SISTEM REPRODUKSI MAKHLUK HIDUP -...

REPRODUKSI

• Reproduksi merupakan sarana makhluk hidup untuk mempertahankan eksistensinya

• Reproduksi:

– Reproduksi Sel

– Reproduksi Tumbuhan

– Reproduksi Hewan dan Manusia

Sistem Reproduksi Makhluk Hidup Priyambodo, M.Sc. Biologi Umum

REPRODUKSI SEL

• Sel merupakan unit struktural dan fungsional terkecil dalam hierarki kehidupan

• Sel mengalami proses pertumbuhan, perkembangan dan perbanyakan.

– Pertumbuhan: Ukuran

– Perkembangan: Fungsi

– Perbanyakan: Jumlah


REPRODUKSI SEL

• Tiga macam cara reproduksi tingkat sel:

– Amitosis

– Mitosis

– Meiosis


AMITOSIS


100 µm

(a) Reproduction. An amoeba,

a single-celled eukaryote, is

dividing into two cells. Each

new cell will be an individual

organism (LM).

Figure 12.2 A

AMITOSIS

• Pembelahan sel tanpa melalui tahapan khusus.

• Dilakukan dengan proses kariokinesis langsung dilanjutkan dengan sitokinesis

• Digunakan sebagai cara perkembangbiakan oleh organisme tingkat rendah.

• Amitosis = Pembelahan biner = Pembelahan spontan


Pembelahan Biner pada E. coli


Origin of

replication

E. coli cell Bacterial

Chromosome

Cell wall

Plasma

Membrane

Two copies

of origin

Origin Origin

MITOSIS DAN MEIOSIS

• Merupakan pembelahan sel dengan melalui tahapan khusus – Interfase

• G1

• S

• G2

– Fase mitotik • Profase

• Metafase

• Anafase

• Telofase

• Sitokinesis


SIKLUS SEL


INTERPHASE

G1 S

(DNA synthesis)

G2

Figure 12.5

MITOSIS

• Pembelahan sel tanpa adanya reduksi jumlah kromosom

• Terjadi pada sel-sel somatis

• Dalam satu kali mitosis hanya sekali terjadi pembelahan (fase mitotik)

• Fungsi: Pertumbuhan, Perbaikan



G2 OF INTERPHASE PROPHASE PROMETAPHASE

Centrosomes

(with centriole pairs) Chromatin

(duplicated)

Early mitotic

spindle

Aster

Centromere

Fragments

of nuclear

envelope

Kinetochore

Nucleolus Nuclear

envelope

Plasma

membrane

Chromosome, consisting

of two sister chromatids

Kinetochore

microtubule Figure 12.6

Nonkinetochore

microtubules

MITOSIS


MITOSIS

Centrosome at

one spindle pole

Daughter

chromosomes

METAPHASE ANAPHASE TELOPHASE AND CYTOKINESIS

Spindle

Metaphase plate

Nucleolus forming

Cleavage

furrow

Nuclear

envelope

forming Figure 12.6

MITOSIS PADA SEL TUMBUHAN


1 Prophase.

The chromatin

is condensing.

The nucleolus is

beginning to

disappear.

Although not

yet visible

in the micrograph,

the mitotic spindle is

staring to from.

Prometaphase.

We now see discrete

chromosomes; each

consists of two

identical sister

chromatids. Later

in prometaphase, the

nuclear envelop will

fragment.

Metaphase. The

spindle is complete,

and the chromosomes,

attached to microtubules

at their kinetochores,

are all at the metaphase

plate.

Anaphase. The

chromatids of each

chromosome have

separated, and the

daughter chromosomes

are moving to the ends

of cell as their

kinetochore

microtubles shorten.

Telophase. Daughter

nuclei are forming.

Meanwhile, cytokinesis

has started: The cell

plate, which will

divided the cytoplasm

in two, is growing

toward the perimeter

of the parent cell.

2 3 4 5

Nucleus

Nucleolus Chromosome Chromatine

condensing

Figure 12.10

Sitokinesis pada sel hewan


Cleavage furrow

Contractile ring of

microfilaments Daughter cells

100 µm

(a) Cleavage of an animal cell (SEM) Figure 12.9 A

Sitokinesis pada sel tumbuhan


Daughter cells

1 µm Vesicles

forming

cell plate

Wall of

patent cell Cell plate New cell wall

(b) Cell plate formation in a plant cell (SEM) Figure 12.9 B

MEIOSIS

• Pembelahan sel disertai adanya reduksi jumlah kromosom

• Terjadi pada sel-sel gamet

• Dalam satu kali meiosis terjadi dua kali pembelahan (fase mitotik)

• Fungsi: Reproduksi organisme tingkat tinggi


MEIOSIS


Figure 13.7

Interphase

Homologous pair

of chromosomes

in diploid parent cell

Chromosomes

replicate

Homologous pair of replicated chromosomes

Sister

chromatids Diploid cell with

replicated

chromosomes

1

2

Homologous

chromosomes

separate

Haploid cells with

replicated chromosomes

Sister chromatids

separate

Haploid cells with unreplicated chromosomes

Meiosis I

Meiosis II


Centrosomes

(with centriole pairs)

Sister

chromatids

Chiasmata

Spindle

Tetrad

Nuclear

envelope

Chromatin

Centromere

(with kinetochore)

Microtubule

attached to

kinetochore Tertads line up

Metaphase

plate

Homologous

chromosomes

separate

Sister chromatids

remain attached

Pairs of homologous

chromosomes split up Chromosomes duplicate

Homologous chromosomes

(red and blue) pair and exchange

segments; 2n = 6 in this example

INTERPHASE MEIOSIS I: Separates homologous chromosomes

PROPHASE I METAPHASE I ANAPHASE I

• Interphase and meiosis I

Meiosis I



TELOPHASE I AND

CYTOKINESIS PROPHASE II METAPHASE II ANAPHASE II TELOPHASE II AND

CYTOKINESIS

MEIOSIS II: Separates sister chromatids

Cleavage

furrow Sister chromatids

separate

Haploid daughter cells

forming

During another round of cell division, the sister chromatids finally separate;

four haploid daughter cells result, containing single chromosomes

Two haploid cells

form; chromosomes

are still double Figure 13.8

• Telophase I, cytokinesis, and meiosis II

Oogenesis dan Spermatogenesis


Perbandingan Mitosis dan Meiosis


Figure 13.9

MITOSIS MEIOSIS

Prophase

Duplicated chromosome

(two sister chromatids)

Chromosome

replication

Chromosome

replication

Parent cell

(before chromosome replication)

Chiasma (site of

crossing over) MEIOSIS I

Prophase I

Tetrad formed by

synapsis of homologous

chromosomes

Metaphase

Chromosomes

positioned at the

metaphase plate

Tetrads

positioned at the

metaphase plate

Metaphase I

Anaphase I

Telophase I

Haploid

n = 3

MEIOSIS II

Daughter

cells of

meiosis I

Homologues

separate

during

anaphase I;

sister

chromatids

remain together

Daughter cells of meiosis II

n n n n

Sister chromatids separate during anaphase II

Anaphase

Telophase

Sister chromatids

separate during

anaphase

2n 2n

Daughter cells

of mitosis

2n = 6

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