Plants

Phytomer:

Basic module of a plant that consists of an internode, node, leaf, and an axillary meristem

Cell walls are composed of:

Cellulose, hemicellulose, pectin

Cell wall functions:

1. Connect adjacent cells

2. Act as an exoskeleton

3. Determine plant shape

4. Act as diffusion barriers

5. Provide anchor point for sensory proteins

6. Act as barrier to pathogens, parasites, and herbivores

7. Provide strength for xylem

Difference between primary and secondary cell walls and lamella:

Primary: must be elastic for young growth

Secondary: thicker and stronger

Middle lamella: cements the walls of neighboring cells together

Glucan:

A polymer of glucose units linked end to end

Cell wall components:

Glucose units → molecules (chains) → microfibrils → macrofibrils → fibers → lamellae (layers)

Cellulose microfibril deposition determines the directions of cell expansion (T or F):

True

Recalcitrance:

The intrinsic resistance of cell walls to deconstruction of their component polymers to sugars and aromatics (lignin and cellulose strongl interact, making it difficult to seperate)

Meristems:

Localized regions of ongoing cell division that enables growth during post-embryonic development (SAM at top, RAM at bottom)

Primary and secondary growth:

Primary: phase of plant development that gives rise to new organs and to the basic plant form; gives rise to primary plant body: part of the plant derived from the shoot and root apicial meristems and primary meristems

Secondary: increase in width or diameter of shoots and roots that happens to a plant as it grows

Layers of trees:

Apical dominance:

Growth habit by a weakly-branched plant, with a strong branching response to decapitation

Plant tissues:

Root system architecture:

The geometric arrangement of individual roots within the plant’s root system

Phyllome:

The collective term for any type of leaf or modified leaf on a plant

Phyllotaxy:

How leaves are arranged on the shoot; three main patterns (alternate, decussate, spiral)

Leaf phases:

Nuclear envelope:

Dotted with nuclear pores: selective channels made up of nucleoporin proteins

Chromosomes:

DNA and associated proteins

Chromosome formation:

DNA double helix → nucleosomes (“beads on a string”) → chromatin fiber → condensed chromatin → chromosome

Plant reproduction

Pollination:

Process of transferring pollen grains from the anther of the stamen to the stigma of the pistil

Operation Outcross: Two Strategies

1. Floral Morphology: Stamen and pistils mature at different times; pistil or stamen longer or shorter than other

2. Self-Incompatibility: biochemical barrier that prevents self pollination (kills pollen grains/tubes when same S locus is expressed

Double fertilization:

One sperm cell fuses with the egg to create the zygote, the other sperm fuses with the binucleate central cell to produce a triploid primary endosperm cell

Embryogenesis:

The process by which plant embryos form and develop; during embryogenesis the basic body plan of the plant is laid down, primary tissue types form, and fats and starches are accumulated that will ultimetly be broken down after

Types or relationships:

Commensalism: symbiotic relationship where one organism benefits and the other gains/loses nothing

Mutualism: symbiotic relationship where both organisms benifit

Coevolution: linked adaptations of two or more organisms

Lichens:

Composite of a fungus and an organism capable of photosynthesis; green algae and/or cyanobacteria

Fungi can photosynthesize (T or F):

False; they cannot and therefore form lichens sometimes

The commonality between lichens is shared genetics (T or F):

False; commonality is mode of nutrition

Photobiont:

Photosythentic symbiont of lichens

Nitrogen-fixing bacteria:

Convert atmospheric nitrogen into usable nitrogen for plant; plant allows bacteria to infect due to chemical “password’’

Mycorrizal fungi:

1. Arbuscular: enhances nutrient absorption efficiency; agriculturally important (grows in cells)

2. Ectomycorrhizal: allow for trees/forest to connect/talk with eachother (grow between/around cells)

Rhizobacteria:

Umbrella term for bacteria that provide several benificial services to plants