Photosynthesis & Respiration

PHOTOSYNTHESIS PLANTS NEED: WATER WATER

PLANTS PRODUCE: SUGAR SUGAR

PHOTOSYNTHESIS 6H 2 O + light energy ➜ C 6 H 12 O ➜ ➜ + are organisms that make their own food – producers (plants) are organisms that make their own food – producers (plants)

In photosynthesis, light energy is changed to (in sugar) (in sugar) Plants, algae, and some all do photosynthesis. HETEROTHOPHS eat autotrophs or other heterothophs to get food ( ) Photosynthesis involves a series of linked biochemical reactions. This is a PATHWAY. Most of photosynthesis takes place in the tissue in the plant.

GRANA are stacks of thylakoids. They are surrounded by fluid called

ALL organisms do. They use oxygen and ➜ They use oxygen and ➜ BUT PLANTS also do photosynthesis. Plants produce more oxygen than they use. LIGHT ABSORPTION IN The 1 st reactions are – chloroplasts absorb light. This occurs in the membrane. Chloroplasts have a double membrane and internal membranes called thylakoids.

LIGHT – visible light (Components of white light) is a combination of many colors. Light that we see = Light travels in waves that can be measured in. Different colors = dif. wavelenghs PIGMENTS are compounds that a light. They absorb them so you don’t see them anymore. If something is blue, it absorbs all colors BUT. It reflects blue back. CHLOROPHYLLS are in the thylakoid membranes that help photosynthesis. CHLOROPHYLL “a” is involved in the reaction of photosynthesis. CHLOROPHYLL “b” helps “a”

Other pigments ( yellow, brown) also help. These are CAROTENOIDS. They and “b” are PIGMENTS. They help absorb more than chlorophyll “a” alone. As day length, chlorophyll is lost and the other pigments show up.

ELECTRON TRANSPORT Chlorophylls + Carotenoids are clustered together in the thylakoid membrane. Each cluster = a. There are 2 photosystems – I and II. In both I and II accessory pigments light (pick up energy) which gets passed down to chlorophyll “a” This is followed by 5 steps.

1. go to a higher energy level in two “a” molecules of photosystem II. 2. The electrons leave “a” and are picked up by a PRIMARY ELECTRON. 3. The electrons are donated to a chain of molecules in the thylakoid membrane (ELECTRON TRANSPORT CHAIN – ETC.) The energy lost as they move is used to move into the thylakoid. 4. During this – light is absorbed by photosystem I. here also move from “a”. But they are replaced by the ones coming from the ETC. here also move from “a”. But they are replaced by the ones coming from the ETC.

5. The photosystem I electrons go to a different which is located to the side of the membrane that faces the stroma (fluid.) Here a chemical picks up the electron to become NADPH. Once that is all over – is used to replace electrons back into photosystem II (Hydrogen is used, then oxygen is released.)

This is the process in which is made. Electrons gave energy to pump protons in H + inside the thylakoid which then move by OSMOSIS to the Energy is released which is harnessed by synthase which adds a phosphate to synthase which adds a phosphate to ADP + phosphate ➜ ATP ADP + phosphate ➜ ATP This energy is used to start the 2 nd part of

The Cycle In photosynthesis carbon dioxide must be formed or FIXED to make the carbon in ATP and NADPH from photosystems I and II give the energy to start the Calvin Cycle – the cycle of forming sugar by getting carbon from CO 2 This is CARBON It happens in the stroma and the products can be used to make, lipids, and carbohydrates.

Calvin Cycle Steps 1. CO 2 diffuses into the stroma. + enzyme + RuBP (ribulose BIS-phosphate) ➜ 6 Carbons (that make 2 PGA compounds each one has 3 Carbons.) + enzyme + RuBP (ribulose BIS-phosphate) ➜ 6 Carbons (that make 2 PGA compounds each one has 3 Carbons.) 2. Each PGA + P (from ATP) + H (from NADPH) ➜ 2. Each PGA + P (from ATP) + H (from NADPH) ➜ 3. Some PGAL is converted to RuBP (has 5 carbons) some PGAL is released. Some PGAL is used to make amino acids, lipids, 3. Some PGAL is converted to RuBP (has 5 carbons) some PGAL is released. Some PGAL is used to make amino acids, lipids,

