6: Energy, Photosynthesis, and Cellular Respiration

Comprehensive vocabulary and concept flashcards covering Lesson 6 of General Biology, including energy laws, photosynthesis stages, and the phases of cellular respiration.

Photosynthesis

The process of generating organic molecules such as sugar using $CO_2$, water, and energy from sunlight.

Balanced Chemical Formula (Photosynthesis)

The requirement of $6$ carbon dioxides to produce $1$ sugar molecule, ensuring the number of atoms on both sides matches.

Light Reaction

The first stage of photosynthesis, also known as the energy capture stage or photoreaction, which happens in the thylakoid.

Calvin Cycle

The second stage of photosynthesis, known as the carbon capture stage or synthesis reaction, which occurs in the stroma.

Cyanobacteria

A type of bacteria that performs photosynthesis and is believed to be similar to the ancestors of chloroplasts.

Chloroplasts

The organelles that perform photosynthesis, packed with the green pigment known as chlorophyll.

Thylakoids

Numerous disk-like membrane structures inside the chloroplast where the light reaction takes place.

Thylakoid Lumen

The inside, fluid-filled portion of the thylakoid structure.

Stroma

The fluid portion of the chloroplast located outside of the thylakoids where the Calvin cycle occurs.

Chemical Energy

The energy stored in chemical bonds, such as those connecting carbon and hydrogen in fuel molecules.

First Law of Thermodynamics

A law stating that energy can never be created or destroyed; it can only be transformed from one form to another.

Second Law of Thermodynamics

A law stating that the conversion of energy is never perfect, and some energy is typically lost as heat during transformation.

Cellular Respiration

The process where living organisms harvest chemical energy from food and convert it into a portable form stored in ATP.

ATP (Adenosine Triphosphate)

A portable form of energy consisting of adenine, a ribose sugar, and three phosphate groups joined by high-energy bonds.

Glycolysis

The first step of cellular respiration, occurring in the cytosol, where glucose ($6$ carbons) is split into two molecules of pyruvate ($3$ carbons).

Investment Phase

The first part of glycolysis that consumes $2$ molecules of ATP to initiate the reaction.

Payoff Phase

The part of glycolysis that generates $4$ molecules of ATP and $2$ molecules of NADH, resulting in a net gain of $2$ ATP.

Acetyl-CoA Production

The second stage of cellular respiration, occurring in the mitochondrial matrix, where pyruvate is split into acetyl-CoA ($2$ carbons) and $CO_2$.

Krebs Cycle

The third stage of cellular respiration in the mitochondrial matrix that breaks down acetyl-CoA into $2$ molecules of $CO_2$, producing ATP, NADH, and $FADH_2$.

Mitochondria Double Membrane

The structure consisting of an outer membrane and an inner membrane with folds called cristae, creating the matrix and intermembrane space.

Electron Transport Chain (ETC)

The final stage of cellular respiration occurring on the inner mitochondrial membrane, producing the majority ($32$ molecules) of ATP.

NADH and FADH2

Electron carriers used in cellular respiration to temporarily store high-energy electrons for the electron transport chain.

NADPH

The specific high-energy electron carrier used in photosynthesis, distinguishably starting with P for 'photosynthesis'.

G3P (Glyceraldehyde 3-phosphate)

A three-carbon molecule produced in the Calvin cycle; one is used to make sugar, while others are recycled to sustain the cycle.

Carotenoids

Additional orange-colored plant pigments that assist chlorophyll in capturing a wider range of light energy.

Reaction Centre

A specific chlorophyll pigment where captured light energy is concentrated, causing electrons to 'jump off' to the electron transport chain.

Water-Splitting Reaction

A process in the photosystems where $H_2O$ is broken down into hydrogen ions, electrons (to replace those lost by the reaction centre), and oxygen.

ATP Synthase

An enzyme that functions like a watermill, using the movement of protons across a membrane to synthesize ATP from ADP.

Triglyceride

Another name for fat, consisting of a glycerol head and three fatty acid tails.

Lactic Acid Fermentation

An anaerobic mechanism used by muscle cells during intense exercise to produce ATP by converting pyruvate into lactic acid to regenerate $NAD^+$.

Ethanol Fermentation

An anaerobic process used by organisms like yeast to produce ATP, with ethanol and $CO_2$ generated as byproducts.