Overview of carbohydrates, including structure and properties of monosaccharides, disaccharides, and polysaccharides.
Log in Gen L 8 years agoPosted 8 years ago. Direct link to Gen L's post “Why are galactose and glu...” Why are galactose and glucose isomers, when the hydroxyl group that is "flipped" is linked to the chain by single bonds only? I thought only double+triple bonds forced atoms to stay where they are. According to the previous lesson about ethene/ethane, galactose and glucose should be the same thing because the flip happens around single bonds. • (19 votes) J Wu 7 years agoPosted 7 years ago. Direct link to J Wu's post “Well, single bonds allow ...” Well, single bonds allow the actual atom/molecule to rotate. However, in this case, when the article is talking about "flipped" molecules, the molecules are not able to rotate, they are just upside-down in relation to the neighboring molecules. (8 votes) Michael 8 years agoPosted 8 years ago. Direct link to Michael's post “Confused about difference...” Confused about differences between beta-glycosidic and alpha glycosidic linkages. Are beta-glycosidic linkages inherently stronger due to some chemical property, or is it just that humans lack the enzymes to digest it? Whatever the answer, this is not to be confused with the reason cellulose is so strong (which is due to the hydrogen bonds acting between different polymers of glucose, forming thin fibrils), am I correct? • (9 votes) Laurent 8 years agoPosted 8 years ago. Direct link to Laurent's post “Well from what I learned ...” Well from what I learned beta-glycosidic linkages are stronger due to the way bonds criss-cross between every alternate glucose molecule such as cellulose making it both physically and chemically stable. These beta-glycosidic linkages can be broken down by enzymes stored by the bacteria stored in a cow's gut for example which why cow's can ingest complex carbohydrates like cellulose and as you suggested humans cannot digest such carbohydrates as we do not have the enzymes that can specifically break beta-glycosidic linkages. (15 votes) Amirhossein Alesheikh 6 years agoPosted 6 years ago. Direct link to Amirhossein Alesheikh's post “What is the advantage of ...” What is the advantage of polysaccharides, storage wise? • (5 votes) RogerP 6 years agoPosted 6 years ago. Direct link to RogerP's post “To add to the excellent r...” To add to the excellent reply from Okapi, another reason why glucose is stored as glycogen is that if it were stored as free glucose, this would cause osmotic pressure to increase such that cell membranes would rupture. Even the elevated glucose level (hyperglycemia) seen in uncontrolled diabetes cause changes in osmotic pressure that are responsible for some of the symptoms, such as increased urination and excessive thirst. (13 votes) sammiihh 5 years agoPosted 5 years ago. Direct link to sammiihh's post “How can you identify a ca...” How can you identify a carbohydrate? Are all molecules with a carbonyl group (C=O) and hydroxyl group (OH) carbohydrates? Or is it so that ONLY carbohydrates have one carbon (C) atom to one H2O? If the latter is true, why is deoxyribose a carbohydrate with a formula C5H10O4? • (5 votes) tyersome 5 years agoPosted 5 years ago. Direct link to tyersome's post “Unfortunately there isn't...” Unfortunately there isn't a universally accepted definition for what makes up a carbohydrate. A very restrictive definition is as follows: However, derivatives of molecules that meet the above definition are still generally thought of as carbohydrates. For example: deoxyribose is a sugar (carbohydrate) found in DNA that has had an oxygen removed. Other modifications including addition of groups containing nitrogen and sulfur are also commonly found. I recommend the wikipedia article on this subject: Does that help? (10 votes) Scott 8 years agoPosted 8 years ago. Direct link to Scott's post “What is the difference be...” What is the difference between a monomer and a monosaccharide? • (3 votes) N Peterson 8 years agoPosted 8 years ago. Direct link to N Peterson's post “A monomer is the smallest...” A monomer is the smallest unit of a polymer. (9 votes) minionsville 7 years agoPosted 7 years ago. Direct link to minionsville's post “Is fructose sugar healthi...” Is fructose sugar healthier than glucose sugar? • (4 votes) HyperNova 8 months agoPosted 8 months ago. Direct link to HyperNova's post “It depends on the context...” It depends on the context of how its used. (5 votes) Bodey Baker 2 years agoPosted 2 years ago. Direct link to Bodey Baker's post “After searching for a bit...” After searching for a bit more info one thing confused me a little with these diagrams. They're all the D form of the molecules, which makes sense because they're naturally occuring, but I noticed that sometimes in other sources when drawn, the oxygen from the carbonoxyl is on the other side. Why is this? • (5 votes) Ala 7 years agoPosted 7 years ago. Direct link to Ala's post “With the glucose and gala...” With the glucose and galactose isomers, can't glucose's 3rd carbon spin around if it doesn't have a double bond? Then it would be exactly like galactose. Does this happen or is there a reason why it can't? • (4 votes) Ivana - Science trainee 5 years agoPosted 5 years ago. Direct link to Ivana - Science trainee's post “Because it requires break...” Because it requires breaking off the bonds. If you want to turn H, and OH into one another, you will have to break bonds and reattach them. This does not happen spontaneously in water. You cannot turn one into another through mere rotations of a bond. :) (3 votes) ujalakhalid01 8 years agoPosted 8 years ago. Direct link to ujalakhalid01's post “we have looked at the lin...” we have looked at the linear structures of these sugars my question is how these atoms of sugars are arranged in real life means in linear form or in ringed form? • (4 votes) William H 8 years agoPosted 8 years ago. Direct link to William H's post “In a solution of water, a...” In a solution of water, around 3% will be in the linear form, the rest are ringed. (1 vote) Danny 8 years agoPosted 8 years ago. Direct link to Danny's post “if single bonds can rotat...” if single bonds can rotate freely do the stereoisomers become each other interchangeably ? • (2 votes) Lim Pin Seng 8 years agoPosted 8 years ago. Direct link to Lim Pin Seng's post “No, single bonds stereois...” No, single bonds stereoisomers such as some enatiomers are not interchangeably because they are stuck in the three dimension world (3 votes)Want to join the conversation?
Carbohydrates consist of carbon, hydrogen, and oxygen — with the hydrogen and oxygen occurring in a 2:1 ratio. There also must be at least three carbons.
In other words, these are organic molecules that incorporate multiple water molecules and have at least three carbons.
(In addition, some molecules that fit these parameters aren't generally thought of as carbohydrates.)
https://en.wikipedia.org/wiki/Carbohydrate
A polysaccharide (carbohydrate) is a polymer. A monosaccharide is the monomer that makes up a polysaccharide.
In short- Monomer is a general term, while monosaccharide is a specific term for the monomer that makes up a carbohydrate.
A monosaccharide is a single sugar molecule. This includes glucose, fructose, and galactose.
Disaccharides are double sugars, such as sucrose (table sugar).
Polysaccharides are long chains, such as plant and animal starches.
