BIOL 226 Lecture Notes - Lecture 9: Meristem, Gametangium, Gametophyte
3 May 2018
School
Department
Course
Professor
Biol226-Ch29
How plants colonized
3billion years --> lifeless earth
1.2B y/a --> Cyanobacteria
500 M y/a --> small plants, fungi and animal
385 M y/a --> taller plants --> first forest
What is a plant/
o Characteristics of a plant
Eukaryotes
Multicellular
Photosynthetic
Chloroplasts
Cellulose cell wall
Terrestrial ancestor
Sexual reproduction
Alternation of generations
Unique to plants:
Develop from embryo( diploid multicellular structure that is enclosed in a multicellular
maternal tissue)
Eukaryotic photosynthetic organisms that develop from an embryo
Alternation of generation : heteromorphic and multicellular sporophyte and
gametophyte
Heterosporous; 2 different type of spore , micro and macro spore
Traits that show green algae closest relative to plants
o Rings of cellulose-synthesizing proteins
o Structure of flagellated sperm
o Formation of a phragmoplast
Derived Traits of Plants
Sporopollenin: layer of polymer that prevents spore to dry out
o Can be seen charophytes and land plant
derived characteristics that are common to all land plants after they diverged from charophyte
i. Alternation of generations
ii. Multicellular dependent embryos
iii. Walled spores produced in sporangia
iv. Multicellular gametangia
v. Apical meristem
If we could see these traits in other lineages from a different ancestor would be convergent
Alternation of generations
o Gametophyte
multicellular haploid
gamete-producing plant by mitosis of haploid gametes—eggs and sperm—that fuse during
fertilization, forming diploid zygotes.
o Sporophyte
From Mitotic division of the zygote
multicellular diploid
Document Summary
500 m y/a --> small plants, fungi and animal. 385 m y/a --> taller plants --> first forest. What is a plant: characteristics of a plant. Develop from embryo( diploid multicellular structure that is enclosed in a multicellular maternal tissue) Eukaryotic photosynthetic organisms that develop from an embryo. Alternation of generation : heteromorphic and multicellular sporophyte and gametophyte. Heterosporous; 2 different type of spore , micro and macro spore. Traits that show green algae closest relative to plants: rings of cellulose-synthesizing proteins, structure of flagellated sperm, formation of a phragmoplast. Sporopollenin: layer of polymer that prevents spore to dry out: can be seen charophytes and land plant. Derived characteristics that are common to all land plants after they diverged from charophyte: alternation of generations, multicellular dependent embryos, walled spores produced in sporangia, multicellular gametangia, apical meristem. If we could see these traits in other lineages from a different ancestor would be convergent.
