chapter 9 cellular respiration and fermentation Flashcards
What do producers do in the carbon cycle?
Producers bring carbon atoms (carbon dioxide) from the air into living things such as plants.
This process involves photosynthesis, where CO2 is converted into sugar molecules.
What happens to carbon in plants during photosynthesis?
Carbon dioxide enters the leaf, moves into a cell, and goes into chloroplasts to make sugar molecules.
These sugar molecules can be used to build larger carbon-containing molecules like carbohydrates, lipids, proteins, and nucleic acids.
Define primary consumers in the carbon cycle.
Primary consumers are herbivores that eat plants, and plant tissue enters their digestive system.
This process involves breaking down plant molecules in the digestive system to build their own tissues.
What role do decomposers play in the carbon cycle?
Decomposers like fungi and bacteria break down dead elements of consumers and producers and use some carbon atoms in their own bodies.
They are essential for recycling carbon back into the ecosystem.
What occurs during cellular respiration?
Carbon-containing molecules are broken down to produce ATP, releasing CO2 as a by-product back into the atmosphere.
This process is balanced with photosynthesis.
Where is most ATP produced in the cell?
Most ATP is produced in the mitochondria.
ATP powers various cellular functions, including contraction.
What is glycolysis?
Glycolysis is the first step of cellular respiration where glucose is broken down into two 3-carbon molecules called pyruvic acid.
It occurs outside the mitochondria and requires energy investment.
What is produced during glycolysis?
Glycolysis produces 2 net ATPs, 2 pyruvates, and 2 NADH.
Although only a small amount of ATP is produced, pyruvic acid retains significant energy.
What happens to pyruvic acid in the mitochondria?
Pyruvic acid is converted into acetyl CoA, with one carbon removed and CO2 released as a by-product.
This process also involves the formation of NADH.
What occurs in the citric acid cycle?
The citric acid cycle (Krebs cycle) breaks down acetyl CoA, releasing CO2 and capturing electrons in NADH and FADH2.
This cycle produces 2 ATPs for each glucose molecule.
What is oxidative phosphorylation?
Oxidative phosphorylation is the process where electrons are transferred through the electron transport chain, leading to ATP production.
It occurs in the inner membrane of mitochondria.
What is the role of oxygen in cellular respiration?
Oxygen acts as the final electron acceptor in the electron transport chain, forming water as a by-product.
This is crucial for aerobic cellular respiration.
Define catabolism.
Catabolism refers to the breakdown of large molecules into smaller ones, releasing energy in the process.
It contrasts with anabolism, which requires energy to build molecules.
What is the relationship between glucose and ATP?
Glucose is broken down during cellular respiration to synthesize ATP, providing energy for cellular work.
This process involves a series of redox reactions.
What is NAD+ and its function?
NAD+ (nicotinamide adenine dinucleotide) is an oxidizing agent that accepts electrons during respiration, becoming NADH.
It plays a key role in energy transfer.
What are the three stages of cellular respiration?
- Glycolysis
- Krebs Cycle
- Electron Transport Chain
Each stage contributes to the production of ATP and involves various biochemical processes.
What is the net energy yield from glycolysis?
The net energy yield from glycolysis is 2 ATP and 2 NADH.
No carbon is released as CO2 during this phase.
What is chemi-osmosis?
Chemi-osmosis is the process where ATP is synthesized as H+ ions flow back across the membrane through ATP synthase.
It relies on an existing H+ ion gradient.
What is the electron transport chain?
The electron transport chain is a series of protein complexes that transfer electrons and pump protons to create a gradient for ATP production.
It is essential for oxidative phosphorylation.
How is ATP synthesized during oxidative phosphorylation?
ATP is synthesized as electrons move through the electron transport chain, creating a proton gradient that drives ATP synthase.
This is the major source of ATP in aerobic organisms.
What is maintained by the electron transport chain?
H+ are pumped from matrix to inner membrane space
What is the process associated with the flow of H+ across the membrane?
chemi-osmosis
What is ATP synthase?
A multisubunit complex with 4 main parts, made up of polypeptides
How does ATP synthase catalyze ATP formation?
Spinning activity similar to a stream turning a water wheel
What couples the redox reactions of electron transport to ATP synthesis?
