Download mitosis

CELL CYCLES!
MITOSIS
Mrs. MacDonnell’s 7th
Grade Science
MITOSIS=ASEXUAL REPRODUCTION!
This helps our body repair itself
by producing more body cells.
WHY DO CELLS NEED TO MAKE COPIES OF
THEMSELVES?
Cells repeatedly divide to make
more cells for growth and repair.
Various organs and tissues
functions to serve the needs of the
cells for food, air and waste
removal.
DNA
Chromosomes are made up of tightly
condensed DNA.
DNA controls all of a cell’s activities
and is considered the blueprint of life.
DNA controls all cell activities including
cell division in mitosis and meiosis!
CHROMOSOMES
Prior to mitosis, the cell’s
genetic material and
organelles are copied, so
that there are two copies
each chromosomes.
At the end of mitosis, 1 cell
with 2 identical nuclei are
produced. Mitosis produces 2
genetically identical body cells.
Let’s look at each phase and learn
what happens in each.
You are to draw each one and
describe what is happening in
each picture.
STAGES OF THE MITOSIS
1. Interphase (I)
2. Prophase (Passed)
3. Metaphase (Mrs. MacDonnell’s)
4. Anaphase (Awfully)
5. Telophase (tough)
6. Cytokinesis (class)
Interphase-Is the nondividing stage. The cell is
engaged in everyday
activities and it is
preparing for mitosis.
(resting cell)
INTERPHASE: RESTING CELL
PROPHASE (PHASE 1)
Chromosomes condense into
rod like structures.
Disappearance of the nucleoli
and the nuclear envelope.
PROPHASE
METAPHASE
Formation of the microtubules of the
spindle (spindle fibers)
The chromosomes line up
along the equator of the cell.
METAPHASE
ANAPHASE (PHASE 3)
The chromatids separate and are pulled
to opposite sides of the cell by the fibers
attached to the centrioles.
LATE ANAPHASE
TELOPHASE (PHASE 4)
The nuclear membrane forms around
the two sets of chromosomes and the
fibers disappear.
Looks like a telephone
Cytokinesis- The process in which
cytoplasm divides after mitosis. (The cell
completely splits in two!)
Mitosis is complete and the
cytoplasm splits in two.
This results in two daughter cells that
are identical.
Then the cells enter interphase and
the cycle starts again.
Daughter cell-The Cell
resulting from the
replication and division of
a single parent cell.
HOMOLOGOUS CHROMOSOMES
Chromosomes that carry the same set of genes and have the same
structure.
DAUGHTER CELLS
MEIOSIS
MITOSIS
1 cell produces four cells!!!
Meiosis produces new sex cells
(haploid) with half the number of
chromosome that the parent
(diploid) had.
Meiosis produces four genetically
different cells.
Each species has a specific number of
chromosomes in each cell of the body
Human body cells have 46
chromosomes in their BODY cells
(Diploid cells)
Humans have 23 chromosomes in their
REPRODUCTIVE cells (egg and sperm)
(Haploid)
GAMETES
Reproductive cells (egg and sperm
cells)
Only have one set of
chromosomes (HAPLOID CELLS!)
When gametes (egg and sperm
combine) they form a diploid cell.
n + n =2n
Sperm (haploid) + Egg(haploid) = diploid cell
UNITING OF SPERM AND EGG=FERTILIZATION
When a haploid egg with 23
chromosomes unites with a haploid
sperm cell with 23 chromosomes it
makes a diploid human cell with 46
chromosomes.
46
Egg
23
23
23
46
Sperm
23
23
46
(new
organism)
23
23
23
2 TYPES: SPERMATOGENEIS & OOGENESIS
NET RESULT:
Spermatogensis
Oogensis
4 mature sperm
1 mature ova or egg.
Each sperm has exactly
half the number of
chromosomes as the
father.
Each egg has exactly
half the number of
chromosomes as the
mother.