Cellular Energy, Photosynthesis, and Respiration Lecture Notes

Practice vocabulary flashcards covering energy forms, cellular work, ATP dynamics, chloroplast anatomy, light properties, and the stages of photosynthesis based on the lecture notes.

Potential Energy

Stored energy, such as the chemical energy stored in glucose molecules.

Kinetic Energy

Energy of motion.

Radiant Energy

Energy carried by electromagnetic waves or light, organized into photons, that serves as the ultimate source of energy for most organisms.

Photon

A packet of light energy.

Wavelength

The distance between corresponding points of a wave; shorter wavelengths have higher energy, whereas longer wavelengths have lower energy.

Mechanical Work

A type of cellular work that involves movement.

Transport Work

A type of cellular work that involves moving substances across membranes.

Chemical Work

A type of cellular work that involves building molecules.

Autotroph

An organism that makes its own organic food from inorganic materials using an energy source.

Photoautotroph

An autotroph that uses light energy to produce organic food.

Chemoautotroph

An autotroph that uses energy from chemical reactions to produce organic food.

Heterotroph

An organism that obtains organic food by consuming other organisms or their products.

Metabolism

The total of all chemical reactions that occur within an organism.

Anabolic Pathway

A metabolic pathway that builds larger, organic molecules (such as glucose) from smaller molecules; exemplified by photosynthesis.

Catabolic Pathway

A metabolic pathway that breaks down complex molecules into smaller molecules to release usable energy; exemplified by cellular respiration.

ATP (Adenosine Triphosphate)

A molecule consisting of adenine, ribose sugar, and three phosphate groups that cells use to temporarily store and transfer usable energy in small, manageable amounts.

ADP (Adenosine Diphosphate)

The molecule formed when ATP loses its terminal phosphate group, releasing usable energy and an inorganic phosphate.

Phosphate Group

A group containing phosphorus and oxygen; removing the terminal phosphate group from ATP releases energy and forms ADP.

Photosynthesis

The process by which light energy is converted into chemical energy, summarized by the equation $6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2$.

Cellular Respiration

The catabolic process cells use to break down food molecules such as glucose to release usable energy.

Glucose

A sugar produced during photosynthesis that stores chemical potential energy for cellular processes.

Chloroplast

The organelle in plants and algae where photosynthesis takes place, containing thylakoids and stroma.

Thylakoids

Flat, saclike membranes arranged in stacks inside a chloroplast where the light-dependent reactions occur and pigments are located.

Grana

Stacks of thylakoids located within a chloroplast.

Stroma

The fluid-filled space outside the grana within a chloroplast where the Calvin cycle takes place.

Pigment

A light-absorbing colored molecule that absorbs specific wavelengths of light.

Visible Spectrum

The range of colors that make up visible light, spanning from the shorter-wavelength, higher-energy violet end to the longer-wavelength, lower-energy red end.

Chlorophyll a

A photosynthetic pigment that absorbs mostly violet and red light and is directly involved in the light reactions of photosynthesis.

Chlorophyll b

An accessory pigment that absorbs mostly blue and reddish-orange light to help chlorophyll a capture light energy.

Accessory Pigments

Light-absorbing compounds, including chlorophyll b and carotenoids, that assist plants in capturing additional wavelengths of light energy.

Carotenoids

Accessory pigments that appear yellow, orange, or brown, and become visible in leaves during autumn when chlorophylls break down.

Beta-carotene

A specific example of a carotenoid accessory pigment.

Absorption (of Light)

The process of taking in light energy by an object or pigment, providing the energy needed to drive chemical reactions in photosynthesis.

Reflection (of Light)

The bouncing of light off an object, which determines the perceived color of that object.

Transmission (of Light)

The passing of light through an object.

Light-Dependent Reactions

The first stage of photosynthesis occurring in thylakoids, where light energy is captured, water is split, $O_2$ is produced and diffuses out, and energy is temporarily stored in ATP and NADPH.

Calvin Cycle

The light-independent stage of photosynthesis occurring in the stroma that uses $CO_2$, ATP, and NADPH to produce organic compounds such as sugars.

NADPH

An energy-carrying molecule produced during the light-dependent reactions that supplies energy to the Calvin cycle.

Enzyme

A molecule that speeds up chemical reactions in cells.

Denaturation

A structural change in an enzyme that renders it ineffective at its job, which can happen at excessively high temperatures.

Biomass

The total mass of living material in an organism or group of organisms; largely derived from carbon dioxide fixed from the air during photosynthesis.