2.18 Light Reactions

0.0(0)
Studied by 0 people
linked notesNote
call kaiCall Kai
learnLearn
examPractice Test
spaced repetitionSpaced Repetition
heart puzzleMatch
flashcardsFlashcards
GameKnowt Play
Card Sorting

1/4

flashcard set

Earn XP

Description and Tags

Biology

Last updated 3:51 AM on 12/4/23
Name
Mastery
Learn
Test
Matching
Spaced
Call with Kai
Chat

No analytics yet

Send a link to your students to track their progress

5 Terms

1
New cards

What is a photosystem?

Collection of photosynthetic pigments linked together to funnel light energy

<p>Collection of photosynthetic pigments linked together to funnel light energy</p>
2
New cards

What are the 3 steps light reactions occur?

  1. Pigments embedded in thylakoid membrane absorb energy from light and release high energy electrons (ionized). Antenna pigments transfer electrons to reaction center. Electrons passed to acceptor molecule in ETC

  2. Movement of electrons and H+ ions leads to production of NADPH and ATP via chemiosmosis

  3. Electrons released by pigments are replaced by splitting of H2O (photolysis) producing O2

3
New cards

Specify Step 1

  1. Light energy of a certain wavelength (680nm) excites chlorophyll a in photosystem II causing release of electrons.

  2. Excited electrons are transferred to carrier molecules within the thylakoid membrane

  3. Electrons released by photosystem II are transferred through series of proteins in thylakoid membrane (ETC) to photosystem I

  4. As electrons move they loose energy and H+ ions move from stroma to thylakoid space

  5. H+ gradient creates proton motive force

  6. Chemiosmosis through ATP Synthase creates ATP via phosphorylation

  7. Light energy (700nm) excites chlorophyll a in photosystem I causing electrons to move into second series of membrane proteins

<ol><li><p>Light energy of a certain wavelength (680nm) excites chlorophyll a in photosystem II causing release of electrons. </p></li><li><p>Excited electrons are transferred to carrier molecules within the thylakoid membrane</p></li><li><p>Electrons released by photosystem II are transferred through series of proteins in thylakoid membrane (ETC) to photosystem I</p></li><li><p>As electrons move they loose energy and H+ ions move from stroma to thylakoid space</p></li><li><p>H+ gradient creates proton motive force</p></li><li><p>Chemiosmosis through ATP Synthase creates ATP via phosphorylation</p></li><li><p>Light energy (700nm) excites chlorophyll a in photosystem I causing electrons to move into second series of membrane proteins</p></li></ol>
4
New cards

Specify Step 2

NADP+ is final electron acceptor. It is reduced to NADPH.

<p>NADP+ is final electron acceptor. It is reduced to NADPH.</p>
5
New cards

Specify Step 3

Photolysis (splitting of water by light) provides electrons to replace ones lost by P680, oxygen gas, and H+ ions

<p>Photolysis (splitting of water by light) provides electrons to replace ones lost by P680, oxygen gas, and H+ ions</p>