ATP, Photosynthesis and Cellular Respiration

ATP What is the role of ATP? A chemical reaction that consumes energy takes lower-energy reactants and changes them into higher-energy product. The atoms are the same, but the amount of energy in the products is higher. Can happen in reverse energy takes lower-energy product and changes them into higher-energy reactant. Bottom line ---this energy helps to power many of the chemical reactions that are essential to life.

Cell’s “Energy Currency”---- ATP stands for adenosine triphosphate Adenine Ribose 3 Phosphate groups

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

A reaction that consumes energy takes lower-energy reactants and changes them into higher-energy products. The atoms are the same, but the amount of energy in the products is higher. This added energy must have a source.

ATP is converted into ADP by breaking the bond between the second and third phosphate groups and releasing energy for cellular processes. ATP and Energy Storage Animation

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

Autotrophs (auto: self) Organisms that use light energy from the sun to produce food Ex: plants and some microorganisms (some bacteria and protists)

Heterotrophs --Organisms that CANNOT use the sun’s energy to make food Ex: animals and most microorganisms

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

Aerobic Respiration: requires oxygen The energy required to reassemble ATP is supplied by cellular respiration. Occurs in the mitochondria of the cell Total of 36ATP molecules produced This process breaks down organic molecules, such as glucose, that originate in food. General overall formula for aerobic respiration: Human cells contain a specialized structure – the mitochondrion – that generates energy.

Electron Transport Chain Animation: Cellular Respiration (Aerobic) Electrons carried in NADH Pyruvate (3 C sugar) In Cytoplasm Electrons carried in NADH and FADH2 Krebs Cycle Electron Transport Chain Glucose (6 C sugar) Glycolysis 2 2 32 NOTE: Kreb’s Cycle produces ATP by breaking down 3 Carbon Sugar but it is the ETC chain that produces the most ATP!!

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

Glycolysis Takes place in the cytoplasm of the cell. Glucose molecules are broken down into smaller molecules Oxygen is not involved in this process, and only 2 molecules of ATP

Kreb’s Cycle and ETC Kreb’s Cycle Takes place in the mitochondrial matrix. The carbon compounds (pyruvate) from glucose are converted to carbon dioxide (CO2). 2 molecules of ATP made. ETC Most of the ATP (32) is produced in the 3rd stage of respiration.

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

Alcoholic fermentation—occurs in bacteria and yeast Process used in the baking and brewing industry—yeast produces CO2 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

NOTE: First step in anaerobic respiration is also glycolysis Diagram Anaerobic Respiration CYTOPLASM Alcoholic fermentation Bacteria, Yeast 2 ATP C6H12O6 Glucose START HERE!!! glycolysis Lactic acid fermentation Muscle cells 2 ATP O2 ETC MITOCHONDRIA Krebs Cycle Aerobic Respiration 36 ATP

Photosynthesis is the process by which the energy of sunlight (light energy) is converted into the energy of glucose (chemical energy)

What is the Chloroplast? Where photosynthesis occurs Has 2 membranes that surround stroma Contains chlorophyll (captures light) In most plants, Leaves take in carbon dioxide from the atmosphere through openings called stomata (singular, stoma),which are small pores on the underside of the leaf. Why would stomata be important to have? They can close them to prevent water loss when temperatures are high.

Chlorophyll is the pigment inside the chloroplast that absorbs light for photosynthesis As the chlorophyll in leaves decays in the autumn, the green color fades and is replaced by the oranges and reds of carotenoids.

Two Stages of Photosynthesis 1st stage: light dependent reactions (LDR) uses chlorophyll and other molecules built into the thylakoid membranes, captures energy from sunlight, produces ATP and other energy-rich molecules, splits water molecules (the hydrogen atoms and electrons are needed in the next stage), and releases oxygen gas from the leaf. 2nd stage: light independent reactions (LIR) **Also called Dark Reaction or Calvin Cycle Requires NO light takes place in stroma Depends on energy from LDR Converts CO2 into organic molecule (sugar)

REVIEW Animation: Photosynthesis Reactants CO2 Light ADP + P Calvin Cycle Light Dependent Reaction ATP Chloroplast C6H12O6 Glucose O2 Products

Cellular Respiration: (2 types—Aerobic and Anaerobic) Cellular respiration is the process by which glucose is broken down 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.

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