4. skema siklus sel mitosis-meiosis

7/26/2019 4. Skema Siklus Sel Mitosis-Meiosis

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QUIZ

Tulislah 2 tipe kromosom

Tulislah 4 bentuk kromosom Jelaskan apakah karyotipe?


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Cell Cyc le (Siklus Sel)

Dr. Budi Setiadi Daryono, M.Agr.Sc.

Laboratorium Genetika

Fakultas Biologi UGM


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The cell cycle


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The stages of interphase

G1 stage cell growth, cell doubles its

organelles, accumulates materials for DNA

synthesis.

S stage DNA synthesis occurs, and DNA

replication results in duplicated chromosomes.

G2 stage cell synthesizes proteins needed for

cell division


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Following interphase is the M stage, including

mitosis and cytokinesis

During mitosis, sister chromatids of each

chromosome separate, and become the nuclei of

the two daughter cells

The cell cycle ends when cytokinesis, the cleaving

of the cytoplasm, is complete

The Mitotic Stage


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Following mitosis, a 2n parental cell gives rise totwo 2n daughter cells, or 2n 2n

Mitosis occurs when tissues grow or when repair

occurs

Following fertilization, the zygote divides

mitotically, and mitosis continues throughout the

lifespan of the organism


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Apoptosis is programmed cell death

Apoptosis occurs because of two sets of enzymes

called capsases

The first set, the initiators receive a signal to

activate the second set, the executioners

The second set of capsases activate enzymes

that tear apart the cell and its DNA

Apoptosis


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In the life cycle of many animals, only sperm and

eggs have the haploidnumber of chromosomes.

The nuclei of somatic cells undergo mitosis, a

nuclear division in which the number ofchromosomes stays constant.

Before nuclear division occurs, DNA replication

takes place, duplicating the chromosomes.


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A duplicated chromosome is made of two sister

chromatids held together in a region called the

centromere

Sister chromatids are genetically identical

At the end of mitosis, each chromosome consists

of a single chromatid

During mitosis, the centromeres divide and thenthe sister chromatids separate, becoming

daughter chromosomes


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centromere


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Late Interphase


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Early Prophase


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Late Prophase


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Metaphase


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Anaphase


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Telophase


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Cytokinesis

The products ofmitosis are 2 diploidcells with identicalchromosomes.


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MITOSIS

itosis pada sel tumbuhan

itosis pada sel hewan


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Why Cells Must Divide

In multi-celled organisms (like humans) cells specialize forspecific functions thus the original cells must divide toproduce different kinds of cells

Cells can only take in nutrients and excrete wasteproducts over the surface of the membrane thatsurrounds them. The surface to volume ratio decreaseswith the square of the volume (unless specialaccommodations are made)

2 cm

Surface 24 cm2/

volume 8 cm3 = 31 cm

Surface 6 cm2/

volume 1cm3= 6


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The process of asexual reproduction in

prokaryotes is called binary fission

The two daughter cells are identical to the

original parent cell, each with a single

chromosome

Following DNA replication, the two resulting

chromosomes separate as the cell elongates

Cell Division in Prokaryotes


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Meiosis involves the same four phases seen in

mitosis prophasemetaphase

anaphase

telophase

The occur during both meiosis I and meiosis II.

The period of time between meiosis I and meiosis II iscalled interkinesis.

No replication of DNA occurs during interkinesis

because the DNA is already duplicated.

Meiosis in Detail


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Meiosis I separates homologous pairs of

chromosomes.

Daughter cells are haploid, but chromosomes are

still in duplicated condition.

Synapsis occurs during meiosis I

Meiosis II separates sister chromatids.

The completely haploid daughter cells mature intogametes.

Fertilization restores the diploid number of

chromosomes during sexual reproduction.


