3.1. Photosynthesis and Starch Synthesis

light-dependent reactions

a phase occurring in the thylakoid membranes where light energy and water are used to produce oxygen, ATP, and NADPH

ATP synthase

key enzyme of light-dependent reactions

calvin cycle

a phase in the stroma where carbon dioxide, ATP, and NADPH are used to synthesize GA3P, ADP, and NADP+, with rubisco acting as the key enzyme; dependent on temperature

glyceraldehyde 3-phosphate

what does GA3P stand for

nicotinamide adenine dinucleotide phosphate

what does NADP+/NADPH stand for

photosynthetically active radiation (par)

the specific range of light wavelengths (400 to 700 nanometers) that plants are capable of using for photosynthesis

limiting factors

variables like light intensity, carbon dioxide concentration, and temperature that, when in short supply, restrict the rate of photosynthesis

sodium bicarbonate

acts as a carbon dioxide source in aquatic experiments by dissolving in water to form CO2 gas

25°C - 35°C

optimum temperature for calvin cycle; the rate typically doubles for every 10 °C increase until enzymes denature

denaturation

what happens to the enzymes when temperature goes beyond the optimum

starch synthesis pathway

a process starting with triose phosphate in the chloroplast that converts fructose-6-phosphate, then glucose-1-phosphate into starch (amylose and amylopectin) via ADP and glucose phosphorylase

fructose-6-phosphate (F6P)

a crucial intermediate in plant carbohydrate metabolism, serving as a key precursor for starch synthesis and acting as a regulatory checkpoint in sucrose-starch partitioning

glucose-1-phosphate (G1P)

a central intermediate in starch metabolism, acting as both a substrate for starch synthesis via ADP-glucose and as a product of starch degradation by phosphorylase

starch

exists in the form of amylose and amylopectin

iki (iodine-potassium iodide) test

a diagnostic test where iodine binds to starch to produce a dark blue or black color

benedict's test

a chemical test used to identify reducing sugars like glucose; a positive result is indicated by a color change from blue to dark orange or red

variegated leaves

leaves containing both chlorophyll-rich and chlorophyll-deficient areas used to show that chlorophyll is essential for starch production

carbon dioxide; water

reactants involved in photosynthesis

G1P; ATP

reactants involved in starch synthesis

glucose; oxygen

products formed by photosynthesis

amylopectin; amylose

products formed by starch synthesis

ribulose-1,5-biphosphate carboxylase/oxygenase

key enzyme involved in photosynthesis

ADP glucose pyrophosphorylase

key enzyme involved in starch synthesis