Chapter 4 - Cells & Energy

ATP Production Total

Glycolysis: 2 (Aerobic) 2 (Anaerobic) Krebs Cycle: 2 (Aerobic) 0 (Anaerobic) Electron Transport: 32 (Aerobic) 0 (Anaerobic) Total: 36 (Aerobic) 2 (Anaerobic)

Chemosynthesis

the production of carbohydrates through the use of energy from inorganic molecules instead of light

2 Kinds of Fermentation

▪ Lactic acid fermentation occurs in muscle cells. - Glycolysis splits glucose into two pyruvate molecules. - Pyruvate and NADH enter fermentation. - Energy from NADH converts pyruvate into lactic acid. - NADH is changed back into NAD+. ▪ Alcoholic fermentation occurs in plant cells and some fungi (like yeast). ▪ Glycolysis splits glucose and the products enter fermentation. - Energy from NADH is used to split pyruvate into an alcohol and carbon dioxide. - NADH is changed back into NAD+. - NAD+ is recycled to glycolysis.

Photosynthesis in Plants Occurs in Chloroplasts

▪ Photosynthesis takes place in two parts of chloroplasts. - Grana - Stacks of coin-shaped, membrane-enclosed compartments called thylakoids. Membranes in thylakoids contain chlorophyll. - Stroma - Liquid that surrounds grana.

Light-Dependent Reactions

▪ The light-dependent reactions capture energy from sunlight. - Take place in membranes of thylakoids. - Water and sunlight are needed. - Chlorophyll absorbs energy from sunlight. - Energy is transferred along thylakoid membrane then to light-independent reactions. - Water is broken down. - Oxygen is released.

Light-Independent Reactions (Calvin Cycle)

▪ The light-independent reactions use the energy from the light-dependent reactions to make sugars. - Take place in stroma. - Needs carbon dioxide from atmosphere. - Use energy to build a sugar (usually Glucose) in a cycle of chemical reactions (Calvin Cycle).

Fermentation is Used in Food Production.

- Yogurt - Cheese - Bread - Beer/Wine

Photosynthesis Occurs in Two Main Stages

1. Light-Dependent Reactions 2. Light-Independent Reactions (Calvin Cycle)

Goal of Fermentation is to Keep Glycolysis Going when:

1. No oxygen is available. 2. Cell doesn't have Mitochondria.

ATP

- ATP is Adenosine Triphosphate (Adenine + three phosphate groups) - It transfers energy from the breakdown of food molecules to cell processes (i.e. building molecules, moving molecules, cell movement, etc.) - Analogy: Food is like a paycheck and ATP is like cash. The paycheck must be converted to cash before you can use it to buy things. - The energy in an ATP molecule is released when a phosphate group is removed. (ATP --> ADP + Energy) - ADP is a lower energy molecule. - ADP can be converted back to ATP by the addition of a phosphate group. - This requires energy (which is supplied by food). - Food supplies the energy to make ATP. - Different molecules in food contain different amounts of energy (measured in calories) so they provide different amounts of ATP. - Food that we eat must first be digested into smaller molecules (carbohydrates, lipids, proteins). - Then those molecules can be broken down to yield energy to make ATP (= cellular respiration).

Energy

- All cells need chemical energy. - The carbon-based molecules in our food (carbohydrates, lipids, proteins) store chemical energy in their bonds, but it is not in a usable form. - The molecules must be broken down through a series of reactions (cellular respiration) and converted into a usable form: ATP.

Cellular Respiration Makes ATP by Breaking Down Sugars and Other Carbon-Based Molecules

- Cellular respiration is aerobic, or requires oxygen. - Aerobic stages take place in mitochondria.

Chlorophyll

- Chlorophyll is a pigment molecule that absorbs light energy. - In plants, chlorophyll is found in organelles called chloroplasts. - Chlorophyll absorbs mostly blue and red wavelengths of light. - Plants appear green because they reflect green light.

Cellular Respiration is like a Mirror Image of Photosynthesis

- Equations are basically the reverse. - Structures in chloroplast and mitochondria are similar.

Fermentation Allows Glycolysis to Continue

- Fermentation allows glycolysis to continue making ATP when oxygen is unavailable. ▪ Fermentation is an anaerobic process. - Occurs when oxygen is not available for cellular respiration. - Does not produce ATP.

Cellular Respiration Takes Place in Three Main Stages

- Glycolysis - Krebs Cycle - Electron Transport Chain ▪ Glycolysis must take place first (2 ATP PRODUCED). - Anaerobic process (does not require oxygen). - Takes place in cytoplasm. - Splits glucose into two three-carbon molecules of pyruvate. - Produces two ATP molecules (net). ▪ The Krebs Cycle (2 ATP PRODUCED) - Transfers energy to an electron transport chain. - Takes place in mitochondrial matrix. - Breaks down three-carbon molecules from glycolysis. - Makes a small amount of ATP. - Releases carbon dioxide. - Transfers energy-carrying molecules. ▪ The Electron Transport Chain produces a large amount of ATP (32 ATP PRODUCED). - Takes place in inner membrane. - Energy transferred to electron transport chain. - Oxygen enters process. - ATP produced. - Water released as a waste product.

Carbohydrates

- Most commonly broken down to make ATP. - Very little stored in the body. - Each molecule of glucose yields about 36 ATP. ▪ Lipids - Store about 80% of the energy in our bodies. - Each triglyceride yields about 146 molecules of ATP. ▪ Proteins - Rarely used for energy. - Most amino acids are used to build new proteins. - Plant cells need ATP too. - Instead of eating food to get chemical energy, they make their own sugars from sunlight energy (photosynthesis). - Then they convert these sugars to ATP (cellular respiration). - Plants rely on sunlight to make chemical energy. - Animals eat plants (or other animals) to get energy. - Some organisms live in places where there is no sunlight (i.e hydrothermal vents--deep ocean).

Functions of Photosynthesis

- Plants produce food for themselves and other organisms. - Plants and animals use the carbohydrates produced by photosynthesis in cellular respiration (releases stored E in the form of ATP). ▪ It provides materials for plant growth and development (simple sugars bonded together form carbohydrates like starch and cellulose). - Starch = Storage Form of Sugar - Cellulose = Major Part of Plant Cell Wall - Regulates Earth's atmosphere (removes carbon dioxide from Earth's atmosphere).

Photosynthetic Organisms are Producers

- Producers make their own chemical energy. - Plants carry out photosynthesis and are producers (so are some protists (algae) and some bacteria). - Photosynthesis captures energy from sunlight to make sugars that store chemical energy. - Photosynthesis uses visible light made up of several different wavelengths of light.

Photosynthesis Equation

The equation for the overall process is: 6CO2 + 6H2O -> C6H12O6 + 6O2

Cellular Respiration Equation

The equation for the overall process is: C6H12O6 + 6O2 -> 6CO2 + 6H2O