# What would it take to directly make carbohydrates? **URL:** \ **Category:** Factual Questions\ **Created:** [February 13, 2025, 5:19pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272 "2025-02-13T17:19:32Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [February 13, 2025, 5:19pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/1 "2025-02-13T17:19:32Z")
Is photosynthesis using chlorophyll the only way? If you can run that process in a test tube what type of carbohydrates might you end up with - anything useful? ---
**Author:** ![Yllaria](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yllaria/32/3452_2.png) [@Yllaria](https://boards.straightdope.com/u/Yllaria)\ **Post date:** [February 13, 2025, 5:29pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/2 "2025-02-13T17:29:33Z")
[Chemotrophic metabolisms](https://en.wikipedia.org/wiki/Chemotroph#Chemoautotroph), such as those at oceanic hydrothermic vents, do not use light to synthesize organic compounds. I didn’t see a specific reference to carbohydrates, but I assume they’d be handy to a microbe. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [February 13, 2025, 5:33pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/3 "2025-02-13T17:33:59Z")
It is possible to create carbohydrates in a lab. Wikipedia even has an article about it. > **[Carbohydrate synthesis](https://en.wikipedia.org/wiki/Carbohydrate_synthesis)** > > Carbohydrate synthesis is a sub-field of organic chemistry concerned with generating complex carbohydrate structures from simple units (monosaccharides). The generation of carbohydrate structures usually involves linking monosaccharides or oligosaccharides through glycosidic bonds, a process called glycosylation. Therefore, it is important to construct glycosidic linkages that have optimum molecular geometry (stereoselectivity) and the stable bond (regioselectivity) at the reaction site (anomeri... Kiliani–Fischer synthesis is one of the techniques referenced in the article, which has its own article. > **[Kiliani–Fischer synthesis](https://en.wikipedia.org/wiki/Kiliani%E2%80%93Fischer_synthesis)** > > The Kiliani–Fischer synthesis, named for German chemists Heinrich Kiliani and Emil Fischer, is a method for synthesizing monosaccharides. It proceeds via synthesis and hydrolysis of a cyanohydrin, followed by reduction of the intermediate acid to the aldehyde, thus elongating the carbon chain of an aldose by one carbon atom while preserving stereochemistry on all the previously present chiral carbons. The new chiral carbon is produced with both stereochemistries, so the product of a Kiliani–Fis... ---
**Author:** ![Elmer\_J.Fudd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/elmer_j.fudd/32/1211_2.png) [@Elmer\_J.Fudd](https://boards.straightdope.com/u/Elmer_J.Fudd)\ **Post date:** [February 13, 2025, 5:34pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/4 "2025-02-13T17:34:12Z")
Aren’t synthetic carbohydrates already used in vaccines? ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [February 13, 2025, 6:18pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/5 "2025-02-13T18:18:43Z")
[Previous discussion.](https://boards.straightdope.com/t/artificial-photosynthesis/804401) ---
**Author:** ![TeroSunbear](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terosunbear/32/14748_2.png) [@TeroSunbear](https://boards.straightdope.com/u/TeroSunbear)\ **Post date:** [February 14, 2025, 10:33pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/6 "2025-02-14T22:33:30Z")
The carbohydrates are not the problem. They are just carbon. A molecule of fat has a lot more CH2s and therefore more calories. It is consumed in 2 carbon units in the same process as starches. The problem in making either is the photon part. We have nothing that useful. It is quite a network of chlorophyl and two pigments that are required. Our best effort so far is solar cells where we capture the energy as electricity. But it is a long process to make carbon molecules out of electricity. So, no. Not a chance in practical terms. ---
**Author:** ![TeroSunbear](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terosunbear/32/14748_2.png) [@TeroSunbear](https://boards.straightdope.com/u/TeroSunbear)\ **Post date:** [February 15, 2025, 2:42pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/7 "2025-02-15T14:42:30Z")
No. All synthetic pieces, whether nucleoside or carbohydrate, are sourced from natural materials. They are then put together by biochemical or lab reagents. we can make peptides of several thousand amino acids on a solid “resin” with a reagent stuck to the column packing while you add amino acids one by one. But all those parts are natural. ---
