Comprehensive Biology Reviewer: Cell Transport, Division, Photosynthesis, and Respiration

Vocabulary flashcards generated from the comprehensive Biology reviewer notes, covering transport processes, cell division, photosynthesis, and cellular respiration.

Simple Diffusion

The passive movement of molecules directly through the lipid bilayer from an area of high concentration to low concentration without requiring ATP (e.g., $O_2$ and $CO_2$).

Facilitated Diffusion

The movement of substances from high to low concentration across a membrane using membrane proteins without requiring ATP.

Osmosis

The movement of water across a selectively permeable membrane toward an area with a higher solute concentration without requiring ATP.

Active Transport

The movement of substances from low to high concentration against their concentration gradient, requiring ATP and transport proteins or pumps.

Sodium-Potassium Pump

A membrane transport protein that uses ATP to move $3\text{ Na}^+$ out of the cell and $2\text{ K}^+$ into the cell.

Hypotonic Solution

A solution with a lower solute concentration outside the cell than inside, causing water to move into the cell and resulting in cell swelling.

Isotonic Solution

A solution with equal solute concentration inside and outside the cell, resulting in no net movement of water.

Hypertonic Solution

A solution with a higher solute concentration outside the cell than inside, causing water to move out of the cell and resulting in cell shrinkage.

Plasmolysis

The shrinking or pulling away of the cell membrane from the cell wall in a plant cell when placed in a hypertonic solution as water leaves the cell.

Endocytosis

A cellular process in which a cell takes substances into the cell by engulfing them in vesicles.

Phagocytosis

A form of endocytosis referred to as 'cell eating,' where the cell takes in large particles or whole cells.

Pinocytosis

A form of endocytosis referred to as 'cell drinking,' where the cell takes in extracellular fluids and dissolved substances.

Receptor-Mediated Endocytosis

A specific type of endocytosis where target substances enter the cell after binding to specific receptors, involving clathrin-coated vesicles.

Exocytosis

A process where vesicles fuse with the cell membrane to release substances outside the cell.

Mitosis

A type of cell division that produces $2$ daughter cells that are genetically similar to the parent cell, essential for growth, repair, and tissue replacement.

Meiosis

A two-round cell division process that produces gametes or sex cells with genetic variation.

Independent Assortment

The random distribution of homologous chromosomes during meiosis that creates unique combinations of chromosomes in gametes.

Crossing Over

The exchange of DNA sections between homologous chromosomes during Prophase I of meiosis, generating new genetic combinations.

Nondisjunction

The failure of chromosomes to separate properly during cell division, leading to abnormal chromosome numbers in resulting cells.

Photosynthesis Equation

The metabolic pathway summarized by the chemical equation $6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2$.

Thylakoid Membrane

The membrane structure inside chloroplasts containing chlorophyll; it serves as the site for light-dependent reactions.

Stroma

The fluid-filled interior area of the chloroplast surrounding the thylakoids; it serves as the site for the Calvin cycle.

Light-Dependent Reactions

Photosynthetic reactions in the thylakoid membrane that use light and $H_2O$ to produce ATP, NADPH, and $O_2$.

Photolysis

The light-driven splitting of water molecules ($H_2O \rightarrow H^+ + \text{electrons} + O_2$) during light-dependent reactions, which serves as the source of released $O_2$.

Calvin Cycle

The light-independent metabolic cycle in the stroma using $CO_2$, ATP, and NADPH to produce G3P through Fixation, Reduction, and Regeneration.

Carbon Fixation

The first stage of the Calvin cycle, where inorganic $CO_2$ is incorporated into an organic molecule by the enzyme RuBisCO.

RuBisCO

The primary enzyme involved in carbon fixation that catalyzes the incorporation of $CO_2$ into the Calvin cycle.

Stomata

Microscopic pores on plant leaves that open and close to regulate gas exchange ($CO_2$ entry, $O_2$ and water vapor exit).

Accessory Pigments

Plant pigments that absorb additional light wavelengths outside chlorophyll's peak range, expanding the spectrum used for photosynthesis.

Photorespiration

An inefficient metabolic pathway occurring when RuBisCO binds $O_2$ instead of $CO_2$, typically accelerated when stomata close and internal $CO_2$ levels drop.

Cellular Respiration Equation

The catabolic pathway summarized by the chemical equation $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$.

Glycolysis

The initial, anaerobic stage of cellular respiration occurring in the cytoplasm, breaking down glucose into $2$ pyruvate molecules while producing ATP and NADH.

Krebs Cycle

Also known as the Citric Acid Cycle; a process in the mitochondrial matrix that processes pyruvate derivatives to yield ATP, NADH, $FADH_2$, and $CO_2$.

Electron Transport Chain (ETC)

A sequence of protein complexes on the inner mitochondrial membrane that uses high-energy electrons from NADH and $FADH_2$ to pump $H^+$ and establish a proton gradient.

ATP Synthase

An enzyme embedded in membranes that uses the energy from a proton ($H^+$) gradient to synthesize ATP.

Oxygen in Cellular Respiration

The final electron acceptor in the electron transport chain, which binds with electrons and $H^+$ ions to form $H_2O$.

Proton Leak

A condition caused by pores in the inner mitochondrial membrane where $H^+$ ions bypass ATP synthase, collapsing the proton gradient, reducing ATP synthesis, and dissipating energy as heat.

NADH and FADH2

Key coenzymes that act as high-energy electron carriers, delivering electrons produced during earlier stages of cellular respiration to the ETC.

Lactic Acid Fermentation

An anaerobic pathway converting pyruvate to lactate to regenerate $NAD^+$ so glycolysis can continue generating small amounts of ATP.

Warburg Effect

The observation that cancer cells preferentially use glycolysis for energy production even in the presence of oxygen to rapidly generate ATP and metabolic intermediates for growth.

Competitive Inhibition

Inhibition where a molecule competes directly with a substrate for binding at an enzyme's active site, thereby slowing or preventing the enzymatic reaction.

Actin Filaments

Cytoskeletal elements crucial for cell shape alteration and movement; required for immune cells like macrophages to perform phagocytosis.

Light Compensation Point

The specific light intensity at which the rate of photosynthesis equals the rate of cellular respiration, resulting in zero net $CO_2$ uptake or release.