beet cells & stress

Topics: Cell membrane, Cell, Vacuole Pages: 17 (1248 words) Published: April 20, 2014

 

Anatomy Physiology 1

 

Report 1

 

April 6, 2014

 

Abstract

 

 Uncharged molecules can diffuse across cell membranes while some substances

 

must be transported across the membrane by proteins. The membrane is in control of

 

what enters and leaves the cell. However, certain conditions may damage the cell

 

membrane’s structure. Beet cells, which are plant cells, have a water-soluble pigment

 

called betacyanin, which is stored in its vacuole. The tonoplast, or the vacuole’s

 

membrane, acts with the cell membrane of the cell to prevent the betacyanin from leaking

 

into the cytosol or out of the cell. This lab investigates the environmental possibilities

 

that can damage membranes. Hypertonic and hypotonic salt solutions place stress on cell

 

membranes, detergents make lipids more water-soluble and disrupt membranes, and

 

acidic and basic pH’s denature proteins and change the color of the betacyanin. The

 

spectrophotometer will record the absorbance of the betacyanin leakage. The more

 

betacyanin leakage the more the solution will absorb light. Membrane damage increases

 

as the solution gets treated with higher pH and salt concentrations. The experiment

 

supported our hypothesis since higher levels of pH and salt concentrations resulted in an

 

increased release of betacyanin.

 

 

 

 

 

Intro

  

 Cell membranes are functionally important because they separate and organize

 

chemicals and reactions within cells by allowing selective passage of materials across

 

their boundaries. Cell membranes are selectively permeable. The cell membrane has a

 

phospholipid layer, with the polar, hydrophilic heads pointing out at the extracellular and

 

intracellular aqueous environment and the nonpolar, hydrophobic heads pointing inward,

 

protected from the water. Membranes surround both cells themselves as well as the

 

organelles within cells.  For example, vacuoles are surrounded by a vacuolar membrane

 

called the tonoplast.  The plasma surrounds the entire cell membrane. Charged molecules

 

can only cross the membrane with help via carrier proteins and pumps. These ionic

 

compounds need energy through active or passive transports or a concentration gradient

 

to get across the membrane.

 

 Many reasons can cause the damage of cell membranes, which include

 

concentration gradients, pH, and detergent. Beta vulgaris or the roots of beet, carry large

 

amounts of water-soluble reddish pigment called betacyanin. It is located almost entirely

 

in the large central vacuoles of cells. In intact, undamaged cells, betacyanin remains

 

inside the vacuole, not being able to pass through the tonoplast. Sources of stress can

 

cause betacyanin to leak through both the tonoplast and plasma membrane.  This leakage

 

will produce a red color in the water surrounding the stressed beet cells.  The amount of

 

leakage can be related to the degree of membrane damage.

 

 The stress agents each have its role in damaging the cell membrane and allowing

 

the red pigment to leak out. Hypertonic and hypotonic salt solutions place stress on cell

 

membranes. As the salt percentage increases in the solution making it hypertonic the cell

 

shrivels damaging its membrane. As the salt concentrations decrease in the solution

 

making it hypotonic, the cell expands and explodes damaging the membrane. Different

 

pH levels also damage cell membranes. Higher acidity will result in denaturing

 

membranes. Even detergent being a basic solution will disrupt the function of the cell

 

membrane changing the reddish color of betacyanin as well. As a result the degree of

 

damage can be directly related to the intensity of...


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