Metabolism in Autotrophs and Heterotrophs

Metabolism in Autotrophs and Heterotrophs Energy is transferred from organism to organism in a process that begins with photosynthesis and ends with cellular respiration.

Unit 5: Key learnings • Autotrophs "produce" the energy that they use, while heterotrophs must "consume" their energy sources. • Although some reactions result in a net storage of energy, others result in a net release. • Biochemical pathways are influenced by enzymes.

Unit 5: Essential question How do the processes of photosynthesis and cellular respiration show evidence of chemical reactions?

Launch activity: Priestley's bell jar experiment Here are three key observations that need to be accounted for: • Plants placed into a sealed bell jar survive. • Mice placed into a sealed bell jar die. • Mice placed into a sealed bell jar withplantssurvive. Click picture to the left to watch overview of PS after launch activity

Question: Why do mice placed into a sealed bell jar only survive when they are accompanied by plants? • Animals depend on the oxygen produced by plants (photosynthesis)to survive • While plants do require carbon dioxide to conduct photosynthesis, they are not dependent on animals to produce it, as they produce it themselves (cellular respiration).

Unit 5: Concepts • Autotrophs versus heterotrophs (C) • Chemical reactions (E) • Photosynthesis (I) • Microtest 1 • Aerobic respiration (I) • Microtest 2 • Chloroplast and mitochondrial similarities in form and function (E) • Anaerobic respiration (I) • Microtest 3

Essential question 1.1: How do the abilities of an autotroph differ from those of a heterotroph? 11/1/2018 7

Energy flows between organisms in living systems. • Almost all of the biochemical energy on Earth comes directly or indirectly from the sun. • Plants, algae, and some bacteria absorb energy from the sun and convert it into chemical energy stored in organic compounds(Photosynthesis). • ALL organisms break down organic compounds and release the energy held in their bonds (Cellular Respiration).

Energy Flow through an ecosystem

Some organisms are producers and others are consumers. • Autotrophsare organisms that use sunlight (Photosynthesis)or inorganic compounds (Chemosynthesis) to make energy containing organic compounds. These organisms will then break down these compounds later for use in their cells (Cellular Respiration). • Heterotrophsare organisms that consume organic compounds in their food and break them down for energy(Cellular Respiration).

Question: Why is photosynthesis called a “synthesis” reaction? • Two small molecules are put together to form a larger one • The energy state of the product (sugar) is greater than the energy state of the reactants (water and carbon dioxide) Glucose Glucose Synthesis H2O & CO2 H2O & CO2

Essential question 2.1: How do special molecules like ATP and NADH aid chemical reactions?

Energy is released from ATP (decomposition) in order to power a cell’s chemical reactions. ATPADP + P + a little bit of energy

Several different molecular systems function like the ATP-ADP system. • NADPH = NADP + H • NADH =NAD + H • FADH2 =FAD + H2 Energy carriers (intermediates) Energy acceptors Add ATP and ADP + Pi to the appropriate columns.

Unit 5: Concepts • Autotrophs versus heterotrophs (C) • Chemical reactions (E) • Photosynthesis (I) • Microtest 1 • Cellular respiration (I) • Microtest 2 • Chloroplast and mitochondrial similarities in form and function (E) • Oxygen free environments (I) • Microtest 3

Essential questions 3.1 - 3.2: 3.1: Why is the process of photosynthesis considered to be a synthesis reaction? 3.2: How does energy flow from process to process during photosynthesis?

Photosynthesis is the production of carbohydrates from CO2 and H2O, with the help of sunlight. sunlight 6CO2 + 6H2O --------------> C6H12O6 + 6O2 carbon dioxide water glucose oxygen Chemical energy out (sugar) Light energy in Inorganic molecules

Photosynthesis happens in 3 parts: • Photolysis (Light dependent) • Electron Transport chain (Light dependent) • Calvin cycle (Light independent)

Chloroplast structure

Excitation of electronsin Chlorophyll

Electron Transport Chains of Photosystems I and II

Photolysis (hydrolysis)of Water Oxygen production

The Light dependent reactions summary Click the picture to watch a video on the light reactions of photosynthesis

Electrons in 2 photosystems are excited and replaced. • Clusters of pigments are embedded in the bilayers of the thylakoids. (Photosystems I and II) • Energy from the sun causes electrons in the pigments to jump to a higher energy level and become excited.(First Photosystem I, then Photosystem II)

The excited electrons move into 2 electron transport chains (ETC). • H2O is split by an enzyme located near the pigments of Photosystem II in the interior of the thylakoid (photolysis). • The electrons come from the hydrogen, which are now released as free protons (H+). • The Oxygen from two water molecules fuse to form O2gas, which is released as waste into the air. • Photosystems II’s missing electrons are replaced by electrons from split water molecules (Photolysis). • Photosystem I’s electrons are replaced by those of Photosystem II.

