Name the intermediate and the end products of glucose breakdown in aerobic respiration.

Fermentation is a widespread pathway, but it is not the only way to get energy from fuels anaerobically (in the absence of oxygen). Some living systems instead use an inorganic molecule other than O 2 \text _2 O 2 ​ start text, O, end text, start subscript, 2, end subscript , such as sulfate, as a final electron acceptor for an electron transport chain. This process, called anaerobic cellular respiration, is performed by some bacteria and archaea. Anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain, driving ATP \text^-) ( NO 3 − ​ ) left parenthesis, start text, N, O, end text, start subscript, 3, end subscript, start superscript, minus, end superscript, right parenthesis , sulfur, or one of a variety of other molecules 1 ^1 1 start superscript, 1, end superscript . What kinds of organisms use anaerobic cellular respiration? Some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels. For example, some archaea called methanogens can use carbon dioxide as a terminal electron acceptor, producing methane as a by-product. Methanogens are found in soil and in the digestive systems of ruminants, a group of animals including cows and sheep. Similarly, sulfate-reducing bacteria and Archaea use sulfate as a terminal electron acceptor, producing hydrogen sulfide ( H 2 S ) (\text H_2\text S) ( H 2 ​ S ) ...

Definition Aerobic respiration is the process by which organisms use oxygen to turn fuel, such as fats and sugars, into chemical energy. In contrast, anaerobic respiration does not use oxygen. Respiration is used by all cells to turn fuel into energy that can be used to power cellular processes. The product of respiration is a molecule called adenosine triphosphate (ATP), which uses the energy stored in its phosphate bonds to power chemical reactions. It is often referred to as the “currency” of the cell. Aerobic respiration is much more efficient, and produces ATP much more quickly, than anaerobic respiration. This is because oxygen is an excellent electron acceptor for the chemical reactions involved in generating ATP. An overview of the stages of aerobic respiration Aerobic vs Anaerobic Similarities Both aerobic and anaerobic respiration are methods of generating energy. They also both start in the same way, with the process of glycolysis. “Glycolysis” literally means “sugar splitting,” and involves breaking a sugar molecule down into two smaller molecules. In the process of glycolysis, two ATP molecules are consumed and four are produced. This results in a net gain of two ATP molecules produced for every sugar molecule broken down through glycolysis. This is where the similarities between aerobic and anaerobic respiration end. In cells that have oxygen and aerobic respiration can proceed, a sugar molecule is broken down into two molecules of pyruvate. In cells that do ...

You, like many other organisms, need oxygen to live. As you know if you’ve ever tried to hold your breath for too long, lack of oxygen can make you feel dizzy or even black out, and prolonged lack of oxygen can even cause death. But have you ever wondered why that’s the case, or what exactly your body does with all that oxygen? As it turns out, the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation, the final stage of cellular respiration. Oxidative phosphorylation is made up of two closely connected components: the electron transport chain and chemiosmosis. In the electron transport chain, electrons are passed from one molecule to another, and energy released in these electron transfers is used to form an electrochemical gradient. In chemiosmosis, the energy stored in the gradient is used to make ATP. So, where does oxygen fit into this picture? Oxygen sits at the end of the electron transport chain, where it accepts electrons and picks up protons to form water. If oxygen isn’t there to accept electrons (for instance, because a person is not breathing in enough oxygen), the electron transport chain will stop running, and ATP will no longer be produced by chemiosmosis. Without enough ATP, cells can’t carry out the reactions they need to function, and, after a long enough period of time, may even die. The electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria. Electro...

Learning Objectives By the end of this section, you will be able to: • Describe how the body digests carbohydrates • Describe how, when, and why the body metabolizes carbohydrates • Explain the processes of glycolysis • Describe the pathway of a pyruvate molecule through the Krebs cycle • Explain the transport of electrons through the electron transport chain • Describe the process of ATP production through oxidative phosphorylation • Summarize the process of gluconeogenesis Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen atoms. The family of carbohydrates includes both simple and complex sugars. Glucose and fructose are examples of simple sugars, and starch, glycogen, and cellulose are all examples of complex sugars. The complex sugars are also called polysaccharides and are made of multiple monosaccharide molecules. Polysaccharides serve as energy storage (e.g., starch and glycogen) and as structural components (e.g., chitin in insects and cellulose in plants). During digestion, carbohydrates are broken down into simple, soluble sugars that can be transported across the intestinal wall into the circulatory system to be transported throughout the body. Carbohydrate digestion begins in the mouth with the action of salivary amylase on starches, continues in the duodenum with the action of pancreatic amylase, and ends with monosaccharides being absorbed across the epithelium of the small intestine. Once the absorbed monosaccharides are transporte...

