01:119:131 Lecture Notes - Lecture 4: Atp Synthase, Tonicity, Endocytosis

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9 Dec 2016

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Osmosis: the diffusion of water from an area of high water concentration to an area of low water concentration. Does not utilize energy bc energetically favorable to do so. Water will always go from most concentrated to least concentrated. 100% pure water to the 1% sugar solution. Experiments that examine the effects of tonicity on osmosis (fig 4. 31) Dont have organisms growing in pure water. Hypotonic solution: concentration of water is higher outside the cell. Water is going outside of cell, shrivel up, and die. High salt or sugar content is keeping food from being contaminated with organisms (means of preservation) Active transport: carrier protein molecules aid in movement of molecules against a concentration gradient. Forcing something to go against the concentration gradient. Isotonic is the environment (salt concentration equivalent to what they are in cytoplasm) Our macrophages recognize foreign material like bacterium; literally engulfs bacterium and wrap membrane around whole organisms and pinches off into vacuole.

Related Questions

True or False: The solution of salt water inside of the hollowpotato has a lower concentration of water molecules so the water onthe outside of the potato should move into the potato cells. Or thewater molecules inside of the grape or pea will move to the outsidewhere there are fewer water molecules and more salt.

True or False: The water on the inside of the potato with thesalt molecules is an isotonic solution the same as the solution onthe outside of the potato.

True or False: Water will not move by simple diffusion (osmosis)into or out of cells it requires energy or proteintransporters.

T or F The salt and water solution inside of the hollow potatois a hypotonic solution.

T or F: Osmosis is the movement of large molecules across a semipermeable membrane which require embedded proteins.

T or F The plain water in this experiment is the solvent and thesalt is the solute.

T or F Active transport requires no energy and the moleculesmove with the concentration gradient from low concentration to ahigh concentration.

T/F Passive transport requires no energy and the molecules movewith the concentration gradient or from high concentration to lowconcentration

T/F A hypotonic solution has a higher level of solutes so thewater moves out of the cells to the surroundings.

T/F A hypertonic solution has a higher level of solutes so thewater moves out of the cells to the surroundings.

Why does a slug die when you put salt on her/him? (Think aboutwhat happened in this lab) :

A. The salt on the outside of the slug causes the water frominside of the cells to move out of the cells. The dehydration ofthe slug causes death

B. The slug does not die but becomes enlarged from the movementof water into the slug cells caused by a hypertonic solution

C. The salt and moisture on the outside of the slug cause anisotonic state and the water leaves the slug quickly byosmosis.

D. Sigh. The poor slug, sacrificed for science by many youngnature lovers around the world. Obviously this happens as theoutside solution is hypotonic and the inside of the slug's cellsare hypertonic. Energy is used for active transport leading toosmosis.

lemonbeetle571

Cell Membranes Lab Report

Diffusion

Compare the following terms: solvent, solute, andsolution.

Go to Lab, Section I, Exercise 1 to explore the factorsinfluencing the rate of diffusion and complete the following:

Predict how molecular mass and temperature may affect theoutcome of this experiment.

Record the data from information in the Lab in the tablebelow.

Time (min)	Diameter (mm)
Time (min)	5Â°C MB	5Â°C PP	23Â°CMB	23Â°C PP
0
15
30
45

Construct a line graph of the data from the table above. Yourgraph should include labeled axes, units, and a legend indicatingwhich treatment is presented. Sign, date and prepare an image ofyour graph and include it with this lab report.

Osmosis

Go to Lab, Section II, Exercise 2 to view a demonstration ofosmosis and answer the following questions:

Describe the net movement of water in osmometer 1.

How is the movement of water molecules related to theconcentration gradient of the solution?

Go to Lab, Section II, Exercise 3 to observe the effect ofsolute concentration on the rate of osmosis. Answer the followingquestions:

Was the net movement of water in bags 1 to 4 into or out of thebags?

Explain the results from bags 4 and 5.

Selective Permeability of Membranes

Go to Lab, Section III, Exercise 4 to learn about theimportance of selectively permeable membranes, then complete thetable and answer the following questions:

	Contents of Beaker
	0 Min	30 Min
Starch
Chloride ion

Which substances diffused through the dialysis membrane?

How does dialysis tubing model the selective permeability of aplasma membrane?

Tonicity

Go to Lab, Section IV, Exercise 5 and 6 to observe plasmolysisin Elodea cells and tonicity in red blood cells. Summarizethe concept of tonicity using blood and Elodea cells asexamples. Your description should incorporate these terms: turgid,plasmolysis, hemolysis, and crenation.

Cells	Isotonic Solution	Hypertonic Solution	Hypotonic Solution
Elodea
RBC

Based on your previous work, reproduce the table below and drawan illustration of a single cell in each box. Include arrows toshow the direction of water flow relative to each cell and dots tosymbolize solutes. Sign, date and prepare an image of your drawingand include it with this lab report.

Cells	Isotonic Solution	Hypertonic Solution	Hypotonic Solution
Elodea
RBC

Summary Questions

Compare diffusion and osmosis. Give an example of each.

2. In which direction will osmosisoccur if a 15% sugar solution is separated from a 25% sugarsolution by a selectively permeable membrane?

3. Why did osmosis, but not diffusionof sucrose molecules, occur across the dialysis membrane containing20% sucrose solution?

4. You are having a party and thecelery is limp. What might you do to make the celery crisp (turgid)again? What will occur in the cells?

5. A small amount of fertilizer(mineral salts) will stimulate plant growth, but over fertilizationcan kill plants? Why?

6. Michael adds sugar to his coffee.Explain what in this drink is the solvent, solute, and solution.

7. You add a cube of sugar to yourdrink. How could you speed up the diffusion of sugar moleculeswithout stirring?

8. How is dynamic equilibriumestablished within a solution?

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01:119:131 Lecture Notes - Lecture 4: Atp Synthase, Tonicity, Endocytosis

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