Download Chromosomes

The Basics of
Organisms
Mitosis Meiosis
Animal Cells
no cell wall
Fungal Cells
have a cell wall (not cellulose)
are small (about 20% the size of animal cells)
otherwise the same chemicals as animal cells
Plant Cells
have a cell wall (cellulose)
have chloroplasts (can photosynthesize)
otherwise the same chemicals as animal cells
Bacterial Cells
have a cell wall (peptidoglycan - not cellulose)
are tiny (< 1% the size of animal cells)
are your basic stripped-down model; no organelles
(chloroplasts and mitochondria are descended from bacteria,
trapped inside a larger cell some 2-3 billion years ago)
http://www.cellsalive.com/cells/cell_model.htm
Animal Cell Basics
http://www.cellsalive.com/cells/cell_model.htm
Sexual
Reproduction
 Type
of
reproduction
where genetic
material (DNA)
from 2 different
(sex) cells
combine
producing
offspring.
2
types of sex cells
(gametes)
 Egg is the female cell
which forms in the ovary.
 Sperm is the male sex
cell which forms in the
testis.
 Fertilization occurs when
the egg & sperm cell join
together to form a new
cell called a zygote.
http://www.sciencekids.co.nz/videos/biology/dnareplication.html
What are Diploid and Haploid Cells?
The sex cells or gametes contain haploid cells that means that these cells have
one set of chromosomes, that is, 23 chromosomes. (There are only 23
chromosomes in the human egg and 23 chromosomes in the human sperm.)
These cells are formed after they go through a special cell division called
meiosis. Therefore, the progeny (child) inherits one set of chromosome from
the mother and one set of chromosome from the father. After fertilization, they
form a diploid zygote. This diploid zygote develops into a diploid species.
Diploid cells have two homologous (same) copies of each chromosome
inherited from the mother and father. All mammals are diploid organisms with
the exception of a few species. There are 46 chromosomes in human diploid
cells and the human haploid cells have 23 chromosomes. The diploid cells are
indicated by 2n = 2x and haploid cells are indicated by n, where n = number
of chromosomes and x = monoploid number.
Difference Between Diploid and Haploid Cells
The gametes (sex cells) from diploid parents undergoes meiosis and the
haploid egg is fertilized by the haploid sperm. This forms a diploid zygote that
contains maternal chromosome and paternal chromosome. This diploid zygote
undergoes mitosis that leads to formation of a diploid organism. The following
table & diagram will help explain the diploid and haploid difference.
Diploid vs. Haploid
Definition
Cell Division and Growth
Examples of Organisms
Haploid cells are cells with
Diploid cells are those cells
half the number (n) of
that contain a complete
chromosomes in the
set (or 2n) chromosomes.
nucleus.
Haploid cells are a result
of the process of meiosis, a
Diploid cells reproduce by
type of cell division in
mitosis making daughter
which diploid cells divide
cells that are exact
to give rise to haploid
replicas.
germ cells. A haploid cell
will merge with another
haploid cell at fertilization.
Animal cells used in sexual
reproduction, sperm and
ova (Gametes). Yeast and
Humans and almost all
fungi are permanently
mammals are diploid
haploid. Other organisms
organisms.
like male bees, wasps and
(skin, blood, muscle cells)
ants are haploid
organisms.
Cell Growth
and Division
Mitosis
MITOSIS
 In
order for the total number of cells to
increase and for an organism to grow, the
cells must undergo cell division
 During cell division, one cell divides into
two cells.
 Each new cell, called a daughter cell, is
identical to the other and to the parent
cell.
Cell division occurs in a series of stages
Stage
1- Interphase
Stage 2 - Mitosis
Phase
1- Prophase
Phase 2- Metaphase
Phase 3- Anaphase
Phase 4- Telophase
Stage
3- Cytokinesis
IPMATC
Stage 1- Interphase
In
this phase, the
cell is not
actually dividing
Chromosomes
(strands of DNA)
appear as
threadlike coils.
Two structures
called centrioles
are outside the
nucleus.
 At
the end of
Interphase, cell
division begins.
 A copy of each
strand of DNA is
created.
 Each DNA strand
and its copy, called
its “sister”
chromosome are
joined in an area
called the
centromere
(Masking Tape!).
 At this time the sister
chromosomes are
called chromatids.
Phase 1- Prophase
 At
this point, we
start to call the cell
division Mitosis.
 The chromatin
begins to shorten
and thicken and
become
chromosomes.
 The centrioles
begin to move to
opposite sides of
the cell.
