Life’s Guardian… Cell Membranes …their Structure & Function.
-
Upload
basil-wheeler -
Category
Documents
-
view
215 -
download
1
Transcript of Life’s Guardian… Cell Membranes …their Structure & Function.
Life’s Guardian…
Cell Membranes…their Structure & Function
How do things enter and leave living cells?
How does oxygen get into our cells?
How does carbon dioxide and other waste products leave our cells?
How do nutrients enter our cells?How do white blood cells
engulf foreign invaders?
Do cells drink and eat?
All living cells are surrounded by an extracellular fluid (ECF).
SMALL HYDROPHOBIC
MOLECULESO2 , CO2 , N2 ,
benzene
SMALL UNCHARGED POLAR MOLECULES
LARGER UNCHARGED POLAR MOLECULES
amino acids, glucose, nucleotides
H2O , alcohols
N+ , Na+ , HCO 3- , K+, Ca2+ , Cl - , Mg 2+
IONS
Besides other organisms, there are many chemicals in the ECF.
Solutions where the water is the solvent such as the ECF and blood
are called aqueous solutions.
Solution
solvent
Solution
solvent
A solution is a combination of a solvent with one or more solutes.
solute
If this solution was blood the solvent would be called plasma and the solute
would be red and white blood cells.
An organism's chemical processes are carried out inside cells and/or it’s
organelles.
Biochemical reactions require raw materials from outside the cell and
generate waste products inside that the cell must discharge back into its
environment.
In order to do this and remain alive a cell must maintain
CHEMICAL HOMEOSTASIS.
Homeostasis is the maintenance of a steady state or balance within the cell
or organism.
The PLASMA MEMBRANE plays a major role in the maintenance of
homeostasis as it determines what enters and leaves the cell.
Life’s Hangout Plasma membrane
Embedded Proteins
Phospholipids
Life’s Hangout Phospholipids hydrophillic or
water loving head
hydrophobic or water fearing end
Gk: phil – loving phob – fear
~75-95% of the cell’s plasma membrane
Life’s Hangout Embedded Proteins
Carrier proteins that regulate transport and diffusion
Marker proteins that identify the cell to other cells
And receptor proteins that allow the cell to receive instructions
~5-25% of the cell’s plasma membrane
Life’s Hangout Embedded Proteins
Diffusion
Embedded proteins provide the cell with a pore for the passive transport of solute particles.
concentrationgradient
Life’s Hangout
Carrier proteins provide the cell with a means of active transport.
Embedded Proteins
facilitated diffusion
concentrationgradient
Life’s Hangout Embedded Proteins
Symport carrier proteins provide the cell with a means of two-way diffusion.
Sodium-Na+
Glucose
Active Transport
ATPconcentrationgradient
Life’s Hangout
Marker proteins extend across the plasma membrane and serve to identify the cell. The immune system uses these proteins to tell friendly cells from foreign invaders.
Embedded Proteins
Life’s Hangout
Receptor proteins are used in intercellular communication. In this animation a hormone binds to the
receptor. This causes the receptor protein to release a chemical signal toperform a specific
action.
Embedded Proteins
Life’s Hangout Embedded Proteins
The passive transport of solvent molecules like water is called ….
concentrationgradient
A
B
Life’s Hangout Review
Cells are essentially a selectively permeable sack of particles dissolved in water with larger complex structures suspended in the resulting solution.
For this reason, it is important to know what a solution is before attempting to understand how cells respond to changes in their environments.
Simple Diffusion