Cellular Respiration

Describe glycolysis in detail.

BASIC OVERVIEW OF GLYCOLYSIS -The first set of reactions in cellu;ar respiration is called glycolysis, which literally means "sugar-breaking". -During glycolysis, 1 molecule of glucose, a 6-carbon compound, is transformed into 2 molecules of pyruvic acid, which is a 3-carbon compound. -As the bonds of the glucose are broken and rearranged, energy is released. ATP PRODUCTION IN GLYCOLYSIS -In order for glycolysis to start, the cell needs a little bit of energy to get it going. -At the beginning of glycolysis, 2 molecules of ATP are used up. -Although the cell puts in 2 ATP molecules into glycolysis to get it going, the process of glycolysis produces 4 ATP molecules. This means that the cell gets a net gain of 2 ATP molecules for each molecule of glucose that enters the process of glycolysis. NADH PRODUCTION -One of the reactions of glycolysis removes 4 electrons, now in a high-energy state, and passes them to an electron carrier called NAD+ (NOT NADP+!). NAD+ stands for nicotinamide adenine dinucleotide. -NAD+ is kind of like NADP+ in photosynthesis, because it accepts a pair of high-energy electrons. Once they are accepted, NAD+ becomes NADH. It will hold the electrons until they can be transferred to other molecules. These high-energy electrons can then be used to produce even more ATP molecules.

What kinds of macromolecules can cells use for food? Explain.

Cells can use all sorts of different molecules for food, like: -Fats (9000 calories per gram) -Proteins (4000 calories per gram) -Carbohydrates (4000 calories per gram) The energy in each of the macromolecules varies because their chemical structures, and thus their energy storing bonds, differ. Ex: 1 gram of the sugar glucose releases 3811 calories of heat energy when burned, but 1 gam of the triglyceride fats found in beef releases 8893 calories when its bonds are broken.

Give an overview of cellular respiration, and include all of the formulas involved.

If oxygen is available, organisms can obtain energy from food by a process called *cellular respiration*. Cellular respiration is the process that releases energy from food in the presence of oxygen. Cellular respiration involves dozens of chemical reactions, but the general overview of the equations is very simple. 6 O2 + C6-H12-O6 --> 6 CO2 + 6 H2O + Energy Oxygen + Glucose --> Carbon dioxide + Water + Energy Cellular respiration involes and requires oxygen and a food molecule like glucose, and it gives of carbon diozide, water and energy. Though the equation of cellular respiration is super simple, the chemical process is actually extremely conplicated. If it all happened in one step, most of the energy released from the glucose would be released all at once in the form of light and heat. That would basically start a fire, and obviously the body can't do that. Thus, it takes the explosive energy in the food and converts it little by little into ATP (adenosine triphosphate).

What organelle is used to convert the chemical energy in food to usable energy that cells can use to carry out their life processes?

In photosynthesis, plants use chloroplasts to get energy from the sun and convert it to energy-rich sugars. In cellular respiration, however, the mitochondria is reponsible for converting chemical energy stored in food to usable energy for the cell. -Glycolysis occurs in the cytoplasm of the cell, but the Krebs Cycle and the electron transport chain, which generate most of the ATP needed for cellular respiration, take place inside of the mitochondria itslef. If there is no oxygen, then another process is used ny the cell to get ATP. This process is known as fermentation, which you will learn about later.

What is the direct difference between aerobic respiration and anaerobic respiration?

Pathways of cellular respiration that require oxygen are said to be aerobic, or "in air". The Krebs Cycle and the electron transport chain are both aerobic processes. Even though the Krebs Cycle doesn't directly require oxygen, it is classified as aerobic because it cannot run without the oxygen-requiring electron transport chain. Glycolysis doesn't directly require oxygen, nor rely on oxygen-requiring processes to run. Thus, it is known as anaerobic, or "without air". Even though it is anaerobic, it is considered part of cellular respiratin because its final products are key reactants for the aerobic stages.

True or false? Cells burn food and release energy as heat.

The correct answer is FALSE, cells do not simply burn food and release energy as heat. Instead, they break down food molecules gradually, capturing a little bit of energy at key steps. This allows them ti use energy stored in the bonds of the food the organisms eat and convert in to ATP, which can be used by the cells.

Describe how cellular respiration and photosynthesis are balanced.

The energy in cellular respirations and photosynthesis flows in opposite directions. Think of the cmeical energy in photosynthesis as money in the Earth savings account. Photsynthesis is the process that deposits this energy, while cellular resporation withdraws the energy, This is why the equations for photosynthesis and cellular respiration are the reverse of each other. Photoysnthesis removes carbon dioxde from the atmosphere, and cellular respiration puts it back. Photosynthesis releases oxygen in the atmosphere, and cellular respiration uses that oxygen to release energy from food.

What are calories?

There is quite a lot of energy trapped in food (it varies with the type of food). Energy stored in food is expressed in a unit called a calorie. A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree celcius. The Calorie, which is different from the calorie, is also known as a kilocalorie, because it contains 1000 calories.

What is the importance of food in all organisms?

Whether the organism is a heterotroph, meaning that it must rely on other organisms for food, or an autotroph, meaning that it can make its own food through photosynthesis, orgnisms get the energy they need from food. Food molecules contain chemical energy that is released when their chemical bonds are broken.