ABP Unit 3 Ch.7: Photosynthesis

ADP

Nucleotide with two phosphate groups that can accept another phosphate group and became ATP

ATP

Nucleotide with three phosphate groups. The breakdown of ATP into ADP + P makes energy available for energy-requiring processes in cells.

Autotroph

Organism that can capture energy and synthesize organic molecules from inorganic nutrients

Carbohydrate

Class of organic compounds that typically contain carbon, hydrogen, and oxygen in a 1:2:1 ratio; includes the monosaccharides, disaccharides, and polysaccharides

Concentration gradient

Gradual change in chemical concentration between two areas of differing concentrations

Diffusion

Movement of molecules or ions from a region of higher to lower concentration; it requires no energy and tends to lead to equal distribution (equilibrium)

Electron

Negative subatomic particle, moving about in an energy level around the nucleus of an atom that is considered to have no atomic mass units.

Inorganic

All elements except hydrogen and carbon

Monosaccharide

Simple sugar; a carbohydrate that cannot be broken down by hydrolysis; also, any monomer of the polysaccharides

Organic

Anything that contains carbon

Polysaccharide

Polymer made from carbohydrate monomers; the polysaccharides starch and glycogen are polymers of glucose monomers

Proton (aka hydrogen ion)

Positive subatomic particle located in the nucleus an assigned one atomic mass unit

Synthesis

the building of larger, more complex molecules or cellular products from simpler building blocks

Absorption spectrum

For photosynthetic pigments, a graph of how much solar radiation is absorbed versus the wavelength of light

C3 plants

plant that fixes carbon dioxide via the Calvin cycle; the first stable product of C3 photosynthesis is a 3-carbon compound

C4 plants

Plant that fixes carbon dioxide to produce a C4 molecule that releases carbon dioxide to the Calvin cycle

CAM

Crassulacean-acid metabolism; a form of photosynthesis in succulent plants that separates the light dependent and Calvin reactions by time

Carotenoids

An accessory photosynthetic pigment of plants and algae that is often yellow or orange in color; consists of two classes- the xanthophylls and the carotenes

Chlorophyll

Green photosynthetic pigment of algae and plants that absorbs solar energy; occurs as chlorophyll a and chlorophyll b

NADP+

a coenzyme that acts as a universal electron carrier in cellular metabolism. Accepts energized electrons during the light-dependent reactions to form NADPH, which then powers the Calvin cycle to build glucose.

NADPH

The reduced, energy-rich form of NADP⁺. Produced during the light-dependent reactions. It then powers the Calvin cycle

Photosynthesis

Process, usually occurring within chloroplasts, that uses solar energy to reduce carbon dioxide to carbohydrate

Pigment

any colored chemical compound produced by living organisms that gives color to plant, animal, or microbial cells by selectively absorbing certain wavelengths of visible light and reflecting other

RuBP carboxylase

An enzyme that starts the Calvin cycle reactions by catalyzing attachment of the carbon atoms from CO2 to RuBP

ATP synthase complex

Complex of proteins in the cristae of mitochondria and thylakoid membrane of chloroplasts that produces ATP from the diffusion of hydrogen ions across a membrane

Bundle Sheath cells

specialized plant cells that form a protective layer around the vascular bundles (xylem and phloem) in leaves.

Chloroplast

Membrane bound organelles in algae and plants with chlorophyll-containing membranous thylakoids; where photosynthesis takes place

Electron transport chain

Process in a cell that involves the passage of electrons along a series of membrane bound electron carrier molecules from a higher to lower energy level; the energy released is used for the synthesis of ATP

Granum

Stack of chlorophyll containing thylakoids in a chloroplast

Mesophyll cells

specialized plant cells located in the middle layer of a leaf, positioned between the upper and lower epidermis. They contain high amounts of chloroplasts and serve as the primary site of photosynthesis in plants

NADP Reductase

a flavoprotein enzyme that catalyzes the transfer of electrons from reduced ferredoxin to NADP+ to produce NADPH.

Photosystem 1

a protein and pigment complex found in the thylakoid membranes of plants, algae, and cyanobacteria. It plays a key role in the light-dependent reactions of photosynthesis by using light energy to re-energize electrons.

Photosystem 2

the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is embedded in the thylakoid membranes of plants, algae, and cyanobacteria.

Stomata

Small openings between two guard cells on the underside of leaf epidermis, through which gases pass

Stroma

Region within a chloroplast that surrounds the grana; contains enzymes involved in the synthesis of carbohydrates during the Calvin cycle of photosynthesis

Thylakoid

Flattened sac within a geranium of a chloroplast; membrane contains chlorophyll; location where the light reactions of photosynthesis occur

Calvin Cycle Reactions

Portion of photosynthesis that takes place in the stroma of chloroplasts and can occur in the dark; it uses the products of the light reaction to reduce CO2 to a carbohydrate

Carbon dioxide fixation

Process by which carbon dioxide gas is attached to an organic compound; in photosynthesis, this occurs in the Calvin cycle reactions

Chemiosmosis

Process by which mitochondria and chloroplasts use the energy or an electron transport chain to create hydrogen ion gradient that drives ATP formation

Cyclic pathway

a closed-loop chain of reactions or electron flows where the starting molecule or carrier is regenerated at the end, allowing the process to repeat continuously.

Electrochemical gradient

the combined effect of a chemical concentration gradient and an electrical charge gradient that determines the net movement of ions across a biological membrane.

Light reactions

Portion of photosynthesis that captures solar energy and takes place in thylakoid membranes of chloroplasts; it produces ATP and NADPH

Noncyclic pathway

Light dependent photosynthetic pathway that is used to generate ATP and NADPH; because the pathway is noncyclic, the electrons must be replaced by the splitting of water

Phosphorylation

the chemical addition of a phosphate group to an organic molecule or protein.

Photorespiration

Series of reactions that occurs in plants when carbon dioxide levels are depleted but oxygen continues to accumulate, and the enzyme RuBP carboxylase fixes oxygen instead of carbon dioxide.