Plant cell structure plant cells are eukaryotic cells , and have - a plasma membrane - a nucleus - a cytoplasm

1. Plant cell structure plant cells are eukaryotic cells, and have - a plasma membrane - a nucleus - a cytoplasm

2. Organelles found in plant cells include: - some found in most eukaryotic cells - some unique to plant cells also unique to plant cells: extracellular matrix intercellular junctions

3. Vacuoles in plant cells - often very large - bound by the tonoplast - varied functions - origin

4. Plastids - various mature types of plastids occur - all originate as proplastids - mature type that forms depends on circumstances ** some plastids can convert from one form into another if conditions change

5. General plastid structure: - interior separated from exterior by plastid envelope - interior matrix material = the stroma - are small (~ 1-5 mm long)

6. Proplastids - the smallest plastids - found in specific cell types - numerous (~ 7 - 40/cell) - can replicate

7. Chloroplasts - develop in shoot cells, if light is available final structure includes - chloroplast envelope - stroma - lamellae arranged into thylakoids and grana ~ 5 mm X 2 mm ~ 20 – 50/cell

8. Etioplasts if light is not available in shoot cells, altered structures (etioplasts) develop if light becomes available etioplast can be converted to chloroplast

9. Leucoplasts = any colorless plastids - commonly develop in cells of storage tissues amyloplast elaioplast

10. Chromoplasts - contain carotenoids, but no chlorophyll - commonly found in fruits and flowers - origin - various functions

11. Glyoxysomes • - a specialized type of peroxisome • - contain enzymes found in peroxisomes • - also contain enzymes needed for glyoxylate cycle • Oleosomes • lipid-storing organelles, found mostly in oil-containing seeds • - internal lipids surrounded by a lipid monolayer

12. Plant cell walls - form at time of cell formation, but may continue to develop over time Primary cell wall - forms at time of new cell formation chemical components include: - cellulose - matrix materials(most are carbohydrates)

13. cellulose - is a polysaccharide of glucose monomers - exists in microfibrils matrix materials hemicelluloses pectic substances proteins & glycoproteins

14. Hemicelluloses - somewhat similar to cellulose, but - are often branched chains - include sugar monomers other than glucose Pectins - are also various polysaccharides Proteins - most are glycoproteins; vary with cell type Various components interact to form overall cell wall

15. cellulose is synthesized by a complex found in the plasma membrane matrix materials are synthesized in the Golgi

16. Secondary cell wall = additional layers of cell wall produced after early cell growth in some cells chemical components include: - cellulose - hemicellulose - pectic substances - lignin

17. Lignin - is a polymer of phenols; not a carbohydrate - insoluble in water - combined with cellulose, forms rigid structure ** Secondary wall ends up between the primary cell wall and the plasma membrane

18. Plasmodesmata - are the intercellular junctions of plant cells - connect the cytoplasms of the adjacent cells - complex structure

19. Two distinct regions within each plant: 1) the symplast 2) the apoplast Transport through plants often occurs within one region or the other - symplastic transport - apoplastic transport