Photosynthesis + Cell Respiration

What is the process of obtaining energy from organic molecules called?

Cellular respiration

What are the two main stages of cellular respiration?

Glycolysis and Krebs cycle

Where does glycolysis occur?

In the cytoplasm

Does glycolysis require oxygen to generate ATP?

No, it does not require O2

Where does the Krebs cycle take place?

Within the mitochondrion

What is the main purpose of the Krebs cycle?

To harvest energy-rich electrons through oxidation reactions

What are redox reactions?

Reactions where oxidation (loss of electrons) and reduction (gain of electrons) occur together

What is the reduced form of an organic molecule compared to its oxidized form?

The reduced form has a higher level of energy

What is substrate-level phosphorylation?

The process of generating ATP by directly transferring a phosphate group to ADP

What is produced during glycolysis from one molecule of glucose?

Two molecules of pyruvate and two ATP

What happens to pyruvate in the presence of oxygen?

It is oxidized to form acetyl-CoA

What is the role of NAD+ in cellular respiration?

It carries hydrogen atoms and energetic electrons

What is the final compound formed from the oxidation of pyruvate?

Acetyl-CoA

What is the significance of glycolysis in terms of evolution?

It was probably one of the earliest biochemical processes to evolve

How many ATP molecules are produced during glycolysis for each glucose molecule?

Two ATP molecules

What is the first step of oxidative respiration in the mitochondrion?

The oxidation of pyruvate

What is released when pyruvate is oxidized?

One carbon as CO2 and electrons to form NADH

What is the role of coenzyme A (CoA) in cellular respiration?

It joins with the two-carbon fragment of pyruvate to form acetyl-CoA

What are the products of glycolysis?

Two pyruvate, two NADH, and two ATP

What is the energy source for living organisms derived from?

Breaking down organic molecules produced by plants

What happens to the chemical bonds in food during cellular respiration?

They are broken down to release energy

What is the significance of NADH in cellular respiration?

It carries electrons to the electron transport chain for ATP production

What is the overall goal of cellular respiration?

To convert energy stored in food into usable ATP

What is the primary product of glycolysis?

Two ATP molecules are produced for each molecule of glucose.

What is the role of pyruvate in oxidative respiration?

Pyruvate is oxidized to form acetyl-CoA in the presence of oxygen.

What enzyme cleaves a carbon from pyruvate during its oxidation?

Pyruvate dehydrogenase cleaves a carbon from pyruvate, releasing it as CO2.

What happens to the hydrogen and electrons during pyruvate oxidation?

They are removed from pyruvate and donated to NAD+ to form NADH.

What is the fate of acetyl-CoA when ATP levels are low?

Acetyl-CoA enters the Krebs cycle for further energy production.

What occurs in the Krebs cycle?

Acetyl-CoA combines with a four-carbon molecule to produce a six-carbon molecule, which undergoes decarboxylation and oxidation to generate NADH, FADH2, and ATP.

How many turns of the Krebs cycle occur per glucose molecule?

Two turns of the Krebs cycle occur for each glucose molecule, as glycolysis produces two pyruvate molecules.

What is the role of NADH and FADH2 in cellular respiration?

They transfer electrons to the electron transport chain, facilitating ATP production.

What is chemiosmosis?

Chemiosmosis is the process where protons diffuse back into the mitochondrial matrix through ATP synthase, driving ATP synthesis.

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

Oxygen acts as the final electron acceptor, forming water.

What is fermentation?

Fermentation is an anaerobic process that allows glycolysis to continue by regenerating NAD+ from NADH.

What are the two types of fermentation in eukaryotes?

Ethanol fermentation in yeasts and lactic acid fermentation in animals.

What is produced during lactic acid fermentation?

Lactate and NAD+ are produced when pyruvate accepts a hydrogen atom from NADH.

What is the starting material for the Krebs cycle?

The starting material is a four-carbon molecule, which combines with acetyl-CoA.

What happens to the four-carbon molecule at the end of the Krebs cycle?

It is recycled to combine with another acetyl-CoA, continuing the cycle.

How do cells metabolize food other than glucose?

Cells digest complex molecules into simpler subunits, which are then modified to enter cellular respiration at various steps.

What are the main products of cellular respiration?

Four ATP molecules, 10 NADH electron carriers, and 2 FADH2 electron carriers.

What is the significance of the electron transport chain?

It facilitates the transfer of electrons from NADH and FADH2, leading to ATP production through chemiosmosis.

What is the role of coenzyme A (CoA) in metabolism?

CoA is involved in the formation of acetyl-CoA from pyruvate, linking glycolysis to the Krebs cycle.

What is the outcome of oxidative phosphorylation?

It produces ATP as protons flow back into the mitochondrial matrix through ATP synthase.

What is the relationship between glycolysis and fermentation?

Fermentation allows glycolysis to continue by regenerating NAD+ in the absence of oxygen.

What is the significance of NAD+ in cellular respiration?

NAD+ acts as an electron carrier, accepting electrons during oxidation-reduction reactions.

What is the primary source of energy for most living cells?

The sun

What process do plants, algae, and some bacteria use to capture sunlight energy?

Photosynthesis

What is the role of chloroplasts in plant cells?

They contain thylakoids and are where photosynthesis occurs.

What are thylakoids?

Internal membranes in chloroplasts that are stacked in columns called grana.

What is the stroma?

A semi-liquid substance that surrounds the thylakoids in chloroplasts.

What is a photosystem?

A network of pigments in the thylakoid membrane that initiates photosynthesis.

What is the primary pigment in photosystems?

Chlorophyll

What are the three stages of photosynthesis?

1. Capturing energy from sunlight, 2. Producing ATP and NADPH, 3. Making carbohydrates from CO2.

What are light-dependent reactions?

Reactions that occur in the presence of light and produce ATP and NADPH.

What are light-independent reactions more commonly known as?

The Calvin cycle.

What is the overall equation for photosynthesis?

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

What are photons?

Packets of energy that make up light.

What is the electromagnetic spectrum?

The range of all types of light energy, including visible light.

What colors of light does chlorophyll primarily absorb?

Blue and red light.

What is chemiosmosis?

The process where protons flow through ATP synthase to convert ADP into ATP.

What is the Calvin cycle's first step?

Carbon fixation, where CO2 is attached to RuBP.

How many times must the Calvin cycle turn to produce one glucose molecule?

Six times.

What is photorespiration?

A process that occurs when O2 levels build up and rubisco fixes oxygen instead of carbon.

What adaptations do C4 plants have for hot climates?

They fix carbon using different types of cells and reactions to avoid running out of CO2.

What is crassulacean acid metabolism (CAM)?

A process where some plants perform photosynthesis at night via the C4 pathway and during the day via the C3 pathway.

What is the role of NADPH in photosynthesis?

It provides reducing power in the form of hydrogens for building organic molecules.

What is the function of ATP in photosynthesis?

It drives endergonic reactions necessary for synthesizing organic molecules.