Molecules {carbohydrate}| can have only carbons, oxygens, and hydrogens, with one oxygen atom attached to each carbon. Carbohydrates have alcohol side chains, except for one carbonyl side chain.
Pancreatic amylase in small intestine digests polysaccharides. Polysaccharides are 98% absorbed. Intestine absorbs fructose passively but transports glucose and galactose across membrane actively {absorption, food} {food absorption}.
If carbohydrate in diet is low, fats provide energy, and acetyl-CoA builds up in cells.
Alpha and beta rings are equivalent {anomer}.
Sugars can link by ether bonds {glycosidic bond}. In glycosidic bonds, carbonyl-carbon hydroxyl leaves with hydrogen atom from other-sugar hydroxyl, forming water. Then other-sugar hydroxyl oxygen binds to carbonyl carbon. First-sugar carbonyl is on either first or second carbon. Other-sugar carbon is fourth or sixth carbon. Glycosidic bonds break by hydrolysis.
Sugar substitutes {artificial sweetener} include saccharin, cyclamate, aspartame, and mannitol.
Connective tissue, skin, cornea, and bone have saccharides {chondroitin sulfate}. Chondroitinase cleaves and dissolves extracellular-matrix chondroitin.
Plants have molecules {fiber, nutrition}| that people cannot digest into smaller molecules and/or absorb across intestinal wall into blood.
solubility
Some fiber {insoluble fiber} {crude fiber} does not absorb water. Other fiber {soluble fiber} {dietary fiber} can absorb water.
bond
Cellulose is crude fiber. Lignin, hemicellulose, and pectin are dietary fiber. Cellulose, lignin, hemicellulose, pectin, and inulin have glycosidic bonds that are not the same as for starch and glycogen. Human intestine cannot break them down.
sources
Soluble fiber is in fruit, oats, barley, beans, peas, lentils, peanuts, and some vegetables. Insoluble fiber is in fruits, grains, nuts, and vegetables. Starchy vegetables have low fiber.
functions
Insoluble fiber adds bulk and maintains regular bowel movements. Soluble fiber increases bile-acid secretion. Soluble fiber absorbs water. Soluble fiber affects blood sugar and cholesterol levels.
Three-carbon monosaccharides {glycerol, saccharide} can have alcohol group at each carbon.
Extracellular proteins {glycoprotein}| have saccharides bound to asparagine, serine, threonine, and lysine. Egg-white ovalbumin, egg-white avidin, mucoprotein, collagen, eye-lens protein, basement-membrane protein, ribonuclease, pepsin, cholinesterase, chorionic gonadotropin, follicle-stimulating hormone, thyroid-stimulating hormone, fibrinogen, gamma-globulin, blood-group proteins, and fish-blood antifreeze protein are glycoproteins.
Animal-cell coats and ground substance have glycosphingolipids, acid mucopolysaccharide, and glycoprotein, which are soft, flexible, and adhesive and are for cell recognition and growth inhibition.
Arterial wall has carbohydrate blood-coagulation blocker {heparin}.
Acid mucopolysaccharides, mucins, and mucoprotein make fluid {mucus}|. Mucus keeps inner body surfaces slippery or sticky. Mouth mucus is antibacterial.
Seeds and fruit have chemicals {psoralen} sensitive to light. Light makes them react with DNA.
To enter TCA cycle, pyruvate {pyruvate} first converts to acetyl-CoA. NAD+ attaches acetyl to CoA by thioester bond and makes carbon dioxide and two NADH, in irreversible reaction. Process uses free enzymes in inner mitochondria. ATP inhibition regulates reaction. Arsenate can poison reaction.
Pigments {pigment compounds} are chlorophyll, carotenoid, xanthophyll, and physobilin. Light oxidizes pigments. Donated electron adds to NADP+. Electron-transport chain and oxidative phosphorylation make ATP and oxygen.
Chlorophyll a {chlorophyll}| absorbs orange light, and chlorophyll b absorbs red light, making plants green.
Yellow, red, or purple pigments {carotenoid} absorb at different wavelengths.
Carotenoid {physobilin} absorbs blue or red.
Carotenoid {xanthophyll} absorbs yellow.
Monosaccharides can form polymers {polysaccharide}|, with glycosidic bonds between units. Polysaccharides are not water-soluble and are not sweet.
Seaweed carbohydrate can make gel {agar}|.
Unbranched polysaccharides {cellulose}| in plant cell walls have linked glucose molecules.
Short polysaccharides {dextran} {dextrin}| of 5 to 15 carbons are for energy.
