Introduction to Botany. Lecture 16 Alexey Shipunov Minot State University October 3, 2016 Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 1 / 10 Outline 1 Questions and answers Quiz 2 Life cycle Basics Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 2 / 10 Outline 1 Questions and answers Quiz 2 Life cycle Basics Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 2 / 10 Questions and answers Quiz Questions and answers Quiz Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 3 / 10 Because it has two goals: Reduce ploidy—split homologous pairs Split X-shaped chromosomes in half Questions and answers Quiz Final question (3 points) Why does meiosis happen in two stages? Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 4 / 10 Questions and answers Quiz Final question (3 points) Why does meiosis happen in two stages? Because it has two goals: Reduce ploidy—split homologous pairs Split X-shaped chromosomes in half Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 4 / 10 Life cycle Basics Life cycle Basics Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 5 / 10 n − Zygote Cells = gametes n + 2n n Y! Vegetative Sexual reproduction reproduction n 2n R! Asexual reproduction n n Life cycle Basics Simple life cycle: unicellular organism Associated terms: mitosis, meiosis (R!), syngamy (Y!), reproduction, sexual reproduction, asexual reproduction, vegetative reproduction, isogamy, heterogamy, oogamy, zygote, gamete, male, female, spermatozoon, oocyte Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 6 / 10 n − Zygote Cells = gametes n + 2n n Y! Vegetative Sexual reproduction reproduction n 2n R! Asexual reproduction n n Life cycle Basics Simple life cycle: unicellular organism Associated terms: mitosis, meiosis (R!), syngamy (Y!), reproduction, sexual reproduction, asexual reproduction, vegetative reproduction, isogamy, heterogamy, oogamy, zygote, gamete, male, female, spermatozoon, oocyte Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 6 / 10 Life cycle Basics Multicellularity, or Origin of Death Sometimes, cells do not part after mitosis. These simple cell aggregates may benefit from their size (e.g., harder to swallow) and putative division of labor (e.g., capture light from different sides and share products of photosynthesis) Next step is to separate germ cells and somatic cells. Somatic cells with eventually die whereas germ cells may give an offspring. This is the beginning of multicellularity. Life cycles of multicellular organisms are based on interleaving gaplont and diplont, the second is making spores Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 7 / 10 Vegetative Sexual reproduction reproduction: (fragments or mitospores) M n Syngamy n (isogamy type) Gamete mother cell Gametangium n n + Y! – n Gametes General (sporic) life cycle life cycle Haplont Diplont 2n Gametic (human) Vegetative reproduction Zygote n (fragments or Asexual mitospores) Spore reproduction: Meiosis Spore mother cell 2n n R! 2n Spores n Sporangium Zygotic life cycle Life cycle Basics General life cycle: multicellular organism Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 8 / 10 Vegetative Sexual reproduction reproduction: (fragments or mitospores) M n Syngamy n (isogamy type) Gamete mother cell Gametangium n n + Y! – n Gametes General (sporic) life cycle life cycle Haplont Diplont 2n Gametic (human) Vegetative reproduction Zygote n (fragments or Asexual mitospores) Spore reproduction: Meiosis Spore mother cell 2n n R! 2n Spores n Sporangium Zygotic life cycle Life cycle Basics General life cycle: multicellular organism Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 8 / 10 Why are there two places of vegetative reproduction in a scheme of the life cycle? Life cycle Basics Final question (2 points) Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 9 / 10 Life cycle Basics Final question (2 points) Why are there two places of vegetative reproduction in a scheme of the life cycle? Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 9 / 10 Life cycle Basics For Further Reading A. Shipunov. Introduction to Botany [Electronic resource]. 2016. Mode of access: http://ashipunov.info/shipunov/school/biol_154 Shipunov (MSU) Introduction to Botany. Lecture 16 October 3, 2016 10 / 10.