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Botany > Test 3 > Flashcards

Test 3 Flashcards

1
Q

Photosynthesis

A
  • Series of energy conversion reactions (solar energy into usable form)
  • Plant use visible light for photosynthesis
  • Occurs in the chloroplast
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2
Q

Photon

A

Unit of the electromagnetic spectrum for photosynthesis

-Packet of energy that travels in waves and measured in wavelengths

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3
Q 
Radio wave (long wavelength) 
Gamma rays (short wavelength)
A
  • Shorter wavelength = higher energy
  • Higher wavelength = lower energy
  • VIsible light: (380-760)
  • Violet (short wave) - red (long wave)
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4
Q

Chloroplast

A
  • outer/inner membrane then thylakoid membrane

- lipid bilayer

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5
Q

Granum

A

Stacked thylakoids

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6
Q

Free thylakoids

A

Thylakoids floating in the stroma

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7
Q

Lumen

A

Inside the thylakoid membrane

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8
Q

Stroma

A

Outside the thylakoids membrane; aqueous matrix

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9
Q

Light reactions

A
  • Energy conversions
  • First steps to occur in photosynthesis
  • Occur on thylakoid membrane
  • e transport chain
  • light energy (photons) -> chemical energy (ATP, NADPH)
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10
Q

Calvin-Benson cycle

A
  • Second step to occur in photosynthesis
  • Occur in stroma
  • CO2 (PE low) -> Carbs/sugar (PE high) energy requirement, from light rxs (ATP, NADPH)
  • E input (from light rxn): ATP, NADPH
  • E output; ADP, NADP+
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11
Q

Pigments (hydrophobic)

A
  • Embedded in thylakoid membrane in chloroplasts.
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12
Q

Chloroplasts

A
  • Chl A and B ( used on land plants only)
  • Carotenoids ( accessory pigments): yellow, red, orange pigments
  • These pigments are anchored in specific structures called photosystems (PS II and I)
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13
Q

Photosystems (II and I)

A
  • Pigment protein complexed that harvest light inside the thylakoid membrane
  • Majority happens in the attena complex
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14
Q

Attena complex

A

Contain accessory pigments, carotenoids, chlorophyll B

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15
Q

Reaction center

A

Contains 2 chlorophyll A molecules that can donate e for the e transport chain

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16
Q

Steps in light/electron harvesting for photosystems

A
  1. Sunlight strikes electron and excites it
  2. Electron then jumps up to another energy level (pinball)
  3. e fall back to ground state and excite the accessory pigments located in the antenna complex
  4. They will then illuminate the e and keep passing e until they reach the reaction center that contain the chl A e
    - The chl A will start redox reactions and donate e to an e receptor
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17
Q

Plastoquinone

A
  • e- delivery guy
  • located inside the lipid bilayer
  • picks up charged e
18
Q

Plastocyanin

A

e shuttle in lumen and replenishes e- for PS1

19
Q

Lumen

A
  • Has a high proton concentration

- stroma has a low proton concentration

20
Q

Electron transport chain (light reaction steps)

PHS II

A
  1. Light strikes an energy, exciting it. It bumps into another e- and pinball reaction until it reaches chlorophyll A in reaction center
  2. Photochemistry occurs; an e- will be taken off of EACH of the chlorophyll molecules. This is an oxidation rxn. At the same time, reduction is occurring from the Plastoquinone accepting the donated e-.
    a. (the plastoquinone is (+) charged, it must neutralize the 2- charged e- it picked up. It does this through grabbing 2 (+) charged protons floating in the membrane from the stroma side and bringing it to the lumen side (proton pump in form of PE)
    b. The oxygen evolving complex (replenishes e- for reaction center in PS II and is what allows oxygen to be released into the environment) splits H2O
    H2O O2 + 2H+ (oxygen is halved); e- from breaking these bonds gets passed to rxn center
  3. After neutralization, the e- gets an H+ and gets transported to the cytochrome. The cytochrome dumps off the extra proton back into the membrane. The H+ are being moved against their concentration gradient from a concentration of highlow (stromalumen), so energy must be inputted
21
Q

PHS I (Linear e flow; light energy (photons -> NADPH)