Short polysaccharides {dextrose}| of 5 to 15 carbons are for energy.
Branched polysaccharides {glycogen}| in animals link glucoses and store energy.
Carbohydrates {gum arabic} can be gum.
Polysaccharides {hemicellulose} can link pentose molecules and be in gum.
Linear soluble polymers {hyaluronic acid} can surround egg cell and have disaccharide units.
Carbohydrates {inulin} can be fructose polymers.
Carbohydrates {lignin} can be in tree and grass cell walls. Lignin is hard and woody. It remains when enzymes turn cellulose into sugar.
Two-carbon to ten-carbon polysaccharides {oligosaccharide} can be for energy.
Glucose chains {pectin, polymer}| can be in unripe fruit and be thickeners or gels.
Mouth amylases {ptyalin} can make polysaccharides into dextrin.
In plants, polysaccharides {starch, plant}| can link glucose molecules and store energy. Starches can be unbranched and helical {amylose} or branched {amylopectin}.
Two delta-aminolevulinic acids make porphobilinogen ring, which becomes tetrapyrrole, which makes molecules {porphyrin}|. Porphyrin can make heme. Chlorophyll has porphyrin ring, as does cytochrome oxidase. If bad metabolism causes porphyrin to have no metal inside, porphyrin goes to skin, bones, and teeth, where light makes free radicals {porphyria}.
Iron-containing ring structure {heme} can derive from succinyl-CoA of TCA cycle. Two delta-aminolevulinic acids make porphobilinogen ring, which becomes tetrapyrrole, which makes porphyrin. Porphyrin can make heme. Heme breakdown product is bilirubin, excreted in urine.
Glucose and galactose {hexose} have six carbons. One amino group can bind at glucose second carbon {glucosamine}. Glucosamine is in insect chitin. One amino group can bind to galactose {galactosamine}. Galactosamine is in glycolipids and chondroitin sulfate. One amino group can bind to aldehyde sugars at first carbon {muramic acid} {neuraminic acid}. Muramic acid and neuraminic acid make cell walls.
Sucrose has one glycosidic bond between fructose and glucose, from second carbon to first carbon {invert sugar}|, to make acetal or ketal.
Carbohydrates {monosaccharide}| can have three to seven carbons and one carbonyl group, as in glucose, fructose, mannose, maltose, and galactose. Monosaccharides {triose} can have three carbons, such as glyceraldehyde. Monosaccharides {tetrose} can have four carbons. Monosaccharides {pentose} can have five carbons, such as ribose. Monosaccharides (hexose) can have six carbons. Aldehyde hexoses are glucose, mannose, and galactose. Ketone hexoses include fructose, in honey and fruit. Monosaccharides {heptose} can have seven carbons.
Sugar aldehyde or ketone group can reduce to alcohol group {reduced sugar}|, to make glycerol, inositol, sorbital, and mannitol.
Carbohydrates {sugar}| can be disaccharides. Glycosidic bonds link two monosaccharides. Sucrose, in sugar cane, sugar beets, and corn syrup, has fructose and glucose. Maltose, in malt, has two glucoses.
Lactose, in milk, has galactose and glucose. Lactase gene, for lactose digestion, can stay active after infancy. Regulatory-region mutations happened in Funnel Beaker culture of Sweden and Holland [-4000 to -3000], in Nilo-Saharan peoples of Kenya and Tanzania [-4800 to -700], in Beja people of northeast Sudan [-4800 to -700], and in Afro-Asiatic peoples of north Kenya [-4800 to -700].
Carbohydrates have reactions {carbohydrate reactions}. Mitochondria have citric acid cycle (Krebs cycle). Cytoplasm and mitochondria have gluconeogenesis. Cytoplasm has glycolysis. Mitochondria have oxidative phosphorylation. Cytoplasm has pentose phosphate pathway. Mitochondria have respiratory chain.
organs
Brains use glucose and do not store fat or glycogen. Muscle stores glycogen and uses glucose when active. Heart muscle uses ketone bodies. Liver puts glucose into blood and regulates glucose blood level.
Reactions {anaerobic} can require no oxygen.
TCA cycle uses oxygen {aerobic respiration} to make carbon dioxide.
