Introduction to

Alexey Shipunov

Minot State University

Lecture 16

Shipunov (MSU) Introduction to Botany Lecture 16 1/9 Outline

1 Life cycle Basics of life cycles

Shipunov (MSU) Introduction to Botany Lecture 16 2/9 Life cycle Basics of life cycles

Life cycle Basics of life cycles

Shipunov (MSU) Introduction to Botany Lecture 16 3/9 n − Cells = n + 2n n Y!

Vegetative Sexual reproduction

n

2n R!

n n

Life cycle Basics of life cycles Simple life cycle:

Associated terms: mitosis, (R!), syngamy (Y!), reproduction, , asexual reproduction, vegetative reproduction, isogamy, heterogamy, , zygote, , male, , , oocyte Shipunov (MSU) Introduction to Botany Lecture 16 4/9 Life cycle Basics of life cycles 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 4/9 Life cycle Basics of life cycles 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 haplont and diplont, the second is making

Shipunov (MSU) Introduction to Botany Lecture 16 5/9 Vegetative Sexual reproduction reproduction: (fragments or mitospores) M

n Syngamy n (isogamy type) Gamete mother cell n n + Y! – n Gametes

General (sporic) life cycle life cycle

Haplont Diplont 2n Gametic (human) Vegetative reproduction Zygote n (fragments or Asexual mitospores) reproduction:

Meiosis Spore mother cell 2n n R! 2n Spores n Zygotic life cycle

Life cycle Basics of life cycles General life cycle: multicellular organism

Shipunov (MSU) Introduction to Botany Lecture 16 6/9 Life cycle Basics of life cycles 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 6/9 Life cycle Basics of life cycles Quiz question (... points)

Shipunov (MSU) Introduction to Botany Lecture 16 7/9 Life cycle Basics of life cycles Quiz question (... points)

Shipunov (MSU) Introduction to Botany Lecture 16 7/9 Life cycle Basics of life cycles Summary

Mitosis is a equal division of DNA, ploidy does not change, genotype does not change Syngamy is a sexual process of cell fusion, ploidy doubles, genotype changes Meiosis is a process of reduction of DNA amount, ploidy halves, genotype changes Meiosis has two stages: first to reduce ploidy, second to split exact copies of DNA

Shipunov (MSU) Introduction to Botany Lecture 16 8/9 Life cycle Basics of life cycles For Further Reading

A. Shipunov. Introduction to Botany [Electronic resource]. Mode of access: http://ashipunov.info/shipunov/school/biol_154

Shipunov (MSU) Introduction to Botany Lecture 16 9/9