Anatomy Chapter 25- Metabolism and Nutrition
because glucose is the body's preferred source for synthesizing ATP, its use depends on the needs of body cells, which include the following:
* ATP production- in body cells that require immediate eenergy, glucose is oxidizes to produce ATP. glucose not needed for immediate ATP production can enter one of several there metabolic pathways * amino acid synthesis- cells throughout th body can use glucose to form several amino acids, which then can be incorporated into proxies * glycogen synthesis- hepatocytes and muscle fibers can perform glycogen's in which hundreds of glucose monomers are combines to form the pholysaccharide glycogen trugkyceride synthesis-when the glycogen storange areas are filled up, hepatocytes can transform the glucose to glycerol and carry acids that can be used for lipogenesis, the synthesis of triglycerides. then the tryglerides are deposited into adipose tissue, which has virtually unlimited storage capaity
what can serve as an electron carrier?
* flavin mononycleotide cytochromoes iron-sulfer centers copper atoms coenzyme Q
protien digestion and absorption
***Begins in the stomach. Low pH in stomach destroys tertiary and quaternary structure Denaturation is process of breaking it down Enzymes used include pepsin, trypsin, chymotrypsin, and elastase Release short peptides and free amino acids Amino acids are absorbed
summary of glycolysis
***GLYCOLYSIS:A partial breakdown of glucose into: 2 molecules of pyruvic acid 4 protons and 4 electrons (accepted by 2NAD+ to form 2NADH + 2H+), and 2 net ATP (from substrate-level phosphorylation). NOTE: this process does not require O2 and does not yield much energy. Glycolysis is the anaerobic catabolism of glucose. It occurs in virtually all cells. In eukaryotes, it occurs in the cytosol. It converts a molecule of glucose into 2 molecules of pyruvic acid. C6H12O6 + 2NAD+ -> 2C3H4O3 + 2NADH + 2H+ The free energy stored in 2 molecules of pyruvic acid is somewhat less than that in the original glucose molecule. Some of this difference is captured in 2 molecules of ATP.
how does chemiosmosis work?
1. energy from NADH+ H+ passes along the electron tranposrt chain and is used to pump H+ from the matrix os the mitochondrion into the space between the inner and outer mitochondrial membrane.s. this mechanism is called a proton pump because H+ ions consist of a single proton. 2. a high concentration of H+ accumulates between the inner and outer mitochndrial membranes 3. ATP synthesis then occurs as hydrogen ions flow back into the mitochondrial matrix through a special type of H+ channel in the inner membrane
what are the 8 reactions of the krebs cycle
1. entry of acetyl group= the chemical bond that attaches the acetly group to coenzyme A breaks and thehe 2 carbon acetyl group attaches to a 4 carbon molecule of oxaloactive acid to form a 6 carbon molecule called citric acid. CoA is free to combine with another acetyl group from pyretic acid and repeat the process 2. isomerization- citric acid undergoes isomerization to isometric acid, which has the same moleculear formula as citrate. the hydrozl group attaches to a different carbon 3. oxidative decarboxylation- isometric acid is oxidized and loses a molecule of CO2 forming alpha ketoglutaric acid. the H+ from the oxidation is passed on to NAD+ which is reduced to NADH+H+ 4. oxidative decarboxylation- alpha ketoglutaric acid is oxidized, loses a molecule of CO2 and picks up CoA to form saucily CoA 5. substrate level phosphorylation- CoA is displaced by a phosphate group, which is then transferred to guanosine diphosphate to form guanosine triphosphate. GTP can donate a phosphate group to ADP to form ATP 6. dehydrogenation- succinct acid is oxidized to fumaric acid as two of its hydrogen atoms are transferred to the xoenzy flavin adenine dinucleotide FAD, which is reduced to FADH2 7. hydration- fumaric acid is concerted to malic acid by the addition of a molecule of water 8. dehydrogenation- in the final step in the cycle, malic acid is oxidized and re rom oaloactic acid. two hydrogen atoms are removed and one is transferred to NAD+ which is reduced to NADH + H+. the regenerated oxaloacetic acid can combine with another molecule of acetyl CoA, bringing a new cycle
what are the ten reactions of glycolysis?
