Dietary Fuels and Body Fuel Stores
A glycosidic bond is formed between what molecules? Q3, p72
Between the anomeric carbon of a sugar and an O-H (or N) of another molecule.
2) Most readily used source for yielding energy?
Carbohydrates
Why store glycogen?
It can be released as glucose quickly.
8-Describe how the chemical structures of animal fats and vegetable oils are similar.
both are composed of triglycerides
3) Describe your need for energy (and hence for dietary fuels). (figures 1.2, 19.4, and 19.2; document on portal titled Nucleotide Schematics)
muscle contraction, active ion transport & biosynthesis.
Why store glycogen in muslce?
muscles require a lot of energy, so by storing it in the muscle itself, it's readily available. Muscle also does not have glucose-6-phosphotase which is what breaks down glycogen in the liver and must convert it directly to glucose thru glycolysis. ATP, lactate, and CO2 are produced.
Why store glycogen in liver and not just store fat here?
Liver has the apparatus to quickly supply glucose to blood; glycogen has high demand for ATP due to work load Takes too long to produce the glucose and the cost of making ATP is too high (costs ATP to make ATP); and risk of increased ketones and ketosis In more detail: pg. 513, Ch. 28, Fig. 28.2 Glycogenolysis in skeletal muscle and liver Notice a major difference in the diagrams that begins after Glucose-6-Phosphate. In the liver, this phosphate is removed to produce bare-naked glucose. Once the phosphate is removed the glucose can move across a cell membrane and into the blood. Liver cells have the enzyme glucose 6-phosphatase to remove that phosphate group. Muscle cells do not. Phsohpatases catalyze the hydrolytic removal of a phosphate group. Water goes in and Pi (inorganic phosphate) comes out. Water in, pee out.
7) What are the two categories of carbohydrates?(page 5; figures 1.4 and 27.1; document on portal titled Dietary Monosaccharides and Disaccharides)
simple carbohydrates and complex carbohydrates
2) How many stages in fuel catabolsim
three
What is the following compound found in high levels in a woman's body admitted to the hospital in a coma? Q2, p72
y-hydroxybutyrate (the date rape drug)
5- describe the electron transport chain, and their connection(s).
- actually generates ATP; occurs in the mitochondria; the mitochondria contain the electron transport chain/generation of power stored in ATP phosphate bond - and ATP synthase; inner membrane has electron transport system; sequential oxidation- reduction reactions where the electrons lose some energy with each transfer: some of this energy goes into the phosphate bond of ATP; the power is in the proton - H pump and the energy lose which is transfer to the phosphate bond by an enzyme complex ATP synthase. extra detail: The electron transport chain does not produce any ATP directly but it is where oxygen is used directly. The oxygen is turning into water. In the terminology of redox chemistry what's happening to the oxygen? The oxygen is being reduced. Gaining of H is reduction. Electrons are negative, if you're gaining something negative that's sort of like a reduction. The electron transport chain creates a situation that can be used by ATP synthase, then ATP will be made. The chain builds up a concentration and electrochemical gradient of H+ ions. This requires an intact mitochondrial membrane and without it this would not work. The concentration of protons on each side of the membrane will not be equal. The matrix of a mitochondrion and the intermembrane space are the two sides of the membrane we are talking about. (A mitochondrion has two membranes, hence intermembrane space.) A gradient produces a situation from which energy can be derived. This is a power source. Like water at the top of a dam, its natural flow from the top of the floodgates can be used as a power source. If the protons stacked up on one side of the membrane are allowed to flow in their natural direction, ATP synthase is a little turbine that generates ATP (energy) by allowing the protons through. The electron transport chain creates a proton gradient across the inner mitochondrial membrane. That's what ATP synthase uses as a power source to make ATP.
13-Distinguish between aerobic and anaerobic use of glucose as fuel.
