Biological Processes and Energetics

This set of flashcards covers key concepts in bioenergetics, metabolism, enzymology, and cellular processes. It serves as a study aid for reinforcing knowledge in these areas in preparation for the upcoming exam.

What is the effect of a drug that binds to an enzyme's active site without converting it into a product?

It acts as a competitive inhibitor by blocking the substrates from binding.

What is bioenergetics?

The study of energy flow through a living system.

What do competitive inhibitors do?

They bind to the enzyme's active site.

If a reaction has a negative G, it is classified as what?

Exergonic.

What is feedback inhibition?

Where the end product of a pathway inhibits an upstream step.

How does feedback inhibition regulate metabolic pathways?

It stops the production of excess product.

What do catabolic pathways do?

Generate energy by breaking down large molecules.

What is activation energy?

The energy required for a reaction to proceed.

What happens when an enzyme is added to a chemical reaction?

The reaction rate increases, but the amount of product formed remains the same.

Where does the energy that sustains most of the Earth's life forms primarily come from?

The sun.

What is a lipid raft?

A rigid section of the membrane rich in cholesterol.

How do T cells recognize HIV as 'self'?

Using CD4 receptor glycoproteins.

Why do polar molecules require transport proteins to cross the plasma membrane?

The hydrophobic core of the membrane prevents diffusion of charged or polar molecules.

What happens to an egg without its shell placed in a hypotonic solution?

It gains weight due to water entering by osmosis.

What is metabolism?

All chemical reactions of a cell or organism.

What causes the weight change in an egg in a hypotonic solution?

Water enters the egg by osmosis.

What does 'amphipathic' refer to in molecules?

Having both hydrophobic and hydrophilic regions.

What is true about integral proteins?

They span the entire membrane.

What happens to a red blood cell placed in an isotonic solution?

It remains the same.

Which part of a phospholipid molecule is hydrophobic?

The tail.

What occurs when a patient is given pure water intravenously instead of saline?

Red blood cells will swell and potentially burst.

Who proposed the fluid mosaic model?

Singer and Nicolson.

What is the role of cholesterol in the membrane?

To stabilize the fluidity.

What is pinocytosis?

The process by which a cell takes in fluids through small vesicles.

What is phagocytosis?

A form of endocytosis.

What best describes anaerobic respiration?

Involves glycolysis and fermentation.

What is the PRIMARY function of the electron transport chain in cellular respiration?

To establish a proton gradient across the inner mitochondrial membrane.

What is a metabolic pathway?

A series of biochemical reactions that converts substrates into a final product.

How do carrier proteins move substances across the membrane?

By changing shape.

What are electrochemical gradients important for?

Transporting ions.

What is diffusion?

The movement of molecules from an area of high concentration to an area of low concentration.

What are the final products of pyruvate conversion in yeast alcohol fermentation?

Ethanol and CO₂.

In the electron transport chain, what serves as the final electron acceptor in aerobic respiration?

Oxygen.

What does the process of photosynthesis convert?

Sunlight into chemical energy.

What happens to glucose during cellular respiration?

It is oxidized.

What do enzymes do in chemical reactions?

They act as catalysts and lower activation energy.

How is enzyme activity typically measured?

By measuring substrate concentration over time.

What happens if mitochondria cannot perform aerobic respiration?

Increased levels of lactic acid production in muscles.

What are cofactors?

Inorganic ions that assist enzyme function.

What does osmosis refer to?

The movement of water.

What molecules primarily carry high-energy electrons during cellular respiration?

NADH and FADH₂.

What are redox reactions?

Reactions where electrons are transferred from one molecule to another.

What is the reaction called where RuBisCO incorporates CO₂ into a 5-carbon compound?

Carbon fixation.

What happens to a cell placed in a hypertonic solution?

It shrinks.

Which component of the plasma membrane is involved in cell signaling and recognition?

Carbohydrates.

What is an example of a cofactor?

$Zn^{2+}$.

Which organisms are classified as autotrophs?

Plants and some bacteria that produce their food.

How are reducing agents defined in redox reactions?

Molecules that donate electrons.

What distinguishes substrate-level phosphorylation?

Direct transfer of phosphate groups.

What structure is responsible for ATP synthesis during chemiosmosis?

ATP synthase.

What is a hypotonic solution?

A solution with a lower solute concentration outside the cell.

What is potential energy?

Energy stored in chemical bonds.

How do enzymes impact biochemical reactions?

They facilitate and speed up the reactions.

What factors can regulate enzyme activity?

Temperature and pH.

What would likely happen in kidney epithelial cells if aquaporins were removed?

Water transport across the membrane would be impaired.

What molecule enters the Citric Acid Cycle to initiate the process?

Acetyl CoA.

Where do amino acids enter the cellular respiration pathway after deamination?

As intermediates of the citric acid cycle.

Where does the Calvin cycle occur in the chloroplast?

In the stroma.

How many sodium ions are pumped out in the sodium-potassium pump?

3 sodium ions.

What is the role of stomata?

Gas exchange.

What type of energy is associated with an object in motion?

Kinetic energy.

What type of transport do white blood cells use to engulf bacteria?

Phagocytosis.

How do temperature changes affect enzyme activity?

High temperatures can denature enzymes; low temperatures can slow reactions.

What type of fermentation produces lactate from pyruvate?

Lactic acid fermentation.

Which ion is commonly involved in secondary active transport?

Sodium.

What is the end product of the Citric Acid Cycle?

Oxaloacetate.

What scenario represents an endergonic reaction in a cell?

The synthesis of glucose from carbon dioxide and water.

What do allosteric inhibitors do to the active site?

Modify it so substrate binding is reduced.

What does NADH represent in cellular respiration?

The reduced form of NAD.

How does the plasma membrane contribute to cellular communication?

By adhering to neighboring cells.

In which parts of the chloroplast do light-dependent reactions and the Calvin cycle occur?

Light reactions: thylakoid membrane; Calvin cycle: stroma.

What occurs when an ion channel is gated?

It opens and closes in response to signals.

What is another explanation for a cell producing ATP without oxygen?

The cell is undergoing anaerobic respiration or fermentation.

What are coenzymes?

Organic molecules that assist enzymes.

What is the significance of chlorophyll being green?

It absorbs red and blue light.

Where do heterotrophs obtain their energy from?

Other organisms.

Which transport method moves molecules against their concentration gradient?

Active transport.

What does the second law of thermodynamics state?

Energy transfer results in increased entropy.

Where does cellular respiration primarily occur?

In the mitochondria.

What do noncompetitive inhibitors do?

Slow reaction rates but do not affect the maximal rate.

How would dysfunctional mitochondria affect a person's energy during intense activity?

They would experience a decline in energy production and increased fatigue.

What is an example of a C₄ plant?

Sugarcane.

Which stage of cellular respiration produces the most ATP?

Oxidative phosphorylation.

What is C₄ photosynthesis adapted for?

High temperature and light intensity.

What is a byproduct of photosynthesis?

Oxygen.

What is a result of the electron transport chain?

Formation of a proton gradient.

What serves as an electron carrier in cellular respiration?

$NAD^{+}$.

From where does the energy stored in carbohydrates in the food chain come?

From autotrophs.

What is transpiration?

The process by which plants lose water through stomata.

What is the primary function of light reactions in photosynthesis?

Capture light energy and convert it into chemical energy.