1. glucose is hosphorylated, using a phosphate group from an ATP molecule to form glucose 6 phosphate 2. glucose 6 phosphate is converted to fructuose 6 phosphate 3. a second ATP is used to add a second phosphate group to fructose 6 phosphate to form fructose 1,6-bisphosphate 4-5 fructose splits into two 3 carbon molecules, glyceraldehyde 3 phosphate and dihydroxyacentron phosphate, each having one phase group 6.oxidation occurs as two molecules of NAD+ accept two pairs of electrons and hydrogen ions from two molecules of G 3-P to form two molecules of NADH. body cells use the two NADH produced in this step to generate ATP in the electron transport chain. a second phophate group attached to G3P, forming 1,3 biphosphogelyceric acid 7-10 these reactions generate four molecules of ATP and produce two molecules of pyruvic acid(pyruvvate)
what are the three chaises of phosphorylation to generate ATP?
1. substrate level phosphorylation genergtes ATP by transferring a high energy phosphate group from an intermediate phosphorylated meabolic compound- a substrate- directly to ADP this occurs in the cytosol in humans 2. oxidative phosphorylation removes electrons from organic compounds and pass them through a series of electron acceptros called the electoral transport chain, to molecules of oxygen, this occurs in the inner mitrocdiral membrane 3. photophosphorylation occurs only in chlorophll containing plant cells or in certain bacteria that contain other light absorbing pigment
final products of glycolysis
2 pyruvic acid Converted to lactic acid if O2 not readily available (lateral diversion) Enter aerobic pathways if O2 is readily available into Krebs cycle 2 NADH + H+ Net gain of 2 ATP
suagar oxidation and ATP formation
3-carbon sugars are oxidized (reducing NAD+) Inorganic phosphate groups (Pi) are attached to each oxidized fragment 4 ATP are formed by substrate-level phosphorylation
lipid transport and distribution
5 types of lipoprotein Lipid-protein complex that contains large glycerides and cholesterol Chylomicrons Largest lipoproteins composed primarily of triglycerides Very low-density lipoproteins (VLDLs) contain triglycerides, phospholipids and cholesterol 5 types of lipoprotein (continued) Intermediate-density lipoproteins (IDLs) Contain smaller amounts of triglycerides Low-density lipoproteins (LDLs) Contain mostly cholesterol Transport cholesterol to peripheral tissues Cholesterol may form plaques in arteries High-density lipoproteins (HDLs) Equal amounts of lipid and protein Transport cholesterol to liver for degradation
what is a coenzyme?
A nonproteinaceous organic substance that usually contains a vitamin or mineral and combines with a specific protein, the apoenzyme, to form an active enzyme system. Coenzymes are organic substances that are essential to enzymes. Coenzymes loosely bind to certain proteins and often contain either a vitamin or mineral. Without a coenzyme as a activator an enzyme is unable to function as necessary.
lipid synthesis- lipogenesis
Almost any organic molecule can be used to form glycerol Essential fatty acids cannot be synthesized and must be included in diet Linoleic and linolenic acid
vitamins
Are needed in very small amounts for a variety of vital body activities Fat soluble Vitamins A, D, E, K Taken in excess can lead to hypervitaminosis Water soluble Not stored in the body Lack of adequate dietary intake causes avitaminosis
Carbohydrate digestion and absorption
Begins in the mouth with salivary amylase Breaks starch into maltose (disaccharide) Pancreatic enzymes continue digestion AFTER it leaves the stomach (2nd phase) Absorption of monosaccharides occurs across the intestinal epithelia (duodenum) Requires facilitated diffusion
what is the oxidation of glucose?