- aerobic use of fuels results in the complete degradation of the source to CO2 and the production of more ATP; anaerobic respiration results in lactic acid and then the process can go no further; as a result there is not as much ATP produced in the process (e.g. sprinting or heavy exercise and lactic acid build up in the muscles)
5-Describe briefly the tricarboxylic acid (TCA also citric acid or Krebs) cycle
- the complete oxidation of Acetyl CoA to CO2 under aerobic conditions; smaller breakdown products are converted to pyruvate (enter into the mitochondria) and then to Acetyl Co A; these enter the cycle and produce the reducing agents; several intermediates have carboxll groups waiting to be reduced; generates the reducing agents NADH and FADH2 (coenzymes) extra detail: Cellular respiration implies the use of oxygen and oxygen is used in the mitochondria. The TCA cycle is in the mitochondria but that is not where oxygen is used or ATP is produced directly. But it is important in oxidizing the carbons in the fuel and harvesting electrons and leaving the carbons as waste: CO2.
8) Give two characteristics of triacylglycerol that make it a very efficient way for your body to store fuel. (page 7)
1) Fats are initially in a more reduced state so it can be oxidized more than other fuels. Thus it's worth more kilocalories per gram than any other fuel. 2.) Fat (triacylglycerol) is a more anhydrous fuel than the others. When you want to store fuel, you store the most kilocalories/gram and the least amount of water weight (fat doesn't mix with water). The hydrocarbon portion of a structure is very hydrophobic, lipophilic, or nonpolar (ie doesn't mix well with water, thus anhydrous). You carry more fuel per pound with fat than carbohydrate. Carbohydrates would require carrying a lot of water weight. If fat is the most efficient fuel to store, why would we store carbohydrate at all?
8-Draw a schematic for the structure of a triacylglycerol (triglyceride). (figure 1.6)
3 fatty acids and glycerol (note: fats are not fatty acids) In more detail: Fig. 1.6 Structure of triacylglycerol Most of the carbons in lipids don't have any oxygen on them, just hydrogen. Which carbons have more electrons? The carbons of the fat molecule or the carbohydrate? The carbons of the fat molecule have more electrons (because oxygen is not pulling them away) and that makes them worth more energy. The way you get energy from a fuel is to take its electrons. You can oxidize a carbon completely by making it CO2. Which carbons are closer to being CO2 already as they appear in fuel? The ones with oxygen (ie carbohydrates). Carbons in carbohydrates are partially burnt already; they're not worth as much energy. In CO2, the oxygen are hogging the electrons to such an extent that carbon does not have any according to this book-keeping method (electronegativity of atoms). Sharing is not always equal sharing.
3-Explain how ATP has the structure of a nucleotide.
5 carbon sugar (ribose) - adenosine plus three phosphates plus the base adenine (subsequently Acetyl CoA also has an adenosine unit with an adenine. In more detail: GLYCOSIDIC LINKAGE Between the adenine and ribose of ATP, there is a bond that can be hydrolyzed - a glycosidic linkage. Understanding the connection between these pieces of a molecule helps you understand how it's build and taken apart again. Carbon number 1 is attached to a nitrogen in the nitrogenous base. The fact that the bond to nitrogen comes from the 1st carbon on the sugar, makes it a glycosidic bond. If that bond came from any other position on the sugar, it wouldn't be a glycosidic bond. PHOSPHOESTER BOND The next hydrolyzable linkage is the linkage between the ribose and a phosphate group. That linkage between the pentose and the phosphate group is a hydrolyzable ester linkage. The ribose acts like an alcohol and phosphate acts like an acid. Ester = alcohol and acid. However, there is more than one type of ester. How do we specify phosphoric acid? We call it a phosphoester bond/linkage/connection. It's represented in a specific way in the schematic. Thus, a nucleotide has a heterocylic nitrogenous base, a pentose and at least one phosphate. Nucleotides are your friends, you've got to love them. ATP is great. Nucleotides do lots of jobs for us. They are the building blocks for your DNA. Also used in cellular energetics. We see up to three phosphates in a nucleotide. PHOSPHOANHYDRIDE BOND When there's more than one phosphate, the linkages between them are hydrolyzable. It's like a linkage between two acids - anhydride linkages. Phosphoanhydride is the term for one of these linkages. Or high-energy phosphate bonds. Either works. You could have as many as 4 hydrolyzable linkages in a nucleotide.
3-(Define a nucleotide by listing the required parts of its chemical structure.)
