Download AP Biology Discussion Notes

AP Biology Discussion
Notes
Wednesday 10/12/2016
Goals for the Day
1. Be able to describe how & why things
are transported in/out of the cell
2. Be able to identify, describe, and predict
the changes to plant & animals cells in
different osmotic solutions.
3. Be able to describe and calculate water
potential
Hand in Assignments!
10/12 Question of the Day
Identify the 2 things that set osmosis apart
from diffusion and what kind of transport it
is considered?
The “tonics”
Hypotonic Solution
(Hypertonic cell)
Hypotonic Solution
(Hypertonic cell)
Animal cell will Lyse or
Break due to becoming
swollen with water.
Hypotonic Solution
(Hypertonic cell)
Turgor Pressure - the
pressure a cell membrane
exerts of a cell wall. – the
cell is said to be Turgid.
Isotonic Solution
(isotonic cell)
Isotonic Solution
(isotonic cell)
Animal cells will be
normal, while plant
cells will become
Flaccid. A plant wants
Turgid cells – need
water for support!
Hypertonic Solution
(Hypotonic cell)
Hypertonic Solution
(Hypotonic cell)
Animal cells will shrivel
in a Hypertonic solution.
Hypertonic Solution
(Hypotonic cell)
Plasmolysis- the cell
membrane breaking away
from cell wall – cell has
been plasmolyzed.
Water Potential Calculations
Ψ= Ψp + Ψs
Water Potential Ψ= Ψp + Ψs
Water “potential” – potential
refers to water’s potential energy,
or water’s ability/capacity to do
work.
Water Potential Ψ= Ψp + Ψs
Water potential – physical
property that predicts which
direction water will flow.
Includes the effects of solute conc.
and physical pressure.
Water Potential Ψ= Ψp + Ψs
Usually measured in MPa.
1MPa = 10x atmospheric pressure,
so typical plant cell might have a
pressure of .5MPa
Pure water in an open container
under standard conditions has 0MPa
Water Potential Ψ= Ψp + Ψs
Solute Potential (Ψs)– directly
proportional to
molarity(_________) of the
solution
Ψs of pure water is by definition 0
Water Potential Ψ= Ψp + Ψs
Solute Potential (Ψs)– solutes bind
to water molecules, which reduces
the capacity of water to move and do
work (reduces
)
As Molarity (amount of solute)
increases the Ψs becomes more
negative
Water Potential Ψ= Ψp + Ψs
Pressure Potential (Ψp)–
physical pressure of a solution so
it can be positive or negative
relative to the atmosphere
Water in living cells is under
positive pressure
Calculating Ψ
Ψ= Ψp + Ψs
1. Add pressure & solute to find Ψ
inside & outside the cell.
2. Determine where Ψ is high and
where it is low.
3. Draw an arrow from high Ψ to
low Ψ.
4. Determine what type of solution
the cell is in and what the cell is
relative to the solution.
5. Use the Direction of Water
Movement to Identify the type
of Solution (and cell).
Questions?
Reading & Notes Assignment
1. Read pages 58-66
•
•
•
•
Take notes on main ideas
Define vocab words
Draw & Describe the experiment in fig 4.2
Add functional groups pg64-65 to notes
• Be able to recognize functional groups
• Draw Cholesterol (pg 77), Estrodial &
Testosterone (pg 63) Compare the 3
chemicals in terms of differences and
similarities in structure/function *Remember
cholesterol is a precursor to making steroids,
including sex hormones.