Acetyl-CoA reactions {Claissen condensation} can lengthen carbon chains by branching. Acetyl-CoA ketone, CH3-CO-S-CoA [3 is subscript], can lose hydrogen when CoA leaves, CH3-CO-, and separate charges to make (C-H2)-(C+O) [2 is subscript and - and + are superscripts]. Ketone carbon is positive, and methyl carbon is negative. Separated charges attack dicarboxylic acid, HOOC-CH2-COOH [2 is subscript], to add ketone, HOOC-(CH2C-H2C+O)-COOH [2 is subscript and + and - are superscripts]. Adding water molecule neutralizes carbon and makes branched carbon chain, HOOC-CHCH2COOH-COOH [2 is subscript], as hydrogen gas leaves.
Reactions {reverse aldol condensation} {condensation reaction, carbohydrate} can lengthen carbon chains by two carbons.
ketol-enol
Proton can transfer from -CO-CH2OH ketol last carbon to next-to-last carbon, to make enol double bond between carbons and alcohol on next-to-last carbon: -COH=CHOH. Enol can add water molecule to make separated charges: -(H2OC+OH)-(C-HOH) [2 is subscript and + and - are superscripts]. Last carbon becomes negative, and next-to-last carbon becomes positive.
aldol
Enol with separated charges can attack aldol, -CHOH-CHO, carbonyl double bond to single-bond carbonyl carbon and carbanion: -CHOH-(C-OH)-CHOH-(H2OC+OH)- [2 is subscript and + and - are superscripts]. Positive charge is still on next-to-last enol carbon, and negative charge is on last aldol carbon.
proton transfer
Water leaves, and proton transfers from positive charge to carbanion and makes atoms neutral: -CHOH-CHOH-CHOH-CHOH-.
Glucose can convert to ethanol and carbon dioxide, using no oxygen {fermentation}|. Glucose converts to pyruvate. Pyruvate converts to acetaldehyde by losing carbon dioxide. Acetaldehyde reduces to ethanol using NADH. Berzelius described fermentation [1837].
Glucose can convert to pyruvate and then to lactic acid {glycolysis}| {Embden-Meyerhof pathway}. Glycolysis makes more ATP than it uses and is anaerobic, requiring no oxygen. Glycolysis enzymes float free in cytoplasm. In first part, glucose becomes glyceraldehyde-3-phosphate by adding two ATPs to ends and splitting into two molecules. In second part, glyceraldehyde-3-phosphate becomes pyruvate and makes four ATPs. Pyruvate makes lactic acid by adding NADH.
Isocitrate makes glyoxalate, and glyoxalate makes malate {glyoxalate cycle}, if acetyl-CoA is present. Glyoxysomes make succinate, which is precursor for fatty-acid synthesis.
Glucose-6-phosphate becomes 6-phosphogluconate by oxidation {phosphogluconate pathway} {pentose phosphate pathway} {hexose monophosphate shunt}. Aldehyde becomes carboxyl. NAD+ becomes NADPH. 6-phosphogluconate makes pentoses, such as ribose-5-phosphate, for nucleotides. Hexose monophosphate shunt in reverse makes hexoses from pentoses for extra energy. Pentose phosphate pathway is in photosynthesis dark reaction.
Sugars can isomerize by keto-enol tautomerism at carbonyl {isomerization}|.
By isomerization {keto-enol isomerization}, enol can become ketol, and ketol can become enol. Keto-enol isomerization must polarize, with lysine, cysteine, or serine.
At cysteine, aldehyde can oxidize to carboxylic acid using two NAD+ {oxidation, carbohydrate}. R-CHO -> R-CHOH-S-cys + 2 NAD+ -> R-CO-S-cys + 2 NADH -> R-COOH. Sugars can oxidize to makes acids: ascorbic acid, gluconic acid, uronic acid, and phytic acid {oxidized sugar}. Sugar aldehyde or ketone group can reduce to alcohol group to make glycerol, inositol, sorbital, and mannitol reduced sugars. Glycerol and inositol bind fatty acids. Sorbital and mannitol are food additives.
Hydrogen-ion transfer provides energy to convert ADP to ATP {phosphorylation}. ADP makes ATP {oxidative phosphorylation}, using hydrogen-ion gradient set up by respiratory chain in mitochondria inner membrane. Channels through membrane allow hydrogen ions to flow past ATPase, which uses electric and flow energy to phosphorylate ADP. ADP controls process by controlling coupling between FAD+ to FADH2 [2 is subscript] and NAD+ to NADH, by folding inner membrane more or less. Arsenate or dinitrophenol destroys pH gradient. Oligomycin binds to ATPase.
