactions that control
synthesis of DNA )
 Genetic material is called chromatin
(DNA molecules and proteins in nucleus)
 Each chromosome (an individual
chromosome is a single DNA molecule and
its proteins) duplicates itself during
interphase

Mitosis

A type of cell division where each
daughter cell receives the same number of
chromosomes as the parent cell.
Parent Cell
Daughter
Cell
Daughter
Cell
Prophase



First phase of mitosis
Chromosomes shorten and thicken
Original chromosome and its duplicate are
attached to each other by a centromere (while
attached they are known as sister chromatids)



Centrioles (in cytoplasm, provide
attachment for spindle fibers) move to
opposite poles of the cell and spindle
fibers start to form
Centrioles assemble and spindle fibers
attach to the centromeres of
chromosomes
Nuclear membrane start to dissolve
Early Prophase
Late Prophase
Metaphase




Second phase of mitosis
Chromosomes line up at the equatorial
plate.
The nuclear membrane completely
dissolves.
Chromosomes are very dark and attached
to spindle fibers
Metaphase
Anaphase


The sister chromatids divide and the
chromosomes move to the opposite poles
of the cell.
An identical set of chromosomes move to
each pole.
Anaphase
Telophase




Chromosomes lengthen again and
intertwine
The spindle fibers dissolve
Nuclear membrane forms around the
chromosomes
Each new nucleus contains 46 unique
chromosomes
Telophase
Cytokinesis




After the chromosomes move to opposite
ends, the cytoplasm begins to divide
Cytokinesis is the division of cytoplasm
In animal cells, organelles move to each
cell and a furrow develops, pinching off
the cell into two daughter cells.
This is the end of cell division
Cytokinesis

Draw it
Cell Clock



Cells have a biological clock.
They can only divide so many times before
they die.
Not all cells in the body have the same
ability to reproduce. Age is one reason
why cells stop dividing.


Cells such as skin cells reproduce more
often than muscle cells, nerve cells and
secretory cells.
Two types of human body cells can divide
continuously: sperm-producing cells
(spermatocytes) and cells of a cancerous
tumor.



Readings Biology 11
P. 82-90
Questions P. 90 #2, #3, #4, #10