C6H12O6 + 6O2 6H2O + 6CO2 + 36 ATP + heat
cells and mitochondria
Cells provide small organic molecules for their mitochondria Carbohydrates are first choice, then triglycerides Proteins only used if necessary Mitochondria produce ATP used to perform cellular functions ATP produced by aerobic respiration The chemical formula for this process is C6H12O6 + 6 O2 6 CO2 + 6 H2O + 36 ATP
forms of metabolism
Cellular respiration: catabolism of food fuels and capture of energy to form ATP in cells Enzymes shift high-energy phosphate groups of ATP to other molecules (phosphorylation) Phosphorylated molecules are activated to perform cellular functions
catabolism
Decomposition (breakdown) reactions Molecules broken into smaller units May release energy ***Aerobic respiration is main catabolic pathway in human cells 1st -Glucose is catabolized to carbon dioxide and water Produces 36 ATP molecules/glucose molecule Other nutrients can be catabolized for energy
transitional phase of krebs cycle
Each pyruvic acid is converted to acetyl CoA Decarboxylation: removal of 1 C to produce acetic acid and CO2 Oxidation: H+ is removed from acetic acid and picked up by NAD+ Acetic acid + coenzyme A forms acetyl CoA
lipoprotien lipase
Enzyme that breaks down complex lipids Found in capillary walls of liver, adipose tissue, skeletal and cardiac muscle Releases fatty acids and monoglycerides that can diffuse into interstitial fluid
postabsorpative state
From the end of the absorptive state to the next meal Body relies on reserves for energy Liver cells break down glycogen, releasing glucose into blood Liver cells synthesize glucose (gluconeogenesis) Lipolysis increases and fatty acids released into blood stream Fatty acids undergo beta oxidation and enter TCA Amino acids either converted to pyruvate or acetyl-CoA Skeletal muscles metabolize ketone bodies and fatty acids Skeletal muscle glycogen reserves broken down to glucose May be converted to lactic acid if muscles are very active Neural tissue continues to be supplied with glucose
sugar cleavage
Fructose-1,6-bisphosphate is split into 3-carbon sugars Dihydroxyacetone phosphate Glyceraldehyde 3-phosphate
Gluconeogenesis
Glucose formation from noncarbohydrate (glycerol and amino acid) molecules Mainly in the liver Protects against damaging effects of hypoglycemia
sugar activation
Glucose is phosphorylated by 2 ATP to form fructose-1,6-bisphosphate
Glycogenolysis
Glycogen breakdown in response to low blood glucose (automatic)
Glucose storage: glycogensis
Glycogen formation when glucose supplies exceed need for ATP synthesis Mostly in liver and skeletal muscle
High-density lipoproteins (HDLs)
High-density lipoproteins (HDLs) Equal amounts of lipid and protein Transport cholesterol to liver for degradation
more on substrate level phosphorylation
High-energy phosphate groups directly transferred from phosphorylated substrates to ADP ***Occurs in glycolysis and the Krebs cycle ***Substrate-level phosphorylation is the production of ATP from ADP by a direct transfer of a high-energy phosphate group from a phosphorylated intermediate metabolic compound in an exergonic catabolic pathway.
what happens during starvation and fasting
Homeless population Fasting -means going without food for many hours or even a few days. Starving- implies weeks or months of food deprivation or inadequate food intake. Tech humans can survive without food X 2 months if they have fluid intake available. ***Nervous system & RBC's still need Glucose for ATP production. The body slows the pace of protein synthesis which is why they last for several wks. Most serious/dramatic change occurs with the increased production of KETONES . Increased ketone levels suck the ATP from the brain & nervous systems =coma.
