Energy Carriers Energy Carriers n n n In

Energy Carriers

Energy Carriers n n n In Photosynthesis, energy in sunlight is used to make food. In Respiration, food is broken down to release energy. Molecules ADP, NAD+ and NADP+ trap and transfer this energy

ADP n ADP = Adenosine Di. Phosphate This molecule is found in ALL living cells. Adenine—Ribose—Phosphate ~ Phosphate n Unstable bond ADP is a low energy molecule n n

ATP = Adenosine Tri. Phosphate n Add another phosphate to ADP = ATP Adenine —Ribose—Phosphate~Phosphate n Extra energy in unstable bond n n n Phosphorylation=adding a phosphate group ADP + energy + P ATP + Water ATP is an Energy rich compound

ATP n ATP stores energy, not for long though n It can be moved around inside a cell n When ATP breaks down to ADP it releases energy n Energy released is used to carry out most reactions in the cells. n ATP + Water ADP + energy n Cells release energy from ATP 10 million times per second

ATP and ADP

NADP+ n n n NADP+ = Nicotinamide Adenine Dinucleotide Phosphate Is a low energy molecule involved in Photosynthesis NADP+ accepts a Hydrogen proton+ 2 electrons = NADPH NADP+ + 2 electrons + H+ NADPH (Low energy) (High energy) n n (High energy) The Addition of Electrons to a molecule = Reduction NADP+ is said to be reduced to NADPH

NADPH n n NADPH is a very High energy molecule. It is an electron carrier Energy it carries is used in photosynthesis When it breaks down it releases 2 high-energy electrons & a hydrogen ion § NADPH NADP+ + 2 electrons + H+ (High Energy) (Low Energy) (High Energy)

ATP Vs NADPH

NADP+ Vs NAD+ n n n NAD+ = Respiration NADP+ = Photosynthesis NAD+ is a low energy molecule just like NADP+ and changes to the high-energy molecule NADH just like NADPH

Photosynthesis Plants making their own food

Role of Photosynthesis n n n Plants use it to make food Animals get their food from plants It produces oxygen which is needed to release energy in respiration It is responsible forming fossil fuels It removes carbon dioxide from the air

Photosynthesis requires: n n carbon dioxide, water, light energy, chlorophyll.

Photosynthesis produces glucose n waste oxygen n

Photosynthesis converts light energy chemical energy

Stages in Photosynthesis n n n Light is absorbed - By Chlorophyll in Chloroplast Water is split - 2 H 2 O 4 H+ +4 e- + O 2 Products are produced - Oxygen, hydrogen ion & electrons Light energises electrons -sunlight energises electrons through chlorophyll Glucose is formed - CO 2 + H+ + E- C 6 H 12 O 6

Sources of Light CO 2 & H 2 O Light n n Sun Artificial bulbs Carbon Dioxide n n Animals respiring Burning of fossil fuels Water n In soil due to rain or nearby rivers & lakes

2 stages of Photosynthesis Light Stage Dark Stage

Light Stage n n n This takes place in the grana of the chloroplast It makes energy for converting ADP + P into ATP It makes hydrogen ions from the splitting of water to use in the dark stage of photosynthesis

Light stage Light Stage Phosphorylation Making ATP Photolysis Splitting water

Photolysis The splitting of water Water 2 H 20 Hydrogen ions 4 H+ Used to convert NADP To NADPH Electrons 4 E- Oxygen 02 Go back to chlorophyll By product Excreted through leaf

Water Splitting Equation Light 2 H 2 O + 4 H +4 e + O 2

Phosphorylation Making ATP and NADPH n n Where do plants get their energy from? - Sun Light There are 7 different colours in white light, the plant can only absorb these if it has a pigment. The most important pigment is Chlorophyll because it sits next to an electron acceptor. The electron acceptor takes the energy from the pigments and adds it into electrons.

Chloroplast Pigments – In Grana Electron acceptor Energised electrons passed on Energy Passed on Light energy absorbed Pigments

Electron Flow Pathways to make ATP & NADPH 2 Different Pathways 1. Cyclic Photo. Phosphorylation 2. (circle) (light) (adding a phosphate) Non-Cyclic Photo. Phosporylation

Electron Pathway 1: Cyclic Photophosporylation ADP traps this energy by adding another phosphate Electron Acceptors E- E- E- Energy E- E- Chlorophyll Light energy absorbed Energy ADP + P ATP + Water Energy Electron flow that looses energy as it goes around

Electron Pathway 1: Cyclic Photo. Phosphorylation n n High energy electrons travel around a series of electron acceptors & back again to chlorophyll As they move around they loose energy This energy is trapped by ADP and a phosphate within their bonds. This forms ATP and water. ADP + energy + Phosphate ATP + water

Electron Pathway 2: Non -Cyclic Photophosporylation Light 2 E- Electron Acceptors O 2 2 H 2 O 4 E 4 H+ 2 E- 2 EADP + P Chlorophyll ATP + Water 2 E- Light energy absorbed 2 E- NADP+ NADP- + H+ NADPH

Electron Pathway 2: Non-Cyclic Photo. Phosphorylation n n 2 high energy electrons passed along at a time through a series of electron acceptors They loose energy as they pass from acceptor to acceptor, this energy is used to make ATP At the end 2 electrons combine with NADP+ to form NADP-. Water is split using light energy, 2 electrons return to chlorophyll while the protons attach to NADP- to form NADPH

Products of Light Stage Oxygen n ATP n NADPH n

Dark Stage n n This is also known as the Calvin cycle It takes place in the stroma of the chloroplast It uses energy got from breaking down ATP into ADP + P It uses hydrogen ions and electrons got from breaking down NADPH into NADP+ + 2 electrons + H+

Dark Stage Calvin Cycle 6 CO 2 Oxygen atoms are removed 12 Hydrogen ions are added Glucose is formed C 6 H 1206 Electrons are added

Dark Stage Calvin Cycle NADPH Carbon Dioxide NADP+ Glucose (C 6 H 12 O 6) ATP ADP + P

Main events in photosynthesis n n n n Light energy is absorbed by chlorophyll Water is split The electrons are passed to chlorophyll The protons are stored in the chloroplasts The oxygen is released Sunlight transfers energy to electrons The high energy electrons, stored protons( the hydrogen ions) and carbon dioxide are used to make glucose

Light Released Chlorophyll Electron Deficient Chlorophyll High Energy Electrons Water Protons + electrons + oxygen ADP Proton Pool ATP NADP+ NADPH