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 Life cycle Basics Simple life cycle: unicellular organism
n − Zygote Cells = gametes n + 2n n Y!
Vegetative Sexual reproduction reproduction
n
2n R! Asexual reproduction
n n
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 Life cycle Basics General life cycle: multicellular organism
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
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