Chapter 10

Photosynthesis

specialized molecular complexes in chloroplasts capture light energy from the sun and convert it to chemical energy that is stored in sugar and other organic molecule is called photosynthesis.

chloroplasts

P;ants amd other photosynthetic organisms contain cellular organelles called chloroplast.

Autotrophs

Self-feeders; they sustain themselves without eating anything derived from other living beings. Produce organic molecules from CO2 and other inorganic raw materials obtained from the environment.

Heterotrophs

Obtain organic material by second major mode of nutrition. Unable to make their own food, they live on compounds produced by organisms (hetero-other). they are biosphere's consumer.

Mesophyll

The tissue in the interior of the leaf.

Stomata

microscopic pores

Stroma

A chloroplast has two membranes surrounding a dense fluid called stroma.

Thylakoid

Suspended within the stroma is a third membrane system, made up of sacs called thylakoid, which segregates the stroma from the thylakoids space inside these sacs.

Chlorophyll

Green pigment that gives leaves their color, resides in the thylakoid membrane choroplast.

light reaction

the photo part of photosynthesis

NADH+

Light absorbed by chlorophyll drives a transfer of the electrons and hydrogen ions from water to an accepter called NADP+

NADPH

The light reactions use use solar energy to reduce NADPH+ to NADPH by adding a pair of electrons along with H+.

Photophosphosphorylation

The light reactions also generate ATP, using chemiosmosis to power the addition of a phosphate group ADP, a process called Photophosphorylation.

Carbon fixation

incorporation of carbon into organic compounds known as carbon fixation.

Light

Light is a form of energy known as electromagnetic energy, also called electromagnetic.

wavelength

The distance between the crests electromagnetic waves is called wavelength.

primary electron acceptor

a molecule capable of accepting electrons and becoming reduced.

Photosystem (PSII) and Photosystem (PSI)

They were named in order of their discovery, but photosystem II functions first in the light reaction.

linear electron flow

Electromagnetic spectrum

Visible light

Photons

Spectrophotometer

Absorption

Chlorophyll A

Chlorophyll B

Action Spectrum

Carotenoids

light-harvesting complex

consist of various pigment molecules bound to proteins.

hydrogen carbon that are various shades of yellow and orange because they absorb violet and blue-green light.

photosynthesis, which profiles the relatives effectiveness of different wavelengths of radiation in driving the process.

The accessory pigment and separate group of accessory pigment called carotenoids.

the key light-capturing pigment that participates directly in the light reactions.

A graph plotting a pigments light absorption versus wavelength is called absorption spectrum.

The ability of a pigment to absorb various wavelength of light can be measured with an instrument called spectrophotometer.

The mode of light as wave explains many of light's properties, but certain respects light behaves as though it consist of discrete particles called photons.

The radiation is known as visible light because it can be detected as various colors by the human eye.

The entire range of radiation is known as electromagnetic spectrum.

it occurs during the light reactions of photosynthesis.

cyclic electron flow

Photoexcited electrons can take an alternative path called cyclic electron flow.

Calvin cycle

similar to the citric acid in that a starting material is regenerated after molecules enter and other exit cycle.

Glyceraldehyde 3-phosphate

the carbohydrate produced directly from the Calvin cycle is not glucose.It is actually a three-carbon sugar.

Phase 1: Carbon fixation

The calvin cycle incorporates each CO2 molecule, one at a time, by attaching it to a five carbon sugar name ribulose biophosphate.

Phase 2: reduction

receives an additional phosphate group from ATP, becoming 1,3-biosphoglycerate.

Phase 3: Regenration of CO2 acceptor (RuBP)

complex series of reactions, the carbon skeletons of five molecules of G3P are are rearranged by the last steps of the Calvin cycle into three molecules of RuBP.

Photorespiration

conditions within the leaf favor an apparently wasteful process called photorespiration.

C3 Plants

Calvin cycle enzyme that adds CO2 to ribulose bisphosphate, because the first organic product of carbon fixation is a three-carbon compound, 3-phosphoglycerate.

Photorespiration

Peroxisomes and mitochondria within the plant cell rearrange and split this compound, releasing CO2.

Bundle-sheath cells

arranged into tightly packed sheaths around the veins of the leaf.

PEP carboxylase

The first step is carried out by an enzyme present only in mesophyll cells called PEP carboxylase.

Crassulaccean metabolism

after the plant family crassulaceae, the succulents in which the process was first discovered.

CAM plants

store the organic acids they make during the night in their vacuoles until morning, when the stomata close.