amino acid catabolism
If other sources inadequate, mitochondria can break down amino acids Enter TCA cycle Removal of the amino group (-NH2) Transamination - attaches removed amino group to a keto acid Deamination - removes amino group generating NH4+ Proteins are an impractical source of ATP production
oxidative phosphorylation summary
In the mitochondria Carried out by electron transport proteins Nutrient energy is used to create H+ gradient across mitochondrial membrane H+ flows through ATP synthase Energy is captured and attaches phosphate groups to ADP
how is lactic acid formed
Lactic acid fermentation. This pathway is common for animal cells and lactic acid bacteria. In animals the anaerobic glycolysis take place in many tissues. Red blood cells take most of the energy from anaerobic metabolism. Skeletal muscle takes energy from glycolysis and from respiration.
lipid digestion and absorption
Lipid digestion utilizes lingual (mouth)and pancreatic lipases (duodenum) Bile salts improve chemical digestion by emulsifying lipid drops Lipids not water soluble ***Lipases break triglycerides into glycerol and fatty acids Lipid-bile salt complexes called micelles are formed Micelles diffuse into lymph which release lipids into the blood as chylomicrons
lipid catabolism
Lipolysis Lipids broken down into pieces that can be converted into pyruvate ***Triglycerides are split into glycerol and fatty acids Glycerol enters glycolytic pathways Fatty acids enter the mitochondrion ***Generate more ATP than carbohydrates More potential energy Beta-oxidation Breakdown of fatty acid molecules into 2-carbon fragments Enter the TCA (Krebs cycle) Irreversible Lipids and energy production Cannot provide large amounts of ATP in a short amount of time Used when glucose reserves are limited
five metabolic compoents of the body
Liver The focal point for metabolic regulation and control Performs anabolic and catabolic reactions Adipose tissue Stores lipids primarily as triglycerides Skeletal muscle Substantial glycogen reserves Neural tissue Must be supplied with a reliable supply of glucose Can only use glucose to form ATP Other peripheral tissues No large metabolic reserves Ability to metabolize various nutrients is dependent upon hormonal control
Low-density lipoproteins (LDLs)
Low-density lipoproteins (LDLs) Contain mostly cholesterol Transport cholesterol to peripheral tissues Cholesterol may form plaques in arteries
metabolism
Metabolism is all the chemical reactions that occur in an organism Catabolic and anabolic reactions Cellular metabolism Cells break down excess carbohydrates first, then lipids to generate ATP Cells conserve amino acids Used as last resort to form ATP 40% of the energy released in catabolism is captured in ATP Rest is released as heat
micelles
Micelles are spheres of lipids that form in aqueous solutions.*** In humans, they form from bile salts. These micellar aggregates help transport the digestive products of lipids to the intestine to be absorbed. Degradation requires the help of biological detergents known as bile salts, secreted by the gall bladder and liver. The principle of micelle formation is like that of oil not mixing with water.
homeostasis
No one cell of the human body can perform all necessary homeostatic functions Metabolic activities must be coordinated
diet and nutrition
Nutrition Absorption of nutrients from food Balanced diet Contains all the ingredients necessary to maintain homeostasis Includes nutrients, vitamins, minerals, water Prevents malnutrition
Digestion
Processing and absorption of nutrients Disassembles organic food into smaller fragments Hydrolyzes carbohydrates, proteins, lipids and nucleic acids for absorption
stages of metabolism
Processing of nutrients Digestion, absorption and transport to tissues Cellular processing (in cytoplasm) Synthesis of lipids, proteins, and glycogen, or Catabolism (glycolysis) into intermediates Oxidative (mitochondrial) breakdown of intermediates into CO2, water, and ATP
difference between OP and SLP?