A nucleotide has 3 parts: a heterocyclic nitrogenous base, pentose sugar, phosphate group: purine and pyrimidine; DNA bases; composed of adenosine (5 carbon ribose sugar), joined to a phosphate bond; attachéd to a base such as adenine, guanine, cytosine, thymine, uracil In more detail: The first is a heterocyclic nitrogenous base (usually a purine or pyrimidine). ATP has a purine, called adenine. Heterocyclic nitrogenous base is a bit redundant. The nitrogens make it a base and heterocyclic (in a ring). Be familiar with purine and pyrimidine. The second part of nucleotides is a pentose sugar. There are only two possibilities for the pentose (5 carbon) sugar: ribose or deoxyribose (one less oxygen atom). For ATP it's a ribose. The third component of a nucleotide is a phosphate group with 1-3 phosphate molecules. A phosphate group involve phosphorus atoms with four oxygens around it. In a full-blown structure, you would have to draw those oxygens too.
3-Distinguish between adenine and adenosine.
Adenosine - whole unit of phosphates, ribose sugar and adenine; Adenine - derivative of purine; nucleic acid base; dicyclic ring with N and C; very different in structure than adenosine; like to think of it containing more N as does the word adenine; In more detail: ATP = adenosine triphosphate, you cannot use acronyms until you know what they stand for. You must be able to spell them as well. Adenosine = adenine + ribose Adenosine is a nucleoside. A nucleoside is a pentose sugar with a purine or pyrimidine base. I.e. when there's no phosphate it's a nucleoside (i.e. adenosine) One phosphate - AMP - adenosine monophosphate (the whole molecule is a nucleotide the two separate parts are nucleoside monophosphate) Two phosphates - ADP - adenosine diphosphate (the whole molecule is a nucleotide and the two separate parts are nucleoside diphosphate) What's high-energy about the phosphoanhydride bonds is that they're exergonic, they release energy. Some of the energy might be heat. The energy is used for muscle contractions, etc. Chemical energy can become mechanical energy (make things move). If we go farther back we can see the energy came from fuel molecules oxidized by carbons, even farther back the energy came from the sun. Changed form a lot of times before moving your arm. Adenosine 5' - triphosphate - the five prime denotes that the phosphate is attached to the 5th carbon of the sugar (ribose). Notice that some of the oxygens around the phosphorus molecule have a negative charge. Why do some have a negative 1 charge and others don't? If you don't understand that, please come to tutorial. You need to understand the charges shown in the pictures shown in the text. If you draw the chemical structure you have to show the charges. That's a very important characteristic that can affect how the molecule acts. A proton (H+) is one of the products of the hydrolysis reaction of ATP. In biochemistry it doesn't matter if the reaction is perfectly balanced. He will often ignore H20 and H+ if he doesn't think they're really important to the discussion. Other Hs are hydrogen atoms or hydride ions. Part of your prerequisite knowledge. Differ in number of elections. They all have a proton in the nucleus. A proton has no electrons or neutrons. Pi not just a phosphorus: it's inorganic phosphate. It has a negative charge and is surrounded by 4 oxygens and 1-2 H. Those molecules are in equilibrium with each other, from 1-2 H. But don't worry about how many Hs it has. It's a mixture of the two. The greek alphabet is part of this class, the first 5 letters and the last letter. Alpha, beta, gamma, delta, epsilon, omega. Lower-case letters usually used.
Q1, p359. The highest energy phosphate bond in ATP is located between which of the following groups?
Between two phosphate groups
2) Distinguish between catabolism and anabolism. (page 1; figure I.1 on page 2)
Blank
6) State the caloric value of each fuel (including alcohol) in kcal/g. (table 1.1 on page 5) -carbohydrates: -fats: -protein: -alcohol:
Caloric value of carbohydrates - 4 calories per gram Caloric value of fats - 9 calories per gram Caloric value of protein - 4 calories per gram Caloric value of alcohol - 7 calories per gram
1) describe Carbohydrates and fuel metabolism
Carbohydrates (mouth and enterocytes)- most diets compose the major source of the body's energy requirements; eg starches (glycogen, amylase and amylopectin); other source may include glycogen, and the disaccharides sucrose and lactose. Many plant carbohydrates like cellulose, pectins, gums, and alginate, are not digestable and they constitute the dietary fiber; Starch = an heterogeneous compound composed of the glucose polymers amylose and amylopectin; differ from starch which is the major storage form of glucose in animals - structure is alpha 1-4 glycosidic bonds and has numerous 1- 6 bonds. Digestion begins in the mouth during chewing and the mixing of salivary amylase which hydrolyze starch to some extent. The enzyme is killed in the acidic stomach and the digestion is resumed in the duodenum - pancreatic amylase; brush border enzymes of the epithelial cells go on to further hydrolyze carbohydrates into oligosaccharides and disaccharides (sucrose, lactose and trehalose/mushroom) to their monomers, these (monosaccharides) are then transported into enterocytes.
