BIO 325 Lecture Notes - Lecture 3: Germ Cell, Cytokinesis, Gamete
Diploid vs Haploid Cell in Drosophila Melanogaster
• 3 types of chromosomes in Drosophila
o 2 pair of autosomes
o 1 pair of sex chromosome
o 1 pair of mini chromosome
Complement of Sex Chromosomes
• Humans – presence of Y determines sex
• Drosophila – ratio of autosomes to X chromosomes determines sex
Homologous Chromosomes
• Homologous chromosomes (homologs)
o Match in size shape, and banding patterns
o contain the same set of genes
o genes may carry different alleles
• Non-homologous chromosomes carry completely unrelated sets of genes
• Karyotypes – can be produced by cutting micrograph images of stained chromosomes
and arranging them in a matched pairs based on adig patters
o Badig patters of hroosoes provide oordiates for the loatios of
genes or alleles
• Autosomes – pairs of nonsex chromosomes
o 22 pairs of autosomes
o 1 pair of sex chromomes
o Autosomes and sex chromosomes are arranged in homologous pairs
Mitosis
• Mitosis – one round of chromosome replication followed by 1 round of nuclear division
to produce 2 daughter nuclei identical to each other and to the original parental nucleus
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