LAB 2

Question 1

MEMBRANE FUNCTION

1) Separation
2) Organization
3) Regulation

Answer 1

1) Separate cell contents from outside environment.
2) Organize chemicals and reactions into specific organelles in cell.
3) regulation of molecules into and out of cells.

Question 2

BETACYANIN

Answer 2

characteristic red pigment in beet cells. Located in cell’s large central vacuole surrounded by a membrane called Tonoplast. Beet cells itself is surrounded by plasma membrane.

Question 3

SPECTROPHOMETER

Answer 3

measures amount of Betacyanin that has leaked into solution from the beet cells.

Question 4

WHY DOES AN OBJECT APPEAR COLORED?

Answer 4

because it absorbs part of a visible spectrum and reflects or transmits other wavelengths.

Question 5

FLUID MOSAIC MODEL

Answer 5

Membrane that is fluid in structure which is held together by a variety of phospholipds.
In order to function well, membrane must be fluid.
Decrease in temperature, solidifies the membrane, phospholipids pack together, changing the permeability. An increase in temperature causes a change in permeability as the membrane becomes too fluid to support protein function. Largest amount of betacyanin release at very low and very high temperatures

Question 6

Chromataphore

Answer 6

absorbs light

Question 7

SPECTROPHOMETER

Answer 7

measure the absorbance of a chromatophore at the wavelength that it maximally absorbs. Or measure the wavelength of a series of wavelengths.

Question 8

SPECTROPHOMETER CAN BE USED FOR:

1) ABSORTION SPECTRUM
2) CONCENTRATION

Answer 8

1) graph that shows the amount of light that is absorbed at different wavelengths.
2) Conc. proportional to abs.

Question 9

PARTS OF A SPECTROPHOMETER

1) LIGHT SOURCE
2) PHOTOELECTRIC TUBE
3) INDICATOR SCALE

Answer 9

1) emits white light.
2) compares incident light to transmitted light.
3) readings from a spectrophometer is expressed on the Indicator scale.

Question 10

READINGS FROM A SPECTROPHOMETER IS EXPRESSED IN
1) TRANSMITTANCE (TOP)
2)ABSORBANCE(BOTTOM)
WE ALWAYS READ THE ABSORBANCE SCALE.

Answer 10

1) ratio of transmitted light to incident light. (%)
2) negative log of transmittance.
NO UNITS.
- specifies wavelength at which it absorbs.

Question 11

STANDARD CURVE LIMITATIONS

Answer 11

1) specific to the pigment and the buffer.
2) cannot be extrapolated for abs. beyond standard curve. needs to be DILUTED
3) calibrate abs. scale to BLANK (0.0). Blank= contains all components of sample except molecule of interest to ensure that spectrophometer only measures the molecule of interest and not the solvent or the media.

Question 12

TURBIDITY

Answer 12

particles in a suspension that SCATTER light.

Question 13

OPTICAL DENSITY

Answer 13

describes the amount of light absorbed or scattered.

ex: OD 600. Subscript= wavelength of light.

Question 14

STANDARD CURVE

Answer 14

graph that shows relationship between absorbance and concentration.
abs directly prop. to []

Question 15

STOCK SOLUTION

Answer 15

concentrated solution

Question 16

DILUTION

CONCENTRATION OF UNDILUTED

Answer 16

vol of original sol. / vol of O.S. + volume of solvent

[] of diluted sample/ Dilution

Question 17

FLUID MOSAIC MODEL

Answer 17

Fluid: membranes can move, things may pass through (selectively permeable)
Mosaic: membranes are composed of phospholipids, enzymes and proteins that act as channels.

Question 18

PHOSPHOLIPID BILAYER

Answer 18

• fatty acid bilayer
• hydrophobic ends of fatty acids attract each other to the inside of the membrane.
• hydrophilic ends are on the outside of membrane in the water, creating double layer of fatty acids.