02 The plant cell

Robert Hooke

first described cells looking at a cork under a primitive microscope

Matthias Schleiden, Theodor Schwann, and later Rudoolf Virchow

established Cell Theory that recognizes the cell as the basic unit of life

Cell wall

encloses all other parts of the cell (protoplast)

Primary wall

forms early and composed of poly saccharides (cellulose)

Secondary wall

internal to primary wall (lignin); tough; helps with protect against pathogens and herbivory

Pits

minute pores that allow the transfer of materials across the cell wall

Plasmodesmata

channels that connect adjacent plant cells

Middle lamella

found between plant cells; cellular cement or glue for cells; made up of pectins

Nucleus

control centre of the cell; contains the cell’s DNA

Cytoplasm

everything inside the cell that isn’t the nucleus (organelles):

Cytosol

fluid matrix (H20 + proteins + organic molecules/ions); maintains internal pressure

Cytoskeleton

a network of proteins within the cytoplasm that give the cell shape and support

Chloroplasts

contain pigments (ie. chlorophyll = green, carotene = orange, xanthophyll = yellow) found in thylakoids; where photosynthesis occurs

Leucoplasts

colorless organelles that store various materials, like starch (amyloplast in potatoes)

Chromoplasts

contains orange, red, and yellow pigments (carotenoids); abundant in petals and fruit

Plastids are composed of

Chloroplasts, leucoplasts, chromoplasts

Cytoplasm

everything inside the cell that isn’t nucleus (organelles)

Mitochondrion

site of cellular respiration; glucose is broken down to release energy into the usable form, ATP

Central vacuole

contains cell sap (water + sugar + ions + proteins + metabolites); sequesters waste and toxic compounds; maintain tugor and homeostasis)

Rough ER

studded with ribosomes, where proteins are synthesized

Smooth ER

synthesizes lipids; packages and transports proteins

Golgi apparatus

storage, modification, and packaging of proteins produced by ER

Microbodies

where enzymatic reactions occur

Peroxisomes

used in photosynthesis

Glyocysomes

convert fats to sugars

Proteasome

houses proteases for breaking down proteins

Tannosome

contains tannins, found in plants to ward off herbivores, UV protection

Endosymbiont Theory

Evolution of the mitochondria

Chromatin

DNA, RNA, proteins

Nucleus

• Centre of control and hereditary information

• Contains chromatin (DNA + RNA + proteins)

• Also has a nucleolus, involved in the formation of ribosomes