BIO 1134 Exam 2 Study Guide - Chapters 5, 6, 7, and 8

Vocabulary practice flashcards covering Chapters 5 through 8 of BIO 1134 (Membrane Transport, Energy & Enzymes, Cellular Respiration, and Photosynthesis).

Amphipathic

Having both hydrophilic (water-loving) and hydrophobic (water-fearing) regions, characteristic of cell membrane phospholipids.

Hydrophilic heads

The water-attracting portions of membrane phospholipids that face outward toward the watery environments inside and outside the cell.

Hydrophobic tails

The water-repelling portions of membrane phospholipids that face inward, away from water.

Cholesterol (in cell membrane)

A membrane component located between phospholipid tails that helps maintain optimum membrane fluidity.

Fluid Mosaic Model

A description of the cell membrane where 'fluid' refers to components moving freely and 'mosaic' refers to various proteins embedded throughout the membrane.

Selectively Permeable

A property of the cell membrane meaning it only allows certain molecules to travel in or out of the cell.

Glycolipids and Glycoproteins

Membrane components that assist with cell-cell recognition, act like an 'ID badge', and help protect membrane proteins from damage.

Passive Transport

The movement of molecules across a membrane from an area of high concentration to low concentration without requiring energy.

Simple Diffusion

A type of passive transport where molecules move directly across the membrane down their concentration gradient without transport proteins or energy input.

Facilitated Diffusion

A type of passive transport where molecules move across a membrane down their concentration gradient with the assistance of transport proteins.

Osmosis

The movement of solvent molecules across a membrane into a solution with a higher solute concentration.

Hypertonic Solution

A solution with a higher solute concentration compared to another solution, causing water to exit the cell and leading to cell shrinkage.

Isotonic Solution

A solution with equal solute concentration compared to another solution, resulting in no net water movement and cell size remaining the same.

Hypotonic Solution

A solution with a lower solute concentration compared to another solution, causing water to enter the cell and leading to cell swelling.

Active Transport

The movement of molecules across a membrane against their concentration gradient (from low to high concentration), requiring energy ($ATP$) and transport proteins.

Bulk Transport

The movement of large or bulky molecules across the plasma membrane using a vesicle, requiring energy input.

Exocytosis

A type of bulk transport that moves bulky molecules out of the cell using vesicles.

Endocytosis

A type of bulk transport that moves bulky molecules into the cell using vesicles.

Potential Energy

Stored energy due to position or chemical structure.

Kinetic Energy

The energy of motion.

Gibbs Free Energy ($\Delta G$)

The difference in energy between products and reactants, calculated as $\Delta G = \text{Energy of Products} - \text{Energy of Reactants}$.

Exergonic Reaction

A spontaneous chemical reaction that releases energy, where reactants have more energy than products and $\Delta G$ is negative.

Endergonic Reaction

A nonspontaneous chemical reaction that requires energy input, where reactants have less energy than products and $\Delta G$ is positive.

Metabolism

All of the chemical reactions that take place in living cells.

Catabolic Pathways

Metabolic pathways that break down complex molecules into simpler ones and release energy.

Anabolic Pathways

Metabolic pathways that build up complex molecules from simpler ones and require energy.

Catalyst

An agent that speeds up the rate of a chemical reaction without being consumed.

Enzyme

A protein catalyst in living cells that speeds up chemical reaction rates by lowering activation energy.

Ribozymes

RNA molecules that function as biological catalysts.

Activation Energy

The initial energy input needed for reactants to reach the transition state in a chemical reaction.

Active Site

The specific location on an enzyme where substrates bind and the chemical reaction occurs.

Substrates

Reactant molecules that bind specifically to the active site of an enzyme.

Enzyme Saturation

The plateau state where all enzyme active sites are occupied by substrate molecules, causing the reaction rate to reach its maximum.

Competitive Inhibition

Enzyme inhibition where an inhibitor resembles the substrate and binds to the active site, blocking the substrate; increases $K_m$ while $V_{max}$ stays the same, and can be overcome by adding more substrate.

Non-competitive Inhibition

Enzyme inhibition where an inhibitor binds to an allosteric site away from the active site, changing enzyme shape and lowering $V_{max}$; cannot be overcome by adding more substrate.

Heterotrophs

Organisms that must consume organic food to obtain energy.

Autotrophs

Organisms that make their own organic food.

Aerobic Cellular Respiration

The metabolic process of converting energy stored in organic food molecules into $ATP$ using oxygen ($C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O$).

Redox Reactions

Chemical reactions involving electron/hydrogen ion transfer, where oxidation is the loss of electrons and reduction is the gain of electrons.

