LS5005: Medical Physiology with Research Methods Assignment Sample
Module code and Title: LS5005: Medical Physiology with Research Methods Assignment Sample
Introduction
Fertilization refers to the process of fusion between female and male gamete including a fusion process of “oocyte with a sperm” through the creation of diploid cells for developing a new organism. Hence, education related to molecular mechanisms is important to gain in-depth knowledge of fertilization. Several molecules play a crucial role in every step of this “intriguing process” that includes attraction of the sperm from the side of an oocyte, maturation of the sperm, the fusion of the sperm and oocyte, and formation of zygote through the fusion of sperm and oocyte.
The approaches of the sperm are one of the critical processes that happen within mammals. The activation of the sperm within the eggs is an essential factor as it brings the new living beings, and the nutrients present in the sperm generally enable the sperm to go longer and use those nutrients for their benefit and to fertilize the egg.
The thesis statement is the molecular mechanism involved in the overall fertilization process of mammals including enabling attraction, penetration of sperm to the egg, activation of the egg, and fertilization of only one sperm.
Main Body
Molecular mechanism in mammals for enabling attraction and penetration of sperms to an egg.
Before penetration of sperm into an egg, it should be matured and activated for the formation of the zygote within the oocyte in mammals. Hence, the first phase of the fertilization process within mammals is sperm activation for achieving mature sperm for penetration. Moreover, eggs use chemical signals for attracting sperms and the chemical is known as “chemoattractants” (Ac.uk, 2020).
This chemical is released by unfertilized eggs to attract sperm and this chemical is present within the “follicular fluid” surroundings of the egg. According to Satouh and Ikawa (2018), the sperm membrane is made with “transmembrane protein” and it is the receptor of sperm for receiving the signal from the egg through the extracellular molecular reaction. The sperm receptor reacts during conformational change through its “cytoplasmic side” and then activates its enzyme activities to enter an egg.
This process triggers the “mitochondrial ATP-generating apparatus” by stimulating the activities of the sperm causing the movement of sperm. “Speract ” is a sperm peptide that activates its movement and is made up of ten amino acids and this increases the pH level and increases sperm movement. According to He et al. (2022), activation of the sperm is the preparatory step of the overall acrosome reaction.
“Proteolytic enzymes” plays a crucial role in activating non-linear movements of sperms by accomplishing its hyper-activation to enter into an egg. Mammals have the motile ejaculation of sperms and some factors like “surface-attached glycoproteins, seminal plasma proteins, and the depletion of membrane cholesterol” impacts the fertilization capabilities of mammals. The preparatory steps of this fertilization involve a “protein phosphorylation state” for the creation of the capacity of both the eggs and sperm for fusion in the later period.
“Fallopian tubes” accelerate the available efflux of the sperm cell with the help of its available higher density lipoprotein element that is called “Sterol binding proteins”. “Oocyte mucous” has different chemical molecules that activate the preparatory stage and control the overall system of fertilization including its “acrosome reactions”. In mammals, the “ZP3 glycoprotein of the zona pellucida” is the reason for the binding of sperms.
According to Stein et al. (2020), for attracting a sperm, the egg goes through several changes and activation of chemical compounds such as increment of intracellular Ca++, and sperm goes through activation of “Spermatic motility” frequently. The penetration of the sperm into an egg generally happens through the molecular mechanism of genetic evaluation and the cell division and the creation of new cells generally happen during this particular process.
“Estrogen and progesterone hormones” plays a crucial role in developing attractive characteristics within egg and sperm reaction for fertilization. “Spermatozoa” of sperms exhibit swimming behavior within the fallopian tubes that is controlled by the “sperm-specific CatSper ion channels” through controlling the concentration of “intracellular Ca2+”. The oocyte has a plasma membrane with two different regions such as the “microvilli-free region and a microvilli-rich region” (Saint-Dizier et al. 2020).
“Evaluation” is one of the significant factors that enable the living being to adapt to the necessary changes within their body in accordance with the external atmosphere. The understanding of speciation generally needs to be understood in order to grasp the several occurrences of the human body. Thus, the fusion process of oocyte and sperm is encountered by the “microvilli-rich region” and triggered through ZP binding.
Moreover, “Fertilizin” is the main chemical element of the egg that attracts and holds the sperm within it and glucose plays a crucial role in achieving successful implementation of the sperm to be fertilized. After completion of the acrosome reaction, ZP2 is activated for further formation of enzymes for fertilization.
Molecular mechanism for activation of the egg
After entering the fallopian tube of sperm, its “zona pellucida” is digested and the fusion of the sperm membrane has started with the egg membrane through the sperm protein of PH-10. “Transmembrane glycoprotein” named PH-30 has two separate subunits called “α and β subunits”.
Among these, the α subunit contains 289 amino acids and β subunit contains 353 amino acids for the creation of “tripeptide RGD” (Nih.gov, 2019). “Speciation” generally refers to the separation of the same group members from the existing group and the development of their own characteristics. The characters of living beings generally follow the adaption of the necessary changes as per the indeed of the external atmosphere.
This “tripeptide RGD ” activates the egg for recognition of the sperm for fusion as PH-30 is presented in the head part of sperm. The acrosome reaction influences “vesicle formation” through the creation of fusion among “acrosome membranes with the overlying plasma membrane of the sperm”. Admixture generally occurs when the previously isolated and diverged generic lineage mix. The consequence of the admixture generally results in introducing new “genetic lineages” into a new population. The positive relationship between the “generic diversity and source number” generally happens within the living cells.
