Transcript Mitosis - benanbiology

REPRODUCTION
ASEXUAL REPRODUCTION
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Reproduction from one organism.
The cell division is mitosis.
The genetic trats are same with the parent organism.
Doesn’t effect evolution or variation.
Seen in primitive organisms
Only mutations can form variations
Monoploid (n) or diploid(2n) organisms can be formed
Reproduce rapidly
Mitosis
Mitosis is important in:
 Repair and regeneration.
 Growth
 Mitosis is a fundamental process for life. During mitosis,
a cell duplicates all of its contents, including its
chromosomes, and splits to form two identical daughter
cells.
As a result of the mitosis:
 2 new cells are formed
 New cells have same genetic material and chromosome
number with mother cell.
 The genetic material and chromosome number of the
new cells are same.
Mitosis
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Interphase: Resting period of the cell.
Cell carries out normal activities.
Prophase: DNA of the cell replicates
itself. 2 sister chromatids are formed
Metaphase: Chromosomes with
sister chromatids stay in the middle
of the cell (equator).
Anaphase: Sister chromatids separate
from each other and go to the
opposite poles.
Telophase: Chromatids reach to the
poles and nuclear membrane is
formed
Asexual reproduction types
1. Division(binary fission)
2. Budding
Young organism is
formed from the
body of the existing
organism.
Yeast cells, hydra
3. Sporing ( fungi, algae, plasmodium,, fern, moss)
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Spores(n)
fertilization
gametophyte plant(monoploid)
diploid plant (2n)
(meiosis)
gametes
Moss, ferns,
fungi and
plasmodium
Spores are
different from
gametes. They
are seen in
asexual
reproduction.
Forms new
individual by
germination.
4. Vegetative reproduction
The parent plant grows
runners and forms new
plant. They are typically
same. Strawberry, onion,
violet, potato
5. REGENERATION
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The parts which are cut off the plant or animal
can form a new organism or an organ. Starfish,
earthworm, lizard. But some animals can not
produce new organism just form the organ or
heal the wound.
SEXUAL REPRODUCTION
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Reproduction from 2 parents. (one forms sperm, the other
forms egg)
Major Division is meiosis and the major process is fertilization.
Newly formed organisms have new traits different from the
parents and the other new organisms.
Sexual reproduction enhance evolution and variation.
These variations help organisms to survive better.
Can be seen in higher organisms like animals and plants.
The reasons for the genetic variations are: meiosis (crossing over,
chromosomal lining in the metaphase) , fertilization and
mutations.
Newly formed organisms are diploid(2n)
It is a long and slow process.
Meiosis
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Meiosis is important in:
 formation of gametes (sperm, egg)
 reducing chromosome number
 genetic variation
As a result of the meiosis:
 4 new cells are formed
 New cells can have different genetic makeup from the
mother cell
 New cells have half of the chromosome number of the
mother cell.(n)
 The genetic makeup of the new cells can be different from
each other.
Meiosis
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Prophase I:
DNA replicates
itself and forms
a new DNA
molecule.
Homologous
chromosomes
exchange genes
(crossing over)
Prophase II: The chromosomes
become shorter and thicker.
Metaphase I: Homologous chromosomes
(tetrad) line up in the middle of the cell(equator).Metaphase II: Spindle fibers attach to
the chromatids of the chromosomes.
Spindle fibers attach to the chromosomes.
Anaphase II: Sister chromatids of the
Anaphase I: Homologous chromosomes
separate from eachother and go to the opposite chromosomes are separated and go to
the opposite poles of the cells.
poles.
Telophase II: Totally 4 cells are formed.
Telophase I: Chromosomes reach to the
Each cell can have a different genetic
opposite poles. Two cells are formed . he
chromosome number is reduced by meiosis I. make up and half of chromosome
number
Mitosis and meiosis
MITOSIS
MEIOSIS
1. takes place in body cells.
1. takes place in germ cells
and forms sex cells.
2. No crossing over (gene
Exchange)
2. crossing over can happen.
3. It has 1 cycle of the phases
(1 division)
3. It has 2 cycle of phases(2
division)
4. Produces 2 cells
4. Produces 4 cells
5. newly formed cells have
the same chromosome
number of the parent cell
5. Newly formed cells have
the half of the
chromosome number of the
parent cell
6. The genetic make up of the
newly formed cells are
same with each other and
with the parent cell
6. The genetic make up of the
newly formed cells can be
different from each other
and from the parent cell
ISOGAMY
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2 Gametes of the same
morphological
structure unite.
algae
HETEROGAMY
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2 gametes of different
morphological gametes
unite. There is a
structural difference
between sperm and egg
but not too much.
Algae, fungi
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2 gametes wqith 2
different structures
unite. The sizes of the
gametes are very
different from each
other. human
SPECIAL REPRODUCTION TYPES
1. CONJUGATION
This process is seen in bacteria,
paramecium and green algae. 2
individuals exchange genetic
material with each other. Most of
the time DNA is not exchanged ,
instead plasmid which is a small
part of DNA found in cytoplasm
is exchanged.
In that way organisms can gain
new traits from the other
organism.
2. PARTHENOGENESIS
It is the formation of a new organism from the unfertilized egg.
Male bee (n)
Queen bee(2n)
Mitosis
Meiosis
Sperm(n)
Egg(n)
parthenogenesis
Female bee(2n)
Male bee(n)
Queen bee(2n)
Worker bee(2n)
3. HERMAPHRODITISM
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Some organisms can carry both male and female
reproductive system and organs. This process is
called hermaphroditism. Earth worms, most of
the plants are hermaphrodites.
3. HERMAPHRODITISM
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Some organisms can carry both male and female
reproductive system and organs. This process is
called hermaphroditism. Earth worms, most of
the plants are hermaphrodites.
Hermaphroditism causes variation but it is not as much as
the variation in sexual reproduction.
If same individual uses sperms and eggs from itself it will
cause little variation.
If gametes from 2 separate individuals fertilize they will
cause more variation.
Metagenesis
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n
Moss
 Plazmodium
(asexual in human, sexual
in mosquito)
Fern
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2n
n
In some organisms
sexual reproduction
follows asexual
reproduction. This is
metagenesis.
Plasmodium
n
(Mayoz)
n
n
2n
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1. a female Anofele takes in gametes from the
blood of human.
2. gametes are fertilized inside the mosquito’s
intestine. Zygote forms.
3. Zygote forms spores by meiosis in mosquito.
4. Mosquito bites human and infects him with
spores.
5. Spores reproduce asexually in blood and liver
of human. And spores form gametes .