Botany Unit 4 - Plant Transport

Xylem

Water transport, Dead at maturity, Conducting cells with lignin (Tracheids and Vessel elements)

Phloem

Transport sugars and certain mineral, Alive at maturity, 2 types of conducting cells (Sieve-tubes and Companion cells), Requires energy source

Passive Transport

No energy required, Simple diffusion, Facilitated diffusion, and Osmosis

Simple Diffusion

Solutes move with their concentration gradient (high to low)

Facilitated diffusion

Diffusion with the aid of membrane transport proteins (Channel Proteins, Transporters)

Chanel proteins

Facilitated Diffusion, Membrane pores

Transporters

Facilitated diffusion, Bind and change conformation

Osmosis

Water diffusion across a selectively permeable membrane in response to different solute concentrations

Active transport

Moving substances against their concentration gradient, requires energy and/or transport proteins

Protein gradient

Creates membrane potential (protein pump)

What state do healthy plant cells want to be in?

Turgid state - so full of water that the plasma membrane pushes against the cell wall

Transmembrane transport

Molecules repeatedly cross the plasma membrane and cell walls via membrane proteins

Symplastic transport

Molecules move through the symplast (the continuum of cytosol and membrane-lined channels called plasmodesmata)

Apoplastic transport

Molecules move through the apoplast (water-filled cell walls and intercelluar spaces)

Solute Potential

Pressure Potential

Bulk Flow

Mass movement of liquid by pressure, gravity, or both

Movement in the xylem is based on…

Differences in root and shoot cell water pressure

Transpiration

The evaporation of water from plant surfaces

Cohesion-tension theory