2) Carbohydrate catabolism pathway:
Carbohydrates = simple sugars - glycolysis (ATP) - pyruvate- Acetyl CoA - citric acid cycle - oxidative phosphorylation - ATP
1) List the three major fuels obtained from a typical diet (not including alcohol). (page 4; figure I.1 on page 2; document on portal titled Oxidation of Carbon)
Carbohydrates, Fats, Proteins:
3-Describe and explain the ATP-ADP cycle.
Ch. 1, Pg. 4, Figure 1.2 The ATP-ADP Cycle The right side of the circle uses ATP and the left side makes ATP. If it's a muscle cell, the ATP will be used for muscle contraction. In the brain, mostly active ion transport, pumping ions across the cell membrane in a direction that is work, against a gradient: active transport. That requires ATP. Described: (from indepthinfo.com) To take advantage of the high energy bonds in ATP there are within many cells a substance called ATPase. This is really an ATP splitter. It cuts off the last phosphate group of the ATP molecule turning it into adenosine diphosphate. (Note the "di-" prefix means "two".) In the process of this splitting a great deal of energy is released and used in the cell to do work, move things and build things. When carbohydrates and other foods are consumed by the body, they also contain energy. When they are broken down, the energy is released and, in many cases, the energy is used to reattach the phosphate molecule to the ADP, turning it back into ATP. Then the cycle of bond-breaking and bond-making begins all over again, alternately releasing and storing energy, as needed. A convenient way to remember the cycle is ATP = ADP + P + Energy1! The adding and subtracting of a phosphate to ADP is a metabolic process. Metabolic proceses can be separated into two phases; catabolism is the process of breaking down (breaking down food to make ATP), and anabolism is the process of building up (using the energy created in converting ATP to ADP to build up cells or move molecules around the cell). The ATP - ADP cycle occurs in plants (in photosynthesis) and animals.
10) Describe the chemical structure of proteins. (figure 1.5)
Chemical structure of protein is repeating amino acids; proteins have an amino terminal end (n-terminal): H3N and a carboxy-terminal amino acids they are joined together by a covalent peptide-bond: exhibits resonance, N-C; they have unique polarities based on their amino acid compostion - that account for their conformations and thus their actiivity and characteristics
13-Generalize about the reactions catalyzed by phosphatases.
Clip off phosphates to make free glucose
2) stage 3 in fuel catabolsim
Complete oxidization of acetyl CoA and the production of ATP
2) stage 2 in fuel catabolism
Conversion of subunits to a form that can be completely oxidaized, usually acetyle CoA
12) Explain why only a limited amount of your body protein can be degraded before body functions are compromised. However, we do degrade body proteins (particularly the proteins of our large muscles) when we fast. Describe how the resultant amino acids are used. Define gluconeogenesis. (part C on page 8; document on portal titled Use of Muscle Protein During Fasting)
Degradation of body protein leads to the production ketone bodies; lead to acidosis and renal compromis
1) describe Fats and fuel metabolism
Fats (duodenum right after stomach)- aka lipids; accounts for 40-45% of total daily energy intake (about 100 grams per day in the average western diet); contain more than twice the energy per unit mass than carbohydrates and proteins; fat absorption under normal circumstance is very high What would be a couple of conditions where circumstances would not be normal - cholecystitis, removed gallbladder Predominant dietary lipid is triacylglycerol - 3-long chain (16+) fatty acids. Include essential fatty acids (omega 3, 6, 9) and the lipid soluble vitamins: A, D, E and K Digestion of: mouth and stomach are minimal, but lingual lipase are activated by acidic pH and initiate the hydrolysis of TAG; the fatty acids released stimulate the CCK cholecyt. (enzyme) and the flow of bile and pancreatic juice.
