Unit 2: Cell Structure and Function #2 Flashcards
What is cell metabolism?
All of the chemical changes and reactions that take place, involving the breakdown of macromolecules and synthesis of new ones (all to maintain life)
Why are cells more efficient when they are small?
At a certain size, it becomes too difficult for a cell to regulate what comes in and what goes out of the plasma membrane (waste must leave, nutrients must enter)
What does the size of a cell dictate?
The function of the cell, because cells need a high SA:V ratio to optimize the exchange of materials so cells with more transport in and out should be smaller.
What is the formula for SA:V for a cubic cell?
6/x (where x is side length)
What is the formula for SA:V in a spherical cell?
3/r (where r is radius)
How can eukaryotic cells be bigger and efficient?
Because they have compartmentalized organelles that can separate chemical reactions and efficiently transport things in and out of cells (but they need more resources)
Describe the parts of a phospholipid.
There is the phosphate group and the glycerol in the hydrophilic head (because it is negatively charged from the phosphate) and long fatty acid chains that make up the hydrophobic tail (because they are non-polar)
What is saturated fatty acids vs unsaturated fatty acids?
Saturated are when there are no double bonds between carbon, so every carbon is filled with Hydrogens, and unsaturated is when there are double bonds (monounsaturated for 1)
Why are the heads of phospholipids hydrophilic?
They are hydrophilic because they are negatively charged, and that allows for polar molecules, like water, to be attached to it in some way.
What does the plasma membrane do?
It separates the internal cell environment from the external environment.
What are plasma membranes composed of?
Phospholipids which form a bilayer (hydrophilic heads pointing out, hydrophobic tails pointing in)
What is selective permeability?
The ability of membranes to regulate the substances that enter and exit, some substances cross more easily than others, small nonpolar hydrophobic molecules (ex. hydrocarbons, CO2, N2, O2) pass easily, and large hydrophilic, polar molecules or ions (ex. sugar, water, amino acids, Na+, K+)
What is the fluid mosaic model?
Model to describe structure of cell membranes: the membrane is held together by weak interactions and can therefore move and shift which creates fluidity
How does temperature affect fluidity of the plasma membrane?
If the hydrocarbon tails are unsaturated (kinked) it helps maintain fluidity at low temperature because kinked tails prevent the tight packing of phospholipids (if they were all saturated, they would pack together causing damage to cells)
How does cholesterol maintain fluidity?
Cholesterol reduces excess movement at high temp, and reduces tight packing of phospholipids at low temp
