Biology 3.1 3.2 Flashcards
Cell membrane is ___ in all living cells.
Cell membrane is ____ permeable, and is made up of ___ and ___.
present
differentially, phospholipids, proteins
What are the properties of phospholipid molecules?
Arrange in a bilayer in cell membrane
can move laterally, hence the membrane is described as ‘fluid’
What are the properties of protein molecules?
intersperesed among the phospholipid molecules
->membrane is described as ‘mosaic’
Some are attached to surface of phospholipid bilayer, some are embedded in the bilayer and others span the entire bilayer
Glycogen protein: a type of protein with carbs attached
What is the structure of a phospholipid?
2 fatty acids, a glycerol and a phosphate group
What are features of phosphate group and fatty acid?
Phosphate group: Polar, attracted by water, forms the hydrophilic ‘head’
Fatty acid: Non-polar, Repelled by water, forms the hydrophobic ‘tail’
What is the arrangement of phospholipid molecule in cell membrane?
Hydrophilic head points outward, being in contact with aqueous solutions inside and outside the cells
Hydrophobic tails points inward, not being in contact with aqueous environments
-> core -> determines major property of cell membrane
What are the types of membrane proteins and their functions?
Channel protein: Provide channels for certain substances to move across membrane
-> substances passing through are usually small and polar
Carrier protein: Bind to certain substance and transport them across membrane,
Change its own shape in order to transport the substances
Requires energy
Receptor: Bind to chemical messengers (hormones) outside cell, binding may turn on certain activities inside cells (growth)
Antigen: Usually are glycoproteins,
For cell recognition -> e.g involved in ABC blood group system
Enzyme: Speed up chemical reactions
There are ____ types of channel proteins, each responsible for ____ substances to pass through.
various, specific
Which substances dissolve in the phospholipid bilayer and move across the membrane?
small, non-polar molecules ( O2, CO2, glycerol, fatty acid, vitamin A and D)
Which substances are repelled by phospholipid bilayer but can be transported by channel proteins or carrier proteins?
Small polar molecules (water, urea, amino acids, glucose), small ions ( sodium ion, calcium ion)
Which substances cannot move across the cell membrane?
Large molecules( starch, triglyceride, proteins
What are factors affecting the permeablity of cell membrane>?
Temperature: permeability of membrane increase with increase temp.
boiling can destroy membrane, making it fully permeable
Organic solvents: Organic solvent can destroy phospholipids, hence making permeability increase
E.g. alchohal can dissolve membrane and extract chlorophyll in plant cells
What is the structure of cell membrane and its relation with its properties and functions?
structure: Phospholipids molecules can move laterally
relation: Cell membrane is fluid in nature
->Allows cell membrane to change shape, and fuse with one another during phagocytosis and cell division
