Plant Pigments Flashcards

1
Q

what are pigments? what does there presence allow?

A

pigment are organic molecules that have colour

-their presence allows organisms to be colourful

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2
Q

what are the two possibilities that a flower may appear purple? how can we distinguish between them?

A
  1. the petals produce a purple pigment
  2. the petal produces both a red pigment and a blue pigment, which when combined appear purple

-if we can separate the mixture of pigments into their individual components –> ie. Chromatography

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3
Q

what was the technique used to separate pigments in this experiment? how does it separate pigments?

A

thin layer chromatography - TLC

-separates pigments based on their level of polarity

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4
Q

what are polar molecules, what kinds of bonds can they make? non-polar molecules, what kinds of bonds can they make?

A

polar molecules are molecules made up of atoms of differing electronegativity, meaning they share their electrons unequally causing a slight charge –> meaning these molecules can form hydrogen bonds

-non-polar molecules are molecules made up of atoms of the same electronegativity, meaning they share their electrons equally and do not carry a charge –> meaning these molecules do not form hydrogen bonds

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5
Q

what is the property of adhesion? which molecules have this property? what is adsorption?

A
  • meaning they will stick to other molecules
  • occurs in polar molecules –> ie will stick to other polar molecules
  • adsorption is the tendency of a substance to stick to a surface
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6
Q

how does thin layer chromatography work?

A

a mixture of molecules are applied to one spot on a solid support (the slide) which is coated with a thin polar surface layer

  • then the slide is placed in a non-polar solvent which will move by capillary action up the slide
  • the molecules mixture will dissolve in the solvent and as it moves upwards, it will pull pigments with it
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7
Q

what is the thin polar layer used in this experiment? why does it work?

A

silica
-it works because is has hydroxyl groups (which are polar) and can form hydrogen bonds with polar regions on other molecules

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8
Q

what is the solvent called that the polar slide is placed into?

A

-the developing solvent

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9
Q

which pigments move the most? the least?

A

nonpolar pigments easily dissolve in the nonpolar solvent and are carried up the slide
-polar pigments stick to the silica and either move slowly or don’t move at all

  • the more non-polar a pigment is, the farther it moves up slide (ie. no polar groups)
  • the more polar a a pigment is, the more likely it is not to move (ie. has the most polar groups)
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10
Q

what are the 2 major polar groups that we are looking for in the pigments in this experiment? which is more polar

A
  1. hydroxyl group (-OH) - more polar

2. carbonyl group (C=O)

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11
Q

what is silica in this experiment? what is the developing solvent?

A

silica –> stationary phase (does not move)

developing solvent –> mobile phase (moves)

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12
Q

where are pigments in leaves/petals located? what is their function?

A

in thykaloid membranes of chloroplasts

-function in the light reactions of photosynthesis

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13
Q

what is the primary pigment molecule in light reactions? where is it located? what are accessory pigments? where are they located? what do accessory pigments do?

A
  • chlorophyll a, located in reaction center of PSI and PSII
  • chlorophyll b, carotenes, and xanthophylls, located outside of reaction centers
  • accessory pigments absorb additional wavelengths of lights and transfer this energy to chlorophyll a –> increase efficiency of photosynthesis and make it possible to use a greater range of wavelengths
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14
Q

what do non-photosynthetic pigments contribute? what are they, where are they located? what are examples of these?

A
  • contribute to colours of flowers/fruits/leaves/stems/roots
  • they are water soluble compounds –> located dissolved in the fluid of vacuoles
  • anthocyanins, anthoxanthins
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15
Q

what needed to be added to the plants ass they were being crushed? why?

A
  • an extracting solvent

- it dissolved the pigments when they were extracted from the leaves

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16
Q

of the 5 pigments molecules observed in this lab:

  1. what were they?
  2. how many polar groups did they contain?
  3. what colour are they?
A
  1. anthocyanin - purple - 7 polar groups
  2. carotene - yellow - 0 polar groups
  3. chlorophyll a - green - 5 polar groups
  4. chlorophyll b - green - 6 polar groups
  5. xanthophyll - yellow - 2 polar groups
17
Q

which 2 plants were used in this? which accessory pigments where found in these?

A
spinach --> Spinacia oleracea
-carotene
-chlorophyll b
-xanthophyll
Tradescantia sp.
18
Q

why were you unable to see each of the individual pigments in the original spinach leaves?

A

-because all the pigments are on a yellow/green/blueish-green scale, so when mixed together, they produce a green pigment