9.1 Cellular Respiration: An Overview

All Living things require ENERGY, energy they acquire from the consumption of FOOD. #eating Of course, the chemical energy in food is released when the bonds of that molecule are broken down. REMEMBER! *Make a bond, Energy is absorbed. *Break a bond, Energy is released.

How much energy is actually present in FOOD? Short Answer: LOTS, but obviously it varies in amount. Amounts of Energy stored in FOOD is expressed in units called calories. calorie – the amount of food energy needed to raise the temperature of 1 gram of water, 1 degree Celsius.

There are 1,000 calories in 1 Calorie. The calories that we are familiar with are actually called kilocalories, or Calories. (notice the Big “C”) There are 1,000 calories in 1 Calorie. For example: 100,000 calories = ______ Calories. ______ calories = 54 Calories. 37,000 calories = ______ Calories.

Cells consider all types of molecules as FOOD. The 3 Main Types are… 1 Cells consider all types of molecules as FOOD. The 3 Main Types are… 1. Carbohydrates (approximately 4,000 calories of energy per gram).

2. Proteins (approximately 4,000 calories of energy per gram).

3. Fats (approximately 9,000 calories of energy per gram). *The differences in the amount of calories for the 3 macromolecules is due to their chemical structures. More bonds to break = more calories

How many Calories should I eat?

Cellular Respiration – process that releases energy Cellular Respiration – process that releases energy from food (chemical energy) in the presence of oxygen. Glucose  Energy The Overall Reaction: In Words:

The Process of Cell Respiration occurs in 3 Stages Stage 1: Glycolysis Need to know Occurs in the Cytoplasm of the Cell Starts with: 1 Glucose molecule Investment of 2 ATP. Produces with: A net gain of 2 ATP is made 2 NADH travels to the E.T.C. 2 Pyruvic Acids are made

Stage 2: Krebs Cycle Need to Know Occurs in the Matrix of the Mitochondria. 2 Turns of the Cycle (1 per Pyruvic Acid) Process Requires the presence of Oxygen Starts with: 2 Pyruvic Acids Produces: 2 ATP (1 per Pyruvic Acid) CO2 is produced (Waste Product) NADH and FADH2 carry electrons to the E.T.C.

Stage 3: Electron Transport Chain Need to Know Occurs in the Intermembrane Space of the Mitochondria. Starts with: Oxygen is required High Energy Electrons carried by NADH and FADH2, (acquired in Glycolysis and the Krebs Cycle). Produces: 32 ATP Water Molecules

2 ATP 2 ATP 32 ATP Cytoplasm  (Net Gain) The Matrix  (1 per Pyruvic Acid) Intermembrane Space  32 ATP

Photosynthesis and Cellular Respiration can be thought of as opposite reactions. The reactants for one become the products of the other.

9.3 Fermentation Cellular Respiration is sometimes called Aerobic Respiration. Aerobic means “With Air” or in the presence of Oxygen. Respiration can also occur in the absence of Oxygen as well. This is called Anaerobic Respiration. (No Air) Without Oxygen, the Pyruvic Acids produced during Glycolysis cannot enter the Krebs Cycle. Instead, an alternative process called Fermentation can occur in order to continue the breakdown and create ATP.

There are two types of Fermentation: Alcoholic Fermentation (performed by yeast cells) Lactic Acid Fermentation (performed by muscle cells)

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