人類染色體核型分析

核型分析

染色體型態 Chromosome morphology 染色體異常 Chromosome abnormal 核型分析 Karyotype analysis

染色體的組成

Chromatin 染色質 Chromatin is the DNA-containing substa

nce extractable from eukaryotic nuclei Chromatin is NOT a macromolecule, thu

s has no fixed composition

染色質的特性 染色反應

– Isopyconosis – without differentiation– Heteropyconosis – with differentiation

• Positively (tightly coiled) v.s. negative (loosely coiled)

Euchromatin v.s. Heterochromatin– Euchromatin

• loose structure genetically active

– Heterochromatin• Compact structure genetically silent

Heterochromatin– Constitutive v.s. facultative

Chromomere 染色粒

Compact form of nucleosome Nucleosome

– Basic structure unit of chromosome

Nucleosome structure

Supercoiled

Linear differentiation

Different degree of coiling Telomere Centromere Chromomere Nucleolar organizer

Telomere

Telomere

Centromere

Kinetochore Spindle fiber attachment First constriction

Chromosome type

Metacentric Submetacentric Acrocentric Telocentric

Nucleolar organizer 核仁

Secondary constriction The collecting point of nucleolar materia

l nucleolus Produce 18s and 28s rRNA

Tomato telomere

Grasshopper telomere

Vicia faba chromosome

Rye chromomere

Zea mays Nucleolar organizer

Change in chromosome morphology

Chromosome break apart Reunion Ununited exchanged

Exchange Chromosome arm rearrangement

Translocation Between the arms of

different chromosomes

Translocation Centric fusion

Chromosome number variation

Euploidy Aneuploidy

Euploidytype symbol Set of chromosome

monoploid n ABC

Diploid 2n AABBCC

Polyploid

Triploid 3n AAABBBCCC

Tetraploid 4n AAAABBBBCCCC

Pentaploid 5n AAAAABBBBBCCCCC

Euploidy

Allopolyploidy– Sets of chromosome came from different s

pecies Autopolyploidy

– Sets of chromosome came from same species

Species A2n=AA

Species B2n=BB

Species C2n=CC

Autotriploid3n=AAA

Autotetraploid4n=AAAA

Autohexaploid6n=AAAAAA

Autopetaploid5n=AAAAA

F1

2n=AB

Allotetraploid4n=AABB

Triploid3n=ABB

Autoallohexaploid6n=AABBBB

Autoallooctaploid8n=AAAABBBB

Triploid3n=ABC

Allohexaploid6n=AABBCC

Aneuploidtype symbol Number of chromosome

Disomic 2n AABBCC

monosomic 2n-1 AABBC

Nullisomic 2n-2 AABB

Polysomic

Trisomic 2n+1 AABBCCC

Double trisomic 2n+1+1 AABBBCCC

Tetrasomic 2n+2 AABBCCCC

Pentasomic 2n+3 AABBCCCCC

Human chromosome

Chromosome number 46– Male 44 + XY– Female 44+ XX

1956 Tjio & Levan– Q-banding: fluorescence– C-Banding: Giemsa stain– G-Banding– R-Banding

Human and rat karyotypes

Rules for arranging chromosome

From Long to short If same in length

– Metacentric chromosome– Submetacentric chromosome– Acrocentric chromosome– Telocentric chromosome

Karyotype analysis1. Get a photo of chromosomes2. Cut off each chromosome3. Pairing the homologous chromosome4. Draw a base line in a piece of paper5. Arrange the chromosome according to the

rules shown in previous page6. Measure each arms of the chromosome pair7. Calculate the fraction of each arm in the

total arms’ length8. Get the short/long arm ratio for each pair of

chromosome9. Do a statistics for at least 30 photos