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Brianna's Bio 111 > Chapter 8 > Flashcards

Chapter 8 Flashcards

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Biology 101 flashcards
1
Q

Chlorophyll

A

pigment that gives plants the green color

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2
Q

photosynthesis

A

energy from light is captured and used to synthesize glucose and other organic molecules

CO2 + H2O + light energy → C6H12O6 + O2 + H2O

  • CO2 is reduced
  • H2O is oxidized
  • Energy from light drives this endergonic reaction
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3
Q

light reactions

A

Stage 1 of Photosynthesis:
-light energy is absorbed by chlorophyll and converted to chemical energy in the form of two energy intermediates: ATP and NADPH.

  • requires light
  • produces ATP, NADPH and O2
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4
Q

Photosynthesis powers the biosphere

A
  • Regions on the surface of the Earth and in the atmosphere where living organisms exist
  • Largely driven by the photosynthetic power of green plants
  • Cycle where cells use organic molecules for energy and plants replenish those molecules using photosynthesis
    - Plants also produce oxygen
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5
Q

Calvin Cycle

A

Stage 2 of Photosynthesis:
ATP and NADPH are used to drive the synthesis of carbohydrates

  • no requirement for light
  • fixes CO2 into an organic molecule
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6
Q

Biosphere

A

the regions on the surface of the earth and in the atmosphere where living organisms exist.

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7
Q

Heterotrophs

A

must consume food- organic molecules from their environment- to sustain life
-most species of bacteria, protist, fungi and
animals

Heterotrophs are the Consumers of the environment

  • Heterotroph - other feeding
  • Require complex organic molecules from other organsims.
  • Decomposers - live on “organic litter”
    • a nice way to say - decaying animal or plant matter
      • carcasses, feces, other debris (plant or animal)
  • Everything not an autotroph, IS a heterotroph
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8
Q

Autotrophs

A

sustain themselves by producing organic molecules from inorganic sources such as CO2 and H2O

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9
Q

Photoautotrophs

A

they are autotrophs that use lift as a source of energy to make organic molecules

-including green plants, algae, and some bacterial species such as cyanobacteria

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10
Q

Autotrophs are the Producers of the environment

A
  • Autotroph - self feeding
  • Require only raw materials (water, minerals and a carbon source) to make their own food
  • Photoautotrophs
  • Green plants, algae, cyanobacteria
  • They need only water, minerals and CO2 + light
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11
Q

Plants FIX CO2

A
  • Plants use light energy to synthesize complex organic molecules
  • HOW???
  • By FIXing the gas CO2 into sugar molecules
    - Start with 1C molecule and make 6C molecules
  • The process of Photosynthesis
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12
Q

Green tissue is Photosynthetic

A
  • Photosynthesis occurs in the green parts of plants, leaves, stems etc.
  • Inside cells, inside the chloroplasts, in the thylakoid membranes
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13
Q

Chloroplast

A

-Organelles in plants and algae that carry out photosynthesis

  • Chlorophyll- green pigment protein
  • Majority of photosynthesis occurs in leaves in mesophyll

-Stomata- carbon dioxide enters and oxygen exits leaf

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14
Q

Chloroplast Anatomy

A
  • Outer and inner membrane
    • Intermembrane space
  • 3rd membrane - thylakoid membrane contains pigment molecules
    • Forms thylakoids
    • Enclose thylakoid lumen
  • Granum- stack of thylakoids
  • Stroma- fluid filled region between thylakoid membrane and inner membrane
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15
Q

Mesophyll

A
  • tissue in the internal part of the leaf
  • contains cells with chloroplast
  • for photosynthesis to occur, the cell must obtain water and carbon dioxide
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16
Q

thylakoid membrane

A
  • contains pigment molecules, including chlorophyll

- forms thylakoids

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17
Q

thylakoids

A
  • flattened, fluid filled tubules

- encloses thylakoid lumen

18
Q

thylakoid lumen

A

a single, convoluted compartment

19
Q

granum

A

formed when thylakoids stack on top of each other

20
Q

stroma

A

fluid-filled region of the chloroplast between the thylakoid membrane and the inner membrane

21
Q

Light Reactions

A
  • in the Thylakoid membranes
  • Take place only when light is present
  • Split water to form ATP, NADPH, and O2
22
Q

Dark Reactions (Calvin Cycle)

A
  • in the Stroma
  • Can take place with or without light being present
  • Takes ATP and NADPH from light reactions + CO2 to make sugar (CH2O)
23
Q

Light as a wave

A
  • Electromagnetic Energy, radiation
  • Travels in waves
    - similar to what you see if you drop a rock into a pond
  • The distance between the tops of the waves = wavelength
  • The wavelengths can vary enormously
    - 1 nanometer - 1 kilometer
  • Visible light has wavelengths from 350nm- 750nm!
    - ROY G BIV
24
Q

Light as a particle

A
  • But light also behaves as a particle
    - Called photons
  • Photons act like particles, but aren’t
  • Each photon has a fixed quantity of energy
  • The amount of energy in a photon is inversely proportional to its wavelength.
    • The shorter the wavelength, the more energy
    • Violet photons have 2x the energy of red photons
25
Q

wavelength

A

distance between the peaks in a wave pattern

26
Q

electromagnetic spectrum

A

encompasses all possible wavelengths of electromagnetic radiation, from relatively short wavelengths

