chapter 10 | photosynthesis

covab only

photosynthesis

plants harness the energy in sunlight (plus CO₂ and water) to create sugar

cellular respiration

the metabolic process cells use to convert nutrients—primarily glucose—into adenosine triphosphate (ATP). ATP acts as the cell’s primary energy currency to power life-sustaining activities like muscle contraction, cell division, and molecule transport

photsynthesis equation

light energy + carbon dioxide + water = glucose + oxygen

cellular respiration equation

glucose + oxygen = carbon dioxide + water + ATP

chloroplasts

gives the green color to plants!

• includes:

• outermembrane

• inner membrane

• granum

• stroma

• thylakoids

• thylakoid space

• thylakoid membrane

chlorophyll excitation

when molecule of chlorophyll absorbs photon of light, it goes from stable to excited state

• electrons in chlorophyll aborbs the light causing the electron to move to outer shell

• as electron falls back to place it gives off energy

light reaction (photo part)

converts light energy to chemical energy! occurs during day only

chloraphyll photosynthesis

light harvesting complexes

• 2 photosystems!

• how one molecule in the plant surrond by other chlorophyll molecules gives eachother energy

• goes from one to another!

• occurs in the thylakoid membrane

photosystem II

chlorophyll a (P680)

• upstream of photosystem I

• charges photosystem I via electron transport chain

• makes atp

• loses water and oxygen

photosystem II

reduces NADP+ and makes NADPH

Calvin Cycle

uses ATP and NADPH from light reaction to reduce CO2 to G3P

• anabolic

• occurs in the stroma

• 3 sub phase

fixation phase (carbon)

“fixes carbonb” by catching it and turning it into a organic molecule

• RuBP (5 carbons), CO2 caught (1carbon) to make a temporary 6 carbon molecule then split into 3-carbon molecules (PGA)

• catalyzed by rubisco

reduction phase

• gains a new electron by 3PGA (turns PGA into G3P sugar)

• ATp and NADPH converyts 6 molecules of 3PGA into 6 molecules of glyceralhyde 3-phosphate.

regeneration (of CO2) phase

regenerates RuBP to start cycle again

stroma

the fluid in chloroplast where calvin cycle occurs

outer membrane

• The smooth, protective outer layer.

• Controls what enters and leaves the chloroplast.

• Relatively permeable to small molecules and ions.

inner membrane

• Located just inside the outer membrane.

• More selective than the outer membrane.

• Regulates transport of proteins, sugars, and other molecules into the chloroplast.

thylakoids

• Flattened, disc-shaped membrane sacs suspended in the stroma.

• Contain the green pigment chlorophyll.

• Site of the light-dependent reactions of photosynthesis.

• Capture sunlight and use it to produce ATP and NADPH.

granum or grana

stack of thylakoids

Thylakoid space

The fluid filled space inside a thylakoid

Chlorophyll excitation

When molecule of chlorophyll absorbs photon of light, it goes from stable to excited state. (Moves back and forth)

• individual electrons in chlorophyll absorbs the light energy causing the electron to move to higher orbital (new shell/outer).

• As electrons falls back to original orbital, it gives off energy

Stages of photosynthesis

2 stages

• light reaction

• Calvin cycle

Light reaction

Converts light energy to chemical energy (day)

Light reaction when

1st phase

Light reaction where

Thylakoid membrane

Light reaction main player

Sunlight

Light reaction What goes in

• light energy

• H2O

• ADP

• NADP

Light reaction Out

• ATP (Calvin cycle) (photosystems II)

• NADPH (Calvin cycle) (photosystems I)

• O2 (Environment)

Light reaction why

Converts light energy 2 chemical energy ATP and NADPH

Chlorophyll photosystems

Light harvesting complexes

• thylakoid membrane

Molecules in plant cells surrounded by other chlorophyll molecules

• electrons jump/give off energy

• Energy given transmitted 2 another

Photosystems II

Chlorophyll a (P680)

• reaction center delivers high energy electrons through electron transport chain

• Upstream of photosystems: charges photosystem I via electron transport chain

Photosystems I

Reduces NADP to NADPH

Light reaction chain

Sunlight hits chloroplast→system II→Water splits(O2 is realeased)→electron transport train→ATP→system I→NADPH→ Calvin cycle

Calvin cycle

Uses products from light reaction to produce G3P sugar (night and day)

• anabolic

• Occurs in the stream

• 3 sub phases(fixation, reduction, regeneration)

Fixation phase

“Fixes carbon”, turns inorganic CO2→organic molecule

Catalyzed by Rubisco (RuBP)

RuBP (5 carbons) + CO2 (1 carbon) →temporary 3 (6-carbon) molecule→ splits into 6 (3-carbon) molecules (PGA)

Reduction phase (Carbon)

ATP/NADH converts 6 molecules of 3-PGA into 6 molecules of glyceraldehyde 3-phosphate. Involves gain of electrons by 3-PGA

(PGA→G3P)

Regeneration phase(of CO2 acceptor phase)

Regenerates RuBP to start cycle again

Calvin Cycle when

After light reaction

Calvin Cycle Where

In stroma

Calvin Cycle Who’s main

CO2

Calvin Cycle What goes in

9 ATP (from light reactions)

6 NADPH (from light reactions)

3 CO2 from atmosphere

Calvin Cycle What comes out

9 ADP (recycles to light reactions)

6NADP (recycles to light reactions)

6 G3P (1, 3-carbon sugar) (other 5 recycle back to RuBP)

Calvin Cycle Why

Make G3P