Energy of the H+ gradient
What happens to H+ during electron transfer?
H+ is taken up from the matrix & deposited into the intermembrane space
What is the H+ gradient referred to as?
proton-motive force
What capacity does the proton-motive force have?
To do work such as ATP synthesis
How does the proton-motive force drive H+ back across the membrane?
Through the H+ channel provided by ATP synthases
What does metabolism refer to?
A set of chemical reactions carried out to maintain the living state of the cells in an organism.
What are the two categories of metabolic pathways?
- Anabolic pathways: synthesise molecules and require energy
- Catabolic pathways: break down molecules and produce energy
What is the role of enzymes in metabolic reactions?
Enzymes help facilitate non-spontaneous chemical reactions.
What is respiration?
The process of breaking glucose to release energy, which can be used by our body.
What does the 1st law of thermodynamics state?
Through photosynthesis, light energy is converted to chemical energy, stored as glucose.
What is the significance of cellular respiration?
Allows organisms to access energy stored in carbohydrates, lipids, and other macromolecules through ATP production.
What does the 2nd law of thermodynamics state?
As energy is transferred or transformed, more is wasted, contributing to entropy.
What is activation energy?
The energy required for a reaction to occur and determines its rate.
What are enzymes?
Biological catalysts produced by cells responsible for the high rate and specificity of biochemical reactions.
What is the lock and key model in enzymatic action?
The substrate has the same shape as the active site.
What is the induced fit model in enzymatic action?
The active site morphs to fit the substrate.
What is feedback inhibition in metabolic pathways?
The product of a pathway controls the rate of its own synthesis by inhibiting an enzyme catalyzing an early step.
What is feed-forward activation in metabolic pathways?
A metabolite early in the pathway activates an enzyme further down the pathway.
What factors affect enzyme activity?
- Substrate concentration
- Enzyme concentration
- Temperature
- pH
- Presence of inhibitors
What is an inhibitor?
A substance that slows down or stops the normal catalytic function of an enzyme by binding to it.
What are the three types of inhibition?
- Reversible competitive inhibition
- Reversible non-competitive inhibition
- Irreversible inhibition
What is irreversible inhibition?
An irreversible inhibitor inactivates an enzyme by binding to its active site with a strong covalent bond.
What are allosteric enzymes?
Regulatory enzymes whose catalytic activities are controlled by non-covalent bonding to activators or inhibitors.
What is the role of allosteric molecules?
They can either increase (stimulate) or decrease (inhibit) enzyme activity.
What is adenosine triphosphate (ATP)?
A molecule required by all living things for energy in processes that keep the organism alive.
What is the net reaction of glycolysis?
1 glucose → 2 pyruvate + 2 ATP (produces 4 ATP, uses 2 ATP) + 2 NAD+ → 2 NADH
What happens during anaerobic respiration in plants and yeasts?
Pyruvate is converted into ethanol and carbon dioxide.
What is the Cori cycle?
A metabolic pathway in which lactate produced by anaerobic glycolysis in muscles is converted to glucose in the liver.
What happens to pyruvate before entering the TCA cycle?
Pyruvate is transported into the mitochondria and oxidized to acetyl-CoA.
What is the TCA/Krebs cycle?
A key metabolic pathway that connects carbohydrate, fat, and protein metabolism.
What is the glyoxylate cycle?
An anabolic pathway in plants that allows synthesis of glucose from lipids via acetate generated in fatty acid β-oxidation.
What occurs during oxidative phosphorylation?
ATP is generated by the phosphorylation of ADP using energy from H+ ions moved back into the matrix.
How many ATP molecules are generated during oxidative phosphorylation from NADH?
≈ 3 ATP per NADH.
How many ATP molecules are generated during oxidative phosphorylation from FADH2?
≈ 2 ATP per FADH2.
What is the energy yield from β-oxidation of fatty acids?
Depends on the number of β-oxidation cycles required to oxidize the entire chain.
What are glycogenic amino acids?
Amino acids that can degrade to pyruvate or oxaloacetate and can form glucose.
What are ketogenic amino acids?
Amino acids that degrade to acetyl-CoA or acetoacetic acid and cannot form glucose but can be converted into ketone bodies.
