ATP Synthesis and Respiration

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Questions and Answers

What is the net gain of ATP produced during glycolysis?

2 ATP (correct)

6 ATP

0 ATP

4 ATP

In which part of the cell does the Krebs cycle occur?

Mitochondrial matrix (correct)

Cytoplasm

Thylakoid membrane

Cell membrane

During oxidative phosphorylation, what is the final electron acceptor?

Carbon dioxide

Oxygen (correct)

Hydrogen

NADH

Which process in anaerobic respiration produces lactate in animals?

Fermentation Signup and view all the answers

What is the primary outcome of non-cyclic photophosphorylation?

ATP and NADPH production Signup and view all the answers

What is the primary function of the Calvin Cycle?

Conversion of carbon dioxide into glucose Signup and view all the answers

In cyclic photophosphorylation, which of the following is true?

Involves only PSI Signup and view all the answers

Which enzyme catalyzes the carbon fixation process in the light-independent reactions?

Rubisco Signup and view all the answers

What is the main role of ATP in the regeneration stage of the Calvin cycle?

To regenerate RuBP Signup and view all the answers

Which hormone is secreted by beta cells in response to hyperglycemia?

Insulin Signup and view all the answers

What occurs in response to hypoglycemia?

Secretion of glucagon Signup and view all the answers

During the depolarization phase of nervous transmission, which ion primarily enters the axon?

Na+ Signup and view all the answers

What happens to blood vessels when the body temperature is too high?

Vasodilation occurs Signup and view all the answers

What is the role of osmoreceptors in the hypothalamus?

To monitor water balance Signup and view all the answers

Which neurotransmitter is released at the synaptic knob upon an action potential?

Acetylcholine Signup and view all the answers

How is resting potential maintained in a nerve axon?

By the sodium-potassium pump Signup and view all the answers

What is the primary function of glucagon?

To stimulate glycogen breakdown Signup and view all the answers

What is the effect of vasoconstriction in response to cold temperatures?

Reduces blood flow to the skin Signup and view all the answers

Study Notes

ATP Synthesis in Respiration

Glycolysis occurs in the cytoplasm. Glucose (6C) is phosphorylated to glucose-6-phosphate using 2 ATP. Glucose splits into two triose phosphate molecules. Oxidation to pyruvate releases 2 NADH and 4 ATP (net gain of 2 ATP).
Link Reaction takes place in the mitochondrial matrix. Pyruvate loses CO2 and forms NADH, producing acetyl-CoA.
Krebs Cycle involves acetyl-CoA (2C) combining with oxaloacetate (4C) to form citrate (6C). Decarboxylation and dehydrogenation reactions produce 2 CO2, 3 NADH, 1 FADH2, and 1 ATP per cycle, regenerating oxaloacetate.
Oxidative Phosphorylation happens in the inner mitochondrial membrane. Electrons from NADH and FADH2 travel along the electron transport chain (ETC), creating a proton gradient. H+ ions flow through ATP synthase, producing ATP. Oxygen is the final electron acceptor, creating water.

Anaerobic Respiration

Animals use pyruvate reduction to lactate, regenerating NAD+ for glycolysis.
Plants/Microorganisms convert pyruvate to ethanol and CO2, oxidizing NADH to NAD+.

Photosynthesis

Light-dependent Reactions

Non-cyclic Photophosphorylation: Light excites electrons in photosystem II (PSII); electrons pass down an electron transport chain (ETC), pumping H+ into the thylakoid lumen. H+ flow through ATP synthase produces ATP. Electrons from PSII replenish PSI. Electrons from PSI reduce NADP+ to NADPH.
Cyclic Photophosphorylation involves only photosystem I (PSI). Electrons cycle back to PSI via the ETC, creating ATP, but no NADPH or oxygen.

Light-independent Reactions (Calvin Cycle)

Location: Stroma of chloroplasts.
Stages:
- Carbon Fixation: CO2 combines with RuBP (5C) to form two molecules of 3-PGA (3C), catalyzed by rubisco.
- Reduction: 3-PGA gets reduced to triose phosphate (TP) using NADPH and ATP.
- Regeneration: Some TP regenerates RuBP for further carbon fixation, using ATP.
Products: Glucose, other carbohydrates, and organic molecules are produced from TP.

Homeostasis

Regulation of Blood Glucose

Hyperglycemia: Beta cells in the pancreas detect high blood glucose and release insulin, promoting glucose uptake and glycogen formation (glycogenesis) in the liver.
Hypoglycemia: Alpha cells in the pancreas detect low blood glucose and release glucagon. Glucagon promotes glycogen breakdown (glycogenolysis) and glucose synthesis (gluconeogenesis).

Regulation of Temperature

High Temperature: Vasodilation (widened blood vessels), sweating, and reduced metabolic rate help cool the body.
Low Temperature: Vasoconstriction, shivering (muscle contractions), and increased metabolic rate with adrenaline and thyroxine aid in heat production.

Osmoregulation

Water Loss: Osmoreceptors in the hypothalamus detect low water levels and trigger the release of ADH from the posterior pituitary, increasing water reabsorption in the collecting duct.
Water Excess: Reduced ADH secretion decreases water reabsorption, promoting water excretion.

Control and Coordination

Nervous Transmission

Resting Potential: Sodium-potassium pump maintains a negative internal charge (-70 mV) by actively transporting 3 Na+ out and 2 K+ in.
Depolarization: Stimulation opens Na+ channels, allowing Na+ influx causing a less negative membrane potential.
Repolarization: Opens K+ channels causing K+ efflux, restoring the negative membrane potential.
Hyperpolarization: Excess K+ outflow results in a potential drop below resting potential, re-established by the sodium-potassium pump.

Synaptic Transmission

Arrival of an action potential at the synaptic knob triggers Ca2+ channels opening and Ca2+ influx. Causing neurotransmitter vesicles release neurotransmitters (e.g., acetylcholine) into the synaptic cleft. Neurotransmitters bind to receptors on the postsynaptic membrane, triggering an action potential in the postsynaptic neuron.

Hormonal Coordination

Endocrine System: Hormones are released into the bloodstream, targeting specific cells with matching receptors. Examples include adrenaline (fight-or-flight) and insulin (blood glucose regulation).

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Description

This quiz covers the essential processes of ATP synthesis during cellular respiration, including glycolysis, the link reaction, the Krebs cycle, and oxidative phosphorylation. Additionally, it explores anaerobic respiration in animals and the regeneration of NAD+. Test your understanding of these vital biochemical pathways!