1. The document discusses cell proliferation, which is the process by which cells divide through mitosis and meiosis to increase their numbers. 2. It describes the stages of the cell cycle including interphase, mitosis, and meiosis. During interphase, the cell grows and duplicates its DNA. Mitosis involves the division of the cell into two identical daughter cells. 3. Meiosis results in four daughter cells that each have half the number of chromosomes as the original parent cell, allowing for genetic variation in the next generation through processes like crossing over.

1. PROLIFERASI SEL
Dr. Rhandyka Rafli, Sp.OnkRad

2. • Pertambahan jumlah sel karena pertumbuhan
dan pembelahan
• Stimulasi 
• Fisiologis : Growth hormon, endometrium pada siklus
mens
• Patologis : trauma, kematian sel

3. Signaling proliferasi sel
• Stimulasi  Growth factor  ikatan reseptor sinyal
sel target  transkripsi gen  mitosis/meiosis
• Model signalling
• Autocrine signaling
• Paracrine signalling
• Endocrine signaling

5. Tujuan sel membelah
• Homeostasis
• Pertumbuhan Mitosis (pembelahan somatic)
• Differensiasi
• Berkembang biak  Meiosis (pembelahan gamet)

6. Homeostasis
pertumbuhan sel
• Positif : pertumbuhan/regenerasi
• Stabil : kematian = pertumbuan
• Negatif : degenerasi

7. Aktivitas proliferasi sel
• continuously dividing tissues (labile tissues)high proliferation
epithelia : mucosal lining, hemopoetik
• Quiescent (stable tissues) low proliferation
mesenkim : hepar, otot, vascular
• Nondividing (permanent tissues)(≠ siklus sel, ≠mitosis)
 tulang, jantung, saraf

8. Siklus Sel
• G0  (siklus arrest)
• G1  presintetik
• G1/S Checkpoint
• S  sintetik
• G2 premitotik
• G2/M Checkpoint
• M  mitosis

9. G1 → (G: Gap1)
• Segera setelah cytogenesis.
• Metabolisme tinggi : transportation, synthesis, lysis reactions, organelle
production, RNA synthesis dan fungsi jaringan paling tinggi
• It is the longest stage. Cells that lose their ability to divide continue with
their functions and life activities (e.g., muscle and nerve cells still function
at this stage).
S → (S: Synthesis)
• DNA is duplicated and the number of chromatins doubles (→ replication).
• The most intense protein synthesis is performed at this stage.
• The order of centromere duplication is observed.

10. G2 → (G: Gap2)
• Sintesis enzim pembelahan
• The number of organelles increases.
• DNA synthesis finishes, but RNA synthesis continues.
• Centrosome synthesis finishes, and these centrosomes start moving
towards opposite poles.
G0 phase
• Cells have a natural mechanism that protects them during difficult
developmental
• conditions. Under these conditions, the cells transiently stop their cellular
activities.
• This phase is called the G0 phase. In the G0 phase, some genes in the DNA
are covered
• with various proteins; i.e., the DNA is programmed.

11. Mitosis
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase

12. Interphase
• Interesting things happen!
1. Cell preparing to divide
2. Genetic material doubles

13. Prophase
• Chromosome pair up!
1. Chromosomes thicken and shorten
-become visible
-2 chromatids joined by a centromere
2. Centrioles move to the opposite sides of the nucleus
3. Nucleolus disappears
4. Nuclear membrane disintegrate

14. Metaphase
• Chromosomes meet in the middle!
1. Chromosomes arrange at equator of cell
2. Become attached to spindle fibres by centromeres
3. Homologous chromosomes do not associate

15. Anaphase
• Chromosomes get pulled apart
1. Spindle fibres contract pulling chromatids to the opposite
poles of the cell

16. Telophase
• Now there are two!
1. Chromosomes uncoil
2. Spindle fibres disintegrate
3. Centrioles replicate
4. Nucleur membrane forms
5. Cell divides

18. Meiosis
• 4 daughter cells produced
• Each daughter cell has half the chromosomes of the parent
• 2 sets of cell division involved