27
Q

photons

A

massless particles traveling in a wavelike pattern and moving at the speed of light

28
Q

Light receptors

A
  • When light hits matter it can be
    • Reflected
    • Absorbed
    • Refracted
  • Chlorophyll absorbs red and blue light
    • Electrons are EXCITED!
  • But it reflects green light
    - So leaves look green
  • The color of an object is dependent on absorption and reflection
29
Q

pigment

A

a molecule that can absorb light energy

-ex: leaves looking green because of radiant light reflection

30
Q

It’s about electrons

A
  • Photosynthetic pigments absorb some light energy and reflect others
  • Absorption boosts electrons to higher energy levels
  • Wavelength of light that a pigment absorbs depends on the amount of energy needed to boost an electron to a higher orbitalAfter an electron absorbs energy, it is in an excited state and usually unstable
  • Releases energy as
    • Heat
    • Light
  • Excited electrons in pigments can be transferred to another molecule or “captured”
  • Captured light energy can be transferred to other molecules to ultimately produce energy intermediates for cellular work
31
Q

Photosynthetic Pigments

A

-Chlorophyll a and accessory pigments are the big players in absorbing light and getting the light reactions started - blue green in color

-One of the accessory pigments is Chlorophyll b (almost identical to chlorophyll a) - yellow green in color
other accessory pigments are carotenoids - yellow orange (carrots!)
-often are photoprotective

32
Q

carotenoids

A
  • another type of pigment found in chloroplasts
  • color ranges from yellow to orange to red
  • found in flowers and fruits
33
Q

Absorption

A
  • wavelengths that are absorbed by different pigments in the plant
  • absorption spectrum is a graph that plots a pigment’s light absorption as a function of wavelengths
34
Q

action spectrum

A

-rate of photosynthesis by a whole plant at specific wavelengths

35
Q

Photoexcitation of Chlorophyll

A
  • A photon can be absorbed only if its energy is exactly the same as the energy it takes for the e- to go from ground state to excited state
  • Electrons that are in an excited state have lots of potential energy and are unstable
  • The electrons have a tendency to emit the absorbed energy or transmit the energy to something else
  • If the electrons don’t have something to pass the energy off to . . .
    - The energy will be emitted as light (fluorescence) and heat
    - This is FAST 0.000000001 seconds
36
Q

Chlorophyll in a Thylakoid Membrane

A
  • Chlorophyll in a thylakoid membrane is organized along with proteins and other organic molecules into photosystems
  • They have antenna complexes that gather the light and pass it along to the reaction center
    • a particular chlorophyll a molecule
    • where the first light-driven reaction of photosynthesis starts
  • The reaction center chlorophyll a passes an electron in the excited state to
  • The primary electron acceptor accepts the excited electron
  • This is a redox reaction
    - the chlorophyll a looses an electron to the primary acceptor
  • By trapping the excited electron, primary electron acceptor prevents the rapid decay of the excited state electron to ground state
37
Q

Photosystems

A
  • Thylakoid membrane
    • Photosystem I (PSI)
    • Photosystem II (PSII)
38
Q

Photosystem II

A
  • 2 main components
    • Light-harvesting complex or antenna complex
      • Directly absorbs photons
      • Energy transferred via resonance energy transfer
  • 2 main components
    • Reaction center
      • A redox machine
      • P680 →P680*
      • Relatively unstable
      • Transferred to primary electron acceptor
      • Removes electrons from water to replace oxidized P680
      • Oxidation of water yields oxygen gas
  • Light excites pigment molecules in PSII and PSI
    • PSII - excited electrons travel to PSI
      • Water is oxidized- generates O2 and H+
      • Releases energy in electron transport chain
      • Energy used to make H+ electrochemical gradient
    • PSI – primary role to make NADPH
      - Addition of H+ to NADP contributes to H+ electrochemical gradient
39
Q

Photosystem I (PSI)

A
  • Key role to make NADPH
  • Light striking light-harvesting complex of PSI transfers energy to a reaction center
  • High energy electron removed from P700 and transferred to a primary electron acceptor
  • NADP+ reductase
    • NADP+ + 2 electrons + H + → NADPH
  • P700+ replaces its electrons from the ETC (plastocyanin)
    • No splitting water, no oxygen gas formed
  • ATP synthesis
    • Chemiosmotic mechanism
    • Driven by flow of H+ from thylakoid lumen into stroma via ATP synthase
  • H+ gradient generated by
    • ↑H+ in thylakoid lumen by splitting of water
    • ↑H+ by ETC pumping H+ into lumen
    • ↓H + from formation of NADPH in stroma
40
Q

Summary

A
  1. O2 produced in thylakoid lumen by oxidation of H2O by PSII
    • 2 electrons transferred to P680+
  2. NADPH produced in the stroma from high-energy electrons that start in PSII and boosted in PSI
    - NADP+ + 2 electrons + H + → NADPH
  3. ATP produced in stroma by H+ electrochemical gradient
    1. Splitting of water places H+ in the lumen
    2. High-energy electrons move from PSII to PSI, pumping H+ into the lumen
    3. Formation of NADPH consumes H+ in the stroma

Brianna's Bio 111 (1 decks)

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