Lecture 11: Bryophytes and movement in the cell

Embryophyte

Multicellular embryo housed in female gametophyte

Bryophyta (mosses)

Seedless non-vascular plants, long seta and conducting tissue resemble vasculature, have stomata

Hydroids

Tissue that conducts water in seta

Leptoids

Tissue that conducts food in seta

Protonemata

First stage of gametophyte, resembles green algae

Moss Gametophyte

Green leafy region with sporophytes attached by seta

Hyaline cells

Dead cell regions in the leafy region (gametophyte) of mosses

Releasing spores

The capsule dries out and opens up releasing spores

Anthocerotophyta (hornworts)

Have stomata on sporophytes, no conducting tissue, large single chloroplast with pyrenoid

hornwart sporophyte

Meristematic region where there is constant active cell division, older tissue at the top and new cells grow at base

Double membranes in the cell

Nucleus, chloroplast, mitochondria

Single membranes in the cell

Vacuole (tonoplast), peroxisome, ER

Water movement

Water moves from higher potential to lower

Hydrostatic pressure

Higher up water is the more pressure required to stop it

Osmosis

Water moving across selectively permeable membrane to a region of lower water concentration

Osmotic pressure

Pressure required to stop water moving from osmosis

Molecules that can freely diffuse across cell membrane

Small gasses, uncharged molecules

Molecules that can’t diffuse across cell membrane

Large molecules, charged or very polar molecules

Transmembrane proteins

Single alpha helix running through hydrophobic part with hydrophilic ends

Peripheral membrane proteins

Anchored in the membrane with hydrophobic helix

Transport across the membrane

Simple diffusion, facilitated diffusion, and active transport

uniport membrane proteins

Allows one solute one way

Symport and antiport membrane transport

Symport brings two substrates into the cell in one direction and antiport brings two substrates opposing directions

Active transport

Moves molecules against electrochemical gradient and uses ATP

Phagocytosis

Cell membrane engulfs large molecule or cell and brings it into cell using a vesicle

Pinocytosis

Vesicle takes water from outside cell inside

Receptor mediated endocytosis

Coated vesicle takes in molecule to be transported from a protein receptor on membrane

Plasmodesmata

Desmotubule connects two cells ERs lined with little spokes running through cytoplasmic sleeve

Apoplastic water pathway

Outside plasma membrane materials diffuse between walls

Symplastic water pathway

Along inner side of plasma membrane via plasmodesmata

Transcellular water pathway

Primary/secondary active transport of solutes across cells