BI110 Lecture Notes - Lecture 16: Sterol, Cholesterol, Active Transport

19 views2 pages

ceruleanlion382

29 Apr 2016

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Module 18: Membrane Transport

Passive Membrane Transport

-Hydrophobic nature of membranes restricts free movement of many molecules and substances

essential for life

Passive Transport: Movement of a substance across a membrane without need to expend chemical

energy such as ATP

Passive Transport and Diffusion

Passive transport can be driven by diffusion

Diffusion: Net movement of a substance from region of high concentration to lower concentration

●Primary mechanism of solute movement within a cell and between cellular compartments

separated by a membrane

●Rate of diffusion depends on the concentration difference on two sides of membrane, or

concentration gradient (A concentration gradient contains potential energy)

○The rate of diffusion is faster in a higher concentration gradient rather than low

Diffusion rates: The higher the temperature, the greater the diffusion rate. At a given temperature,

smaller molecules diffuse faster

Two types of passive transport (Simple and facilitated)

Simple Diffusion: Passive transport of substances across lipid portion of membranes with their

concentration gradients

-Small uncharged molecules move rapidly. Large or charged molecules may be strongly impeded from

crossing membranes

Not every small or uncharged molecule is equal.

Even though ions are small, their charge does not allow them to pass the membrane

Friday October 23, 2015

Cholesterol and cortisol are derivatives of sterol which is a lipid found in the membrane which allows

them to enter the cell directly through the plasma membrane

Osmosis: Diffusion of water

-Two compartments separated by a semipermeable membrane.

Tonicity

Water moves into or out of cells depending on the tonicity of the solutions

●Isotonic solution has the same solute concentration as the intracellular fluid (No net movement)

●Hypotonic solution has a lower concentration of solute molecules compared to the intracellular

fluid (water moves into the cell)

●Hypertonic solution has a higher concentration of solute molecules compared to the

intracellular fluid (water moves out of the cell)

find more resources at oneclass.com

Unlock document

This preview shows half of the first page of the document.
Unlock all 2 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Hydrophobic nature of membranes restricts free movement of many molecules and substances essential for life. Passive transport: movement of a substance across a membrane without need to expend chemical energy such as atp. Diffusion: net movement of a substance from region of high concentration to lower concentration. Primary mechanism of solute movement within a cell and between cellular compartments separated by a membrane. Rate of diffusion depends on the concentration difference on two sides of membrane, or concentration gradient (a concentration gradient contains potential energy) The rate of diffusion is faster in a higher concentration gradient rather than low. Diffusion rates: the higher the temperature, the greater the diffusion rate. At a given temperature, smaller molecules diffuse faster. Two types of passive transport (simple and facilitated) Simple diffusion: passive transport of substances across lipid portion of membranes with their concentration gradients. Large or charged molecules may be strongly impeded from crossing membranes. Not every small or uncharged molecule is equal.

Related Questions

1 Which of the following statements is false?

(a) CO₂ and O₂ can diffuse freely across the cell membranes.

(b) The differences in permeability between artificial lipid bilayers and cell membranes arise from variations in phospholipid content.

(d) Cells expend energy in the form of ATP hydrolysis to maintain ion concentrations that differ from those found outside the cell.

2 Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell?

(a) Na⁺

(b) K⁺

(d) Cl^â

3 Pumps are transporters that are able to harness energy provided by other components in the cells and drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________.

(a) active transport.

(b) free diffusion.

(d) passive transport.

harlequinbuffalo618

1. predict the direction of water movement based on differences in solute concentrations. Use the terms osmotic pressure, hypotonic, isotonic, and hypertonic
2. Why do membranes have to be selectively permeable?

3. What determines whether a particular substance can diffuse (simple or facilitated) through a membrane?

4. What mechanisms drive molecules across membranes? Use the terms concentration gradient, (facilitated) diffusion and active transport.
5. Which parts of the plasma membrane proteins do you expect to be hydrophobic or hydrophilic? Justify your answer.
concise and short answers pls

A hypertonic solution has a higher level of solutes so the water moves out of the cells to the surroundings

A hypotonic solution has a higher level of solutes so the water moves out of the cells to the surroundings

The salt and water solution in the potato is a hypotonic solution

Osmosis is the movement of large molecules across a membrane which require embedded proteins

The plain water in this experiment is the solvent and the salt is the solute.

Passive transport requires no energy and the molecules move with the concentration gradient or from high concentration to low concentration

Active transport required no energy and the molecules move with the concentration gradient or from high concentration to low concentration.

The water on the inside of the potato with the salt molecules is an isotonic solution the same as the solution on the outside of the potato.

Water will not move by simple diffusion (osmosis) into or out of cells it requires energy or protein transporters

The solution of salt water in the potato has a lower concentration of water molecules so the water on the outside should move into the cells

BI110 Lecture Notes - Lecture 16: Sterol, Cholesterol, Active Transport

Document Summary

Get access

Related Documents

BI110 Chapter 18: Module 18

BI110 Lecture Notes - Lecture 14: Semipermeable Membrane, Lipid Bilayer, Osmosis

BI110 Chapter Notes - Chapter Module 18: Hydrostatics, Systematic Chaos, Water Potential

Related Questions