Plant Bio Day 1

I. Importance of plants II. Botany, the study of plants III. What is a plant? IV. Ancestors of land plants V. Land plants, the embryophyta

Botany

Botany

Evolution, Ecology, Molecular Genetics, Mathematical Modeling, Morphology, Anatomy, Physiology, Cell Bio, Systematics, Development

Importance of Plants

1. Energy: Food

2. Energy: Fossil fuels

3. Clothing

4. Drugs, meds

5. Ecosystem functioning

6. Biodiversity

Plants evolved from what

Algae

Plants evolved from what/how

Algae, Eukaryote engulfment of cyanobacteria (plastid) Red/Green split

Streptophytes

Fresh water (Charophytes) & Land plants (Embryophytes)

Plants = all organisms within clade ___

Viridiplantae

Primary Endosymbiosis

Prokaryote + Eukaryote = Eukaryote (plastid)

Secondary endosymbiosis

Eukaryote (nonphotosynthetic) + Eukaryote (photosynthetic) = Eukaryote

Plants 1500 MYA

• Single cell & multicellular

• Marine

• Moist environments

Plants 500 MYA

Colonization dryer environments

Cuticle Vascular tissue: roots & shoots Relationship w fungi Seeds & pollen

Oxygen Revolution

Cyanobacteria changing O2 levels

• Plants created (2400 MYA)

• Plants move to land (700MYA)

  • Results in Oxygen spikes

Features of plants

Starch, Chlorophyll b, Cellulose, Thylakoids in stacks

Starch

• Amylose (20%) chain

• Amylopectin (80%) Branches

  • Sugar stored as starch

Chlorophyll b

• Chl a: all photosynthetic eukaryotes

• Chl b: accessory pigment; passes energy to Chl a

Cellulose

• Polysaccharide: unbranched glucose residues

• Most common polymer

Thylakoids in stacks

• Rather than as simple bands

• Membranes inside chloroplast - contain chlorophyll

Common ancestor of plants (not descended from)

Charophytes

Features of charophytes & land plants

1. Cell plate & phragmoplast (short microtubules)

2. Plasmodesmata

3. Rose-shaped cellulose synthesizing complexes

4. Sporopollenin

Plasmodesmata

Extensions of cell membrane thru pores in cell wall

Sporopollenin

• Durable polymer

• Found in walls of plant spores & pollen

• Chemically inert (stable, persists in environment)

• Protects from desiccation, decay, etc.

Move to land: Advantages

• Air filters less sunlight than water

• Air has more CO2

• No predators/herbivores on land

• More nutrient rich soil

Plants in water:

Supported, retain water, Reproduction easier

Plants on land

Not supportive, Lose water, Reproduction Harder

Land Plant Adaptations

Turgor (+ pressure),

Cuticle; vascular tissue; roots; stomates

Egg & embryo retained on parent; sporopollenin; protected embryo; seed coat; pollen; flower; fruit

Cuticle

Waxy covering

Antheridium

Male sex organ (produces sperm)

Archegonium

Female sex organ, produces egg

All sexual reproduction

diploid → haploid

Alternation of generations

mulitcellular diploid → Multicellular haploid

The alternating generations are

Gametophyte (haploid 1n)

Sporophyte (diploid 2n)

Origination of alternation of generations

• Zygote delays meiosis & instead divides and grows.

• Result: Multicellular diploid

Meisis makes _# cells

4

Green alga w/o alt of generations

Chlorophyta