20. Term
• Homologous chromosome
Chromosome with the similar size, shape and the position of
their centromeres.
• Synapsis
Condition of chromosome pairing
• Bivalent
Structure of homologous pair
• Tetrad
Homologous chromosome that have 4 chromatids
• Sister chromatid
Chromatid from same homologous chromosome
• Chiasma
Point at which crossing over occur

21. Bivalent

23. Stages of meiosis I
Reduction division
• It reduces the number of chromosome from 46 (2n) to 23
(n).
• The cell divide has homologous pair of chromosome.
• One homolog comes from mother (maternal) and one from
father (paternal).
• When meiosis begins, DNA of each homologous replicates,
forming two chromatids joined at two centromeres.

24. Prophase I
1. Duplicated chromosomes condense and become visible.
2. Pairing up of homologous chromosomes forming bivalent. This process is called
synapsis.
3. Synapsis cause the homologous chromosomes closely associated.
4. Both homologous chromosomes interwine at chiasma and this process is known as
crossing over.
5. Crossing over causes exchange the genetic material (DNA) between paternal and
maternal chromosomes.

25. 6. Crossing over produces new combination of genes.
7. The genetic recombination from this process greatly
enhance the genetic variation.
8. Spindle fibers are form.
9. Nuclear envelope breaks down.

26. Metaphase I
1. Homologous chromosomes line up
at the equator of the cell.
2. Form double rows of homologous
chromosomes.
3. Unipolar spindle attachment to
single kinetochore at each
homologue.

27. Anaphase I
• Homologous chromosomes
separate and move to opposite
poles of the cell.
• Sister chromatids remain
attached at their centromeres.

28. Telophase I
1. One of each pair of
homologous chromosomes is
at each pole.
2. Cytokinesis occur.
3. The nuclear envelope reforms
and the nucleoli reappear.

29. Stages in meiosis II
•Equational division
•Same like mitosis.
•Produce 4 daughter cells with haploid
(n) number of chromosomes.

30. Prophase II
• The chromosomes are again
condensed and visible, become
short and thick.
• Nucleolus and membrane nucleus
dissapear.
• Centriole move to opposite poles.
• DNA does not replicate again.

31. Metaphase II
• Chromosomes line up at the equator of
the cell.
Anaphase II
• Centomere separation occurs.
• Chromatids moves to opposite poles.
Telophase II
• Nuclei formed at opposite poles of each
cell.
• Chromosomes gradually elongate to form
chromatin fibers.
• Cytokinesis occurs.
• Four haploid cells are produced.

32. Importance of meiosis
• For sexual reproduction.
• Maintains the chromosome numbers constant from
generation to generation.
• Assures a different genetic make up for the next
generation as a result of crossing over and new
combination of genes.

33. Comparison between mitosis and meiosis
Mitosis Meiosis
Dividing cells can be diploid or
haploid
Dividing cells are diploid
Occurs in somatic cell in all parts of
the body
Only in sexual reproduction cell,
gamete cell
DNA replicates once during the S
phase of interphase, and nucleus
divides once.
DNA replicates once during S phase
of interphase but there are two
successive nuclear division.
Chromosomes do not associate
during prophase.
Homologous chromosomes
associated to form bivalen during
prophase I.
Chiasma are never formed and
crossing over never occurs.
Chiasma form and crossing over
occurs during prophase I.

34. Mitosis Meiosis
Chromosomes form a single row at the
equator of the cell during metaphase.
Chromosomes form two rows at the
equator of the cell during metaphase I.
Chromatids move to opposite poles
during anaphase.
Chromosomes move to opposite poles
during anaphase I.
Daughter cells have the same number
of chromosomes as the parent cell.
Daughter cells have only half the
number of chromosomes found in the
parent cell.
In the absence of mutation, daughter
cells are genetically identical to
parental cell.
Daughter cells are genetically different
from parental cell.
2 daughter cells are formed. 4 daughter cells are formed. In male
human, 4 sperm cells are formed. In
female human, one ovum and 3 polar
bodies are formed.