12/10/18
Professor Mike Philpott
Cell Organelles - Structure and Function
Cell Membrane
• Plasma membrane
o Single lipid bilayer
o Selectively permeable
o Barrier between intracellular
fluid and extracellular fluid
o Fluid mosaic model
• Consist of many components including
1. Amphipathic lipids (both hydrophilic and hydrophobic)
2. Integral and peripheral proteins
3. Carbohydrates
▪ Glycolipids
▪ Glycoproteins
▪ Peptidoglycans
▪ Glycosaminoglycans
Cell Wall
• Found in plant cells and most bacterial cells
• Surround plasma membrane, further limiting movement in and out of the cell
• In plants it is made of cellulose
o Digested by cellulase which is not present in animals
• In bacteria made of peptidoglycan
o Also surrounded by gelatinous polysaccharide layer called a capsule/glycocalyx
o Gram positive bacteria have thick cell walls that retain Gram’s stain
▪ They look blue
o Gram negative bacteria have thin cell walls that lose Gram’s stain when washed
▪ They look pink
Cell Surface Appendages
1. Villi/microvilli
a. Found in the gut to increase surface area
2. Cilia
a. Help movement of extracellular fluid especially in the respiratory tract (smaller)
3. Flagella
a. Help movement of cells in sperm
Professor Mike Philpott
Cell Organelles - Structure and Function
Cell Membrane
• Plasma membrane
o Single lipid bilayer
o Selectively permeable
o Barrier between intracellular
fluid and extracellular fluid
o Fluid mosaic model
• Consist of many components including
1. Amphipathic lipids (both hydrophilic and hydrophobic)
2. Integral and peripheral proteins
3. Carbohydrates
▪ Glycolipids
▪ Glycoproteins
▪ Peptidoglycans
▪ Glycosaminoglycans
Cell Wall
• Found in plant cells and most bacterial cells
• Surround plasma membrane, further limiting movement in and out of the cell
• In plants it is made of cellulose
o Digested by cellulase which is not present in animals
• In bacteria made of peptidoglycan
o Also surrounded by gelatinous polysaccharide layer called a capsule/glycocalyx
o Gram positive bacteria have thick cell walls that retain Gram’s stain
▪ They look blue
o Gram negative bacteria have thin cell walls that lose Gram’s stain when washed
▪ They look pink
Cell Surface Appendages
1. Villi/microvilli
a. Found in the gut to increase surface area
2. Cilia
a. Help movement of extracellular fluid especially in the respiratory tract (smaller)
3. Flagella
a. Help movement of cells in sperm
