Biology_Ch6-8_Flashcards
6.1 - What is energy?
The ability to promote change or do work.
6.1 - What is the difference between potential and kinetic energy?
Potential energy is stored energy due to structure or position, while kinetic energy is energy associated with movement.
6.1 - What is the first law of thermodynamics?
Energy cannot be created or destroyed, only transformed or transferred.
6.1 - What is the second law of thermodynamics?
Every energy transfer increases the entropy (disorder) of the universe.
6.1 - How does free energy determine the direction of a chemical reaction?
Reactions proceed in the direction that leads to a decrease in free energy (negative ΔG).
6.1 - What are exergonic and endergonic reactions?
Exergonic reactions release energy (ΔG < 0); endergonic reactions require energy input (ΔG > 0).
6.1 - How does ATP hydrolysis drive endergonic reactions?
By coupling with ATP hydrolysis, the overall ΔG becomes negative, allowing the reaction to proceed.
6.2 - How do enzymes lower activation energy?
By stabilizing the transition state and reducing the energy needed for the reaction.
6.2 - What is substrate specificity and induced fit?
Enzymes bind specific substrates and change shape to improve binding (induced fit).
6.2 - What is competitive inhibition?
Inhibitor binds to the enzyme’s active site, preventing substrate binding.
6.2 - What is noncompetitive inhibition?
Inhibitor binds to a different site on the enzyme, changing its shape and reducing activity.
6.2 - What factors influence enzyme activity?
Temperature, pH, cofactors, coenzymes, and inhibitors.
6.3 - What is a metabolic pathway?
A series of chemical reactions catalyzed by enzymes to transform molecules.
6.3 - Difference between catabolic and anabolic reactions?
Catabolic breaks down molecules for energy; anabolic builds complex molecules.
6.3 - How do catabolic reactions help in biosynthesis and energy production?
They provide building blocks and energy intermediates like ATP and NADH.
6.3 - What is a redox reaction?
A chemical reaction where electrons are transferred between molecules.
6.3 - What are three types of metabolic regulation?
Gene regulation, cellular regulation (e.g., hormones), and biochemical regulation (e.g., feedback inhibition).
6.4 - What are the four stages of aerobic respiration?
Glycolysis, pyruvate breakdown, citric acid cycle, oxidative phosphorylation.
6.5 - What are the three phases of glycolysis?
Energy investment, cleavage, energy liberation.
6.5 - What are the net products of glycolysis?
2 ATP, 2 NADH, 2 pyruvate.
6.5 - What is the principle behind PET scans in tumor detection?
Cancer cells consume more glucose, which is traceable using radioactive glucose analogs.
6.6 - What happens to pyruvate in the mitochondrial matrix?
It is oxidized to acetyl-CoA, releasing CO2 and producing NADH.
6.7 - What is the citric acid cycle?
A metabolic cycle that oxidizes acetyl-CoA to CO2 and generates NADH, FADH2, and ATP.
6.7 - What are the products of the citric acid cycle?
3 NADH, 1 FADH2, 1 GTP (or ATP), and 2 CO2 per acetyl-CoA.
6.8 - How does the electron transport chain (ETC) create an H+ gradient?
Electrons move through ETC complexes, pumping H+ into the intermembrane space.
6.8 - How does ATP synthase work?
It uses the H+ gradient to rotate and catalyze ATP formation from ADP and Pi.
6.8 - How was ATP synthase shown to be a rotary machine?
Experiments attached fluorescent actin filaments and observed rotation.
6.9 - How are carbohydrate, fat, and protein metabolism connected?
They feed into glycolysis and the citric acid cycle at various points.
6.10 - What is anaerobic respiration?
Respiration using a final electron acceptor other than oxygen.
6.10 - How does fermentation allow ATP synthesis without oxygen?
It regenerates NAD+ by reducing pyruvate to lactic acid or ethanol.
7.1 - What is the overall photosynthesis equation?
CO2 + H2O + light → C6H12O6 + O2
7.1 - How does photosynthesis power the biosphere?
By producing organic molecules and oxygen used by most organisms.
7.1 - What is the structure of a chloroplast?
Double membrane organelle with thylakoids, stroma, and grana.
7.1 - What are the two stages of photosynthesis?
Light reactions and the Calvin cycle.
7.2 - What are pigments?
Molecules that absorb light; chlorophyll a, b, and carotenoids are examples.
7.2 - What does PSII produce?
O2, ATP, and NADPH.
7.2 - What is cyclic photophosphorylation?
An alternative light reaction path that produces ATP but not NADPH or O2.
7.3 - How does PSII produce O2?
By splitting water molecules (photolysis).
7.3 - What is the energy flow from PSII to NADP+?
Electron loses energy as it moves through carriers to NADP+.
7.4 - What are the three phases of the Calvin cycle?
Carbon fixation, reduction, and regeneration of RuBP.
7.4 - How does carbon in CO2 differ from carbohydrate carbon?
CO2 carbon is oxidized; carbohydrate carbon is reduced.
7.5 - What is photorespiration?
A process where RuBisCO fixes O2 instead of CO2, reducing efficiency.
7.5 - How do C4 and CAM plants reduce photorespiration?
They spatially (C4) or temporally (CAM) separate carbon fixation from the Calvin cycle.
8.1 - What are the two reasons for cell signaling?
Responding to environment and communication with other cells.
8.1 - What are five ways cells communicate?
Direct contact, paracrine, autocrine, endocrine, and contact-dependent signaling.
8.1 - What are the three stages of signaling?
Receptor activation, signal transduction, and response.
8.2 - What happens during receptor activation?
Ligand binds receptor, causing a conformational change and activation.
8.2 - What is dissociation constant (Kd)?
A measure of receptor-ligand binding affinity; lower Kd = higher affinity.
8.3 - What are the three cell surface receptors?
Enzyme-linked receptors, G-protein-coupled receptors, and ligand-gated ion channels.
8.4 - What are intracellular receptors?
Receptors within the cell that bind hydrophobic ligands like steroids.
8.5 - How does a receptor tyrosine kinase work?
Ligand binding leads to dimerization, phosphorylation, and signal transduction.
8.6 - How do GPCRs work?
Ligand activates receptor → G protein activates → second messengers produced.
8.6 - Why use second messengers like cAMP?
They amplify signals and allow fast, distributed responses.
8.7 - What is crosstalk in signaling?
Interaction between different signaling pathways to fine-tune responses.
