Cellular Respiration

Cellular respiration

A process that releases energy, water, and carbon dioxide by breaking down glucose and other food molecules in the presence of oxygen

Identify the type of bond a substrate must have in order to react with ADP to form ATP

A substrate must have a high-energy phosphate bond that can be passed to ADP in order to produce ATP

Krebs cycle (definition)

An enzyme speeds the removal of an acetyl group from CoA The acetyl group joins with a 4-carbon molecule, forming a 6-carbon citrate molecule An oxidation reaction occurs twice and both times NADH is produced and CO2 is released Substrate-level ATP synthesis occurs Additional oxidation reactions produce 1 FADH2 + 1 NADH

Recognize that the overall breakdown of glucose is a redox equation.

As cellular respiration occurs, H atoms are removed from glucose and the result is carbon dioxide (oxidation). On the other hand, oxygen receives H atoms and becomes water (reduction).

Explain the function of NAD+ and FAD during cellular respiration.

As oxidation occurs, coenzymes NAD+ and FAD remove hydrogen atoms (e- + H+) from glucose. NAD+ becomes NADH and FAD becomes FADH2, and these molecules take two electrons each to the electron transport chain (ETC).

What are the energy-investment steps of glycolysis

At the beginning of glycolysis, two ATP are used to activate glucose, a 6-carbon (C6) molecule that splits into 2 C3 molecules, known as G3P.

Compare and contrast fermentation to glycolysis

During glycolysis, NAD+ carries out oxidation of substrate molecules and brings electrons to the ETC. In fermentation, NAD+ carries out oxidation and brings H atoms to pyruvate which is broken down to 2 lactate molecules or 2 alcohol molecules with the release of CO2.

Chemiosmosis

Electron transport carriers pump protons across the inner membrane. As H+ flows down the H+ gradient from the intermembrane space through the ATP synthase complex to the matrix, the enzyme, ATP synthase, synthesizes ATP

Glycolysis

Glycolysis breaks down glucose into two molecules of pyruvate. It produces and sends NADH to the ETC, producing 2 ATP.

List the inputs and outputs of the Krebs cycle.

Inputs: 2 acetyl groups, 6 NAD+, 2 FAD, 2 ADP + 2 P Outputs: 4 CO2, 6 NADH, 2 FADH2, 2 ATP

List the inputs/outputs of glycolysis

Inputs: glucose, 2 NAD+ Outputs: 2 pyruvate, 2 NADH, net gain of 2 ATP

Cristae

folds of inner membrane that jut out into the matrix

What are the inputs and outputs of fermentation?

input: glucose outputs: 2 lactate or 2 alcohol and 2 CO2, net gain of 2 ATP

Aerobic + Anaerobic

process that requires oxygen (preparatory reaction, Krebs cycle, electron transport chain) process that does not require oxygen (glycolysis)

Identify the four phases of cellular respiration and the location of each within the cell.

glycolysis (cytoplasm), preparatory (prep) reaction (matrix of the mitochondrion), Krebs cycle (matrix of the mitochondrion), electron transport chain (cristae of mitochondrion)

How are carbohydrates metabolized?

Carbohydrates are broken down into glucose which is broken down during cellular respiration.

Recognize the relationship between protein, carbohydrate, and fat metabolism.

Carbohydrates, fats, and proteins can all be catabolized to produce ATP molecules.

How are fats and oils metabolized?

Fats and oils are broken down into glycerol, which enters glycolysis, and 3 fatty acids, which are converted to acetyl CoA and enter the Krebs cycle.

Why is fermentation beneficial to the body

Fermentation is essential to organisms because it is anaerobic. When our muscles are working vigorously over a short period of time, like when we run, fermentation is a way to produce ATP even though oxygen is temporarily in limited supply.

Fermentation

Fermentation is glycolysis followed by the reduction of pyruvate by NADH either to lactate or alcohol and CO2, depending on the organism.

preparatory reaction

Pyruvate is converted to a 2-carbon acetyl group and combines with CoA to form Acetyl CoA, 2 NADH are produced, and 2 CO2 are given off.

Mitochondria

Membrane-enclosed organelle in which ATP molecules are produced during the process of cellular respiration

the electron transport chain (phase of cellular respiration)

NADH and FADH2 bring electrons to the ETC, which contains several cytochrome molecules. As electrons move from one complex to another, H+ is pumped into the intermembrane space, creating an H+ gradient. As H+ flows down its gradient through an ATP synthase complex, 32-34 ATP are produced. Oxygen is the final acceptor of electrons from the ETC and is reduced to water.

What are the energy-harvesting steps of glycolysis

Oxidation of G3P occurs by the removal of H atoms as NAD+ receives high-energy electrons and becomes NADH. The addition of phosphate results in two high-energy phosphate groups. An enzyme passes a high-energy phosphate to ADP so that ATP results (substrate-level ATP synthesis). Oxidation occurs by the removal of water Substrate-level ATP synthesis occurs again and two molecules of pyruvate result

How are proteins metabolized?

Proteins are broken down into amino acids, which undergo deamination. Their carbon skeletons can enter glycolysis, be converted to acetyl CoA, or enter the Krebs cycle directly.

Explain how CO2 (and specifically CO2 molecules) is a product of the preparatory reaction after noting the number of carbons in the reactants and the acetyl groups

Pyruvate is oxidized by the removal of hydrogen atoms and this releases a CO2 molecule. Because two pyruvates result from glycolysis, the reaction occurs twice and 2 CO2 molecules are produced per glucose molecule

the Krebs cycle (phase of cellular respiration)

The Krebs cycle finishes the oxidation of glucose breakdown products and produces CO2. It produces and sends both NADH and FADH2 to the ETC, producing 2 ATP.

Describe how the Krebs cycle is the workhorse of cellular respiration by comparing its outputs to those of glycolysis

The Krebs cycle produces 2 ATP, six NADH, and 2 FADH2. NADH and FADH2 bring high-energy electrons to the ETC, resulting in 22 ATP. Therefore, 24 ATP are produced per glucose molecule during the Krebs cycle.

Describe the organization of mitochondrial cristae

The cristae of a mitochondrion separate the matrix from the intermembrane space. It contains the ETC and the ATP synthase complex

ATP synthase

The enzyme that produces ATP from ADP and P (inorganic phosphate)

NAD+ & FAD

They are coenzymes that assist the enzymes involved in the oxidation of glucose breakdown products. They bring electrons to the electron transport chain in mitochondria during cellular respiration

Electron transport chain (definition)

a series of electron carriers in the cristae of a mitochondrion that allow the passage of electrons from a higher to lower energy level; the energy released is used for the synthesis of ATP

Matrix

an innermost compartment of a cell filled with a gel-like fluid

Anabolism

metabolic process by which large molecules are synthesized from smaller ones

Catabolism

metabolic process that breaks down large molecules into smaller ones

Products

molecules formed by the reaction

Reactant

molecules that participate in the reaction