Two electron transport chainsin the thylakoid membrane produce energy storage compounds- ATP and NADPH. • Excited electrons from Photosystem I travel through an ETC and help produce NADPH. • The energy from the electrons is stored in the form of NADPH as an H+ is added to NADP+. • These electron will be replaced by electrons from Photosystem II.

Excited electrons from photosystem II move to replace the ones lost from photosystem I. • Along the way, PS II’s electrons pass through a pumpthat pulls in H+. • A concentration gradient of H+is created inside the thylakoid. • H+ floods back out through an enzymechannel calledATP synthase. • Each H+that is transported catalyzes the production ofone ATPmolecule.

NADPH and ATP now hold chemical energy that can be used later (converted from light energy). • The energy in these compounds will be used in the Calvin cycle to build sugars. • Energy will be released by breaking bonds & converting them back into their original forms: ADP and NADP+ • ADP and NADP+ will be returned to allow the light reactions to occur again- these are the necessary reactants for those reactions.

Question:Is there a net gain or loss of energy after the light reactions? Gain: The organism did not need to use it’s own energy to form ATP and NADPH It got this energy from the Sun!

Summary: With your partner, answer the following questions: • What molecule donates electrons to keep the electron transport process going? • Where are the electrons from PS I going? • What two molecules carry energy out of the light dependent reactions?

NADPH and ATP from the light reactions enter the Calvin Cycle for Carbon Fixation. • These are the Light independent reactions since they don't require light directly. • Carbon Fixation is the transfer of atmospheric carbon into energy containing organic compounds. • The Calvin cycle is the most common type of carbon fixation.

The Calvin Cycle Click the picture above to watch a video review of the Calvin cycle

The Calvin cycle is a series of enzyme-assisted chemical reactions that produces ONE glucose sugar molecule. • 6 carbon dioxide molecules are added to 6 five-carbon compounds forming 6, six-carbon molecules. • Each resulting six-carbon compound immediately splits into 2 three-carbon compounds (a total of 12 are formed). • Phosphate groups from ATP and electrons from NADPH are added to the 12, three-carbon compounds forming 12, three-carbon sugars.

6CO2 ATP 12 PGA 6 RuBP 12 6 ADP 12 ADP + Calvin cycle 12 Pi ATP 12 NADPH 4 Pi 12 NADP+ 12 PGAL 10 PGAL 1 Pi phosphorylated glucose 1

Calvin Cycle Continued... • Two of the resulting three-carbon sugars are used to produce glucose. • The other 10 three-carbon sugars are used to regenerate the initial five-carbon compounds (ATP is required). • In the end, 6 carbon dioxide molecules enter the cycle to make one six-carbon glucose. • The energy required to do this came from the NADPH and ATP that was formed with the help of the sun’s energy.

Question:Why is this a “cycle”? We finish where we started?

Three factors determine the rate of photosynthesis. • Each of these factors will increase the rate of photosynthesis until a saturation point is reached. • Amount of Sunlight • Amount of Carbon Dioxide • Temperature • Increasing these factors above the saturation point will not increase sugar production.

Stomata allowing gas into a plant Question: Why might plants want to regulate the opening of their stomata? To prevent water loss in dry climates

sunlight Light- Dependent Reactions Question:Which molecules link the “light dependent” reactions to the “light independent” reactions? 12H2O 6O2 ATP ADP + Pi NADP+ NADPH 6CO2 Calvin-Benson cycle 6 RuBP 12 PGAL Light- Independent Reactions 6H2O phosphorylated glucose end products (e.g., sucrose, starch, cellulose)

The “ins” and “outs” of photosynthesis In what part of the process are each of these molecules important? 6CO2 + 6H2O --------------> C6H12O6 + 6O2 Calvin Cycle Photolysis Calvin Cycle Photolysis

Label the diagram and then describe Photosynthesis to a partner.

MICROTEST 1 Includes all notes prior to this slide in your notes packet.

Essential questions 4.1 - 4.2: 4.1: Why is cellular respiration considered to be decomposition reaction? 4.2: How does energy flow through the process of cellular respiration?

Pulmonary and cellular respiration Click the picture to the right to watch a video overview of cellular respiration

Cellular respiration is a stable release of energy. • Burning matter releases energy very quickly as heat and light. (very unstable release) • Cellular respiration is a series of controlled reactions that occurs slowly, releasing a little energy at a time, re-storing it again and eventually producing useable ATPmolecules.

Cellular respiration converts the energy contained in organic compounds into a usable form (ATP). Enzymes C6H12O6 + 6O2 --------------> 6CO2 + 6H2O + energy Glucose gasgas water ATP

Metabolism in Autotrophs and Heterotrophs