Cell Energy (Photosynthesis and Respiration) Notes Energy: Energy for living things comes from food. Originally, the energy in food comes from the sun.

Autotroph- Organisms that use an energy source (such as light from the sun) to produce sugar They can make their own food in their cells. auto = self feeders Ex: plants and some microorganisms (some bacteria and protists)

Heterotrophs- Organisms that must obtain food (sugar) from another organism. Hetero – “other feeder” Ex: animals and most microorganisms

Solar Energy Process: Photosynthesis Location: Chloroplast Enzyme: Rubisco Pigment: Chlorophyll Occurs in autotrophs O₂ C6H12O6 (glucose) Chemical energy

Process: Respiration Location: Mitochondria Occurs in: Autotrophs and Heterotrophs Puts a phosphate on ADP to produce ATP (chemical energy) Some energy lost as HEAT These energy transformations provide energy for LIFE CO2 and H2O

AdenineRibose3 Phosphate groups (triphosphate) Cell Energy: Cells usable source of energy is called ATP ATP stands for adenosine triphosphate

ATP is the only molecule the cell can actually use for cell energy. The energy released from breaking down glucose is used to put a phosphate on Adenosine diphosphate- ADP (2 Phosphates). When ATP provides the energy for the cell it loses a phosphate.

ADP stands for adenosine diphosphate AdenineRibose2 Phosphate groups

ATP Cycle ATP Loses a P- Provides energy for all cell work ADP Energy from food used to add a P ATP is like a rechargeable battery

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All energy is stored in the bonds of compounds—breaking the bond releases the energy When the cell has energy available it can store this energy by adding a phosphate group to ADP, producing ATP

General formula for photosynthesis : carbon dioxide + water + light glucose + oxygen 6CO 2 + 6H 2 O + light C 6 H 12 O 6 + 6O 2

Steps of Photosynthesis 1.Light reaction (depends on light) Traps sunlight Produces electrons and ATP required to power the dark reaction Oxygen given off here 2.Dark reaction, aka Calvin Cycle (does not directly depend on light) Uses ATP and electrons from light reaction and CO2 to make glucose

Diagram Reactants Products Light H2OH2OCO 2 O2O2 C 6 H 12 O 6 Glucose Chloroplast Light Dependent Reaction Calvin Cycle NADP+ ADP + P ATP NADPH

Summary: Light Dependent Reaction—H 2 O is broken down and light energy is stored temporarily in inorganic energy carriers, ATP and NADPH Calvin Cycle—energy is transferred from ATP and NADPH to the organic compound glucose

Cellular Respiration: (2 kinds—Aerobic and Anaerobic) Cellular respiration is the process by which the energy of glucose is released in the cell to be used for life processes (movement, breathing, blood circulation, etc…)

Cells require a constant source of energy for life processes but keep only a small amount of ATP on hand. Cells can regenerate ATP as needed by using the energy stored in foods like glucose. The energy stored in glucose by photosynthesis is released by cellular respiration and repackaged into the energy of ATP.

Respiration occurs in ALL cells and can take place either with or without oxygen present.

Aerobic Respiration: requires oxygen Occurs in the mitochondria of the cell Total of 36 ATP molecules produced General formula for aerobic respiration: C 6 H 12 O 6 + 6O 2 6 CO 2 + 6H 2 O + 36 ATP glucose + oxygen carbon dioxide + water + energy Human cells contain a specialized structure – the mitochondrion – that generates energy.

Overall Reaction C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + 38 ATP Overall this is a three stage process 1.Glycolysis: Occurs in the cytoplasm Glucose is broken down 2.Krebs Cycle Breaks down pyruvate into CO2 Occurs in mitochondrial matrix 3.Electron Transport Chain (ETC) ATP is synthesized

Glycolysis Glyco = glucoseLysis = break down Occurs in the cytoplasm This stage occurs in BOTH aerobic and anaerobic respiration Glucose breaks down into 2 pyruvate (2 ATP are also made) – Glucose is a 6-carbon sugar – Pyruvate is a 3-carbon molecule (there are two of them)

Krebs Cycle (Citric Acid Cycle) Occurs in the matrix of mitochondria Main purpose is to generate electrons for use in ETC 2 ATP is given off

Electron Transport Chain ETC: A series of reactions occur (this is not just one step), to generate ATP and H2O

Diagram Glucose Glycolysis Electron Transport Chain 2 Krebs Cycle Mitochondria In Cytoplasm 232 Electrons carried in NADH Electrons carried in NADH and FADH 2

Summary: 3 steps: 1 st glycolysis 2 nd Krebs cycle 3 rd Electron Transport Chain (ETC)

Anaerobic Respiration: occurs when no oxygen is available to the cell (2 kinds: Alcoholic and Lactic Acid) Also called fermentation Much less ATP produced than in aerobic respiration

fermentation—occurs in bacteria and yeast Process used in the baking and brewing industry—yeast produces CO 2 gas during fermentation to make dough rise and give bread its holes glucose ethyl alcohol + carbon dioxide + 2 ATP

Lactic acid fermentation—occurs in muscle cells Lactic acid is produced in the muscles during rapid exercise when the body cannot supply enough oxygen to the tissues—causes burning sensation in muscles glucose lactic acid + carbon dioxide + 2 ATP