**Author:** ![TeroSunbear](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terosunbear/32/14748_2.png) [@TeroSunbear](https://boards.straightdope.com/u/TeroSunbear)\ **Post date:** [February 15, 2025, 3:23pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/8 "2025-02-15T15:23:21Z")
Also, here are all the 5 carbon sugars. Some of the isomers are made by man in the lab. There are several “chiral” centers. But you cannot make a carbohydrates from scatch. You can extend a 2 carbon piece to 5, but the first piece will nevertheless have some natural origin. [Pentose - Wikipedia](https://en.wikipedia.org/wiki/Pentose) ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [February 16, 2025, 1:54pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/9 "2025-02-16T13:54:28Z")
This topic is less of interest for any practical synthesis of sugars, but is of interest to those studying abiogenesis. Pentoses can be synthesized from glycoaldehyde and formaldehyde, both found in space, no biology required for the feedstocks or the synthesis. ---
**Author:** ![TeroSunbear](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terosunbear/32/14748_2.png) [@TeroSunbear](https://boards.straightdope.com/u/TeroSunbear)\ **Post date:** [February 17, 2025, 5:19pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/10 "2025-02-17T17:19:22Z")
The solution will lie sowhere with the light. Polarized light is the record of what happened. The molcules retain info that was in the light. [Optical rotation - Wikipedia](https://en.wikipedia.org/wiki/Optical_rotation) ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [February 17, 2025, 7:48pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/11 "2025-02-17T19:48:43Z")
If you’re referring to biological homochirality, circularly polarized light is indeed one hypothesis for an extraterrestrial origin. ---
**Author:** ![bordelond](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bordelond/32/150_2.png) [@bordelond](https://boards.straightdope.com/u/bordelond)\ **Post date:** [February 17, 2025, 7:55pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/12 "2025-02-17T19:55:13Z")
If I may piggyback a slightly tangential question into this thread: Are chiral molecules necessary for life as we understand it? Putting aside theoretical forms of life that may exist elsewhere in the universe. EDIT: Thinking on it briefly, it seems chiral molecules are necessary to produce a helical structure (e.g. DNA). ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [February 17, 2025, 9:41pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/13 "2025-02-17T21:41:38Z")
“As we understand it” is tricky because we only have the one example. It’s not so much necessary but hard to avoid given than any carbon with four different functional groups is a chiral center. Not that every molecule with a chiral center is itself chiral, but close enough. So carbohydrates (and by extension, nucleic acids) and amino acids (and thus proteins). If you’re asking if we could get by without homochirality, that would be tricky. Linking different enantioners of monomers can produce chemically distinct diasteriomers. I’m not going to list out permutations here but see any freshman organic chemistry textbook. > **[Homochirality](https://en.m.wikipedia.org/wiki/Homochirality)** > > Homochirality is a uniformity of chirality, or handedness. Objects are chiral when they cannot be superposed on their mirror images. For example, the left and right hands of a human are approximately mirror images of each other but are not their own mirror images, so they are chiral. In biology, 19 of the 20 natural amino acids are homochiral, being L-chiral (left-handed), while sugars are D-chiral (right-handed). Homochirality can also refer to enantiopure substances in which all the constitu It... ---
**Author:** ![TeroSunbear](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terosunbear/32/14748_2.png) [@TeroSunbear](https://boards.straightdope.com/u/TeroSunbear)\ **Post date:** [February 18, 2025, 2:21pm UTC](https://boards.straightdope.com/t/what-would-it-take-to-directly-make-carbohydrates/1014272/14 "2025-02-18T14:21:46Z")
Yes. But there is no requirement for it to be one or the other. For a single molecule, we can say it is R or S by chemistry rules. For simplification, let us say one half of life comes about as R series, and another set of single cell life as S. They would compete for molecules in the surroundings. They can both use the same fat molecules as those are not chiral. They cannot use the same amino acids. Eventually, on any planet, the one half, R or S, would invent something the other did not. Say it is the current photosynthesis we have. Then the other half of life could not compete and would go extinct. I came up with this about ten years ago, but since I am not an academic, I can’t publish it. I have papers up to 1996. Then everything I did later was just patents. (R and S works for all molecules but actually refers to each carbon. D and L is for amino acids). [Absolute configuration - Wikipedia](https://en.wikipedia.org/wiki/Absolute_configuration)