8) Distinguish between fats and fatty acids.
Fats - a long chain of carbon molecules with corresponding hydrogen; Triglyceride - three chains of 16 or more ending with a carboxylic acid Fatty acids - carboxylic acid with a long aliphatic tail (chain) which is either saturated or unsaturated; most evenly numbered carbon atoms; they are usually derived from triglycerides or phospholipids; yield large quantities of ATP when metabolized; heart and skeletal muscles prefer fatty acids as energy source for ATP; the brain can not use fatty acids as a fuel source, it must relay on glucose or ketone bodies - by products of fatty acid break down in the liver, vital during fasting in the brain, acetone, acetoacetic acid, and beta hydroybutyric acid (hepatocytes produce them when energy is extremely scarce
9) Explain, based on a comparison of their chemical structures, why fats have a higher caloric value than carbohydrates. (pages 5-6; figures 1.4 and 1.6; document on portal titled Carbon of a Fat versus Carbon of a Carbohydrate)
Fats have a higher caloric value than carbohydrates because fats split into glycerol and fatty acids; the fatty acids go to Acetyl CoA and the glycerol portion goes into pyruvate and then acetyl CoA; carbohydrates go directly into acetyl CoA; therefore the answer is that there is more redox potential with fats than there is with carbohydrates.
2) Lipid catabolism pathway:
Fatty Acids and glycerol - glycolysis or Acetyl CoA - if glycolysis - pyruvate - Acetyl CoA - Citric Acid Cycle - oxidative phosphorylation - ATP
4) Name the building blocks into which each major fuel must be broken prior to cellular oxidation. (page 4; figure 1.3). In other words, when the fuel is consumed, what is it broken down into in order for it to be metabolized into energy (catabolism)?
First describe cellular oxidation/cellular respiration - the oxidation and reduction process leading to the the manufacture of ATP; There are four processes involved with cellular respiration; 1) glucose ---- to pyruvate (glycolysis; cytoplasm of the cell) 2) Pyruvate ----- to Acetyl CoA (goes into the mitochondria) 3) Krebs Cycle ----- to various redox reactions generating NAD and FADH2 4) Oxidative phosphorylation ---- electron transport chain --- to ATP (mitochidrial membrane) Carbohydrate - sugars Fats - triacyglycerides Protein - amino acid
12-How are the amino acids used from fasting?
Gluconeogenesis - is the metabolic process that generates glucose from non-carbohydrate carbon substrates like amino acids, lactate, glycerol; often associated with ketosis; process occurs during periods of starving, fasting, low carbohydrate diets, or intense exercise; restricted to the liver, kidney and intestine; processes ultimately convert a.a to phosphoenolpyruvic acid (PEP); one of two main mechanisms to keep the blood glucose levels from dropping to low (hypoglycaemia) (other mechanism is glycogenolysis - degradation of glycogen);
In the liver, is glycogen or fat a better source of glucose for the blood?
Glycogen
In muscle, is glycogen or fat the better source of fuel for anaerobic use?
Glycogen because more efficient use of than fats.???
5-Describe the generation of ATP from fuel components during cellular respiration
In more detail: It refers to the oxidation of carbons in fuel for the purpose of generating ATP. We start seeing cellular respiration right away in this diagram because you remove electrons from the carbons when you oxidize them (oxidation = loss of electrons). Acetyl CoA is a major point of convergence with all the fuels, regardless of whether it's fat, carbs or protein. The acetyl groups can come from any of the fuels. Acetyl groups are 2 carbons large. Glucose has 6 carbons. You would think that you could generate 3 Acetyl groups with glucose, but it's not that easy. You only get two. Some of the carbons of all the fuels become acetyl groups and then they go into the tricarboxylic acid cycle (TCA cycle). That's a sequence of reactions that occurs in mitochondria of cells. A lot of the oxidation of the carbon occurs there, all the way to CO2. Coenzyme A delivers carbons to the TCA cycle, the carbons come out fully oxidized as CO2 (a waste process). But in the process a lot of electrons have been removed, and those electrons are collected in the electron transport chain - another sequence that occurs in the mitochondria. The electron transport chain does not make ATP as directly as it looks. It's missing some detail.
