Cell Biology Quiz

Cell Wall Structure

• Composed of three layers: Middle Lamella, Primary Wall, and Secondary Wall
• Cellulose is present in young cells, and lignin is added to thicken the wall in older cells

Plasma Membrane

• A flexible, thin, and fluid membrane surrounding the cytoplasm in prokaryotic and eukaryotic cells
• Composed of two thin layers of phospholipids with hydrophilic and hydrophobic ends
• Protein particles are embedded between the phospholipid layers, controlling passage of materials
• Selectively permeable, allowing passage of some micro-particles and blocking larger particles

Structure of Plasma Membrane

• Phospholipids have hydrophilic heads and hydrophobic tails
• Tails face the inner and outer parts of the membrane, while heads point inwards
• Protein channels transport materials between the inside and outside of the cell

Cytoplasm Composition

• Consists of 80% water, 15% proteins, and 5% fat, sugars, and salts
• Composed of many cellular organelles and non-living components

Endoplasmic Reticulum

• A reticulate, interconnected system of tubules and vesicles
• Attached to the plasma membrane and nuclear membrane at certain places
• Site of lipid, carbohydrate, and protein synthesis
• Divided into two types