1: Plant Cell Architecture: Cell wall and Cell membrane

Question 1

Cell wall

Answer 1

almost all plant cells have cell wall except some sperm cells and seeds of plants

shape of plant cell is constrained by its cell wall

Impart rigidity - cellular exoskeleton

The plant cell wall is a highly organized composite of many different polysaccharides, proteins, and aromatic substances

Question 2

Cell wall composition

Answer 2

Most are transparent/translucent

contains cellulose

different layers of cell wall may have different patterns due to microtubule’s depolymerization and repolymerization

Question 3

Cell wall types

Answer 3

Primary cell wall - thin, characteristic of young, growing cells

Secondary cell wall - thick, stronger than primary cell wall
- has lignin for added strength

Question 4

Primary cell wall

Answer 4

Carbohydates
- cellulose
- cross linking glycans
- pectins
- middle lamella; maceration is process of separating middle lamella

Structural proteins
- Hydroxyproline - rich glycoproteins
- proline
- glycine
- arabinogalactan proteins

Aromatic
- hydroxycinnamates

Question 5

Protoplasm

Answer 5

Protoplasm - substance of the cell

protoplast - substance of a single cell

Question 6

Cell membrane

Answer 6

Enshroud genetic material

delimit boundaries of other internal structures

regulates fluxes of ions and metabolites

Question 7

Fluid mosaic membrane

Answer 7

all biological membranes have same basic molecular organization:
- bilayer of lipids -> spontaneous assembly
- embedded proteins -> selective traffic routes

Question 8

Phospholipids

Answer 8

Amphipathic: hydrophobic and philic regions

Hydrophilic:
Phosphatidic acid
Alcohol groups

Hydrophobic:
Glycerol backbone
Fatty acid chains
- saturated
- unsaturated

Can assume any shape
Ability of self-assembly

Question 9

Membrane proteins

Answer 9

Provide enzymatic and structural functions

Integral proteins - embedded in bilayer

peripheral proteins - bound to bilayer by non covalent bonds

Anchored proteins - bound to covalently to bilayer via lipid molecules