A
mesh-like spindle
fiber forms between
the two centrioles,
forming a bridge
between the
opposite ends of the
cell.
 At the end of
Prophase, the
nuclear membrane
surrounding the
nucleus begins to
break down.
Phase 2- Metaphase
 The
chromosomes move to the center of
the cell, and begin to attach to the
spindle fibers that runs from end to end of
the cell.
 The
chromosomes attach to the spindle
by means of the centromere.
Phase 3- Anaphase
The
centromere, which holds
the sister chromatids together,
splits
One chromosome from each
pair of “sisters” move toward
one end of the cell along the
spindle.
Chromatids are again called
chromosomes.
Phase 4- Telophase
 Chromosomes
reach
the end of the cell and
begin to unwind.
 A nuclear membrane
forms around the
chromosomes at each
end, forming 2 nuclei.
 Mitosis is complete, but
cell division is not over.
Stage 3- Cytokinesis
 During
this phase, the membrane
surrounding the cell begins to move
inward until the cytoplasm is pinched into
two nearly equal parts. Each part
contains a nucleus with identical
chromosomes.
 Soon
two new cells are formed
Cytokinesis- The end of Mitosis
http://www.cellsalive.com/mitosis.htm
http://www.youtube.com/watch?v=VlN7K1-9QB0
http://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/Mi
tosisFlash.html
http://www.sciencekids.co.nz/videos/biology/meiosis.html
Meiosis
2 divisions of the
nucleus & the
cytoplasm,
resulting in 4
haploid cells with
½ the # of
chromosomes of
the original cell.
http://www.neok12.com/php/watch.php?v=zX7
60969185a636b69736d02&t=Cell-Division
Meiosis differs from mitosis
primarily because there are two cell divisions in meiosis, resulting in cells
with a haploid number of chromosomes.
Interphase: Before meiosis begins, genetic material is duplicated.
First division of meiosis
Prophase 1: Duplicated chromatin condenses. Each chromosome consists
of two, closely associated sister chromatids. Crossing-over can occur
during the latter part of this stage.
Metaphase 1: Homologous chromosomes align at the equatorial plate.
Anaphase 1: Homologous pairs separate with sister chromatids remaining
together.
Telophase 1: Two daughter cells are formed with each daughter
containing only one chromosome of the homologous pair.
Second division of meiosis: Gamete formation
Prophase 2: DNA does not replicate.
Metaphase 2: Chromosomes align at the equatorial plate.
Anaphase 2: Centromeres divide and sister chromatids migrate separately
to each pole.
Telophase 2: Cell division is complete. Four haploid daughter cells result.
http://www.youtube.com/watch?v=5fg3Q-hbSsI
Asexual Reproduction
What is it?
 1 parent organism
produces offspring
without meiosis &
fertilization.
What uses it?
 Fungus (mold)
 Bacteria
 Protists
 Plants
 Animals (planarians)
+ Pros
-Cons
+ No mate needed.
+ Selective breeding
+ Less time & energy used.
+ Large # of offspring result
so quickly colonizes.
- No genetic variation, so
less chance of surviving a
change in environment.
- Negative traits are passed
on to the next generation.
- Cloning costly & debated.





Fission – rapid cell division
making 2 identical prokaryote
daughter cells because no
nucleus. Ex Prokaryotic Bacteria
Mitotic Cell Division – nucleus
divides by mitosis & cytoplasm
divides by cytokinesis in
eukaryotes. Ex Amoebas
Budding – copying of the parent
on its body by cell division &
mitosis. Ex Coral & Yeasts
Regeneration – grows from a
piece of its parent.
Animal Ex Planarian, Sponges,
Sea Stars, Newts, Hydras, Zebra
Fish, Salamanders, Tadpoles
Plant Ex Strawberries,
raspberries, potatoes,
geraniums.
Cloning – copying in a lab by
fusing cells from 2 animals.
Ex “Dolly” & farm animals
Planarian Budding
Star Fish Regeneration
Neamatodes Mitotic Div
Bacteria Fission
5 Types of
Asexual
Reproduction
To be continued…
http://www.neok12.com/php/watch.php?v=zX6d545a6d4d40420e5a7851
&t=Cell-Division Take the Quiz!
http://www.sumanasinc.com/webcontent/animations/content/meiosis.html
Animations & Notes
http://cybersleuthkids.com/sleuth/Science/Life_Science/Mitosis_and_Meiosis/index.ht
m Review Help!
http://quizlet.com/4655976/meiosis-pictures-flash-cards/
Flash Cards!
This is
not the
end, but
only the
beginning
of life! 