BIO153H5 Lecture Notes - Lecture 5: Sister Chromatids, Dna Replication, Cohesin
Document Summary
Cell cycle= life from when first formed- its own division. Eukaryotes and prokaryotes, involves distribution of dna to 2 daughter cells (not meiosis) Genome= genetic material of an organism: prokaryotic= single dna molecule, eukaryote= many molecules. All dna must be replicated before division, and separated. Chromosomes= in nucleus, 1 dna molecule, carries many genes. Somatic cells= all body cells except reproductive: 46 chromosomes (2 sets of 23 from each parent, varies among species. Gametes= reproductive cells (sperm +egg: 23 chromosomes. When not dividing/ replicating, chromosomes are long, thin strands. Duplicated chromosomes each have 2 sister chromatids (joined copies, x) Sister chromatids separate, move into different nuclei (each end of cell) Mitosis= division of dna in the nucleus. Meiosis= produce sperm/ eggs: half the chromosomes a parents, 2 sets 46- 1 set 23. Mitotic phase= mitosis/ cytokinesis: shortest part. 2 identical sister chromatids joined at centromere, sometimes joined by cohesion. Mitotic spindle begins to form: centrosomes, microtubules extending, (cid:862)stars(cid:863)
