Part VI

Carbohydrates

Structure, storage, and photosynthetic efficiency — from the cellulose microfibrils of the cell wall to the source-sink partitioning of sucrose and the carbon-concentrating mechanisms of C4 and CAM plants.

Carbohydrate Metabolism Overview

PhotosynthesisCO2 fixation / Calvin cycleCell WallCellulose + Hemicellulose+ Pectin + LigninSucrose & StarchC3 vs C4 vs CAMsource-sink partitioningPhotorespiration2-PG recyclingC4/CAM avoidancePrimary cell wall (growing)Secondary wall + ligninStarch granule(amylose + amylopectin)C4/CAM CO2 pump(PEP carboxylase)

Foundational Equations

AGPase (starch precursor)

\( \text{G1P} + \text{ATP} \xrightarrow{\text{AGPase}} \text{ADP-glucose} + \text{PP}_i \)

RuBisCO oxygenase

\( \text{RuBP} + \text{O}_2 \xrightarrow{\text{RuBisCO}} \text{3-PGA} + \text{2-phosphoglycolate} \)

PEP carboxylase (C4)

\( \text{PEP} + \text{HCO}_3^- \xrightarrow{\text{PEPC}} \text{OAA} + \text{P}_i \)

SPS (sucrose synthesis)

\( \text{UDP-glucose} + \text{F6P} \xrightarrow{\text{SPS}} \text{sucrose-6-P} + \text{UDP} \)

Chapters