Why are cells so small?
Cells are so small as their function limits their size
Two factors effecting cell size
Volume of the cell, the larger the volume the larger the amount of chemical activity per unit time needs to be carried out
Surface area of the cell, the larger the surface area the more it needs to excrete waste products and take in nutrients from its environment
As the cell increases
- the centre of the cell to the membrane increases
- it produces more carbon dioxide
- it absorbs more nutrients
Think of it as a human when we grow our heart is further away from our toes, we exhale more c02 and we eat more.
Function of cholesterol in the plasma membrane
Reduces permeability in the plasma membrane.
Protein molecules may be
Extrinsic proteins, these are on the periphery of the cell, attached to the outer membrane by weak bonds
Intrinsic proteins, these are proteins imbedded into the plasma membrane
Carbohydrates may be what if they attach to lipids and proteins on the cell membrane
- Glycoproteins- when attaching to proteins
- Glycolipids- when attaching to lipids
They serve as receptors in cell to cell contain,distinguishing whether a cell is foreign or not, and serve as a fingerprint on a species level, cellular level and individual level.
What’s the reason for fluidity in the plasma membrane
It’s due to no covalent bonds between molecules, only hydrophilic, hydrophobic interactions.
What do the molecules do in the phospholipid?
ALL membrane molecules move on their own axis,and sideways. This makes the plasma membrane fluid, the more unsaturated fatty acids the more fluid the membrane becomes.
Where’s the ide of mosaic brought about from?
It’s brought from the proteins imbedded in the plasma membrane floating around surrounded by phospholipids.
Some general functions of the plasma membrane
- Seperated the exterior from the interior cells
- acts as an active site for respiration to occur
-provides a surface area for enzymes - contains receptors on its outer membranes
