Hort 1001 Lecture 20

Front 1

Autotrophs

Back 1

Self-nourishing

(autos = self, trophe = nutrition)

Front 2

Plants are considered to be what?

Back 2

Autotrophs (Photoautotrophs)

Front 3

Why are plants photoautotrophs?

Back 3

They use the energy from light to produce organic molecules with which they build their cells and store energy

Front 4

Organic molecules

Back 4

Compounds associated with living organisms with carbon atoms.

Front 5

Inorganic compounds

Back 5

Lifeless minerals dug up from the ground

Front 6

Organic molecules that a plant produces must be (5 things)

Back 6

1. Storable in plant

2. Capable of being broken back down

3. Reasonable compact

4. Transportable

5. Stable and non-toxic

Front 7

Photosynthesis

Back 7

Photoautotrophs rely to capture that light energy and to produce carbon based organic molecules. The carbon comes from carbon dioxide in the atmosphere.

Front 8

Photosynthesis is said to "fix" carbon. What does this mean?

Back 8

To secure or sequester carbon

Front 9

Removal of carbon dioxide from the atmosphere by planting trees is a method of what?

Back 9

Carbon sequestration

Front 10

Carbon credits

Back 10

Industries that discharge CO2 purchase credits from organizations whose activities (like tree planting) sequester carbon.

Front 11

5 Characteristics of Light

Back 11

1. Travels in waves

2. Wavelength differs for each color

3. Within visible wavelengths, red is longest. Outside of visible wavelengths, infrared and radio are even longer

4. Shorter wavelengths (like blue) are not visible

5. Light has a particulate nature (photons)

Front 12

Photons

Back 12

Provide energy that drives photosynthesis

Front 13

Photosynthesis equation

Back 13

water + carbon dioxide -> oxygen, water and simple sugars

OR

12H20 + 6CO2 -> 6O2 + 6H2O + C6H12O6

Front 14

Glucose/Fructose formula

Back 14

C6H12O6

Front 15

Two reactions that make up photosythesis

Back 15

1. Light Reaction (LR)

2. Light Independent Reaction (LIR)

Front 16

Light Reaction (LR)

Back 16

Requires light - uses energy to split water which transforms energy from sun into hydrogen ions and electrons

Front 17

Light Independent Reaction (LIR)

Back 17

Does not require light - uses energy to grab carbon from CO2 and build simple sugars, second part of photosynthesis, takes place in stroma

LIR (Larry Intelligent Ramstad) is a kid that wants candy bars on a rainy day

Front 18

Two chlorophyll pigments that absorb light

Back 18

Chlorophyll a

Chlorophyll b

Front 19

True or False: High absorbance at a particular wavelength means that pigment is collecting those waves to harvest energy. Low absorbance means that the plant is reflecting that light back to us and we see that color.

Back 19

True

Front 20

High absorbance

Back 20

Pigment is collecting waves to harvest energy

Front 21

Low absorbance

Back 21

Plant is reflecting light back, we see it

Front 22

Chlorohpyll absorbs blue and red and reflect what color?

Back 22

Green

Front 23

Accessory Pigment example

Back 23

Carotenoids

Front 24

Carotenoids

Back 24

Assist chlorophyll in light capture and energy transfer and also contribute to regulation of excessive excitation of pigment molecules during intense sunlight.

Front 25

Carotenoids absorb/reflect what colors

Back 25

Absorb: Green

Reflect: red and yellow

Front 26

What type of cell in the leaf has the highest concentration of chloroplasts?

Back 26

Palisade mesophyll cells

Front 27

Stroma

Back 27

Interior of chloroplast

Front 28

Thylakoids

Back 28

Coin-like objects in the stroma

Front 29

Grana

Back 29

Stacks of Thylakoids

Front 30

Thylakoid membrane

Back 30

Surrounds thylakoids

Front 31

Antenna Complex

Back 31

Captures and routes energy from sunlight down to the reaction center (collector)

Front 32

What pigments are embedded in the thylakoid membranes?