Glycolysis

The first stage of aerobic respiration in cytosol, breaking down 1 glucose molecule into 2 pyruvate, yielding 2 $ATP$ and 2 $NADH$.

Conversion of Pyruvate

The second stage of respiration converting 2 pyruvate into 2 acetyl $CoA$, generating 2 $NADH$ and 2 $CO_2$.

Citric Acid Cycle

The third stage of respiration consisting of 8 enzyme-catalyzed reactions that convert 2 acetyl $CoA$ into 4 $CO_2$, 2 $ATP$, 6 $NADH$, and 2 $FADH_2$.

Oxidative Phosphorylation

The final stage of respiration where electron transport chain transfers electrons to oxygen, building an electrochemical $H^+$ gradient to produce approximately 34 $ATP$ through $ATP$ synthase.

Chemiosmosis

The movement of $H^+$ ions across a membrane through $ATP$ synthase down their electrochemical gradient to generate $ATP$.

Photosynthesis

The process occurring in chloroplasts that uses light energy to synthesize glucose from carbon dioxide and water ($6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$).

Light Reactions

The first stage of photosynthesis occurring in the thylakoid membrane where Photosystem II generates $ATP$ and Photosystem I generates $NADPH$ for the Calvin cycle.

Calvin Cycle

The second stage of photosynthesis occurring in the stroma that uses $CO_2$, $ATP$, and $NADPH$ through carbon fixation, reduction/sugar production, and RuBP regeneration to make carbohydrates.

Photorespiration

An inefficient process occurring in hot, dry conditions when Rubisco adds $O_2$ to RuBP instead of $CO_2$.

C4 Plants

Plants that utilize specialized metabolic pathways to minimize photorespiration in warm or dry environments.

Cholesterol acts as a buffer that maintains membrane fluidity

the cell membrane contains phospholipids, proteins, glycoproteins/glycolipids, and cholesterol. if cholesterol were removed, the membrane would become less stable at temperature changes. Why?

proteins drift laterally within the membrane

the fluid-mosaic model describes the membrane as fluid. what observation describes the model?

hypertonic

a cell placed in a solution begins shrinking as water leaves the cytoplasm. the solute concentration outside the cell is higher then inside. what describes this?

small and non polar

a molecule moves from high to low concentration directly through the membrane without energy. what characteristic does it have

no; facilitated diffusion

a cell uses a membrane protein to move amino acids from high to low concentration. is ATP used? which transport process is occurring?

water entering a cell placed in pure water

osmosis involves water moving toward the area with higher solute concentration. which scenario demonstrates osmosis

it is active and moves against the gradient

a cell uses ATP to move ions from low to high concentration. what describes this

endocytosis

a large bacterium is engulfed by a white blood cell. which transport mechanism is responsible

cholesterol

a cell membrane becomes too rigid in cold temperatures. which component normally prevents this problem?

solute concentration is equal inside and outside

a cell placed in an isotonic solution shows no net movement of water. why?

it releases energy and is spontaneous

a reaction has DELTA G= -15 kcal/mol. what describes this reaction

endergonic

a reaction has products with more energy than reactants. what classification applies

it speeds up the reaction

an enzyme lowers activation energy. which effect does this have on the reaction?

induced fit

a substrate binds to an enzyme’s active site, causing the enzyme to slightly change shape. what model explains this?

it binds to the active site and can be overcome by more substrate

a competitive inhibitor is added to a reaction. what’s true?

enzymes denature and lose function

a cell is exposed to extreme heat. what effect on enzymes is most likely?

the enzyme is saturated

a reaction stops increasing in rate even when more substrate is added. what does it indicate?

cellular respiration

a heterotroph consumes organic molecules to obtain energy. which process converts this energy to ATP?

loss of electrons

during cellular respiration, oxidation refers to:

citric acid cycle

most NADH and FADH2 are produced during this stage.

the final electron acceptor

oxygen is required in aerobic respiration because it is:

it creates a gradient used by ATP synthase

the electron transport chain pumps H+ ions into intermembrane space. why is it important?

into the matrix

ATP synthase produces ATP when H+ ions move;

NADH cannot unload electrons without oxygen

a cell without oxygen can perform glycolysis but not the citric acid cycle. why?

chloroplast

photosynthesis uses light energy to produce glucose. which organelle performs this process

ATP

light reactions begin in Photosystem 2. what is the main product of photosystem 2?

it provides electrons for carbon fixation

Photosystem 1 produces NADPH. why is NADPH important for the Calvin cycle?

hot, dry conditions

photorespiration occurs when rubisco binds O2 instead of CO2. under which conditions is this most likely?

separating carbon fixations into different cells

C4 plants minimize photorespiration by :