Substrate-level phosphorylation occurs during Glycolysis and the Kreb's Cycle and involves the physical addition of a free phosphate to ADP to form ATP. Oxidative phosphorylation, on the other hand, takes place along the electron transport chain, where ATP is synthesized indirectly from the creation of a proton gradient and the movement of these protons back across the membrane through the protein channel, ATP synthase. As the protons pass through, ATP is created.
anabolism
Synthesis reactions Formation of carbohydrates, lipids, proteins, nucleic acids, etc. Necessary for structural maintenance (cytoskeletal elements) and repairs to tissues (2ͦ to scraps, etc.) and cells Support of growth Necessary for cell reproduction (DNA replication, RNA synthesis) Production of secretions Hormones, etc. Building of nutrient reserves Glycogen, triglycerides, etc.
more on oxidative phosphorylation
The NADH and FADH2 formed in glycolysis, fatty acid oxidation, and the citric acid cycle are energy-rich molecules because each contains a pair of electrons having a high transfer potential. When these electrons are used to reduce molecular oxygen to water, a large amount of free energy is liberated, which can be used to generate ATP. Oxidative phosphorylation is the process in which ATP is formed as a result of the transfer of electrons from NADH or FADH 2 to O 2 by a series of electron carriers. ***This process, which takes place in mitochondria, is the major source of ATP in aerobic organisms. For example, oxidative phosphorylation generates 26 of the 30 molecules of ATP that are formed when glucose is completely oxidized to CO2 and H2O. The flow of electrons from NADH or FADH2 to O2 through protein complexes located in the mitochondrial inner membrane leads to the pumping of protons out of the mitochondrial matrix. The resulting uneven distribution of protons generates a pH gradient and a transmembrane electrical potential that creates a proton-motive force. ATP is synthesized when protons flow back to the mitochondrial matrix through an enzyme complex. Thus, the oxidation of fuels and the phosphorylation of ADP are coupled by a proton gradient across the inner mitochondrial membrane. Oxidative phosphorylation is the culmination of a series of energy transformations that are called cellular respiration.
more on glycolysis
The metabolism of glucose trough aerobics or anaerobic pathways is a nonoxidative process. Both types of glycolysis release a small fraction of potential energy stored in the glucose molecules. During the first 10 steps of glycolysis, only a small part of all glucose energy is released and the rest of the potential energy is released during the last steps after glycolysis. . For this reason aerobic degradation is much more efficient than anaerobic metabolism. That is why the aerobic mechanism is now much more spread within living organisms, but nevertheless anaerobic pathways still take place even in animals under certain physiological circumstances.
Electron Transport Chain and Oxidative Phosphorylation
The part of metabolism that directly uses oxygen Chain of proteins bound to metal atoms (cofactors) on inner mitochondrial membrane Substrates NADH + H+ and FADH2 deliver hydrogen atoms Hydrogen atoms are split into H+ and electrons Electrons are shuttled along the inner mitochondrial membrane, losing energy at each step Released energy is used to pump H+ into the intermembrane space Enzyme complexes I, III, and IV pump H+ into the intermembrane space H+ diffuses back to the matrix via ATP synthase ATP synthase uses released energy to make ATP Electrons are delivered to O, forming O- O- attracts H+ to form H2O
the absorptive state
The period following a meal Nutrients enter the blood as intestinal absorption proceeds Liver closely regulates glucose content of blood Lipemia commonly marks the absorptive state (lipemia = high level chylomicrons in plasma) Adipocytes remove fatty acids and glycerol from bloodstream Glucose molecules are catabolized and amino acids are used to build proteins Insulin is dominant hormone
three major phases of glycolysis
Three major phases Sugar activation Sugar cleavage Sugar oxidation and ATP formation
Absorption of Other Nutrients
Water Nearly all that is ingested is reabsorbed via osmosis Ions Absorbed via diffusion, and active transport Vitamins Water soluble vitamins are absorbed by diffusion Fat soluble vitamins are absorbed as part of micelles Vitamin B12 requires intrinsic factor
when oxygen is present..
