Cell Division
Gamete – The male or female reproductive
cell that contains half of the DNA – sex cell
Egg Cell – The Ovum; the female
reproductive cell (gamete); usually not
mobile
Sperm Cell– The male reproductive cell
(gamete) ; usually mobile
Parent Cell – The old product being divided
or used
Daughter Cell – The new product(s) being
formed or used
Sisters – Identical products that are joined
Diploid – Meaning the cell has two sets of
chromosomes = full set of chromosomes
- In humans it would be 46 chromosomes
Haploid – Meaning the cell has one set of
chromosomes = half the chromosomes
- Gamete cells
-In humans it would be 23 chromosomes
Why do cells divide?
• Grow
• Reproduce
• Repair
Cell Reproduction
• All organisms REPRODUCE.
• Why?
– This allows for growth, development and
the survival of the species
There are 2 types of
reproduction
1. Asexual Reproduction
– Requires A single parent!!!
– Results in the offspring having the
same hereditary material (DNA)
Asexual Reproduction (cont)…
• In other words, the new cells are an exact
copy of its parent (allow for little variation
among species)
Types of Asexual Reproduction
• Fission – cell splits in half (ex: Amoeba)
Types of Asexual Reproduction (cont)…
•
Budding – a new organism grows off
from the side of an adult (ex: Hydra)
Types of Asexual Reproduction (cont)…
• Regeneration – a new organism grows
from a severed body part (ex: starfish)
MITOSIS
Mitosis
The process of cell division which results
in the production of two daughter cells
from a single parent cell.
The daughter cells are identical to
one another and to the original parent
cell.
Mitosis
Mitosis is the method used for cell
division and reproduction in asexual
organisms
Mitosis is associated with growth
and repair in sexually reproducing
organisms.
.
Mitosis can be divided into stages
• A preparation stage – Interphase
• The four main MITOTIC STAGES
Prophase – Metaphase Anaphase –
Telophase
• The separation stage - Cytokinesis
Interphase – Preparation Step
The cell prepares for the main four
division phases
• Animal Cell
– DNA replicated
– Organelles replicated
– Cell increases in size
• Plant Cell
– DNA replicated
– Organelles replicated
– Cell increases in size
Interphase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Prophase – 1st Mitotic Stage
• Animal Cell
– Chromatin condense
to form chromosomes
as chromatids joined
by a centromere
– Centrioles move to
opposite ends of the
cell
– Nuclear membrane
dissolves.
• Plant cell
– Chromatin condense
to form chromosomes
as chromatids joined
by a centromere
– Centrioles move to
opposite ends of the
cell
– Nuclear membrane
dissolves.
Prophase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Metaphase – 2nd Mitotic Stage
• Animal Cell
– Spindle fibers align
chromosomes at the
center of the cell
• Plant Cell
– Spindle fibers align
chromosomes at the
center of the cell
Metaphase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Anaphase – 3rd Mitotic Stage
The paired chromosomes divide
• Animal Cell
– Spindle fibers pull
chromosomes apart
– ½ of each
chromosome (called
chromotid) moves to
opposite sides of the
cell
• Plant Cell
– Spindle fibers pull
chromosomes apart
– ½ of each
chromosome (called
chromotid) moves to
opposite sides of the
cell
Anaphase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Telophase – 4th Mitotic Stage
Partitioning of the cell begins
• Animal Cell
– 2 nuclei form
– Cell membrane starts
to pinch in to form the
2 new daughter cells
– Spindle fibers
disappear
• Plant Cell
– 2 nuclei form
– Cell membrane starts
to pinch in to form the
2 new daughter cells
– Spindle fibers
disappear
Telophase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
What happens to a cell after Mitosis
is complete?
• Cytokinesis
– Cell splits into two identical daughter cells
with complete set of organelles
– Animal – nuclear membrane develops and
cells pinch apart
– Plants – Cell wall forms between two new
cells and nuclear membrane develops.
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
How did you get here?
• Sexual Reproduction
– Reproduction in which two (2) parents are
involved
– Sex cells are called gametes (egg and
sperm cells are gametes)
What is sexual reproduction?
• Sexual reproduction
– starts with the formation of gametes and
ends when one gamete joins another gamete.
The joining of egg and sperm is called
fertilization, resulting in the production of a
zygote
zygote
How are gametes produced?
• Meiosis
– A process whose purpose is to reduce the
chromosome number in the cells
– Produces 4 new cells with half the number of
chromosomes as the parent - haploid
Meiosis – two divisions of the nucleus
Parent Cell
1st Division
2nd Division –
4 new daughter
cells with ½ the #
of chromosomes
Meiosis continued
• Diploid Cells: have two of every
chromosome (body cells)
• Haploid Cells: have just one
chromosome from each pair (gametes)
MEIOSIS
Meiosis
Meiosis is the type of cell division by which
germ cells (eggs and sperm) are produced.
One parent cell produces four daughter
cells.
Daughter cells have half the number of
chromosomes found in the original
parent cell
Meiosis
During meiosis, DNA replicates
once, but the nucleus divides twice.
Meiosis
Four stages can be described for each
division of the nucleus.
Meiosis I
First division of meiosis
First Division of Meiosis
• Prophase 1: Each chromosome duplicates and
remains closely associated. These are called sister
chromatids.
• Metaphase 1: Chromosomes align at the center of the
cell.
• Anaphase 1: Chromosome pairs separate with sister
chromatids remaining together.
• Telophase 1: Two daughter cells are formed with
each daughter containing only one chromosome of the
chromosome pair.
Prophase I
http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
Prophase I
http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
Metaphase I
http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
Telophase I
http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
Meiosis
Second Division of Meiosis
Second Division of Meiosis
• Prophase 2: DNA does not replicate.
• Metaphase 2: Chromosomes line up at the center of
the cell
• Anaphase 2: Centromeres divide and sister
chromatids move separately to each pole.
• Telophase 2: Cell division is complete.
Four haploid daughter cells are formed.
Prophase II
http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
Metaphase II
http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
Telophase II
http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html
Meiosis
http://www.biosci.uga.edu/almanac/bio_103/notes/apr_3.html.
Differences in Mitosis & Meiosis
• Mitosis
– Asexual
– Cell divides once
– Two diploid daughter
cells
– Genetic information is
identical
• Meiosis
– Sexual
– Cell divides twice
– Four haploid daughter
cells
– Genetic information is
different