Module 5 - Mitochondria and Cellular Energy Production Flashcards
What is catabolism?
The breakdown of cellular macromolecules. With respect to cellular energy, catabolism breaks down macromolecules and releases the energy stored within them. This released energy is transferred to other molecules and is ultimately stored as adenosine triphosphate (A T P) for use as the cell’s primary source of energy.
Ex: A T P, amino acids, waste products
What is Anabolism?
The production of cellular macromolecules. Anabolic reactions consume this A T P as small molecules are built into macromolecules that the cell needs.
Ex: Proteins, complex sugars, fatty acids
What is ATP?
ATP is composed of an adenosine molecule, a ribose sugar, and a chain of three phosphates. These phosphates are important as a lot of energy is stored in the bond between the 2nd and 3rd phosphates (as shown in the figure).When the 3rd phosphate is removed, adenosine diphosphate (A D P) is formed and energy is released, which can be used in cellular processes.
ATP=GTP
What are the 2 other energy molecules?
NAD+
Nicotinamide adenine dinucleotide
NAD+ is changed to its high energy form by the addition of an H+ion and two electrons, producing NADH
FAD
Flavin adenine dinucleotide
FAD is changed to its high energy form by the addition of two H+ions and two electrons, producing FADH2
What are the key components/structures of the mitochondria?
Outer Membrane: The outer membrane of the mitochondria wraps around the organelle. Acts like the skin of the mitochondria.
Intermembrane space: The space between the inner and outer membrane is called the inner membrane.
Inner Membrane/Cristae: The inner membrane folds into layers forming the structures called cristae. The cristae is the area where the high energy molecules are converted into Adenosine Triphosphate (ATP).
Matrix: The matrix is the space that is inside the mitochondria enclosed within the cristae and is the location where macromolecules are converted into high energy molecules.
What is cellular respiration?
Cellular respiration is the term used to describe A T P production and comprises the catabolic reactions and processes that convert organic macromolecules into ATP.
Stage 1 -
The stripping of high-energy electrons off these macromolecules and storing them in high-energy electron carriers.
Stage 2 -
In these processes, energy is stored as a proton gradient across the mitochondrial inner membrane and this gradient is then used to generate A T P.
What are the 3 types of carbohydrates?
Monosaccharide: Glucose
Monosaccharides, or “one sugar” are most commonly consumed in the form of glucose, which is widely used
as a sweetener.
Disaccharides : Lactose
More complex are the disaccharides, which consist of two monosaccharides bonded by an α-or β-1,4-glycosidic linkage. An example of a disaccharide is lactose found in milk, which consists of a molecule each of glucose and galactose.
Polysaccharide: Glycogen
Even more complex are the polysaccharides, which are much longer chains of monosaccharides. Polysaccharides, such as glycogen, act as energy storage molecules and must be broken down before being used to produce cell energy.
How does Glucose enter the cells?
Glucose first enters the bloodstream from ingested foods, de novo synthesis in the body, or from the breakdown of glycogen stores. Once in the blood, glucose circulates and is available for cells to use.
The most common way to get glucose into cells is by what are called glucose transporters (GLUT) found in most mammalian cells.
De novo synthesis: The formation of complex molecules in the body from simpler molecules
What are the 10 steps of Glycolysis?
Glucose + 2 A D P + 2 N A D+produces 2 pyruvate + 2 A T P + 2 N A D H
How is pyruvate further processed?
Pyruvate is not the endpoint of glucose metabolism. All of the enzymatic reactions of glycolysis are reversible meaning that if pyruvate or one of the intermediary products were to accumulate to a sufficient concentration, then it is possible that the forward conversion of glucose to pyruvate would stop and discontinue ATP production. Therefore, in order to prevent this, pyruvate must be further processed.
What is oxidative phosphorylation?
Oxidative phosphorylation is the process used by the cell’s mitochondria to convert N A D H and F A D H2into A T P through the electron transport chain (E T C), the protons in the intermembrane space (known as a chemiosmotic gradients), and A T P synthase.
How is energy stored in the body?
Carbohydrates
Carbohydrates are stored mainly as glycogen in muscles and the liver. Obviously, muscle glycogen is more readily available for use as liver glycogen needs to be broken down into glucose and secreted into the plasma. In times of glucose excess, glycogen stores are built up.
Fats
Fats are stored as triacylglycerols throughout the body. They must be broken down to release free fatty acids that need to be transported into the cells that need energy production.
Proteins
Proteins are stored mainly as skeletal muscle which is why there is muscle wasting if the body needs to use proteins as an energy source
What happens when too much ATP is produced or too little?
Excess ATP
When levels of A T P are in excess for the cells immediate use, the enzyme class creatine kinases convert creatine and A T P into phosphocreatine and A D P.
Deficiency in A T P
When A T P demands are high, these reactions reverse and the phosphate from phosphocreatine is transferred to A D P to form A T P. Importantly, this pathway for A T P generation does not require molecular oxygen so it can occur during anaerobic conditions.