A
  1. The electrons then get excited through the same procedure from steps 1-3 and ends up at reaction center with 2 chlorophyll A e- and donated to acceptor molecule, the ferredoxin
    a. The “dead” e- (low PE) and must be recharged. The e- in plastocyanin are shuttled to reaction center to be reenergized
  2. ferredoxin interacts with ferredoxin NADP+ reductase. Ferredoxin gives e- to reduce NADP+ to make NADPH (redox reaction)
    Not part of electron transport chain because no redox reactions taking place:
  3. ATP synthetase (diffusion): H+ will diffuse through and turn the “catalytic knob” to transfer ADP+ + Pi ATP (phosphorylation) using kinetic energy
    CYCLIC E- FLOW: involves PS1 and Cytochrome
  4. PS I get excited by light and donates e- to ferredoxin. Ferredoxin reacts with the cytochrome (proton pump) use up all energy so to regenerate energy it goes to plastocyanin who give it back to PS I (rxn center)
    a. Used to move proton for a higher proton gradient
22
Q

Cyclic e flow; involves PS1 and cytochrome

A
  1. PS I get excited by light and donates e- to ferredoxin. Ferredoxin reacts with the cytochrome (proton pump) use up all energy so to regenerate energy it goes to plastocyanin who give it back to PS I (rxn center)
    a. Used to move proton for a higher proton gradient
23
Q

Calvin-Benson Cycle

A
  • Occurs in stroma
  • Convert inorganic C (CO2) -> organic form (sugar) (c fixation)
  • CO2 (PE low) -> carbs/sugar (PE high) energy req from light reactions (ATP, NADPH)
  • Energy input: ATP, NADPH
  • Energy output : ADP, NADP
  • Product (3-C sugar) Glyceraldehyde-3-phosphate
    3 phases:
    1. Carbon fixation (CO2-> organic C)
    2. Carbon reduction (converting C into higher energy form)
    3. Regeneration
24
Q

Photorespiration

A
  • Occurs when oxygen levels increase and CO2 levels decrease
  • Recycling of photoglycolate made form oxygenase (RUBP + O2)
  • Requires energy
  • O2 is released and CO2 is consumed ( when stomata is closed, it prevents O2 release
  • Found in. hot temps (tropics) and arid conditions (desert/tundra)
25
Q

Alternate photosynthesis:

A

a. PEP carboxylase: both C4 and CAM plants use this for carbon fixation
i. sticks CO2 onto PEP compounds (PEP = phosphoenol pyruvate)
ii. PEP (3C) + CO2 (1C) -> oxaloacetate (4C) -> malate (4c)
1. The malate can be decarboxylated (released CO2) back into PEP

26
Q

C4 plants (monocots)

A

a. Tropic plants only in calvin cycle
b. Big cells are bundle sheath cells next to veins (kranz anatomy)
i. spatial separation of C fixation
c. PEP carboxylase (PEP +CO2 -> malate) malate and CO2 diffuse into the bundle sheath cells (increases the CO2 concentration) and the CO2 is released into the Calvin-Benson Cycle

27
Q

CAM plants

A

a. arid plants
b. can decided what photosynthesis to undergo (C4 or C3)
c. close stomata in daytime and open in nighttime
i. temporal separation of C fixation
d. Night: PEP +CO2 -> malate -> malic acid (stored in vacuole)
e. Day: malic acid (decarboxylated) -> malate (releases CO2), CO2 goes to fuel Calvin Benson cycle

28
Q

Water transport

A

Water transport happens in the xylem tissue from root to shoot
- Xylem tissue composed of xylem fibers (dead; structure) and xylem parenchyma (alive; storage). Vessel elements (wide/short/open walls) and tracheids (long/narrow/tapered walls) are responsible for conducting water and minerals apoplectically (outside) throughout the cell and both are dead at maturity

29
Q

Rates translocation in the xylem

A
  • Moving lot of water long distances
  • Passive process and requires no energy for the plant
  • 120-15K cm/hour (vines)
  • 40L gallons/year (oak tree)
30
Q

Tension cohesion model

A

Pulling of water through the xylem and can only work because of the tension between the hydrogen bonds in water

  • Water movement in the xylem is unidirectional root to shoot
  • Soil water moves through the roots, up through the xylem, into the leaves, and out through stomata into the atmosphere
  • Xylem is the drinking straw, drink is the water in the sale, and the person drinking is the atmosphere
  • Passive process that doesn’t require energy input
  • 96% of water that moves through a plant is lost into the atmosphere through transpiration
  • water is a limiting source
31
Q

Embolism

A

Air bubble that forms in the xylem (breaking the water column)

