Editing Chloroplast (section)

===== Sugars and starches =====

{{Plain image with caption|File:Saccharose2.svg|Sucrose is made up of a [[glucose]] monomer (left), and a [[fructose]] monomer (right).|width=220px|align=left|caption position=top|triangle=triangle|triangle color=#aaa}}

Glyceraldehyde-3-phosphate can double up to form larger sugar molecules like [[glucose]] and [[fructose]]. These molecules are processed, and from them, the still larger [[sucrose]], a [[disaccharide]] commonly known as table sugar, is made, though this process takes place outside of the chloroplast, in the [[cytoplasm]].<ref name="Berg-2002a">{{cite book| first1=Jeremy M | last1=Berg | first2=John L | last2=Tymoczko | first3=Lubert | last3=Stryer | name-list-style=vanc |title=Biochemistry|year=2002|publisher=W. H. Freeman|location=New York, NY [u.a.]|isbn=0-7167-3051-0|pages=Section 20.1|edition=5. ed., 4. print.|url=https://archive.org/details/biochemistrychap00jere| url-access=registration }}</ref>

Alternatively, glucose [[monomers]] in the chloroplast can be linked together to make [[starch]], which accumulates into the [[chloroplast starch granule|starch grains]] found in the chloroplast.<ref name="Berg-2002a" />
Under conditions such as high atmospheric CO<sub>2</sub> concentrations, these starch grains may grow very large, distorting the grana and thylakoids. The starch granules displace the thylakoids, but leave them intact.<ref name="Wample-1983" />
Waterlogged [[root]]s can also cause [[starch]] buildup in the chloroplasts, possibly due to less [[sucrose]] being exported out of the chloroplast (or more accurately, the [[plant cell]]). This depletes a plant's [[free phosphate]] supply, which indirectly stimulates chloroplast starch synthesis.<ref name="Wample-1983">{{cite journal | vauthors=Wample RL, Davis RW | title=Effect of Flooding on Starch Accumulation in Chloroplasts of Sunflower (Helianthus annuus L.) | journal=Plant Physiology | volume=73 | issue=1 | pages=195–8 | date=September 1983 | pmid=16663176 | pmc=1066435 | doi=10.1104/pp.73.1.195 }}</ref>
While linked to low photosynthesis rates, the starch grains themselves may not necessarily interfere significantly with the efficiency of photosynthesis,<ref>{{cite journal| vauthors=Carmi A, Shomer I |year=1979|title=Starch Accumulation and Photosynthetic Activity in Primary Leaves of Bean (''Phaseolus vulgaris'' L.)|journal=Annals of Botany|volume=44|issue=4|pages=479–484|doi=10.1093/oxfordjournals.aob.a085756 }}</ref> and might simply be a side effect of another photosynthesis-depressing factor.<ref name="Wample-1983" />