BIO 151 – Exam 2 Study Guide Flashcards

Comprehensive vocabulary flashcard deck covering membrane transport, bioenergetics, enzymes, photosynthesis, and cellular respiration for BIO 151 Exam 2.

Phospholipid

The main structural component of the plasma membrane, consisting of a hydrophilic head containing a phosphate group and two hydrophobic tails composed of fatty acids.

Cholesterol

A lipid located between the phospholipid tails that maintains membrane fluidity, prevents the membrane from becoming too rigid in cold temperatures or too fluid in warm temperatures, and stabilizes the membrane.

Integral Proteins

Membrane proteins that are embedded directly within the membrane or extend all the way through the phospholipid bilayer.

Peripheral Proteins

Proteins that are attached to the exterior or interior surface of the plasma membrane rather than embedded within it.

Membrane Carbohydrates

Chains found on the outside surface of the plasma membrane that function in cell recognition, cell communication, and cell adhesion.

Passive Transport

The movement of substances across a cell membrane down their concentration gradient from high to low concentration without requiring energy.

Active Transport

The movement of molecules against their concentration gradient from low to high concentration, which requires energy input, typically from ATP.

Diffusion

The passive movement of molecules from an area of high concentration to an area of low concentration, easily crossed by small nonpolar molecules such as $O_2$ and $CO_2$.

Facilitated Diffusion

A form of passive transport that uses membrane carrier proteins or channel proteins to help specific molecules cross the membrane without energy expenditure.

Carrier Proteins

Transport proteins that change shape to move specific molecules, such as glucose, across the plasma membrane during facilitated diffusion.

Channel Proteins

Transport proteins that provide open pores through the membrane allowing specific ions to pass through.

Osmosis

The diffusion of water across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration.

Hypotonic Solution

An environment with a lower solute concentration outside the cell, causing water to flow into the cell and leading animal cells to swell and potentially burst.

Isotonic Solution

An environment with an equal solute concentration inside and outside the cell, causing equal water movement and keeping animal cells at their preferred normal size.

Hypertonic Solution

An environment with a higher solute concentration outside the cell, causing water to exit the cell and resulting in animal cell shrinkage.

Turgor Pressure

The internal pressure created in plant cells when placed in a preferred hypotonic environment where water enters and presses against the rigid cell wall.

Endocytosis

A cellular process in which the cell engulfs and brings external materials inside using vesicles.

Phagocytosis

A type of endocytosis referred to as cell eating, where the cell engulfs large particles.

Pinocytosis

A type of endocytosis referred to as cell drinking, where the cell takes in extracellular fluids.

Receptor-Mediated Endocytosis

A specialized form of endocytosis that utilizes membrane receptors to selectively bring specific target molecules into the cell.

Exocytosis

A cellular process where the cell releases intracellular materials to the outside environment via vesicles.

Bioenergetics

The study of how energy flows through living organisms.

Metabolism

All the chemical reactions occurring inside a cell or living organism.

Catabolism

Metabolic pathways that break down larger molecules into simpler ones, releasing energy.

Anabolism

Metabolic pathways that build larger complex molecules from smaller units, requiring an input of energy.

Endergonic Reaction

A non-spontaneous chemical reaction that requires an input of energy and has a positive free energy change.

Exergonic Reaction

A spontaneous chemical reaction that releases free energy and has a negative free energy change.

Entropy

A thermodynamic measure of disorder or randomness within a system.

First Law of Thermodynamics

The fundamental law stating that energy cannot be created or destroyed, only transferred or transformed.

Second Law of Thermodynamics

The fundamental law stating that every energy transfer or transformation increases the entropy of the universe.

Adenosine Triphosphate (ATP)

The primary energy currency of the cell, composed of adenine, a ribose sugar, and three phosphate groups, which releases usable energy upon hydrolysis to ADP.

Activation Energy

The minimum energy required to initiate a chemical reaction.

Enzyme

A biological catalyst, usually a protein, that speeds up chemical reactions by lowering the activation energy without being consumed.

Denaturation

A structural change in an enzyme caused by extreme temperature or pH that alters its active shape and eliminates its biological activity.

Oxidation

The loss of electrons from a molecule, atom, or ion during a chemical reaction.

Reduction

The gain of electrons by a molecule, atom, or ion during a chemical reaction.

Autotroph

An organism, such as a plant, that produces its own organic food molecules from inorganic substances.

Heterotroph

An organism that obtains chemical energy and food by consuming other organisms.

Thylakoid

A flattened membrane sac inside the chloroplast where the light-dependent reactions of photosynthesis take place.

Stroma

The fluid-filled space surrounding the thylakoid membranes in the chloroplast where the Calvin cycle occurs.

Chlorophyll

The principal green photosynthetic pigment that absorbs blue and red wavelengths of light and reflects green light.

NADPH

An electron carrier that transports high-energy electrons and hydrogen produced during the light reactions to the Calvin cycle.

Photosystem II

The photosynthetic protein complex where light excites chlorophyll electrons and water is split, yielding oxygen, hydrogen ions, and replacement electrons.

Photosystem I

The photosynthetic protein complex where light re-energizes electrons before transferring them to $NADP^+$ to produce NADPH.

ATP Synthase

An enzyme complex that utilizes the flow of hydrogen ions down their concentration gradient to generate ATP from ADP and inorganic phosphate.

Rubisco

The chloroplast enzyme responsible for catalyzing carbon fixation by attaching $CO_2$ to RuBP during the Calvin cycle.

G3P (Glyceraldehyde 3-phosphate)

The three-carbon sugar product synthesized by the Calvin cycle using $CO_2$, ATP, and NADPH.

Glycolysis

The initial cytoplasmic step of cellular respiration that breaks down $1$ glucose molecule into $2$ pyruvate molecules, producing a net gain of $2\text{ ATP}$ and $2\text{ NADH}$.

Citric Acid Cycle (Krebs Cycle)

The metabolic pathway located in the mitochondrial matrix that breaks down acetyl-CoA to release $4\,CO_2$, $6\text{ NADH}$, $2\text{ FADH}_2$, and $2\text{ ATP}$ per glucose molecule.

Electron Transport Chain (Cellular Respiration)

A series of electron carrier proteins in the inner mitochondrial membrane that use electron energy from NADH and $FADH_2$ to pump $H^+$ and generate approximately $26\text{--}28\text{ ATP}$.

Oxygen ($O_2$) in Cellular Respiration

The final electron acceptor in the mitochondrial electron transport chain that accepts electrons and hydrogen ions to produce water.

Fermentation

An anaerobic pathway that allows ATP production to continue through glycolysis by converting NADH back into $NAD^+$ in the absence of oxygen.

Lactic Acid Fermentation

An anaerobic process occurring in muscle cells and certain bacteria that converts pyruvate into lactate to regenerate $NAD^+$.

Alcoholic Fermentation

An anaerobic process occurring in yeast and certain microorganisms where pyruvate is converted into ethanol and $CO_2$ to regenerate $NAD^+$.