Influence of yolk on cleavage, Biology

Assignment Help:

Influence of Yolk on Cleavage

Though biological significance of yolk is to provide nourishment to the developing embryo, it is not part of the active cytoplasm. Yolk is dead and inert component not participating in the cellular activities, but, it influences cleavage in, the following ways:

  1. With gradual increase in the amount of stored yolk, the total amount of the active cytoplasm tends to decrease.
  2. Cell division is the activity of only the nucleus and cytoplasm. With increase in the yolk amount the formation of spindles, cell membranes and cleavage furrows takes place in the active cytoplasm which is restricted to relatively smaller areas of the zygote and its daughter blastomeres.
  3. The speed of cleavage is inversely proportional to the amount of yolk present. In the telolecithal eggs, blastomeres nearer to the animal pole divide at a faster rate than the blastomeres located towards the vegetal pole because the passive behaviour of the inert yolk in the yolky parts of the zygote and its daughter blastomeres obstructs the formation of cleavage furrows.

Therefore, the nature of various metabolic activities of the egg and the blastomeres derived from it depends upon the amount and placement of yolk mass.


Related Discussions:- Influence of yolk on cleavage

Describe about development of sexual maturity in children, Briefly Describe...

Briefly Describe about Development of Sexual Maturity in Children? Sexual maturity develops along with growth spurt in adolescence. In girls, growth stops on attaining menarche

Early-recurrence of angina, Early: Recurrence of angina soon after the pa...

Early: Recurrence of angina soon after the patient resumes activities is either due to inadequate 1.evascula1isation or acute graft closure. In the immediate post-operative per

What are the phytoplankton and the zooplankton, What are the phytoplankton ...

What are the phytoplankton and the zooplankton? Phytoplankton and zooplankton are parts of the plankton. The phytoplankton comprises the autotrophic floating beings: cyanobacte

What is tagma, What is Tagma, Tagmosis and Tagmatization? Distinct body...

What is Tagma, Tagmosis and Tagmatization? Distinct body regions resulting when different segments of a metameric animal become involved in specific functions. These segments a

How is the skin involved in the regulation of temperature, Q. How is the sk...

Q. How is the skin involved in the regulation of body temperature? Skin is one of various organ systems participating in maintaining a core temperature, meaning the temperature

Define the fact that we must eat to gain the energy, Which law of thermodyn...

Which law of thermodynamics explains the fact that we must eat to gain the energy to perform the functions of life, such as breathing? a. fourth law b. first law c. second law d

Explain severe acute respiratory syndrome, Severe Acute Respiratory Syndrom...

Severe Acute Respiratory Syndrome (SARS) After travelers' diarrhea, respiratory infection is the most common infectious disease affecting travelers. In the winter of 2003 a ne

Osmotic function - essential elements, Osmotic Function - Essential Element...

Osmotic Function - Essential Elements Plant cells generally contain mineral ions 10 to 1000 times higher in concentration than the surrounding soil. That is why water enters t

Illustrate steps of polymerase chain reaction , There are three steps of PC...

There are three steps of PCR a) Denaturation.  The reaction combination is heated to 95°C for a short time period (about 15-30 sec) to denature the goal DNA into one strands w

What are the values of dpd for plant cells under hypertonic, What are the v...

What are the values of DPD for plant cells under hypertonic, isotonic and hypotonic media? In plant cells under hypertonic medium there is loss of water for the exterior, SF >

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd