1: Plant Cell Architecture: Cytoplasmic Elements

Question 1

Vacuoles

Answer 1

Fluid filled compartments encompassed by a tonoplast membrane

occupy ~30-90% of cell volume

contains vacuolar sap (water + solutes)

Question 2

multifunctional compartment of vacuole

Answer 2

• Storage
• digestion
• pH and ionic homeostasis
• defense against microbial pathogens and herbivores
• Sequestration of toxic compounds
• pigmentation

Question 3

Storage

Answer 3

store solutes, primary metabolites and proteins

Question 4

Digestion

Answer 4

contain acid for breakdown and recycling of nearly all cellular components

Question 5

pH and ionic homeostasis

Answer 5

serve as reservoirs of protons and metabolically important ions

Question 6

Defense against microbial pathogens and herbivores

Answer 6

accumulate toxic compounds to reduce feeding by herbivores and destroy microbial pathogens

Question 7

Sequestration of toxic compounds

Answer 7

plants isolate or sequester toxic compounds into vacuoles

accumulation of toxic compounds in leaf vacuoles is one reason leafs are shed regularly

Question 8

Pigmentation

Answer 8

used to attract pollinators and seed dispersers

screen out UV and visible light to prevent photo-oxidative damage

Question 9

Plastids

Answer 9

Semiautonomous and contain genetic machinery required to make some of their own proteins

differentiate, redifferentiate, and dedifferentiate

inhertied maternally in most flowering plants and paternally in gymnosperms

Question 10

Plastid structures

Answer 10

outer membrane: non-specific pore membrane that allows water and variety of ions and metabolites to pass into intermembrane space

innermembrane: allows small, uncharged molecules like oxygen to pass into intermembrane space
- some use specific transporters to cross

Question 11

Proplastid

Answer 11

Precursor of all plastids

characteristic feature of meristematic cells

defined by appearance and location

small, undifferentiated with few internal membranes found only in young undifferentiated cells

Question 12

Chloroplasts

Answer 12

responsible for energy capture

stores starch

double membrane envelope

Granal thylakoid - pressed together in stacks = grana

stromal thylakoids - unpressed, and span the stroma to interconnect grana

Question 13

plastoglobules

Answer 13

Breakdown products of chlorophylls

synthesize and metabolize core lipids

vary in size and number, become more abundant to environmental stresses when they deteriorate (senescence)

confer color to fruits and petals during chromoplast development

Question 14

Etioplasts

Answer 14

development arrested by absence or very low light conditions

Transitional stage between proplastid to chloroplast through process of degreening

Question 15

Chromoplasts

Answer 15

responsible for bright red, roange, and yellow colors of fruits, flowers, and roots come from cartenoid; attract seed dispersers

develop directly from proplastid or dedifferentiate from chloroplasts

Question 16

Gerontoplasts

Answer 16

formed from chloroplasts during deterioration of foliar tissues

degrading of thylakoid and stroma protein provide source of amino acid for plant

Question 17

Colorless Plastid: amyloplasts

Answer 17

contain starch granules and resemble proplastids

common in storage organs

contain statoliths to help sense gravity to direct roots downwards and stem upwards

Question 18

Colorless plastids: elaioplasts

Answer 18

round plastids that store oil in form of droplets

produced in tapetal cells fundamental for pollen grain development

Question 19

Colorless Plastids: Leucoplasts

Answer 19

synthesis of monoterpenes and other volatile compounds contained in essential oils ~ exploited by humans

Question 20

Plasmodesmata

Answer 20

control passage of large molecules between cells
cell-to-cell communication

Question 21

Ergastic substances: Starch grains

Answer 21

high energy storage compound and gravity perception in green plants

Question 22

Ergastic compounds: Aleurone grains

Answer 22

granular protein deposits, functioning as storage compounds

found in outermost endosperm layer

formed in vacuole of storage cells

Question 23

Ergastic compounds: Tannins

Answer 23

deter herbivory and parasite growth

found in leaves, seat coats, unripe fruits

produced in vacuole or cytoplasm

functions against dehydration; forms barrier against water loss and prevents rotting and damage by animals

Question 24

Ergastic compounds: Calcium oxalate crystals

Answer 24

protect plant tissues, protect from herbivores, and regulate calcium

Question 25

Ergastic compounds: Calcium carbonate crystals

Answer 25

Structural components in plants, also regulates calcium and protects plant rom herbivores