B-3.1: Summarize photosynthesis & interpret the formula
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Transcript of B-3.1: Summarize photosynthesis & interpret the formula
B-3.1: SUMMARIZE PHOTOSYNTHESIS & INTERPRET THE FORMULA
PHOTOSYNTHESIS 1
CHAPTER 8 SECTION 1 Essential Question:
What is the role of ATP in cellular activity?
SC B- 3.3:recognize the overall structure of ATP, namely, adenine, the sugar ribose, & three phosphate groups – and summarize its function(including ATP-ADP cycle
PHOTOSYNTHESIS
AUTOTROPHS HETEROTROPHS Organisms that can
make their own food (energy source) plants some bacteria algae
Organisms that cannot make their own food; they have to consume food (energy source) Animals
have to eat other organisms
Fungi decomposers
AUTOTROPHS HETEROTROPHS
DRAW & LABEL FIGURE 8-3 ON PAGE 203 ONTO TOP ½ 0F PAGE 53 OF NOTEBOOK
ATPAdenosine
Triphosphate is the
principle chemical
compound cells use to store and release energy
ATP ADP + P releasing energy in the 3rd phosphate bond. This is a reversible reaction:
ADP + P ATP
PHOTOSYNTHESIS OVERVIEWCHAPTER 8-2
EQ: How would you describe the relationship between chlorophyll and the color of plants?
Photosynthesis uses the energy in sunlight and carbon dioxide from the air to make glucose and releases oxygen into the air.
Draw, color, label figure 8-4 from page 206 on page 55 of your notebook
Pigments are also a necessary part of photosynthesis.Pigment: any light absorbing moleculeChlorophyll: principle pigment of plants; absorbs light energy
PHOTOSYNTHESIS REACTIONSCHAPTER 8-3
EQ: What happens in the light reactions of photosynthesis?
Inside a Chloroplast:thylakoids: saclike membrane folds; appear like coinsgranum: stack of thylakoidsstroma: space between granum and inner membrane
PHOTOSYSTEMS• clusters of pigments in thylakoid membrane that capture energy from light•Photosystem I & II
NOTICE THIS IS HAPPENING IN THE THYLAKOID MEMBRANE
LIGHT REACTIONS Use energy from light to
excite electrons. Electrons absorb energy from light and go from their ground state to their excited state. These excited electrons then jump out of that atom & move through a series of molecules called the electron transport chain
LIGHT REACTIONS: STEP 1 Photosynthesis begins when photons
of light are absorbed by pigments in Photosystem II
Ground state electron excited electrons enter electron transport chain
The electrons that left must be replaced: Enzymes breakdown 2 water 4H+ + O2 + 4 electrons
LIGHT REACTIONS: STEP 2 The excited electrons move thru the
electron transport chain to Photosystem I Their energy is used to move H+ from
the stroma to inner thylakoid space
Light Reactions: Step 3( in Photosystem I now)
One of the electron carrier molecules is NADP+
NADP+ carries 2 excited electrons with a H+
In the process NADP+ NADPH thus converting some of the light energy into chemical energy
NADPH carries excited electrons to other molecules
LIGHT REACTIONS: STEP 4 Over time the inside of the thylakoid
membrane fills with H+ making the outside of the membrane relatively negative compared to the inside (creating a difference in charge across the membrane)
The difference in charges provides energy to make ATP
LIGHT REACTIONS: STEP 5 The thylakoid membrane is
impermeable to H+ Membrane protein called ATP synthase
allows H+ to pass through membrane As H+ is passing through ATP synthase
changes shape & in the process binds ADP + P ATP
OVERVIEW OF LIGHT REACTIONS Things required
Light Water NADP+ ADP + P
Things produced Oxygen NADPH ATP
LIGHT REACTIONS ANIMATIONS Harvesting Light Photosynthetic Electron Transport and A
TP Synthesis
TIME FOR THOUGHT How would you compare the role of
Photosystem II and Photosystem I
LIGHT-INDEPENDENT REACTIONS aka:
Thermochemical cycle
Calvin Cycle
LIGHT-INDEPENDENT REACTIONS: PART 1
6 carbon dioxide molecules enter chloroplast from atmosphere
Each combines with a 5-carbon sugar which then splits (12) 3-carbon molecules
LIGHT-INDEPENDENTREACTIONS: PART 2
Energy source for Dark reactions is the ATP made in light reactions
H added to carbon molecules is from NADPH made in light reactions
LIGHT-INDEPENDENT REACTIONS: PART 3
2 of the (12) 3-carbon molecules leave the cycle & are used by the plant to make compounds needed by the plant for metabolism and growth
LIGHT-INDEPENDENT REACTIONS: PART 4
(10) C-C-C + 6 ATP (6) C-C-C-C-C + 6 ADP
The remaining (10) 3-carbon molecules are converted back into 5-carbon sugars in a series of reactions powered by 6 ATP
These are used in the next turn of the cycle
LIGHT-INDEPENDENT REACTIONS OVERVIEW
Things required: 6 CO2 18 ATP 12 NADPH
Things produced: 1 glucose (6-
carbon) 18 ADP 12 NADP+
PHOTOSYNTHESIS EQUATION
FACTORS AFFECTING PHOTOSYNTHESIS
availability of water
1. too much2. too little
temperature1. Photosynthesis
enzymes work best 0 ◦C – 35 ◦C
FACTORS AFFECTING RATE OF PHOTOSYNTHESIS-2
3. light intensityas it increases rate of photosynthesis increases but only to a certain point, then it levels off
RAINFORESTS About 2 ½ acres of
Amazon rainforest absorbs 1 ton of CO2 per year
20% of world’s O2 produced in Amazon