solute transport (ch. 6) 1. the need for specialized...
TRANSCRIPT
![Page 1: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/1.jpg)
Solute Transport (Ch. 6)
1. The need for specialized membrane transport systems.
2. Passive vs. Active Transport
3. Membrane Transport Mechanisms
![Page 2: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/2.jpg)
Fig. 1.4
Why the need for specialized transport systems?
![Page 3: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/3.jpg)
Fig. 1.5A
![Page 4: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/4.jpg)
Fig. 6.6
That the permeability of biological membranes differsfrom that of a simple phospholipid bilayer indicates
that transporters are involved.
![Page 5: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/5.jpg)
Passive vs. Active Transport
Passive transport requires no energy input, !G < 0Active transport requires energy, !G > 0
Whether active or passive transport is required isdetermined by the chemical potential of a solute oneither side of a membrane.
We can use the !G concept to understand the chemicalpotential.
Hydrostatic
![Page 6: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/6.jpg)
Chemical potential difference
1. Concentration component2.3 RT log (Cj
i/Cjo)
What is the concentration influence on wherethe solute will tend to move spontaneously?
2. Electrical componentzjFE
What is the electrical influence on wherethe solute will tend to move spontaneously?
![Page 7: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/7.jpg)
Movement along electrical and concentration gradients(from Lecture 3)
!G = zF !Em + 2.3 RT log(C2/C1)
At equilibrium (!G = 0) can rearrange this as:
!Em = -2.3(RT/zF) log(C2/C1)
![Page 8: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/8.jpg)
Nernst potential•The difference in electrical potential (voltage) between twocompartments at equilibrium with respect to a given solute.
•The membrane electrical potential at which the concentrationand electrical influences on a solute’s movement are exactlybalanced, so there is no net movement.
!Ej = 2.3RT (log Cjo/Cj
i)zjF
The Nernst
Equation
Note that outsideconc. is in numerator, inside is in denominator.Not Cto/Cfrom as we used before in !G eqn.
!Ej is the membrane potential (inside relative to outside), and is negative for the plant plasmamembrane.
See that for an anion (z negative), Nernst predicts Cjo/Cj
i > 1and for a cation (z positive), Nernst predicts Cj
o/Cji <1
![Page 9: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/9.jpg)
How can we use the Nernst Equation to understand thedifference between passive and active transport?
Compare the concentration gradient predicted by theNernst Equation to that actually observed.
If they differ, then active transport must be involved.
![Page 10: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/10.jpg)
cell
-0.11Volts (inside is neg.)
medium
What concentration gradient of an anion or cationwould be maintained by the membrane potential without an input of energy?
![Page 11: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/11.jpg)
Cjo Cj
i
Examples of predicted and observed concentrationdifferences between outside and inside of pea root cells.
![Page 12: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/12.jpg)
Predict higher internal than external for cations because the membrane potential attracts cations.
![Page 13: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/13.jpg)
Predict lower internal than external for anions because the membrane potential repels anions.
![Page 14: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/14.jpg)
Observed internal matches predicted internal:conclude no energy required to maintain this condition.
![Page 15: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/15.jpg)
Observed very different than predicted:conclude energy (active transport) is required
to maintain this condition.
![Page 16: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/16.jpg)
Active transport is moving cations out of cell and anions into cell.
![Page 17: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/17.jpg)
-0.11Volts (inside is neg.)
NO3- = 28 mM
NO3- = 2 mM
Ca+2 = 2 mM
Ca+2 = 1 mM
Active transport is maintaining [NO3-] internal at higher
than expected and [Ca+2] internal at lower than expected.
![Page 18: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/18.jpg)
Plasmamembrane and the tonoplast are sites of much ion transport.
Fig. 6.4
![Page 19: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/19.jpg)
Maintenance of cell membrane potential requires energy produced by respiratory metabolism
![Page 20: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/20.jpg)
1. What is the pH gradient across plasmamembrane?2. How is the pH gradient maintained?3. How is pH gradient related to electrical potential?
Inside cell
Outside cell
![Page 21: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/21.jpg)
What is the pH gradient across plasmamembrane?Which way will H+ move spontaneously?
Lower pHc. 5.5
Higher pHc. 7
![Page 22: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/22.jpg)
1. What is pH gradient across plasmamembrane?Which way will H+ move spontaneously?
Lower pHc. 5.5
Higher pHc. 7
![Page 23: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/23.jpg)
1. What is pH gradient across plasmamembrane?2. How is the pH gradient maintained?3. How is pH gradient related to electrical potential?
Inside cell
Outside cell
![Page 24: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/24.jpg)
Proton pumping ATPases maintain pH gradients. This is a major use of ATP in all living cells!
![Page 25: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/25.jpg)
-0.11Volts (inside is neg.)
1. What is pH gradient across plasmamembrane?2. How is the pH gradient maintained?3. How is pH gradient related to electrical potential?
![Page 26: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/26.jpg)
-0.11Volts (inside is neg.)
How is pH gradient related to electrical potential?Pumping of charged molecules (protons) generatesthe membrane potential.
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+H+
H+
H+
H+
H+
![Page 27: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/27.jpg)
So, the proton pumping ATPases create boththe proton concentration gradient (pH gradient)and the membrane electrical potential.
•The electrical gradient explains why some ionsare distributed unequally across the membrane,even without the direct input of energy.
•The proton concentration gradient provides thefree energy for many kinds of secondary activetransport.
![Page 28: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/28.jpg)
Primary active transport of H+
Secondary active transportusually requires a protonconcentration gradient (p.m.f.).
![Page 29: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/29.jpg)
Primary active transport: Energy use is directly linked to transport,e.g. ATP is hydrolyzed as transporter moves a solute acrossmembrane
Secondary active transport: Energy use establishes conditions fortransport, which itself does not directly require energy.
e.g. establishment of a proton motive force by a proton pumpingATPase (primary active transport) then allows H+/sucrose co-transport (secondary active transport).
![Page 30: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/30.jpg)
Secondary active transportersSymports and Antiports
![Page 31: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/31.jpg)
![Page 32: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/32.jpg)
Proton pumping ATPases are inverted on vacuole membrane.
![Page 33: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/33.jpg)
Fig. 6.7
![Page 34: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/34.jpg)
Fig. 6.8
![Page 35: Solute Transport (Ch. 6) 1. The need for specialized ...jan.ucc.nau.edu/gwk/Bio4262006/Bio426Lecture12Feb20.pdf · Passive vs. Active Transport Passive transport requires no energy](https://reader033.vdocuments.us/reader033/viewer/2022042803/5f438ac36460a93f27757de6/html5/thumbnails/35.jpg)
Fig. 6.9
even
Transport of a solute against its concentration gradient canoccur by coupling it to proton transport with its concentration
gradient.