With the present of oxygen in cells pyruvate is oxidized to acetyl-CoA, which then enters the citric acid cycle. The NADH molecules are reoxidized through the mitochondrial electron transport chain with electrons transferred to the O2 molecules. The aerobic Glycolysis consists from two major steps: Glucose + 2xADP + 2xPi + 2xNAD+ => 2xPyruvate + 2xATP + 2xNADH + 2H+ + 2xH2O
glycolysis
a set of reactions in which one glucose molecule is oxidized and two molecules of pyretic acid are produced. the reactions also procuce two molecules of ATP and two energy containing NADH plus H
formation of acetyl coenzyme A
a transition step that prepares pyretic acid for entrance into the krebs cycle this step also produces energy containing NADH + H+ plus CO2
metabolism
all chemical reactions that occur in the body
glycoylsi can occur under what conditions?
anarobic or aerobic cause it does not need oxygen krebs cycle and electron tranposrt chain require oxygen and are collectively referred to as aerobic respiration when there is oxygen all 4 stages can occyr if no oxygen- or little- pyretic acid is converted to a substance called lactic acid and the remaining steps of cellular respiration do not occur
what happens during glycoysis>
chemical reactions split a 6 carbon molecule of glucose into two 3 carbon molecules of pyretic acid it consumes two ATP molecules but produces four, so the gain is 2 for each glucose moleulce that is oxidized
very low density lipoprotines
contain triglycerides, phospholipids and cholesterol
what is the fate of pyruvic acid?
depends on the availibily of oxygen if it is scarce then the acid is rescued via an aerobic pathway by the addition of two hydrogen atoms to form lactic acid this regenerates the NAD+ that was used in the oxidation of the glyceraldehyde 3-phosphate and allows glycolysis to continue as lactic acid is produced it diffuse out of the cell and enters blood- removed by hepatocytes and then converted back to pyruvic acid build up of lactic causes muscle fatigue when there is a lot of oxygen- most cells convert pyruvic aid to aceply coenzyme A the molecule links glycolysis which occurs in the cytosol, with the krebs cycle which happens in the mitochondria
coenzyme A
each step in the oxidation of glucose requires a different enzyme and often a different coenzyem too. this one is used for cellular respiration it does from pantothenic acid, a B vitamin during the transitional step between glycolysis and the krebs cycle, pyretic acid is prepared for entry into the cell
chylomicrons
form in mucosal epithelial cells of the small intestine, transport dietary lipids to adipose tissues for storage contaon 1-2 percent of proteins 85 percent triglycerides 7 percent phopholids 7 percent cholestorl small amount go fat soluble vitamins - they give the blood plasma a milky appearance and remain in the blood for a few minutes as chylomicrons circulate through the capillaries of adipose tissue, one of their apportions, app c2, activates endothelial lipoprotein lipase, an enzye that removes fatty acids from chylomicron remnants from the blood via receptor mediated endocytosis in which another chylomicron apportion, apo E, is the docking protein
glucose anabolsim
glucose takes part in many anabolic reactions- one is the synthesis of glycogen another is synthesis of new glucose molecules from some of the products of proton and lipid breakdown
catabolism
hydrolysis- break down complex organic molecules into simpler ones exergonic produce more energy than they use important reactions occur in glycosis, the krebs cycle, and the electron transport chain
lipoprotine
lipid and protine combination outer shell is protines, phospholipids, and cholestorl molecules surrounding an inner core to triglycerides and other lipids
lipids
nonpolar and are hydrophobic do not dissolve in water to be tranposrted in watery blood, such moleucesl must be combined with proteins to be made more water soluble by combining them with proteins produced by the liver and intesitine
the krebs cycle
once the pyretic acid has undergone decarboxylation and the remaining acetyl group has attached to CoA the resulting compound (acetyl CoA) is ready to enter the krebs cycle The Krebs cycle refers to a complex series of chemical reactions in all cells that utilize oxygen as part of their respiration process. This includes those cells of creatures from the higher animal kingdom, such as humans. The Krebs cycle produces carbon dioxide and adenosine triphosphate (ATP). This chemical provides cells with the energy required for the synthesis of proteins from amino acids and the replication of deoxyribonucleic acid (DNA). Within the Krebs cycle, energy in the form of ATP is usually derived from the breakdown of glucose, although fats and proteins can also be utilized as energy sources. Since glucose can pass through cell membranes, it transports energy from one part of the body to another.
