Energy in a Cell

Terms Autotroph creates their own food through photosynthesis or chemosynthesis. These organisms are producers. Heterotroph depends upon other organisms for nutrition. These organisms are consumers. Some organisms, such as the Euglena, will be photosynthetic in the presence of light and heterotrophic without light. Chemosynthetic Organisms that obtain cellular energy by breaking down inorganic chemicals

Energy Carriers ATP temporary energy storage molecule in all cells NADH H+ and e- carrier molecule NAD + + H+ + e- NADH FADH2 FAD + 2H+ + e- FADH2 Think of NADH and FADH2 as taxi cabs!

NADH and FADH2

All Cells Need Energy Cells need energy to do a variety of work: Making new molecules Building membranes and organelles Moving molecules in and out of the cell Movement

Where Does A Cell Get Energy? Food is broken down to a form the cell can use. Extra energy is stored in an ATP molecule, a nucleotide.

What Is ATP? ATP – adenosine triphosphate is a molecule made up of an adenine, ribose, and 3 phosphate groups. Adenine Ribose phosphate groups

A Simple Review Adenine Ribose P What basic unit of what organic compound is pictured to the right?

How Does ATP Work? Energy is stored in the bond between the second and third phosphate group. When the bond is broken, energy is released and ADP is formed. Adenine Ribose

ATP – Energy Currency Within a cell, formation of ATP from ADP and phosphate occurs over and over, storing energy each time. As the cell uses energy, ATP breaks down repeatedly to release energy and form ADP and phosphate.

Making Energy Cells make energy in two ways: Photosynthesis – takes place in the chloroplasts. Respiration – takes place in the mitochondria.

Photosynthesis Autotrophs make their own food by trapping light energy and converting it to chemical energy (carbohydrates).

Photosynthesis Using light from the sun, plants combine water and carbon dioxide to make sugar . General Equation: 6CO2 + 12H2O C6H12O6 + 6O2 + 6 H2O Reactants Products light

Chemosynthesis Some autotrophs can convert inorganic substances to energy. Most are adapted to live in conditions where there is no oxygen. Marshes Lake sediments Digestive tracts of mammals Deep in the ocean

This is a Black Smoker in the Pacific This is a Black Smoker in the Pacific. A tubular hydrothermal vent that releases hot water, known as a "black smoker", in the Pacific Ocean. http://gallery.yahoo.com/

Cellular Respiration The process of breaking down food molecules to release energy. Aerobic respiration occurs in the mitochondria. Two types: Aerobic – requires oxygen. Anaerobic – requires an absence of oxygen.

Cellular Respiration – Chemical Equation enzymes C6H12O6 + 6 O2 _ CO2 + _ H2O + 36-38 ATP

Cellular Respiration Cellular Respiration Steps Glycolysis Citric Acid Cycle Electron Transport Chain

Glycolysis Chemical Equation Glucose is split to form pyruvate. Takes place in the cytoplasm of the cell. ATP and NADH are byproducts. Glycolysis Chemical Equation Glucose + 2 NAD+ + 2 ADP + 2 Pi 2 pyruvate + 2 NADH + 2 ATP + 2 H2O Enzymes

Glycolysis C6H12O6 NAD+ 2 ATP NADH C3H3O4 +

2 ATP C6H12O6 (6 carbon molecule) 2 NAD+ (coenzyme) 2 ADP+P Review What are the inputs for Glycolysis? Glucose 2 ATP C6H12O6 (6 carbon molecule) 2 NAD+ (coenzyme) 2 ADP+P What are the outputs for Glycolysis? 2 pyruvic acid (3 carbon molecules) 2 NADH 2 ATP (makes 4 but 2 are needed in the process)

Anaerobic Respiration Two types of anaerobic respiration: Fermentation Occurs when bacteria break down plants (vegetables and fruit) and release alcohol or vinegar. Lactic Acid Fermentation Occurs in muscles – a buildup of lactic acid causes soreness.

Aerobic Respiration 2. Citric Acid Cycle A.K.A. Kreb’s Cycle Pyruvate is used to build citric acid (a carbon compound), which is broken down to release ATP. (# Net 2 ATP) Takes place in the cristae (the folded membrane in the mitochondrion) CO2 is released, and NADH & FADH2 carry electrons and hydrogen ions to the electron transport chain. Each glucose molecule takes two trips around the cycle!

Each glucose molecule takes 2 turns through the cycle! Inputs Pyruvate NAD+ FAD ADP + Pi Outputs 4 NADH 1 FADH2 1 ATP 3 CO2 Outputs 8 NADH 2 FADH2 2 ATP 6 CO2

3. Electron Transport Chain Electrons are reduced, and that energy forms large amounts of ATP. (#32-34 ATP) Takes place in the inner membrane of the mitochondrion The used ions are combined with oxygen to form H2O.

Electron Transport System NADH H2O NAD+ O2 FADH2 FAD 36-38 ATP

Review What are the inputs for the Krebs cycle? 1 Pyruvate (3 carbon molecule) 4 NAD+ 1 FAD 1 ADP + Pi What are the outputs for the Krebs cycle? (Per 1 pyruvate – 1 glucose yields 2X) 4 NADH 1 FADH2 1 ATP 3 CO2

Review What are the inputs for the ETS per one molecule of glucose? 10 NADH: 8 from Krebs, 2 from glycolysis 2 FADH2 : from Krebs cycle O2 What are the outputs for the ETS? 32-24 ATP molecules H2O

Total ATP Production 36 -38 ATP molecules enzymes C6H12O6 + 6 O2 6 CO2 + 6 H2O + 36-38 ATP

Heat O2 ATP H2O CO2 Glucose ATP Pyruvate MITOCHONDRION Electron Transport System O2 ATP H2O NAD+ FAD NADH FADH2 CO2 citric acid cycle Glucose ATP Pyruvate ATP MITOCHONDRION

CHLOROPLAST MITOCHONDRION Sunlight Heat O2 Photo- system II Photo- System I Electron Transport System ATP H2O ATP NADH FADH2 NADP+ ADP NADPH NAD+ FAD CO2 Calvin Citric Acid Cycle ATP Glycolysis Cycle ATP Glucose Pyruvate CHLOROPLAST MITOCHONDRION

CHLOROPLAST MITOCHONDRION Sunlight Photo- System I system II NADP+ ADP NADPH ATP Cycle Calvin CO2 H2O O2 NAD+ FAD NADH FADH2 Electron Transport Heat CHLOROPLAST MITOCHONDRION Glucose Pyruvate Glycolysis Citric Acid Cycle

Cellular Respiration C6H12O6 + O2 CO2 + H2O + 36-38 ATP 6 6 6

Oxidation - Reduction Oxidation is the loss of elecrons from an atom or molecule. It is also the loss (removal) of hydrogen atoms from a molecule. A loss of energy is associated with the loss of electrons or hydrogen atoms. Reduction is the gain of electrons or the gain of hydrogen atoms. This process stores energy.

Oxidation - Reduction Oxidation and reduction occur together. When a atom or molecule is oxidized, another must be reduced. Example: Na + Cl ®  Na+Cl-  - The Na is oxidized; the Cl is reduced.