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.

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Answer 1

Question

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

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.

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True or False Questions 1. The equilibrium potential of an ion will affect the membrane potential of the cell if the permeability for that ion is zero. (T/F) 2. When there is only one ion permeability and the cell is at rest, then Eion = Vrest (T/F) 3. In a generic neuron, Vrest is positive and close to Ek (T/F) 4. the three ions that have biggest contribution to Vm value are K+, Na+ and Cl- (T/F) 5. In a generic cell, the concentration of Na+ is larger outside than inside (T/F) 6. In a generic cell, the concentration of Cl- is lower outside than inside (T/F) 7. A cell at rest only has 2 types of ion permeabilities (where P ion_1 = 1 and P ion_2 =1) the concentration gradients of the two ion types have the same magnitude but opposite polarity (Assume both types of ions have the same valence). Thus, Vm = 0 mV (T/F)

Answer 2

Question

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

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.

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Answer 3

Question

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

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.

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Answer 4

Question

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

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.

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Answer 5

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

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.

Answer 6

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

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.

Answer 7

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.

Answer 8

Expert Solution & Answer

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.

Answer 9

Expert Solution & Answer

Answer 10

Expert Solution & Answer

Answer 11

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.

Answer 12

Ch. 7 - Prob. 1DQ Ch. 7 - Prob. 2DQ Ch. 7 - Prob. 3DQ

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