1.ERD Part 4 Introduction and make a summary 2.    Briefly explain the following concepts: a.     Asexual – sexual reproduction b.    Mitosis – Meiosis c.    Diploid – Haploid d.    Gametes e.    Fertilization f.     Zygote g.    Syngamy h.    Blastocyst i.     Implantation j.     Gastrulation k.    Embryo – Fetus 3.    Describe fertilization process from cellular level to fetus. 4.    According on what you learned about fertilization process, when does human life begin? Your answer must be objective and based on scientific evidence. Personal opinions are not allowed.

1. ERD Part 4 Introduction and Summary

The ERD (Entity-Relationship-Diagram) is a conceptual tool used to represent the entities and their relationships in a database system. Part 4 of the ERD focuses on the relationship aspects of the entities. This section introduces and explains various concepts that are crucial for understanding the relationships between entities in a database.

In this part, we will explore the concepts of asexual and sexual reproduction, mitosis and meiosis, diploid and haploid cells, gametes, fertilization, zygote, syngamy, blastocyst, implantation, gastrulation, and embryo-fetus development.

2. Brief Explanation of Key Concepts

a. Asexual – Sexual Reproduction: Asexual reproduction is a type of reproduction that involves only one parent. It leads to the production of offspring that are genetically identical to the parent. Sexual reproduction, on the other hand, involves the fusion of two gametes (reproductive cells) from two parents, resulting in offspring that exhibit genetic variations.

b. Mitosis – Meiosis: Mitosis and meiosis are types of cell division. Mitosis is a process that results in two identical daughter cells, each containing the same number of chromosomes as the parent cell. It is involved in the growth, development, and repair of somatic (non-reproductive) cells. Meiosis, on the other hand, is a special type of cell division that occurs in the reproductive cells (gametes). It leads to the formation of cells with half the number of chromosomes as the parent cell, contributing to genetic diversity.

c. Diploid – Haploid: Diploid refers to cells that contain two complete sets of chromosomes, one from each parent. These cells are present in most somatic cells of an organism. Haploid cells, on the other hand, contain only one set of chromosomes and are found in the gametes.

d. Gametes: Gametes are specialized reproductive cells that are involved in sexual reproduction. In humans, the male gametes are called sperm cells, while the female gametes are called egg cells or ova.

e. Fertilization: Fertilization is the process in which the sperm and the egg fuse together, resulting in the formation of a zygote. This process typically occurs in the fallopian tube of the female reproductive system.

f. Zygote: A zygote is a single cell formed by the fusion of sperm and egg during fertilization. It contains the complete set of genetic material from both parents and marks the beginning of an individual’s development.

g. Syngamy: Syngamy refers to the fusion of two haploid gametes, such as the fusion of sperm and egg during fertilization, resulting in the formation of a diploid zygote.

h. Blastocyst: After successful fertilization, the zygote undergoes several divisions and forms a hollow ball of cells called a blastocyst. The blastocyst is the stage at which the developing embryo implants into the wall of the uterus.

i. Implantation: Implantation is the process by which the blastocyst attaches to and embeds itself into the lining of the uterus. This allows the developing embryo to obtain nutrients and continue its growth.

j. Gastrulation: Gastrulation is a critical process that occurs after implantation. It involves the rearrangement and differentiation of cells within the blastocyst, leading to the formation of three distinct germ layers: the endoderm, mesoderm, and ectoderm. These germ layers give rise to various tissues and organs during the later stages of development.

k. Embryo – Fetus: The developing individual is referred to as an embryo during the early stages of development, up until around the ninth week. After this, it is referred to as a fetus. This distinction is based on the maturity and formation of various organ systems.

3. Description of the Fertilization Process

The fertilization process involves the journey of sperm through the female reproductive tract, penetration of the egg, fusion of genetic material, and development of the zygote into a fetus. At the cellular level, it begins with the release of a mature egg from the ovary, which is then captured by the fallopian tube. During sexual intercourse, millions of sperm are ejaculated into the vagina, and through the process of capacitation, they gain the ability to swim towards the fallopian tube. Only a few hundred or thousand sperm reach the egg, and one sperm successfully penetrates the egg’s outer layer, leading to the fusion of genetic material. This fusion forms a zygote, which undergoes rapid cell divisions and forms a blastocyst. The blastocyst then implants itself into the uterus, and from there, further development takes place.

4. When Does Human Life Begin?

The question of when human life begins is an important ethical and philosophical inquiry. From a scientific standpoint, human life begins at fertilization when the sperm and egg fuse to form a genetically unique organism with its own set of DNA. This marks the beginning of development and the potential for human characteristics and life to emerge. This scientific understanding is based on the objective observation of the biological processes involved in fertilization and embryonic development. It is important to note that this perspective does not imply any moral or legal implications but serves as a scientific understanding of the initiation of human life.