AP Biology - Unit 3: Cellular Energetics All Topics

What do all living systems require to survive and function?

An input of energy

What is energy defined as in biological terms?

The ability to do work, which is any change in the state or motion of matter

What must energy input do to sustain life?

It must exceed energy output

What happens if there is a loss of order or energy flow in a living system?

It can result in death

What metabolic pathways are conserved across all domains of life?

Glycolysis and oxidative phosphorylation

How do cells receive energy?

In many forms, such as light and organic molecules like glucose

What must happen to energy before it can be used by cells?

It must be converted or transformed

What is the first law of thermodynamics?

Energy cannot be created or destroyed; it can only be transferred or transformed

What does the second law of thermodynamics state?

Energy transformation increases the entropy of the universe

What is metabolism?

The sum of all chemical reactions in a cell that transform energy and matter

What are metabolic pathways?

Series of linked chemical reactions that either break down or build complex molecules

What is ATP and why is it important?

Adenosine triphosphate is a molecule used as a source of energy to perform work

What happens during ATP hydrolysis?

ATP is converted to ADP and inorganic phosphate, releasing energy

What is denaturation in the context of enzymes?

A loss of both structure and function of an enzyme due to conditions that cause it to unfold

What can cause denaturation of enzymes?

Temperature, pH, and chemical environment

What are competitive inhibitors?

Substances that reduce enzyme activity by blocking substrates from binding to the active site

What are noncompetitive inhibitors?

Substances that bind to an area other than the active site, changing the shape of the active site

What is allosteric regulation?

Regulatory molecules bind to an allosteric site, which can either increase or decrease enzyme activity

What is feedback inhibition?

When the end product of a metabolic pathway acts as an allosteric inhibitor to an early enzyme in the same pathway

What is the role of enzymes in metabolic reactions?

Enzymes catalyze reactions by lowering the activation energy

What is the active site of an enzyme?

The area where substrates bind to the enzyme

What is the effect of substrate concentration on enzyme activity?

At low concentrations, reactions are slow; as concentration increases, reaction rates increase until enzymes become saturated

What is the significance of the enzyme-substrate complex?

It helps position the substrate for easier bond breaking/forming

What are cofactors in relation to enzymes?

Non-protein molecules that assist enzyme function, which can be metallic ions or small organic compounds

What physiological changes occur in the body when a fever is present?

Increased body temperature can enhance immune response and inhibit viral enzyme activity

Why can a fever be beneficial in combating viral infections?

It can inhibit the activity of viral enzymes, slowing down the infection

What are the potential impacts of a prolonged fever on the body?

It can be detrimental by affecting the body's own enzymes and proteins, potentially leading to dysfunction

What is photosynthesis?

The conversion of light energy to chemical energy.

What type of organisms are autotrophs?

Organisms that produce their own food from simple substances in their surroundings.

What distinguishes heterotrophs from autotrophs?

Heterotrophs are unable to make their own food and rely on other organisms for sustenance.

Which organisms first evolved photosynthesis?

Prokaryotic organisms, specifically cyanobacteria.

What role did cyanobacteria play in Earth's atmosphere?

They oxygenated the atmosphere of early Earth.

Where does photosynthesis primarily occur in plants?

In the leaves, specifically within chloroplasts.

What are chloroplasts?

Organelles where photosynthesis takes place, found in the mesophyll of leaves.

What are stomata?

Pores in leaves that allow CO2 to enter and O2 to exit.

What is the simplified formula for photosynthesis?

6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2.

What are the two main processes involved in redox reactions during photosynthesis?

Oxidation (loss of electrons) and reduction (gain of electrons).

What is the role of pigments in photosynthesis?

To absorb light energy.

What is the primary pigment in photosynthesis?

Chlorophyll a.

What are the two stages of photosynthesis?

The light reactions and the Calvin cycle.

What occurs during the light reactions?

Solar energy is converted to chemical energy (ATP and NADPH).

Where do the light reactions take place?

In the thylakoid membrane of chloroplasts.

What is the Calvin cycle's main function?

To produce carbohydrates (sugar) from CO2 using ATP and NADPH.