Egg activation in mammals is the early phenomenon of the fertilization process with the building of an embryo. Two main activities involved in this egg activation process are “meiotic resumption and cortical granules exocytosis” which is triggered through a transient increment in the “cytosolic-free Ca2+ concentration”. Furthermore, “Ca2+ oscillations” is the main process of activating an egg to receive responses from the sperms. This oscillation is introduced by the “IP3 receptors” of the sperms.
According to James et al. (2020), sperms influence the ejaculation of IP3 receptors in the membrane of eggs through the introduction of a “diffusible cytosolic factor” within an egg. An increase in the “cytosolic Ca2+” is due to the increase of “intracellular Ca2+ release” which is an important influx for maintaining the Ca2+ level in the plasma membrane of an egg (Ac.uk, 2019).
Furthermore, “introgression” generally refers to the slow movement of the genes from one specific species into “the gene pool” of another. This particular princess happens when there is an opportunity for hybridization present between them. Introgression is essential for the evaluation of living beings.
The molecular mechanism that prevents fertilization of more than one sperm
The immediate response of the egg after fertilization is to stop and prevent the process of “polyspermy” which refers to the fertilization of more than one sperm within the egg. The molecular mechanism to stop entering of other sperm through the cell membrane is stopped in two steps of filtration such as “oocyte membrane block, and zona reaction”. The oocyte membrane stops further entering any sperm into the egg with the application of “fast block” after binding the first “spermatozoa”.
According to Evans (2020), this action is achieved by changing the electric potential of the plasma membrane of the egg. The reproductive barrier further refers to the inability of a particular species to “breed successfully” due to geographical, physiological, behavioral, differences, or generic barriers. The inability of the sperm to fertilize an egg can create specific issues of the reproductive barrier within living beings. This difference is continuously maintained bby the cell membrane of the egg. Moreover, the egg mounts a “cortical reaction” for the prevention of polyspermy by creating barriers through its membrane.
After entering the sperm within the oocyte, the egg has recognized the “cytoplasmic material”. The incident of polyspermy caused catastrophic impacts on sperm penetration. The blocking of the oocyte membrane is called “depolarization” through the increment of Na+ influx that is the main reason behind changing characteristics of the oocyte membrane.
According to Kern et al. (2018), this is also prevented through “Ca2+ oscillation” that triggers the “exocytosis of cortical granules” for preventing the space from entering a sperm to the egg placenta Some important enzymes like “hydrolase, proteinase, and peroxidase” of the “cortical granules” ‘prevent this entering of another sperm by modifying the structure of the sperms (Nih.gov, 2018).
This phenomenon is also called “slow block” by destroying the sperm and hardening the ZP so that another sperm cannot enter. All these phenomena of mammals’ reproduction system denote a delicate system of attracting sperm for fusion with the egg.
Conclusion
The essay focuses on the evaluation of the molecular mechanism involved in the mammal reproduction system. The essay has given all relevant information and data on the molecular structure and molecular reaction of the sperm and egg during their fusion. The discussion has given some important points about the molecular mechanism that enables the attraction and binding of sperm. This knowledge focuses on the development of molecular knowledge related to cell interaction with each other based on the cells involved in the fertilization process of mammals.
Thus, it has developed in-depth knowledge and perspective of the development of the fertilization process within mammals. This discussion has given the molecular mechanism of the egg that restricts the entry of more than one sperm within its cells. The essay has given information about the process of blocking further sperms to enter the egg membrane the elimination of the chance of polyspermy. Hence, the overall discussion established the overall procedure of fertilization and its involved mechanism to establish a healthy reproductive system with delegation.
Reference list
Journals
Evans, J.P., 2020. Preventing polyspermy in mammalian eggs—Contributions of the membrane block and other mechanisms. Molecular reproduction and development, 87(3), pp.341-349.
He, Z., Xie, M., Li, Q.Q., Duan, J. and Lu, X., 2022. Research progress on the microregulatory mechanisms of fertilization: a review. in vivo, 36(5), pp.2002-2013.
James, E.R., Carrell, D.T., Aston, K.I., Jenkins, T.G., Yeste, M. and Salas-Huetos, A., 2020. The role of the epididymis and the contribution of epididymosomes to mammalian reproduction. International Journal of Molecular Sciences, 21(15), p.5377.
Kerns, K., Zigo, M. and Sutovsky, P., 2018. Zinc: A necessary ion for mammalian sperm fertilization competency. International journal of molecular sciences, 19(12), p.4097.
Saint-Dizier, M., Mahé, C., Reynaud, K., Tsikis, G., Mermillod, P. and Druart, X., 2020. Sperm interactions with the female reproductive tract: a key for successful fertilization in mammals. Molecular and Cellular Endocrinology, 516, p.110956.
Satouh, Y. and Ikawa, M., 2018. New insights into the molecular events of mammalian fertilization. Trends in biochemical sciences, 43(10), pp.818-828.
Stein, P., Savy, V., Williams, A.M. and Williams, C.J., 2020. Modulators of calcium signalling at fertilization. Open biology, 10(7), p.200118.
Websites
Ac.uk, 2019, “Molecular triggers of egg activation at fertilization in mammals”. Viewed on: 02.11.2022, https://orca.cardiff.ac.uk/id/eprint/103338/1/Molecular%20Triggers%20of%20egg%20activation%20at%20fertilization%20in%20mammals.pdf
Ac.uk, 2020, “Human eggs prefer some men’s sperm over others, research shows”. Viewed on: 02.11.2022, https://www.manchester.ac.uk/discover/news/human-eggs-prefer-some-mens-sperm-over-others-research-shows/
Nih.gov, 2018, “Possible mechanism of polyspermy block in human oocytes observed by time-lapse cinematography”. Viewed on: 02.11.2022, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3463667/
Nih.gov, 2019, “The molecular basis of fertilization (Review)”. Viewed on: 02.11.2022, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5029953/
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