Cellular Energy, Photosynthesis, and Cellular Respiration

Vocabulary practice flashcards covering cellular energy, ATP structure, photosynthesis mechanisms, aerobic cellular respiration, and anaerobic fermentation.

Energy

The ability to do work, which exists in various types such as light, mechanical, and chemical.

Chemical Energy

Energy that is stored in the bonds of chemical compounds, enabling it to be transported around the cell.

Adenosine Triphosphate (ATP)

The energy currency for cells composed of adenine, ribose, and $3$ phosphate groups; it stores and transports chemical energy in the bonds between its phosphate groups.

Adenosine Diphosphate (ADP)

The molecule formed, along with an independent phosphate ($\text{P}$), when the bond between the $2\text{nd}$ and $3\text{rd}$ phosphate groups of ATP is broken to release energy.

Autotrophs

Organisms that make their own food from sunlight through the process of photosynthesis.

Heterotrophs

Organisms that must consume other organisms for food to obtain energy.

Chloroplasts

Organelles with $2$ membranes where photosynthesis reactions take place, containing thylakoid stacks and stroma.

Thylakoids

Sac-like stacks inside chloroplasts where chlorophyll pigments absorb light and the light-dependent reactions occur.

Stroma

The fluid-filled space surrounding the thylakoid stacks within the chloroplast where the light-independent reactions (Calvin Cycle) take place.

Chlorophyll

A photosynthetic pigment in chloroplasts that absorbs blue/violet and red light, reflects green and yellow light, and energizes electrons.

NADP+

A transport molecule that carries high-energy electrons from the light-dependent reactions to the light-independent reactions.

Photosynthesis Equation

The chemical reaction summarized by $6\text{CO}_2 + 6\text{H}_2\text{O} + \text{light} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$.

Light-Dependent Reactions

Reactions occurring in the thylakoids that absorb sunlight and $\text{H}_2\text{O}$, produce ATP and NADPH, and release $\text{O}_2$.

Photosystems

Combinations of chlorophyll pigments and specialized proteins in the thylakoid membrane that collect sunlight to energize electrons.

Photolysis

The light-dependent process where $\text{H}_2\text{O}$ molecules are broken apart, supplying electrons to the Electron Transport Chain, protons ($\text{H}^+$) to form NADPH, and releasing $\text{O}_2$.

Calvin Cycle (Light-Independent Reactions)

Reactions in the stroma that do not require sunlight; they utilize $\text{CO}_2$, ATP, and NADPH to produce glucose ($\text{C}_6\text{H}_{12}\text{O}_6$).

Cellular Respiration

The process by which all organisms break down glucose to gradually produce energy in the form of ATP.

Cellular Respiration Equation

The chemical reaction given by $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{energy}$, representing the reverse of the photosynthesis equation.

Aerobic Respiration

The cellular respiration pathway that proceeds in the presence of oxygen through glycolysis, the Krebs Cycle, and the Electron Transport Chain, yielding about $36\text{ ATP}$.

Anaerobic Respiration

The cellular energy pathway that occurs when oxygen is not available, following glycolysis with fermentation and yielding only $2\text{ ATP}$.

Glycolysis

The initial step of cellular respiration in the cytoplasm/cytosol where $1$ glucose molecule is broken into $2$ pyruvic acid molecules, yielding $2\text{ ATP}$ and NADH.

Krebs Cycle

The stage of aerobic respiration in the mitochondria where pyruvic acid breaks down to release $\text{CO}_2$, ATP, and high-energy electrons transported on NADH and $\text{FADH}_2$.

Electron Transport Chain (Cellular Respiration)

A series of mitochondrial membrane molecules that pass high-energy electrons, pump $\text{H}^+$ ions, and bond electrons with $\text{H}^+$ and $\text{O}_2$ to form and release $\text{H}_2\text{O}$.

ATP Synthase

A membrane molecule that rotates as $\text{H}^+$ ions move back across the mitochondrial membrane, generating large amounts of ATP.

Fermentation

An anaerobic process occurring after glycolysis when oxygen is absent that recycles NAD+ from NADH so glycolysis can continue generating $2\text{ ATP}$.

Alcoholic Fermentation

A form of fermentation carried out by yeast that produces ethyl alcohol and $\text{CO}_2$, used commercially to bake bread and produce beer, wine, and other alcohols.

Lactic Acid Fermentation

A form of fermentation producing lactic acid; used by humans for quick energy and by food industries to make kimchi, sour cream, sauerkraut, pickles, and yogurt.