struktur dan fungsi kromosom

Transcription

STRUKTUR DAN FUNGSI
KROMOSOM
•Siklus Sel
•Pembelahan Meiosis
•Proses Reproduksi
Ganies Riza Aristya, S.Si.,M.Sc.
Laboratorium genetika, Fakultas Biologi UGM
Siklus Sel pada Tumbuhan
03 Agustus 2011
ga_nicebio@yahoo.com
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In Eucaryotes,
DNA is enclosed in a cell nucleus
Plant cells
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Animal cells
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Sklus Sel
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Siklus sel (lanjutan)
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MITOSIS
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MITOSIS (lanjutan)
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Chromosomes exist in different states
throughout the life of a cell
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STRUKTUR
KROMOSOM
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Macam Kromosom
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Bagian-bagian Kromosom
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DNA is packaged into a set of chromosomes
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Humans have 23 pairs of chromosomes, which makes the
diploid number 46.
The diploid number is the number of chromosomes of a normal
cell.
The haploid number is the number of chromosomes in a gamete.
Usually, the diploid number is twice the haploid number. The
number of chromosomes varies depending on the species.
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They are Difference
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Eukaryotic Chromosome

DNA is enclosed in a cell nucleus

Packaged into a set of chromosomes

Each chromosome contains one linear DNA
molecule (has not yet been completely
proved)
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Nucleosomes are the basic unit
of Eukaryotic chromosome structure
Nucleosome:
• The basic, beadlike
unit of DNA packaging
in Eukaryotes,
• Consisting of a
segment of DNA wound
around a protein core
composed of two copies
of each of four types of
histone.
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Nucleosome
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Pengemasan kromosom
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ANIMASI
STRUKTUR
KROMOSOM
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Packaging DNA
Histone
octomer
Histone proteins
2 nm
B DNA Helix
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Packaging DNA
Histone
octomer
Histone proteins
B DNA Helix
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2 nm
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Packaging DNA
11 nm Histone
octomer
Histone proteins
Nucleosome
B DNA Helix
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2 nm
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Packaging DNA
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Packaging DNA
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Packaging DNA
“Beads on
a string”
11 nm
30
nm
Tight helical
fiber
Looped
200 nm Domains
Protein scaffold
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Packaging DNA
11 nm
Nucleosomes
30
nm
Tight helical fiber
Metaphase
Chromosom
e
700 nm
200 nmLooped Domains
2 nm
B DNA Helix
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Protein scaffold
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Chromosome structure
A chromosome is the visible state of genetic
material during a phase of the division of the cell
(prometafase/metaphase)
DNA in metaphase chromosomes must be
shortened 10,000-fold by very efficient packing.
The DNA molecule is twisted onto itself, and the
supercoiled molecule is wrapped around proteins
which maintain its shape.
These proteins are histone proteins.
The complex DNA protein is called chromatin,
while the structure formed by two turns of DNA
around one histone is called a nucleosome.
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The DNA is wrapped
around the protein,
and then, twisted
together again in the
shape of a spring.
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HISTONES are proteins with a
high proportion of positively
charged amino acids (lysine and
arginin), which enable them to
bind firmly to the negatively
charged DNA double helix.
There are 5 types of histone
molecules: H1, H2A, H2B, H3,
and H4.
Except for H1, they occur in
exactly equal numbers.
In less condensed chromatin
fibers, it becomes apparent
that DNA between nucleosome
is bound to H1 histones.
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Review Pengemasan Kromosom
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struktur dan fungsi kromosom

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