BIO 1144 Sec 03 Week of Feb 15 Notes
BIO 1144 Sec 03 Week of Feb 15 Notes BIO 1144
Popular in Biology II Thomas Holder
Popular in Biology
This 5 page Class Notes was uploaded by Jaren Davis on Monday February 15, 2016. The Class Notes belongs to BIO 1144 at Mississippi State University taught by Thomas Holder in Spring 2016. Since its upload, it has received 30 views. For similar materials see Biology II Thomas Holder in Biology at Mississippi State University.
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Date Created: 02/15/16
Androecium = male household (pollen) • All stamens Stigma Style Pistil Ovary with ovules Stamen Anther = future seeds Filament Gynoecium = female household • All pistils Corolla • Collection of petals Pedicel • Collection of petals • =stalk • Function: attract • 4 sets of mod. leaves pollinators arise from the receptacle Calyx • Collection of sepals Androecium and Gynoecium are "fertile" modified leaves • Protection of the unopened bud Calyx and Forolla are "sterile" modified leaves. Pedicel, receptacle, 4 sets of modified leaves are 2N (part of sporophyte generation) • Gametophyte generation (1N) ◦ Pollen (sperm) ◦ Eggs • Sexual Cycle ◦ Male: ‣ Pollen formation - sign anther of stamen ‣ Anther - bilobed with 2 pollen chambers per lobe ‣ Anthers C.S. "Micro" - males 2N microscope mother cells Tube cell (1N) Each undergoes Large cell) mitosis/ cytokinesis Generative cell Meiosis Unequal dir. (1N) Cytokinesis incomplete 2N 2-felled pollen microspore grain (male 4N (1N) gametophyte mother cell microspore Each 2N microspore mother cell produces 4 2-celled pollen grains Pollen produced within anther of stamen(s) Pollination: • Transfer of pollen from an anther to a stigma • Self-pollination ◦ The transfer within the same flower or the same plant • Cross Pollination ◦ Transfer of pollen between plants • Pollinating Agents (Mechanisms) - transfer ◦ Wind - blows pollen from one flower to the next ‣ Pollen sticks ◦ Water ‣ True aquatic plants use this ◦ Animals - majority! ‣ Trick/reward ‣ Nectar and color and aroma attract pollinator Ovule Development (female) Ovule = future seed • Ovule = future seed ◦ Enclosed within ovary of pistil (carpel) ◦ 1 to many per ovary • Ovule attached to central axis of hollow ovary or to ovary wall ◦ Always "enclosed" ---> angiosperm • Within ovule is 1 large 2N cell ◦ Megaspore mother cell Ovary Wall Ovules Central Axis Stalk attached to wall of ovary or central axis Embryo sac is within nucellus and integuments inside ovary of pistils Pollen grain = male gametophyte 3 antipodal cells (1N) - opposite end from micropyle 1 central cell with 2 1N nuclei (large) [polar nuclei] 2 synergid cells (1N) at micropyle end (outer) 1 egg (1N) at micropyle end in between synergids Syngamy: 1N + 1N ---> 2N (single cell)(fert. egg) egg sperm zygote Stigma Pollen Pollen "germination" • Tube cell produces pollen tube Style • Generative cell (1N) divides by mitosis/cytokinesis to produce 2 1N sperm Pollen tube enters micropyle; "digests" nucellus; tip of pollen tube Tube nucleus 2 sperm Pollen tube enters one synergid; releases its content and synergid ruptures. Tube nucleus degrades 2 sperm released into the large central cell -micropyle closes (seals up) Double Fertilization: 1N + 1N ---> 2N (= fertilized egg) Sperm Egg Zygote 1N + 2 1N ---> 3N 1°endosperm cell sperm central uclei (Polars) Post Fertilization: within ovule • 2N zygote ---> mitosis/cytokinesis ---> multicellular 2N embryo • 3N 1° endosperm cell ---> mitosis/cytokinesis ---> multicellular 3N endosperm (nutritive tissue for embryo) Ovule with 2N zygote ---> seed with 2N embryo; 2 seed coats (2N) (integuments) Ovary of pistil matures/enlarges with sugars and h2o ---> fruit with enclosed seeds (=ovules) (fruit = mature ovary with ovules) Seed Dispersal - enclosed in fruit • Agents ◦ Wind ◦ Water ‣ Helps float ◦ Animals - majority! ‣ Trick/reward ‣ After eaten, seed is passed through Seed Germination • Seed with 2N embryo ---> broken by combination of environmental (external) factors and internal factors ◦ Temp, day length, soil moisture ◦ Hormones • Radicle (1st root) emerges • Shoot emerges
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