\( \newcommand\) • • • • • • • • • • • Learning Objectives • Briefly describethe function of glycolysis during aerobic respiration and indicate the reactants and products. • State whether or not glycolysis requires oxygen. • Compare where glycolysis occurs in prokaryotic cells and in eukaryotic cells. • State whether steps 1 and 3 of glycolysis are exergonic or endergonic and indicate why. • State why one molecule of glucose is able to produce two molecules of pyruvate during glycolysis. • Define substrate-level phosphorylation. • State the total number and the net number of ATP produced by substrate-level phosphorylation during glycolysis. • During aerobic respiration, state what happens to the 2 NADH produced during glycolysis. • During aerobic respiration, state what happens to the two molecules of pyruvate produced during glycolysis. Steps of Glycolysis • A phosphate from the hydrolysis of a molecule of ATP is added to glucose, a 6-carbon sugar, to form glucose 6-phosphate. • The glucose 6-phosphate molecule is rearranged into an isomer called fructose 6-phosphate. • A second phosphate provided by the hydrolysis of a second molecule of ATP is added to the fructose 6-phosphate to form fructose 1, • The 6-carbon fructose 1,6-biphosphate is split into two molecules of glyceraldehyde 3-phosphate, a 3-carbon molecule. • Oxidation and phosphorylation of each glyceraldehyde 3-phosphate produces 1,3-biphosphoglycerate with a high-energy phosphate bond (wavy red line) and NADH....

Learning Objectives By the end of this section, you will be able to: • Explain the processes of glycolysis • Describe the pathway of a pyruvate molecule through the Krebs cycle • Explain the transport of electrons through the electron transport chain • Describe the process of ATP production through oxidative phosphorylation • Summarize the process of gluconeogenesis Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen atoms. The family of carbohydrates includes both simple and complex sugars. Glucose and fructose are examples of simple sugars, and starch, glycogen, and cellulose are all examples of complex sugars. The complex sugars are also called polysaccharides and are made of multiple monosaccharide molecules. Polysaccharides serve as energy storage (e.g., starch and glycogen) and as structural components (e.g., chitin in insects and cellulose in plants). During digestion, carbohydrates are broken down into simple, soluble sugars that can be transported across the intestinal wall into the circulatory system to be transported throughout the body. Carbohydrate digestion begins in the mouth with the action of salivary amylase on starches and ends with monosaccharides being absorbed across the epithelium of the small intestine. Once the absorbed monosaccharides are transported to the tissues, the process of cellular respiration begins (Figure 1). This section will focus first on glycolysis, a process where the monosaccharide glucose is oxidized, rel...

Learning Objectives By the end of this section, you will be able to: • Explain how energy can be derived from fat • Explain the purpose and process of ketogenesis • Describe the process of ketone body oxidation • Explain the purpose and the process of lipogenesis Fats (or triglycerides) within the body are ingested as food or synthesized by adipocytes or hepatocytes from carbohydrate precursors. Lipid metabolism entails the oxidation of fatty acids to either generate energy or synthesize new lipids from smaller constituent molecules. Lipid metabolism is associated with carbohydrate metabolism, as products of glucose (such as acetyl CoA) can be converted into lipids. Figure 1. A triglyceride molecule (a) breaks down into a monoglyceride (b). Lipid metabolism begins in the intestine where ingested triglycerides are broken down into smaller chain fatty acids and subsequently into monoglyceride molecules by pancreatic lipases, enzymes that break down fats after they are emulsified by bile salts. When food reaches the small intestine in the form of chyme, a digestive hormone called cholecystokinin (CCK) is released by intestinal cells in the intestinal mucosa. CCK stimulates the release of pancreatic lipase from the pancreas and stimulates the contraction of the gallbladder to release stored bile salts into the intestine. CCK also travels to the brain, where it can act as a hunger suppressant. Figure 2. Chylomicrons contain triglycerides, cholesterol molecules, and other apolip...

Aerobic respiration is a biological process that takes energy from glucose and other organic compounds to create a molecule called Adenosine TriPhosphate (ATP). ATP is then used as energy by nearly every cell in the body -- the largest user being the muscular system. Aerobic respiration has four stages: Glycolysis, formation of acetyl coenzyme A, the citric acid cycle, and the electron transport chain. The first step of aerobic respiration is glycolysis. This step takes place within the cytosol of the cell, and is actually anaerobic, meaning it does not need oxygen. During glycolysis, which means breakdown of glucose, glucose is separated into two ATP and two NADH molecules, which are used later in the process of aerobic respiration. The next step in aerobic respiration is the formation of acetyl coenzyme A. In this step, pyruvate is brought into the mitochondria to be oxidized, creating a 2-carbonacetyl group. This 2-carbon acetyl group then binds with coenzyme A, forming acetyl coenzyme A. The acetyl coenzyme A is then brought back into the mitochondria for use in the next step. The third step of aerobic respiration is called the citric acid cycle -- it is also called the Krebs cycle. Here, oxaloacetate combines with the acetyl coenzyme A, creating citric acid -- the name of the cycle. Two turns of the citric acid cycle are required to break down the original acetyl coenzyme A from the single glucose molecule. These two cycles create an additional two ATP molecules, as w...