In some plants only the Calvin Cycle is used ( plants.) Plants have pores (Stomata) that allow CO 2 to enter and to leave. They are on the bottom of the leaf. Some plants fix Carbon Dioxide using a C 4 pathway. These plants lose less water and make 4 carbon compounds. These include corn and. Then they go to the Calvin Cycle. CAM is another pathway. These plants open their stomata at night and close during the day. Example :

Rate of Photosynthesis is the most important factor in rate. is the most important factor in rate. Carbon Dioxide is important. influences it (too high or low will cause a decrease.) influences it (too high or low will cause a decrease.) When light and carbon dioxide amounts reach certain levels photosynthesis is saturated and can not

PHOTOSYNTHESIS SUMMARY ➜ CHLOROPLAST ➜ CHLOROPLAST ⇓ PHOTOSYSTEM II, then PHOTOSYSTEM I PHOTOSYSTEM II, then PHOTOSYSTEM I (moving electrons) (moving electrons) ⇓ ➜ NADPH and ATP ➜ NADPH and ATP ⇓ ➜ CALVIN CYCLE ➜ CALVIN CYCLE ⇓ ⇓ ⇓ ⇓ O 2 SUGAR O 2 SUGAR

RESPIRATION GLYCOLYSIS & Glycolysis is a process in which glucose (sugar) is changed to acid and produces ATP. Cellular Respiration is a process in which cells make ATP by breaking down Glycolysis is the 1 st step in Cellular. The products of glycolysis are further broken down.

In cells where oxygen is present respiration takes place. If no is present – Anaerobic respiration. Fermentation is an example of anaerobic respiration. Anaerobic respiration produces less GLYCOLOSIS happens in the of the cell. It is the 1 st step in any respiration and uses the products of It is the 1 st step in any respiration and uses the products of

Glycolysis Step 1 – Glucose (six carbons) uses 2 ATPs to make: A Compound which then makes 2 PGALs which makes 2 Compouds. In this step, 2 NAD + form 2 NADH + 2 H +. 2 phosphates are put in and 4 ADPs are changed to 4 ATPs. of Pyruvic Acid are made. of Pyruvic Acid are made. OVERALL – 2 ATPS are used, 4 ATPs are made, so the overall (net) production is 2 ATPs. In the process NAD + accepts

When no Oxygen is present, follows. NO ATPs are made, but NAD+ i i i is made to keep Glycolsis going. There are different fermentation pathways. In one Pyruvic Acid forms Lactic Acid. In another Pyrucic Acid makes Carbon Dioxide is given off in alcoholic fermentation of yeast (makes bread rise.) Yogurt and cheese are made using bacteria that undergoes lactic acid fermentation. When your muscles work and use up oxygen they change to anaerobic lactic acid fermentation ➜ and pain.

ENERGY Kilocalorie – a way to measure energy ( calories.) Glycolysis is only 3.5 % efficient in energy production because much energy remains in

AEROBIC RESPIRATION This is respiration with oxygen. It follows It has 2 major stages: – it finishes the breakdown or oxidation of glucose. NAD + gains electrons and is reduced to NADH and in the ETC it is used to make ATP. – it finishes the breakdown or oxidation of glucose. NAD + gains electrons and is reduced to NADH and in the ETC it is used to make ATP. In prokaryotes Krebs is in the cytosol and ETC is in the cell

In eukaryotes the Krebs Cycle happens in the of the mitochondria.

1 st Pyruvic Acid is changed to Acetyl

ELECTRON TRANSPORT CHAIN 2 nd stage of aerobic respiration: NADH and supply electrons which get passed from one molecule to another. The electrons lose energy. This energy pumps protons to create a concentration difference of protons that move creating the energy to form ATP. This is CHEMIOSMOSIS. Protons from NADH and FADH 2 accumulate in the matrix of the OXYGEN is the final acceptor of electrons in the ETC so the chain can continue. O 2 also O 2 + 4e - + 4H + ➜

Energy in Aerobic Respiration The amount of ATPs may vary, but overall 38 ATPs are produced (that is the highest possible number.) It is More energy is transferred in the than in any other step. 6H2O + 6CO2 light energy ➜ C6H12O6 + 6O2 C6H12O6 + 6O2 ➜(Energy ) + 6H2O + 6CO2