http://www.ebsi.co.kr/ebs/lms/lmsx/retrieveSbjtDtl.ebs?sbjtId=S20180001026 /mnt/1T-5e7/mycodehtml/Biology/CSByun/Bio1_2020/005_Chromosome_and_genetic_materials_001/main.html ================================================================================ Nucleosome = DNA + histone protein $$$(\text{Nucleosome})_n$$$: chromatin, during ordinary time Chromosome: during cell division ================================================================================ Cell division: Interphase, Mitotic phase, Interphase, Mitotic phase, ... Interphase: chromatin G1 S G2 Mitotic phase: chromosome Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis ================================================================================ One chromosome in one cell, but before DNA replication One chromosome in one cell, but after DNA replication ================================================================================ In one body cell, 46 number of chromosomes exist (44 + 2) ================================================================================ Gene (which has information for expression) $$$\subset$$$ DNA True sentence: gene1 + gene2+ ... = DNA ================================================================================ ================================================================================ Note that following shows 2 chromosomes ================================================================================ ================================================================================ Meiosis Extract one chromosome out of following 2 chromosomes ================================================================================ ================================================================================ Homologous chromosome - Same size - Same shape ================================================================================ Half of homologous chromosome is from male Half of homologous chromosome is from female ================================================================================ Distinguish "homologous chromosome" and "chromatid" Relationship of following 2 is "homologous chromosome" ================================================================================ From following one Following 2 are chromatid ================================================================================ Following is possible case Following is also possible case because "homologous chromosome" come from parents Alleles: Genes which are located in the same location in the chromosome Genes which have specific information to express specific characteristic ================================================================================ Case: Homozygote dd AA Case: Heterozygote Bd ================================================================================ Note that the case of chromatid dd AA BB ================================================================================ You can see, "alleles" and "homologous chromosome" This is DNA before DNA replication during interphase period Number of chromosome (number of kinetochore) in the cell: 2 Relative DNA quatity: if this is 1 ================================================================================ This is DNA after DNA replication during interphase period Number of chromosome (number of kinetochore) in the cell: 2 Relative DNA quatity: this is 2 ================================================================================ Body cell of male: 2n = 44 + XY Body cell of female: 2n = 44 + XX ================================================================================ B: gene for straight hair from male b: gene for curvy hair from female ================================================================================ Since this is DNA after DNA replication, ABD ABD ================================================================================ Recap on important point 2 homologous chromosome - For example, this comes from male - For example, this comes from female Allele - AA, A (straight hair gene) comes from male, A (straight hair gene) comes from female, Homozygote - Bb, B (green eye gene) comes from male, b (blue eye gene) comes from female, Heterozygote - DD, D (rolling tongue possible) comes from male, D (rolling tongue possible) comes from female, Homozygote * Pic1 ================================================================================ After DNA replication during interphase period You can see above one in the following way AA: Homozygote Bb: Heterozygote ================================================================================ * Pic1: https://history.nih.gov/exhibits/genetics/sect1.htm