Plant Phys exam 1 material

Plant Life: Commonalities in design elements

• Primary producers

• Non-motile

• Terrestrial plants are structurally reinforced

• Terrestrial plants have mechanisms for moving water, minerals, & photosynthates

• Terrestrial plants lose water continuously via evaporation

• Meristematic growth is indeterminate

• Alternation of generations

alternation of generations

Plant structure

• rigid cell wall

• middle lamella

• primary cell wall

• secondary cell wall

• simple pits

• pit pairs

• cytoplasm

• cytosol

middle lamella

• made of Ca and Mg

• pectins that act as a glue between plant cell walls.

primary cell wall

• thin (<1um) characteristic of young, growing cells

• that provides support and flexibility.

Secondary cell wall

• thicker and stronger. Lignin makes cell walls tough.

• It is formed after the primary cell wall and provides additional support and protection to the plant cell, often found in mature cells.

simple pits

• circular gaps in secondary wall with thin primary cell wall.

• Facilitates water movement between cells

pit pairs

• adjoining simple pits

cytoplasm

• everything except for the nucleus (ions, molecules, organelles, cytoskeleton, NOT nucleus)

cytosol

• liquid portion, separate from organelles, vesicles, ribosomes

plasmodesmata

• channel connecting adjacent cells through cell wall. Filled with cytoplasm, derived from the endoplasmic reticulum. Allows movement of molecules from cell to cell through the symplast

symplasm/symplast

• Continuous system of cell interconnected by

plasmodesmata.

• Allows for intercellular transport of water

and solutes

apoplast

• Mostly continuous system of cell walls, intercellular

air spaces and xylem vessels

symplasm

transports water, solutes, macromolecules between cells without crossing the plasma membrane. However, there is a restriction on the size of molecules

how do plant viruses spread

systemically through the symplast if viral movement proteins expand the size exclusion limit

pericycle

lateral roots

vascular cambium

• between xylem & phloem, increases girth, produces wood

cork cambium

produces periderm (water-resistant protectant layer)

three major tissue system

• dermal tissue

• vascular tissue

• ground tissue

parenchyma tissue

• very little intercellular space 

• and is involved in storage, photosynthesis, and tissue repair.

collenchyma tissue

• provides support and flexibility to young plants.

• more intercellular space

sclerenchyma tissue

• provides structural support with thickened secondary cell walls.

• typically contains dead cells at maturity.

dicot stem vs monocot stem

• dicot = vascular tissue in ring

• monocot = vascular tissue throughout

Endomembrane system & peroxisomes

• ER, nuclear envelope, Golgi apparatus,

  vacuole, endosomes, plasma

  membrane, oil bodies, peroxisomes,

  glyoxysomes.

• organelle functions,

  secretory processes, cell signaling,

  metabolits and hormone production,

  membrane recycle, cell cycle, cell

  expansion.

Independently dividing semiautonomous organelles of

endosymbiotic origin

Plastids, mitochondria

Function: energy metabolism and

energy storage

fluid mosaic model

double layer (bilayer) of either phospholipids or

glycosylglycerides in which proteins are

embedded

phosolipids

• Hydrophilic head containing a

phosphate group with a variable

component (such as serine, choline, or

inositol).

• Hydrophobic tail derived from fatty

acids

• Tail and head joined by a glycerol

molecule

GLYCOSYLGLYCERIDES

• Head group: galactose, digalactose, sulfated galactose

• Primarily found in chloroplast membranes

• Consist of glycerol, attached to one or two sugar molecules and two fatty acids.

• The sugars attached to the glycerol are either glucose,

galactose, or a digalactose unit

protein functions

enzymes

transport molecules

storage

electron carriers

integral proteins

embedded in the lipid bilayers. Usually span the entire

width of the phospholipid bilayer.

Transporters (ion channels, carriers, pumps), signal transduction

peripheral proteins

bound to membrane by noncovalent bonds (ionic or hydrogen bonds) and hydrophobic interactions, and can be dissociated from membrane with high-salt solutions or agents that break ionic and hydrogen bonds.

Receptors, Microtubules, and Actin microfilaments

• (Anchored): bound to membrane surface by lipid molecules to which they are covalently attached. Usually reversible

endoplasmic reticulum

RER: secretory protein synthesis

(carried to destination by vesicle)

SER: membrane phospholipids and

carbohydrate synthesis

golgi aparatus

• Golgi body: polarized stack of

cisternae (i.e., sided – cis/trans).

• Accepts tubules and vesicles from ER

• Transport, modify & package proteins and lipids into vesicles for delivery to target destination

• Plant cells can contain 100s of G.A.

COP II proteins

ER to Golgi

COP I proteins

Golgi to ER

Clathrin

endocytosis (envagination)

oil bodies

• organelles that accumulate oil during seed development

• store triglycerides

• oil bodies break down during seed germination

peroxisomes

• Peroxisomes and glyoxisomes

• Peroxisomes – detoxify ROS

• Glyoxysomes – associated with

mitochondria and oil bodies

mitochondria

• Cellular site of respiration

• Synthesis of ATP from ADP and inorganic phosphate (Pi)

• Contains proton-pumping ATP synthase

• Proton gradient

• Electron transport chain

Leucoplasts

non –pigmented, store starch & oils

Amyloplasts

produce & store starches

microtubules

a microscopic tubular structure present in numbers in the cytoplasm of cells, sometimes aggregating to form more complex structures.

• tublin dimers

• can “treadmill” through the cell

• orientation determines the shape (sphere vs cube)

microfilaments

• actin subunits

the plant cytoskeleton

• Monomers contain bound nucleotide

• Actin – ATP/ADP

• Tubulin – GTP/GDP

• Both polarized

• Proteins prevent depolymerization

myosins

move along microfilaments (toward the + end)

kinesins

move along microtubules

cell cycle

• G1: newly formed daughter cell has not yet replicated its DNA

• S: DNA is replicated.

• G2: a cell with replicated DNA has not yet proceeded to mitosis

• G1, S, G2 = Interphase

• M-phase = mitosis