Cellular Energy, Photosynthesis, and Cellular Respiration

Vocabulary flashcards covering the key terms, definitions, and biochemical processes of cellular energy (ATP), photosynthesis, and cellular respiration.

Chemical Energy

Energy stored in the bonds of chemical compounds, which allows energy to be transported around the cell.

Adenosine Triphosphate (ATP)

The cellular energy currency that transports energy within the cell, consisting of adenine, ribose, and three phosphate groups.

Adenosine Diphosphate (ADP)

The molecule formed alongside an independent phosphate ($P_i$) when the bond between the second and third phosphate groups of ATP is broken to release energy.

Autotrophs

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

Heterotrophs

Organisms that need to consume other organisms for food.

Chloroplast

A two-membrane organelle containing thylakoids and stroma where photosynthesis reactions take place.

Chlorophyll

A pigment found in chloroplasts that absorbs blue/violet and red light and reflects green and yellow light to energize electrons for chemical reactions.

Thylakoids

Sac-like membrane stacks inside the chloroplast where the light-dependent reactions of photosynthesis occur.

Stroma

The fluid-filled space surrounding the thylakoid stacks in a chloroplast where the light-independent reactions take place.

$$NADP^+$$

A transport molecule that carries high-energy electrons and a hydrogen ion ($H^+$) from the light-dependent reactions to the light-independent reactions, becoming $NADPH$.

Photolysis

The process in light-dependent reactions where $H_2O$ molecules are broken apart, releasing $O_2$, replacing electrons in the electron transport chain, and transferring $H^+$ to $NADP^+$.

Light-Dependent Reactions

Photosynthetic reactions occurring in the thylakoids that collect sunlight using photosystems and break down $H_2O$ to generate ATP, NADPH, and $O_2$.

Calvin Cycle

The light-independent reactions occurring in the stroma that convert $CO_2$, ATP, and NADPH into a 6-carbon simple sugar compound known as glucose.

Cellular Respiration

The process by which all organisms break down glucose to gradually produce energy in the form of ATP ($C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$).

Aerobic Respiration

Cellular respiration that occurs when oxygen is available to the cell, proceeding through glycolysis, the Krebs cycle, and the electron transport chain to yield about $36\text{ ATP}$.

Anaerobic Respiration

A process occurring when oxygen is not available to the cell where glycolysis is followed by fermentation, yielding only $2\text{ ATP}$.

Glycolysis

The first step of cellular respiration in the cytoplasm/cytosol where one glucose molecule is broken down into two pyruvic acid molecules, producing $2\text{ ATP}$ and $NADH$.

Krebs Cycle

The second step of aerobic respiration occurring in the mitochondria where pyruvic acid is broken down, releasing $CO_2$, ATP, and high-energy electrons on $NADH$ and $FADH_2$.

Electron Transport Chain

The third step of aerobic respiration where electrons are passed along molecules and combine with $H^+$ and $O_2$ to form $H_2O$, while pumping $H^+$ ions across the mitochondrial membrane.

ATP Synthase

A molecule that turns as $H^+$ ions move back across the mitochondrial membrane, generating large amounts of ATP.

Fermentation

An anaerobic process that recycles $NAD^+$ from $NADH$ so that glycolysis can continue to produce small amounts of ATP when oxygen is absent.

Alcoholic Fermentation

A type of fermentation used by yeast that breaks down pyruvic acid to produce ethyl alcohol and $CO_2$, utilized in bread baking.

Lactic Acid Fermentation

A type of fermentation that produces lactic acid, used in human muscles for quick energy and by microorganisms in foods such as kimchi, pickles, sauerkraut, yogurt, and sour cream.