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Questions and Answers
What changes in membrane potential occur immediately at fertilization?
How does nicotine affect the fast block to polyspermy?
Which of the following statements about the voltage clamp experiment is accurate?
Which mechanism in fish aids in preventing polyspermy?
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What effect does a voltage clamp of +15 mV have on the fertilization process?
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What is the duration of the cortical reaction during fertilization?
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What happens when sodium iodide artificially depresses potential difference during fertilization?
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Which of the following species is NOT mentioned in relation to the micropyle mechanism?
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What role does membrane potential play immediately after fertilization?
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In the context of the fast block to polyspermy, how does a low voltage affect fertilization?
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What was the effect of nicotine on the fast block mechanism as per Laurinda Jaffe's findings?
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Which physiological measurement method was used by Laurinda Jaffe to study fertilization?
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How long does the fast block to polyspermy last according to the provided content?
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What effect does a voltage clamp of -70 mV have during the fertilization process?
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What alternative mechanism to prevent polyspermy is mentioned for fish?
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What experimental condition permits visualization of multiple inseminations in eggs?
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Study Notes
Polyspermy Prevention Mechanisms
- Polyspermy: the entry of multiple sperm into an egg, which can lead to developmental issues.
- Only one sperm typically fertilizes the egg despite the presence of millions due to effective prevention mechanisms.
Fast Block to Polyspermy
- Fast block occurs almost immediately at fertilization, lasting around 5-10 minutes.
- This mechanism involves changes in membrane potential that deter additional sperm from entering.
- Laurinda Jaffe's research with sea urchins used electrophysiology techniques to analyze membrane potential.
Electrophysiological Findings
- Measuring current or voltage changes is crucial in understanding fertilization dynamics.
- Voltage clamping can manipulate membrane potential to either prevent (high voltage) or facilitate (low voltage) polyspermy.
Role of Nicotine
- Nicotine can inhibit the fast block mechanism, leading to polyspermy.
- Studies replicated findings from 1887, showing nicotine reduces electrical block amplitude.
Generalized Response across Species
- Observations of fast block mechanisms apply broadly to frogs, echinoderms, marine worms, and mammals.
- The initial membrane potential is around -70 mV, changing to +15 mV after fertilization, affecting the likelihood of polyspermy.
Final Proof Tests
- High voltage clamps prevent fertilization by maintaining depolarization.
- Releasing the voltage clamp restores the potential for fertilization, confirming the fast block's role.
Additional Polyspermy Prevention Mechanisms
- Micropyle structures in fish eggs guide sperm entry, reducing chances of polyspermy.
- Research by Yanagimachi et al. in 2017 explores sperm guidance in fish using chemical and physical cues through the micropyle.
Polyspermy Prevention Mechanisms
- Polyspermy: the entry of multiple sperm into an egg, which can lead to developmental issues.
- Only one sperm typically fertilizes the egg despite the presence of millions due to effective prevention mechanisms.
Fast Block to Polyspermy
- Fast block occurs almost immediately at fertilization, lasting around 5-10 minutes.
- This mechanism involves changes in membrane potential that deter additional sperm from entering.
- Laurinda Jaffe's research with sea urchins used electrophysiology techniques to analyze membrane potential.
Electrophysiological Findings
- Measuring current or voltage changes is crucial in understanding fertilization dynamics.
- Voltage clamping can manipulate membrane potential to either prevent (high voltage) or facilitate (low voltage) polyspermy.
Role of Nicotine
- Nicotine can inhibit the fast block mechanism, leading to polyspermy.
- Studies replicated findings from 1887, showing nicotine reduces electrical block amplitude.
Generalized Response across Species
- Observations of fast block mechanisms apply broadly to frogs, echinoderms, marine worms, and mammals.
- The initial membrane potential is around -70 mV, changing to +15 mV after fertilization, affecting the likelihood of polyspermy.
Final Proof Tests
- High voltage clamps prevent fertilization by maintaining depolarization.
- Releasing the voltage clamp restores the potential for fertilization, confirming the fast block's role.
Additional Polyspermy Prevention Mechanisms
- Micropyle structures in fish eggs guide sperm entry, reducing chances of polyspermy.
- Research by Yanagimachi et al. in 2017 explores sperm guidance in fish using chemical and physical cues through the micropyle.
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Description
This quiz explores the mechanisms preventing polyspermy during fertilization, focusing on the fast block response and its electrophysiological aspects. It also examines the impact of nicotine on these mechanisms, highlighting key research findings from Laurinda Jaffe. Test your knowledge on the dynamics of fertilization and the role of membrane potential changes.