Back 32

Cartinoid and xanthophyll pigments

Front 33

Thylakoid membranes are arranged in a structure known as what?

Back 33

Antenna complex

Front 34

True or False: When light hits a pigment molecule in the antenna complex, the energy from the light photon demotes (pushes down) an electron in one of the pigment's atoms to a lower orbital.

Back 34

FALSE: When light hits a pigment molecule in the antenna complex, the energy from the light photon promotes (pushes up) an electron in one of the pigment's atoms to a higher orbital.

Front 35

Resonance

Back 35

Released energy passed to another pigment molecule

Front 36

True or False: Electrons can stay in higher orbitals forever.

Back 36

False

Front 37

Splitting water

Back 37

Light reaction (light dependent reaction), first major chemical reaction in photosynthesis. Requires light.

Front 38

How is water split?

Back 38

When the reaction center grabs electrons from water, separating water into electrons, oxygen gas and hydrogen ions.

Front 39

Steps to photosynthesis

Back 39

1. Light captured by antenna complex

2. Electrons in chlorophyll jump to higher orbital

3. Electron drops back

4. Energy transferred to adjacent atom (resonance)

5. Resonance energy travels down antenna

6. Water is split to oxygen gas, electrons and hydrogen ions

Front 40

Layers of antenna complex

Back 40

1. Cartenoids

2. Chlorophyll b

3. Chlorophyll a

(then comes the reaction center)

Front 41

Light Reaction Portion of the Photosynthesis Equation

Back 41

12H2O -> 6O2 + 24e- + 24H+

Front 42

Where do Light Independent Reactions take place?

Back 42

In the stroma of the chloroplast

Front 43

In Light Independent Reactions, what compounds carry energy from light that was transformed into hydrogen ions and electrons?

Back 43

NADPH and ATP

Front 44

Calvin Cycle

Back 44

NADPH, ATP and carbon dioxide enter, energy is used to fix carbon into G3P.

Front 45

Calvin Cycle requires help from what protein? What does that protein even do?

Back 45

It requires rubisco, which catalyzes the step in the process where carbon is incorporated into an organic molecule.

Front 46

Rubisco is most abundant in what?

Back 46

Leaves

Front 47

True or False: Rubisco might just be the most abundant protein in the world.

Back 47

True

Front 48

G3P (triose phosphate)

Back 48

Produced by the carbon fixation process (Calvin Cycle), 3-carbon sugar with phosphorous and oxygen

Front 49

Why is sucrose important?

Back 49

It is the sugar that is transported by the phloem throughout the plant to provide energy for other organic molecules (like starch/cellulose)

Front 50

Light Independent Reaction portion of the Photosynthesis Equation

Back 50

24H+ + 24e- + 6CO2 -> C6H12O6 + 6H2O

Front 51

Source

Back 51

Regions of photosynthesis and sugar production

Front 52

True or False: Leaves are not the main source within the plant that is where most photosynthesis takes place.

Back 52

False! It is.

Front 53

Sinks

Back 53

Regions that do not support photosynthesis but still need organic molecules to survive (roots)

Front 54

Translocation

Back 54

Movement of solutes like sucrose from source to sink through the phloem

Front 55

Sucrose can be broken down into glucose and frucose. What can glucose and frucose then build?

Back 55

Useful organic compounds (starch and cellulose)

Front 56

Starch

Back 56

Key storage compound in plant cells

Front 57

Cellulose

Back 57

Main constituent of cell wall and structural integrity

Front 58

1,4 linkage

Back 58

Bonds between carbon #1 and carbon #4

Front 59

Big difference between starch and cellulose

Back 59

Alpha bond between glucose molecules results in starch

Beta bond between glucose molecules produces cellulose

Essentially, bond angle determines whether it will be starch or cellulose

Front 60

Humans cannot digest cellulose but can digest starch. Why?

Back 60

Because plants use starch for nutrient storage while they use cellulose for structure (it's the difference between eating potatoes and sawdust)