13-Describe the use of liver glycogen.
In the liver glycogen is readily metabolized to glucose on demand to increase overall blood glucose levels;
Explain the caloric content per gram of fuel in relation to energy: Q2, p20
It is the amount of energy that can be obtained from oxidation of the fuel.
13-Describe the importance of storing glycogen. (Why not just store excess glucose after a meal as fat if fat has more kcal/g ?) (part B on pages 7-8; figures 1.4 and 28.2; document on portal titled Aerobic versus Anaerobic Use of Glucose 6-P)
Muscles use a lot of energy and glycogen is readily available when they need it whereas fat must be converted to a form that can be used for energy. Pound per pound, fat stores much more energy per unit weight than glycogen. Glycogen stored in muscle cells is used as a fuel in that very same muscle cell, whereas glycogen in liver cells is converted to exportable glucose used to raise blood sugar levels. Why store glycogen in the liver? Glycogen is a much better source of glucose than fat. It's not possible to convert fatty acids into sugar. You body cannot convert the carbons on fatty acids to carbohydrates. There is one part of a fat molecule that can serve to build glucose: glycerol. But most of a fat molecule is made up of fatty acids. Why store glycogen in muscle? So that it can produce ATP quickly via anaerobic respiration. And glucose is the only fuel that can be used anaerobically.
7-List the major carbohydrates in the human diet and classify each as a polysaccharide, disaccharide, or monosaccharide.
Polysaccharides - starch Disaccharides - lactose, maltose, sucrose Monosaccharides - glucose, galactose, fructose
2) Protein catabolism pathway
Protein = amino acids - pyruvate - acetyl CoA - Citric Acid Cycle - oxidative phosphorylation - ATP
1) describe Proteins and fuel metabolism
Proteins (stomach and brush boarder membrane on enterocytes) - essential for human growth, development and homeostasis; constitutes about 10-15% of the average total energy intake; the nutritive value of dietary proteins depends upon its amino acid composition and digestibility; contain essential amino acids which are not synthesized in our bodies; nonessential can be synthesize from from appropriate precursor molecules. Essential amino acids include: valine, luecine, isoleucine, lysine, methionine, phenyalanine, tryptophan, threonine; histidine in children Animal protein provide all the essential amino acids Vetable protein differ in their content of essential a.a., but a mixture will satisfy the essential acid req. e.g. lysine lackin gin grains - add legumes legumes lack methionine Endogenous sources of protein - enzymes, glycoproteins and mucins (20-30 grams per day), rapid turnover of gi epithelium (30 grams/d), plasma protein (1-2 grams per day) Protein digestion starts in the stomach via denaturation, pepsin is secreted by chief cells in the stomach as the precurson, pepsinogen which causes hydrolysis of proteins at the carboxyl group of the aromatic a.a. leucine, methionine, and acidic residues; the alkaline pancreatic juices are secreted that contain trypsinogen, chymotrypsin, prolastase, etc. These are activated by enzymes on the brush boarder membranes of the enterocytes and the a.a. are broken down into oligopepetides and then finally into smaller units and a.a.
2) Three fuel sources for Catabolism
Proteins, carbohydrates and fats
13- Compare and contrast starch and glycogen.
Starch and glycogen (see above) Starch is amylose and amylopectin Glycogen - similar but branches more frequently; multibranched polysaccharide; stored in liver and muscles; secondary energy source to adipocyte stores;
In the process of respiration, fuels most often undergo what fate? Q1, p20
They are oxidized to generate ATP.
What is a universal characteristic of water soluble compounds? Q1 p72
They contain polar groups that can hydrogen bond with water.
5-the pathway from glucose to Acetyl CoA
This ATP did not require oxidative phosphorylation or mitochondria, the electron transport chain, ATP synthase or oxygen. It's the anaerobic way for the cell to make ATP. see image You get two pyruvates and two acetyl CoA from a molecule of glucose. The two carbons not used in the glucose are converted to CO2. Complete oxidative use of glucose would involve the TCA cycle, oxidative phosphorylation, etc. Anaerobic use of glucose would only require glycolysis.
The condition hypertirglyceridiemia is named for the high blodd levels of lipids composed of what? Q4, p72
Three fatty acyl groups attached to a glycerol backbone.
