Developmental Biology
Developmental Biology
11th Edition
ISBN: 9781605354705
Author: Scott F. Gilbert, Michael J. F. Barresi
Publisher: Sinauer Associates is an imprint of Oxford University Press
bartleby

Videos

Question
Book Icon
Chapter 7, Problem 1DQ
Summary Introduction

To review:

The mechanism by which fast block of polyspermy is achieved by amphibians in an freshwater environment that lacks the high Na+ concentration, unlike ocean.

Introduction:

Polyspermy is defined as the fusion of an egg by the multiple sperms, which leads to the formation of embryo with multiple paternal centrioles. Such type of fusion are sometimes lethal, thus prevention of polyspermy in different organisms is accompained by different modes. Two important modes are, fast block to polyspermy and slow block of polyspermy. The fast block of polyspermy is a mechanism of change in the electric potential of the egg cell membrane, following the entry of a sperm immediately. The slow block to polyspermy is accompained by the cortical granule reaction. In this reaction, the entry of a sperm is followed by the fusion of cortical granules with the egg membrane, this fusion leads to the formation of fertilization envelope which prevents the entry of multiple sperm.

Expert Solution & Answer
Check Mark

Explanation of Solution

After the fusion of egg and sperm, a soluble substance (probably NAADP: Nicotinic acid adenine dinucleotide phosphate) is released by the sperm which helps in the change of egg cell membrane potential. The resting membrane potential is -70mV, indicates the inner negative membrane potential compare to the outer surface of egg membrane. The binding of sperm reverse the negative to positive potential by means of Na+ influx via the opening of sodium channels. Sperm can not fuse with egg cell membrane having positive membrane potential, thus prevents polyspermy.

In case of freshwater ambhibians where the sodium concentration is low, egg activation needs a signal from the fertilizing sperm known as Ca+ wave (increase of free calcium intracellularly in egg) which induces a propagative opening of Cl- channels on the egg membrane, this leads to an increase in fertilization potential under the low Cl- condition of freshwater. Thus the mechanism of positive fertilization potential acts as a fast electrical block to polyspermy in voltage sensitive species.

Conclusion

Thus it is concluded that fast block to polyspermy in freshwater conditions is achived by the egg activation via the calcium wave produced by the sperm followed by the opening of chlorine channels which increase the fertilization potential, and also prevents polyspermy.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
Structures REVIEW QUESTIONS The table below compares structures found in bacterial (prokaryotic) cells with those found in animal and plant (eukaryotic) cells. Indicate by writing Yes or No if the structure is present in the cell types. Cell Wall Cell Membrane Nuclear Envelope Chromosome (DNA) Mitochondria Cytosol Ribosome Lysosome Cytoskeleton Plastids Endoplasmic Reticulum Central Vacuole Peroxisome Golgi Complex LABORATORY 4 Centrosome Cilia Section Bacterial Cell Animal Cell Plant Cell
Resting Membrane Potential Review Fill in the blanks 1. The average resting membrane potential for a neuron is 2. This means that the inside of the neuron is mV more than the outside. 3. There are more positive ions outside the cell and more ions inside the cell. 4. During the resting potential, all channels are closed and both Na+ and K+ channels are open. 5. Neurons are more permeable to ions than to ions because the cell membrane has more channels. 6. The concentration gradient for Na+ favors its diffusion the cell; while the concentration gradient for K+ favors its diffusion the cell. 7. Both sodium and potassium diffuse down their concentration gradients with diffusing out of the cell and diffusing into the cell. 8. The maintains the concentration gradient by sodium ions the cell, while pumping buidund potassium ions the cell. 9. Why do neurons need so much ATP? THINK and connect ALL the dots!!!!
Resting Membrane Potential Review Fill in the blanks 1. The average resting membrane potential for a neuron is 2. This means that the inside of the neuron is mV more than the outside. 3. There are more positive ions outside the cell and more ions inside the cell. 4. During the resting potential, all channels are closed and both Na+ and K+ channels are open. 5. Neurons are more permeable to ions than to ions because the cell membrane has more channels. 6. The concentration gradient for Na+ favors its diffusion the cell; while the concentration gradient for K+ favors its diffusion the cell. 7. Both sodium and potassium diffuse down their concentration gradients with diffusing out of the cell and diffusing into the cell. 8. The maintains the concentration gradient by sodium ions the cell, while pumping potassium ions the cell. 9. Why do neurons need so much ATP? THINK and connect ALL the dots!!!!

Chapter 7 Solutions

Developmental Biology

Knowledge Booster
Background pattern image
Biology
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
Human Anatomy & Physiology (11th Edition)
Biology
ISBN:9780134580999
Author:Elaine N. Marieb, Katja N. Hoehn
Publisher:PEARSON
Text book image
Biology 2e
Biology
ISBN:9781947172517
Author:Matthew Douglas, Jung Choi, Mary Ann Clark
Publisher:OpenStax
Text book image
Anatomy & Physiology
Biology
ISBN:9781259398629
Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa Stouter
Publisher:Mcgraw Hill Education,
Text book image
Molecular Biology of the Cell (Sixth Edition)
Biology
ISBN:9780815344322
Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter
Publisher:W. W. Norton & Company
Text book image
Laboratory Manual For Human Anatomy & Physiology
Biology
ISBN:9781260159363
Author:Martin, Terry R., Prentice-craver, Cynthia
Publisher:McGraw-Hill Publishing Co.
Text book image
Inquiry Into Life (16th Edition)
Biology
ISBN:9781260231700
Author:Sylvia S. Mader, Michael Windelspecht
Publisher:McGraw Hill Education
Phlebotomy: Venipuncture Procedure; Author: Medical Lab Lady Gill;https://www.youtube.com/watch?v=LC9LABPts7M;License: Standard Youtube License