Cell Wall And Plasma Membrane Flashcards
What is the cell wall?
A non-living, stiff outer covering of some cells.
Where is the cell wall found?
In bacteria, fungi, algae, and plant cells.
What is the composition of the bacterial cell wall?
Made of peptidoglycan.
What is the composition of the fungal cell wall?
Made of modified polysaccharide chitin.
What is the composition of the plant and algal cell wall?
Made of cellulose.
What is the composition of the plant cell wall?
Composed of cellulose, pectin, and other polysaccharides.
How is the plant cell wall synthesized?
Synthesized by protoplasm and deposited outside the plasma membrane.
What are the three layers of the plant cell wall?
Middle Lamella, Primary Cell Wall, Secondary Cell Wall.
What is the Middle Lamella?
The first formed layer during cell division, cementing layer between two daughter cells.
What is the composition of the Middle Lamella?
Made of calcium and magnesium pectates.
What is the Primary Cell Wall?
Formed next to the middle lamella, thin and elastic in young cells.
What is the composition of the Primary Cell Wall?
Contains cellulose arranged in criss-cross for strength.
What is the Secondary Cell Wall?
Forms between plasma membrane and primary wall after full maturity.
What is the composition of the Secondary Cell Wall?
Thick and rigid due to lignin, inorganic salts, and waxes.
What are the functions of the cell wall?
Provides mechanical support, maintains cell shape, and acts as a skeletal framework.
What is the plasma membrane?
The outer most living boundary found in all prokaryotic and eukaryotic cells.
What is the chemical composition of the plasma membrane?
Made of phospholipid bilayer interspersed with proteins.
How are phospholipids arranged in the plasma membrane?
Non-polar hydrophobic tails face inward and polar hydrophilic heads face outward.
What is the composition by weight of the plasma membrane?
50% lipids, 50% proteins, 5–10% carbohydrates.
What is the Sandwich Model?
An older model where lipid bilayer is sandwiched between protein layers.
What is the Fluid Mosaic Model?
Describes plasma membrane as a fluid mosaic of lipids and proteins.
Who proposed the Fluid Mosaic Model?
Proposed by Singer and Nicolson in 1972.
What are Integral Proteins?
Embedded within the lipid bilayer, forming channels for passage of substances.
What are Peripheral Proteins?
Located outside the lipid bilayer with loose association to the membrane.
What are the functions of the plasma membrane?
Protection of cell cytoplasm and regulation of substance flow.
How does the plasma membrane maintain pH and ionic concentration?
By regulating the flow of substances in and out of the cell.
What helps control the fluidity of the plasma membrane?
The lipid bilayer and unsaturated fatty acids.