11) List the three forms in which the body stores fuel, and for each give the cells of the body in which the fuel is principally stored. (Section II on pages 7-8)
Three storage forms of body fuels: glycogen (hepatocytes), triglycerides (adipocytes; fat cells), protein (muscles)
13-Describe the use of muscle glycogen.
Using muscle glycogen - glycogen is found in low concentration; appears to serve as a immediate reserve for muscle cells; muscle cells lack a necessary enzyme called glucose 6 phosphate which is required to pass glucose into the blood; selfish muscle cells won't share with other cells their glucose from glycogen; Glucose 6 phosphatase - enzyme that hydrolyzes g6p resulting in the creation of a phosphate group and free glucose;
7- Say what is meant by each of the following: -table sugar, -cane sugar, -milk sugar, -fruit sugar, -blood sugar, -dextrose.
What is table sugar? Table sugar What is cane sugar? Sucrose from sugar cane or beet juice What is milk sugar? Lactose; disaccharide; galactose and glucose What is fruit sugar? Fructose; monosaccharide What is blood sugar? glucose What is dextrose? Monosaccharide; D-glucose; major fuel for cell function; used as a fluid and nutrient replenisher
5-Describe the process known as oxidative phosphorylation
a series of reactions that couples the oxidation of NADH and FADH2 to the phosphorylation of ADP to generate ATP; Electrons are carried in the reduced form of NADH and can produce 3 ATP molecules and FADH2 can be used to produce 2 ATP; extra detail: Oxidative phosphorylation refers to what starts with the electron transport chain and ends with ATP synthase making ATP. Oxidative refers to the electron transport chain (uses O2) and phosphorylation refers to ATP synthase (ADP to ATP). ATP synthase is an enzyme (protein) that catalyzes the synthesis of ATP. ADP + Pi → ATP. Going that direction is energy-requiring, it is endergonic. Thus, it requires an input of energy and it gets that energy from the proton gradient, produced by the electron transport chain in the inner mitochrondrial membrane. One makes the proton gradient (electron transport chain), the other (ATP synthase) uses it.
3-List types of work that cells do to create this need for energy (and hence for dietary fuels).
biosynthesis and renewal of tissues, metabolic processes like detoxification, production of hormones, new proteins, etc; locomotion, biosynthesis, transport of molecules across cell membranes
Define Anabolism
energy consuming; synthesis of new molecules; usually larger than the reactants; e.g. proteins from a.a.; TCA also comes into play here - provides the precursors for the biosynthesis of amino acids, nitrogenous bases and porphyrins
2) Define Catabolism
energy yielding process involved with the breakdown of large molecules into smaller ones; eg TCA cycle; carbohydrates and amino acids enter cycle and are oxidized to produce the reducing agents NADH and FADH2 which by means of oxidative phosphorylation makes ATP
5) Describe the generation of ATP (from ADP and Pi) using the energy in fuel molecules during cellular respiration. , . (pages 4-5; figure 1.3)
genration of ATP from fuel components during respiration. , Glucose, fatty acids, and AAs are oxidized to acetyl CoA, a substrate for the TCA cycle. In the TCA cycle, they are completely oxidized to CO2. As fuels are oxidized, electrons (e-) are transferred to O2 by the ETC, and the energy is used to generate ATP.
13) Name the enzyme that liver cells use to convert glucose 6-phosphate into glucose, and explain why this enzyme is needed if glycogen stores are to be a source of blood glucose.
glucose 6 phosphatase; is a hydrolytic enzyme which cleaves the phosphoryl group to form free glucose and orthophosphate. This glucose 6-phosphatase, located on the lumenal side of the smooth endoplasmic reticulum membrane, is the same enzyme that releases free glucose at the conclusion of gluconeogenesis. Recall that glucose 6-phosphate is transported into the endoplasmic reticulum; glucose and orthophosphate formed by hydrolysis are then shuttled back into the cytosol (Section 16.3.5). [NCBI] Glucose 6-phosphatase is absent from most other tissues. Consequently, glucose 6-phosphate is retained for the generation of ATP. In contrast, glucose is not a major fuel for the liver.
2) stage 1 in fuel catabolsim
hydrolysis of macromolecules to subunits