Carbon dioxide, water, and sunlight can make oxygen and glucose {photosynthesis}|.
process
First, light reacts with water, NADP+, and ADP to make oxygen, NADPH, H+, and ATP {light phase}. Light oxidizes pigments, to release electron. Donated electron adds to NADP+. Electron transport chain and oxidative phosphorylation make ATP and oxygen. Then carbon dioxide, NADPH, H+, and ATP make glucose, NADP+, and ADP {dark phase}, with no light required.
pigments
Chlorophyll a absorbs orange light, and chlorophyll b absorbs red light, making plant green. Yellow, red, or purple carotenoid pigments absorb at different wavelengths. Xanthophyll carotenoid absorbs yellow. Physobilin carotenoid absorbs blue or red.
Older system absorbs light at 710 nanometers and makes ATP but no oxygen. Newer system absorbs light at 680 nanometers and makes oxygen.
bacteria
Nitrogen-fixing bacteria use photosynthesis to make nitrogen into ammonia. Nitrate-fixing bacteria use photosynthesis to make ammonia. Sulfur bacteria use photosynthesis to make sulfates.
NADH and NADPH from glycolysis, TCA cycle, and other oxidations reduce oxygen to water in mitochondria {respiration, metabolism}. Hydrogen ions increase inside mitochondria and make pH gradient across mitochondrial membrane.
respiratory chain
Aerobic reduction reactions {respiratory chain} make the following compounds: FMNH2 [2 is subscript], ferrous iron, coenzyme Q, cytochrome b, iron-sulfur bond, cytochrome c, cytochrome c1, cytochrome a, cytochrome a3, and water from oxygen.
phosphorylation
Oxidative phosphorylation links to respiratory chain at three places: coenzyme Q reduction, cytochrome c reduction to cytochrome c1, and oxygen reduction to water. At the three steps, respiratory chain places hydrogen ions on mitochondria inner-membrane outside.
poisons
Hydrogen cyanide, carbon monoxide, and hydrogen sulfide inhibit oxygen reduction to water.
Fruit can increase sugar and decrease complex carbohydrates {ripening}|. After picking, starch builds up, and sugar breaks down. Ethylene can ripen fruit.
Citrate and ATP can make acetyl-CoA. Acetyl-CoA enters cycles {TCA cycle} {tricarboxylic acid cycle} {citric acid cycle} {Krebs cycle} and becomes two carbon dioxides and four NADH hydrogens. TCA cycle makes citrate, isocitrate, alpha-ketoglutarate, succinyl-CoA, succinate, fumarate, malate, oxaloacetate, and citrate again. These are mostly three-carbon carboxylic acids. Pyruvate, carbon dioxide, and ATP can make oxaloacetate and malate, which can enter cycle.
purpose
NADH hydrogens are for reduction reactions.
aerobic
TCA cycle uses oxygen to make carbon dioxide.
Acetyl compounds {acetyl-CoA} can enter lipid chain, go to TCA cycle, or become pyruvate. Acetyl-CoA breaks down to water and carbon dioxide. Pyruvate can become acetyl-CoA. Amino acids can make acetyl-CoA. Fatty acids can become acetyl-CoA.
Last carbon can have aldehyde functional group and next-to-last carbon can have alcohol functional group, -CHOH-CHO {aldol}. Aldol and ketol have tautomerism. Aldol can transfer two protons to last carbon to make ketol, -CHO-CHOH. Ketol can transfer two protons to next-to-last carbon to make aldol.
Carbohydrates have carbonyl group {carbonyl group}. First carbon can have aldehyde group {aldose}. Second carbon can have ketone group {ketose}. In water, ketone oxygen can substitute for hydroxyl on next-to-last carbon, to make five-carbon ring {furanose}. Furanose is hemiketal. In water, aldehyde oxygen can substitute for hydroxyl on next-to-last carbon to make six-carbon ring {pyranose}. Pyranose is hemiacetal.
anomer
Carbonyl carbon can be axial {alpha-glycosidic bond} or equatorial {beta-glycosidic bond} to sugar ring. Oxygen can be on right {alpha ring} or left {beta ring}. Alpha and beta rings have similar properties.
Proton can transfer from ketol last carbon to next-to-last carbon to make alkene double bond between carbons and alcohol on next-to-last carbon, -COH=CHOH {enol}. Enol can add water molecule to make separated charges, -(H2OC+OH)-(C-HOH) [2 is subscript and + and - are superscripts].
Ketone can be at next-to-last carbon and alcohol on last carbon, -CO-CH2OH [2 is subscript] {ketol}. Aldol and ketol exhibit tautomerism. Ketol can transfer two protons to next-to-last carbon to make aldol, -CHOH-CHO. Aldol can transfer two protons to last carbon to make ketol.
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Date Modified: 2022.0225