Plant Biology Lecture 2- What is a plant?

what are the three domains of life?

Eukarya, Bacteria and Archaea

what is Domain Bacteria

 microscopic, single-celled organisms that occupy all habitats on earth

what is Domain Archaea

single-celled organisms that tend to occupy extreme environments (high pH, extreme temps, etc.)

what is Domain Eukarya

organisms with a nucleus (eukaryotes); plants, animals, fungi and protists

what organisms can photosynthesise?

• Viridiplantae (land plants and green algae)

• cyanobacteria (blue-green algae)

• non-green algae (brown algae, gold algae, yellow-green algae and diatoms)

What is Endosymbiotic Theory

Idea that one type of single-celled organism is engulfed by another, to form the start of an endosymbiotic relations: where one cell resides/lives within the other

what can sometimes happen when an organism is engulfed by another in endosymbiotic theory?

engulfed organism will turn into an organelle (subcellular structure to perform one or more job)

• organism is no longer free-living

• only performs bare essential tasks and becomes a part of host

• loses cell walls and transfers some symbionts to host’s genome

what was the first organism to evolve the cellular machinery for photosynthesis

cyanobacteria

how was cyanobacteria eventually transformed into chloroplasts (organelle?)

cyanobacteria was involved in an endosymbiotic event with a eukaryotic organism (engulfed by eukaryote) and transformed into chloroplasts

what is the primary endosymbiotic event

cyanobacteria was engulfed by eukaryotes, and eukaryotes developed the abiltiy to photosynthesise (and became green algae)

what is the secondary endosymbiotic event

green algae was engulfed by another lineage of eukaryotes, and became non-green algae (with ability to photosynthesise)

what characteristics do land platns have

• evolvedfrom green algae

• eukaryotic

• multicellular

• they are photosynthetic autotrophs (make their own food through photosynthesis)

• have cellulose cell walls

• are Embryophytes (embryo develops within the body of the mother plant)

what differentiates land plants from green algae

land plants are embryophytes, while green algae are not

what are the two other names for land plants

1. ‘true’ plants

2. Embryophytes

what clades make up true plants

• angiosperms

• gymnosperms

• ferns

• bryophytes

what are angiosperms

flowering plants

what are gymnosperms

plants that reproduce through cones

what are ferns

plants that reproduce through spores

what are bryophytes

• reproduces through spores

• lacks vascular tissues (differentiates from angiosperms, ferns and gymnosperms)

• consists of liverworts, hornworts and mosses

what group do gymnosperms and angiosperms make up

seed plants

what group do seed platns and ferns make up

vascular plants

•  develop specialised vascular tissue to move nutrients, water, sugars, hormones, proteins, etc. around plant body

what group do vascular plants and bryophytes make up

land plants

• develops embryos within the maternal plant body (embryophytes)

what group do charophytes and chlorophytes make up

green algae

what did true plants evolve from

charophytes

what group do true plants and green algae make

vridiplantae

what group do all plant clades together make

archaeplastida

primary endosymbiotic events (bacteria engulfed by organism) occurred at the origin of archeplastida