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Interphase

Mother cell Stages Of Meiosis :

Meiosis I

Meiosis II

Prophase I:Tetrad formation/

crossing over

Metaphase I

Telophase I

Prophase I:

CondensingChromosomes

Anaphase I


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Prophase - Meiosis I

Leptotene

Zygotene

Pakhitene

Diplonema

Diakinesis


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Stages Of Meiosis :

Meiosis II

Metaphase II

Anaphase II

Telophase II

The products of meiosis are 4haploid cells each with a

unique set of chromosomes.

Prophase II


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Synapsis and crossing-over


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Prophase I:Tetrad formation/

crossing over

Crossing Over

Anaphase I

Telophase II

Metaphase I

Telophase IBecause of crossing over, every

gamete receives a unique set of

genetic information.


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Meiosis II


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There are two sources of genetic recombination

during meiosis :

1. Crossing-over

Non-sister chromatids of a chromosome pairexchange their genetic material

2. Independent assortment

Homologous chromosomes are distributed to

daughter cells randomly

Both events assure new genetic combinations in

the offspring.

Genetic Recombination


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Independent assortment


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Meiosis I: Prophase I - pairing of

homologous

chromosomes Metaphase I

homologous pairs lineup at metaphase plate

Anaphase I

homologouschromosomes separate

Telophase I daughtercells are haploid

Mitosis: Prophase has no such

pairing

Metaphase

chromosomes align at

metaphase plate

Anaphase sister

chromatids separate

Telophase diploid cells

Comparison of Meiosis I with Mitosis


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The events of meiosis II are like those of mitosis except

in meiosis II, the nuclei contain the haploid number of

chromosomes

At the end of telophase II of meiosis II, there are four

haploid daughter cells that are not genetically identical

At the end of mitosis, there are two diploid daughter cellsthat are identical

Comparison of Meiosis II with Mitosis


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In males, meiosis occurs as spermatogenesis and

produces sperm.

In females, meiosis occurs as oogenesis and

produces egg cells.

Mitosis is involved in the growth of a child and

repair of tissues during life.

The human life cycle requires both mitosis

and meiosis


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Fertilization Results In A


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Egg

1n

Haploid

nucleus


Diploid Zygote

Sperm

1nHaploidnucleus



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Sperm

1n


Diploid Zygote

Egg

1n

Haploid

nucleus

Haploid

nucleus



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Sperm

1n


Diploid Zygote

Egg

1n

Haploid

nucleus

Haploid

nucleus


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From Zygote to Embryo

Zygote

2n

Zygote

2n


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Cleavage



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Cleavage



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Cleavage



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Cleavage



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Morula



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Gametogenesis involved mitosis and

meiosis

Oogenesis egg formation in humans

Diploid germ cells called oogonia multiply by mitosis

to produce primary oocytes

Primary oocytes undergo meiosis I to produce one

secondary oocyte and one small polar body (which

arrests development)

Secondary oocyte undergoes meiosis II to produce

one ovum and one small polar body

Polar bodies disintegrate leaving one large functional

gamete

O i i h


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Oogenesis in humans


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Gametogenesis

Spermatogenesis in humans Symmetrical meiotic divisions produce four functional

sperm

Begins in male testis in germ cells calledspermatogonia

Mitosis produces diploid primary spermatocytes

Meiosis I produces two secondary spermatocytes per

cell Meiosis II produces four equivalent spermatids

Spematids mature into functional sperm


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Spermatogenesis in humans


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Spermatogenesis dan oogenesis pada hewan

QUIZ


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QUIZ

Kromosom-kromosom homolog akan bergerak ke kutub-kutub yang

berlawanan dari suatu sel yang membelah diri selama fase

Sel otot pada manusia mempunyai jumlah kromosom diploid 46.

Dengan demikian jumlah kromosom pada sel telur (ovum) adalah

.. yang terdiri dari . autosom dan

seks kromosom

Apabila suatu jenis ikan laut mempunyai jumlah kromosom diploid

(2n) = 30, maka :a) jumlah kromosom pada saat metafase I-meiosis I adalah

b) jumlah kromosom pada saat metafase-mitosis adalah .

c) jumlah kromosom pada saat metafase II-meiosis II adalah

4. skema siklus sel mitosis-meiosis

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