reduction
opposite of oxidation, is the addition of electrons to a molecule. reduction results in an increase in the potential energy of the molecule
glucose
polysacrahides and disacharrises are hydrolyzes not the monoscacharide glucose, fructose, galactose during the digestion of carbohydrates some fructose is connected into glucose as it is absorbed through the intestinal epithelial cells hepatocytes(liver cells) convert most of the remaking fructose and practically all of the galactose to glucose
apopprotins
protines in the outer shell that has a specific funtiocn but are essentially transport vesicles
electron transport chain reactions
reactions ozidize NADH +H+ and FADH2 and transfer their electrons through a series of electron carriers
oxidation
removal of electrons from an atom or molecule- the result is a decrease in the potential energy of the atom or molecule they are dehydrogenation reactions
electron tranport chain
serious of electron carriers, integral membrane proteins in the inner mitochondial membrane. this membrane is filed into cristae that increase its surface area, accommodating thousands of copies of the transport chain in each mitochndrian. each carrier in the chain is reduced as it picks up electrons and oxidized as it gives up electrons.as electrons pass through the chain, a series of exergonic reactions release small amounts of energy; this energy is used to form ATP. in cellular respiration, the final electron acceptor of the chain is oxygen. because of this mechanism of ATP generation links chemical reactions with the pumping of hydrogen ions, it is called Chemiosmosis together chemiomosis and the electron transport chain constitute oxidative phosphorylation
phosphorylation
some of the energy released during oxidation reactions is captured within a cel when ATP is formed a phosphate group P is added to ADP with an input of energy to make ATP ~(means high energy phosphate bond) the high energy phosphate bond that attaches the third phosphate group contains the erngy stored in this reaction the addition of a phosphate group to a molecule is phosphorylation and it increases its potential energy
anabolism
synthesis- chemical reactions that combine simple molecules and monomers to form the body's complex structural and functional components endergonic
ATP is...
the "energy currency" of a cell- it is spent and earned over and over-ATP is not long term storage- it is in the moment
acetyle coenzyme A
the acetyl group that attaches to coenzyme A results in this molecule
acetyl group
the enzyme pyruvate dehydrogenase (located in the mitochondrial matrix) converts pyruvic acid to this- a 2 carbon fragment called the acetyl group, by removing a molecule of carbon dioxide
decarboxylation
the loss of a molecule of Co2 by a substance
ATP
the molecule that participates most in energy exchanges in living cells couples energy releasing catabolic reactions to energy requiring anabolic reactions
glucose catabolism
the oxidation of glucose to produce ATP is aka cellular repsiration involves four sets of reactions- glycolysis, formation of the acceptably coenzyme A, krebs cycle reactions, electron transport chain reactions
nicotinamide adenine dinucleotide (NAD) flain adenine dinucleotide (FAD)
these are two coenzymes commonly used by animal cells to carry hydrogen atoms when a substance is oxidizes the liberated hydrogen atoms to not remain free in the cell but are transferred immediately by coenzymes to another compound NAD- a derivatiev of the B vitamin niacin FAD_ derivative of vitamin B2(riboflavin) ***Both of these will gain a "H+" ion NAD + H NADH FAD+ + 2H FADH2 ???? different in book
krebs cycle reactions
these reactions oxidize acetyl coenzyme A and produce CO2, ATP, NADH + H+ and FADH2
oxidation reduction redox reactions
they are also coupled, each time a substance is oxidized another is reduced oxi is exergonic Coenzymes act as hydrogen (or electron) acceptors
summary of cellular respiration
various electron transfers in the electron transport chain generate either 26 or 28 ATP molecules from each molecule of glucose that is catabolized: either 23 or 25 from the ten molecules of NADH +H + and three from the two molecules of FADH2.
anarobic glycosis
when glycols occurs by itself under anaerobic conditions