32
Q

Stomata

A
  • Pair of guard cells that regulates gas exchange and transpiration of water out of the leaves. Pressure determines the shape of the cell
  • Inner portion: cellulose is laid down very thick and ridged
  • Outer part: cellulose is laid down very lose and stretchy
33
Q

Open state:

A

Higher pressure inside the cells. Need water to move in to increase turgid pressure. Potassium concentration is high inside the cell; K moves into the cell and makes the cell bend

34
Q

Closed state:

A

Lower pressure inside the cells. Need water to move out to decrease turgid pressure. Potassium concentration is low outside the cell; K is exported of the cell and makes the cells collapse on each other

35
Q

Monocot guard cells

A

Open: Cellulose is thick around middle portion; the outside is stretchy; outside swells and middle does not when you increase the turgid pressure in the plant.
Closed: inside is ridged, outside is stretchy. When water rushes in the cell, the outside swell and push two cells apart

36
Q

Mineral nutrient

A

Associated with xylem transport because minerals are being transported long distance throughout the plant in the xylem.
Essential elements: 19 elements that plants need:
- 3 that do not come from the soil is the carbon, oxygen, hydrogen
- they come from water and CO2
The other 16 come from the soil

37
Q

Macronutrients

A
  • Needed in large increments
    1. C, H, O ( needed for everything )
    2. N - need for making proteins, chl, nucleic acids
    P- need for making nucleic acids, ATP, and phospholipids K- needed for osmotic balance and stomatic functioning
    S- need for making amino acids
    Ca- need for making middle lamella
    Mg-need for making chl
    Si- need for cell wall strength
38
Q

Micronutrients

A
  • needed in small increments
    1. Chlorine, Boron, Molybdenum
    2. Iron, Manganese, Sodium
    3. Copper, Zinc, Nickle (needed for enzyme cofactors
39
Q

Minerals from the soil

A

o Typically, in an ionized form and small.
o Roots are responsible for taking up materials in soil
 Need transport proteins in the root that will take up one ion (phosphate, nitrate, calcium, etc.) to the xylem
o Plants provide minerals to humans
o Nitrogen, Potassium, and Phosphorus are limiting resources for plants
 The nitrogen in the atmosphere is not accessible by plants because of the triple bonds in nitrogen’s are too strong to break and use (N2)
 Haber-Bosch: came up with chemical reaction to convert molecular N2 to organic N2 (ammonia) (N2 —-natural gas—> ammonia)
• Have to burn natural gas to convert it to ammonia. CO2 is the biproduct.
• Farmers apply extra fertilizer which runs off into the watershed which initiates algal bloom 

40
Q

Phytoremediation

A

o (“phyto” = plant, “remediation”= cleanup of toxic soil in an environment)
o Plants cleaning up soil that is toxic to the environment
 Hyperaccumulator plants: developed the ability to live in toxic environments and clean them up.
• Cadmium (Cd), Lead (Pb), Zinc (Zn), Selenium (Se) toxic in large quantiles; these hyperaccumulator plants will take up these elements and bind them in their cells to neutralize these and suck the bad elements out of the soil.

41
Q

Phloem transport

A

• Carbohydrate transportation (starch) moves (multidirectional) from “source to sink” or immature leaves to mature leaves (shoot to root) (high carb concentration  low)
o “source” is where carbohydrates are made available in excess amounts (high carbohydrate concentration). The main source organs in plants are the mature leaves
o Sink organs are where carbohydrates are not made available in high amounts (low carbohydrate concentration). The main sink organs in plants are (main) immature leaves, with the roots, flowers, SAM/RAM
 Root function is carbohydrate storage. If herbivore eats leaves off the plant, immature leaves lose their source of carbohydrate and the roots will convert from a sink to a source and begin exporting carbohydrates up to the growing shoot tip.
• Phloem tissue contains the phloem parenchyma (storage), phloem fibers (support), sieve tube members (conducting water/minerals long distance) and their companion cells (alive, metabolic functioning for STM)
• Phloem moves carbohydrates (sucrose) throughout the cell
o Sucrose is an inert sugar (doesn’t react). Sucrose is a disaccharide (small) made up of fructose and glucose together.
• The minerals/water can move through the phloem in many directions. The movement is going to be symplastic (inside). Move from source to sink and pusing the minerals up to SAM and down to RAM (positive pressure, low pressure) that results in bulk flow. (“squeezing the end of toothpaste to the top”)
o This is not a passive process it requires energy!

Botany (4 decks)

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