What enzyme catalyzes the incorporation of CO2 into the Calvin cycle?

Rubisco.

What are the three phases of the Calvin cycle?

Carbon fixation, reduction, and regeneration of RuBP.

What is photorespiration?

A process where Rubisco binds to O2 instead of CO2, leading to no sugar production.

What adaptations do C4 plants have for photosynthesis?

Spatial separation of steps and partial closure of stomata to conserve water.

How do CAM plants adapt to their environment?

They open stomata at night and close them during the day to minimize water loss.

What is the significance of the electromagnetic spectrum in photosynthesis?

It includes visible light, which is absorbed by pigments for photosynthesis.

What happens to electrons when chlorophyll absorbs light?

Electrons are boosted to a higher energy level.

What is photophosphorylation?

The process of electrons being removed from water and passed through the photosystems to produce NADPH.

What is the net gain of G3P in the Calvin cycle?

One G3P molecule is produced for every three cycles of the Calvin cycle.

What is the role of ATP in the Calvin cycle?

ATP is used to phosphorylate 3-PGA into an intermediate during the reduction phase.

What is the main disadvantage of photorespiration for plants?

It leads to a loss of carbon and no sugar production, which is detrimental to plant growth.

What is the function of the thylakoid membrane in chloroplasts?

It is where the light reactions of photosynthesis occur.

What is the significance of the stroma in chloroplasts?

It is the internal fluid where the Calvin cycle takes place.

What is the primary purpose of cellular respiration?

To harvest chemical energy stored in organic molecules and generate ATP.

What is the major source of fuel for animals?

Starch, which breaks down into glucose.

What is the overall equation for the catabolic breakdown of glucose?

C6H12O6 + 6O2 → 6CO2 + 6H2O + energy (ATP and heat).

What are the four stages of cellular respiration?

Glycolysis, Pyruvate oxidation, Citric acid cycle (Krebs cycle), Oxidative phosphorylation (ETC and chemiosmosis).

Where does glycolysis occur?

In the cytosol.

What is produced during glycolysis?

2 pyruvates, 2 ATP, and 2 NADH.

What happens to pyruvate if oxygen is present?

It is oxidized into acetyl CoA in the mitochondrion.

Where does the citric acid cycle occur?

In the mitochondrial matrix.

What is the net production of ATP in the citric acid cycle?

2 ATP.

What are the two main components of oxidative phosphorylation?

Electron transport chain and chemiosmosis.

What is the final electron acceptor in the electron transport chain?

Oxygen.

How is a proton gradient formed across the inner mitochondrial membrane?

As electrons pass down the ETC, they release energy used to pump H+ ions into the intermembrane space.

What role does ATP synthase play in chemiosmosis?

It converts ADP + Pi to ATP using the energy from H+ ions flowing down their gradient.

What is anaerobic respiration?

ATP generation using an ETC in the absence of oxygen.

What is fermentation?

ATP generation without an ETC, recycling NAD+ and occurring in the cytosol.

What are the two types of fermentation?

Alcohol fermentation and lactic acid fermentation.

What is produced during alcohol fermentation?

Ethanol and CO2 from pyruvate.

What occurs during lactic acid fermentation?

Pyruvate is reduced by NADH to form lactate.

What causes the burning sensation in muscles during strenuous exercise?

The accumulation of lactate due to lactic acid fermentation.

How does lactate affect blood pH?

It lowers the pH, and excessive buildup can lead to lactic acidosis.

What is the role of NAD+ in cellular respiration?

It acts as an electron carrier, accepting electrons during glycolysis and the Krebs cycle.

What is the significance of the cristae in mitochondria?

They increase the surface area for reactions, allowing more ATP to be synthesized.

What is the energy yield from the complete oxidation of glucose by aerobic respiration?

Approximately 30-32 ATP per glucose molecule.

What happens to the energy level of electrons as they move through the ETC?

They move from a higher to a lower energy level, releasing energy.

What is the importance of the electrochemical gradient formed in the mitochondria?

It drives ATP synthesis as protons flow back into the matrix.

What is the primary function of the electron transport chain?

To transfer electrons and pump protons to create a gradient for ATP synthesis.