What is the composition of a phospholipid?
- Fatty acid chains - hydrophobic
2. Phosphate head - hydrophillic
What is the function of protein in the cell membrane?
- Enzyme activity
- Signal transduction (cell signaling)
- Transport
What are the two types of transport protein?
- Passive
2. Active
What is passive transport?
- movement of molecules across plasma membrane from high concentration to low concentration
- no ATP required
What is active transport?
- movement of polar molecules (ions) across plasma membrane from low concentration to high concentration
- requires ATP
What is transport protein?
proteins that transport molecules across plasma membrane
What does enzyme do in cell membrane?
Enzymes attach to interior surface of membrane help to catalyse chemical reactions
What does receptors do in cell membrane?
- To receive chemical messages from other cells
- The binding ofa messenger to a receptor may trigger signal transduction (cell signaling)
What does structural protein do in cell membrane?
supports the shape of membranes
What does cell adhesion proteins do in cell membrane?
they are proteins that glue cells to one another
What does cell surface markers do in cell membrane?
cell surface markers make themselves recognisable
What is glycoproteins?
recognition with protein/carbohydrate chain shape
What is glycolipids?
recognition by lipid/carbohydrate chain shape
What is the function of plasma membrane?
Plasma membrane keeps essential substances inside the cell
Regulates the passage of materials between a cell and its environment
Phospholipid bilayer acts primarily as a barrier
What is osmosis?
Osmosis is the passive transport of water across a membrane
In osmosis, water travels from an area of lower solute concentration to an area of higher solute concentration
What is hypotonic solution?
Lower solute and more water concentrations than cell cytoplasm
- Hence, water enters the cell causing swelling
What is hypertonic solution?
higher solute and lower water concentration than the cell cytoplasm
Hence, water tends to leave the cell causing shrinkage
- Hence, water tends to leave the cell causing shrinkage
What is Isotonic solution?
Solute and water concentrations are same inside and outside of the cell
No net movement of water
Hence, volume of the cell remains the same
What is exocytosis?
exocytosis is the act of moving large molecules or particles out of cells through plasma membrane.
A vesicle containing molecules or particles fuse with the membrane and expel its contents (exocytosis)
What is endocytosis?
endocytosis is the act of taking in large amount of materials into the cell.
The membrane fold inwards, trapping the material from the outside.
Materials are enclosed within invaginations of the plasma membrane which subsequently pinched off to form cytoplasmic vesicles.
What are the 3 types of endocytosis?
- Phagocytosis
- ingestion of large solid particles (eg. white blood cell ingesting bacteria) - Pinocytosis
- Cell ingests liquid, dissolved solutes and small suspended particles - Receptor-mediated endocytosis
- Plasma membrane indents to form a pit lined with receptor proteins that have picked up particular molecules. Pit will close to form vesicle, carrying the molecules into cytoplasm.
What is bacterial cell wall made of?
peptidoglycan
Does gram postive bacteria have thick or thin peptidoglycan layer?
Thick
Does gram negative bacteria have thick or thin peptidoglycan layer?
Thin
