CAS BI 315 Lecture Notes - Lecture 4: Molar Concentration, Tonicity, Facilitated Diffusion
1 Jun 2018
School
Department
Course
Professor
I. Bone calcium level
A. Not homeostatically regulated - blood calcium is regulated not bone
B. Not everything that is important to us is homeostatically regulated
C. Evolution does not take into consideration old age problems bc its focused on
reproduction
Membrane Transport and Signaling
I. Plasma Membrane Review
A. Membrane is made up of
1. Phospholipid bilayer
2. Proteins (transmembrane or peripheral)
3. Some carbohydrates, cholesterol, glycolipids
B. Fluid mosaic model reflects the allowable movement of proteins within the
phospholipid bilayer
C. Plasma membranes can be joined together for stability and structure, to create
an impermeable barrier, or to unite in function
D. Anchor cells together
1. Desmosome
a) Anchored two pieces together
b) Structural together
c) “Button” or “snap”
d) Movement between cells is possible but from cytoplasm to
cytoplasm isn’t
2. Tight junction
a) “Zipper” - seal neighboring cells together
b) Material can’t slip between or between cytoplasms
3. Gap Junction
a) Provides channels between inside of one cell to other
b) Material can pass between the cells but if inside the cytoplasm,
can pass between the cytoplasms of the cells
II. Diffusion
A. Movement of molecules from an area of greater concentration to an area of
lesser concentration
B. Concentration gradient - describes areas of higher and lower concentration of a
given molecule
III. Why do molecules move at all?
A. Brownian motion and kinetic energy
B. As they move around they bounce off each other randomly
C. The closer molecules are to each other, the more random collisions
D. Over time, they will spread apart as far as possible
E. Continues until equilibrium- equally spread out
1. Not a static state bc keeps moving and no net effect of motion
IV. Difusion
A. Passive: no cellular energy
B. Move down concentration gradient due to own kinetic energy
find more resources at oneclass.com
find more resources at oneclass.com
