The whitefish slide is from a blastula, an early stage in embryonic development. why do you think that this sample was chosen rather than a sample of adult tissue? hint: recall the discussion about how many times a cell must divide to create all of the cells in an adult human.

In the morula phase, the zygote begins to divide by mitosis, which is from one cell to two cells, two cells to four cells, four cells to 8 cells, and so on.

This cell division occurs continuously during the zygote journey to the uterus (approximately 4 days). This division produces daughter cells that are collected in a colony like a round ball, hereinafter called morula. In its growth, the morula will become a blastula that has cavities. This process of forming a morula is called morulation.

The blastula phase is a continuation of the formation of the morula which is continuously dividing. The shape of the blastula begins with irregularly curved cell changes. This blastula formation process is called blastulation. Inside the blastula, there is a cell fluid called the blastocoel. In the blastula wall, there is a sticky part that will help the process of attaching the zygote to the endometrium (uterine wall) or called the implanting process. Furthermore, the blastula will undergo a process of gastrulation or the process of cavity formation (gastrus).

Single-cell (which has been fertilized)

After initial fertilization, a diploid zygote nucleus is formed. Next will undergo mitotic division and begin the next stage of embryogenesis which is the formation of morula, blastula, gastrula, neurula, and ends in organogenesis)

Morula

After the initial cell division (cleavage), the cells in the embryo will divide miosis quickly into many small cells called blastomeres.

Blastula

Morula will experience a division that continues to form a cavity in the middle. This cavity is getting bigger and bigger with liquid. An embryo that has this cavity is called a blastula. This is called the blastocele.

Gastrula

Gastrula comes from the word gastric (stomach) because at this stage it will form a cavity that will become the digestive tract. The gastrula cavity is called a gastrosel (archenteron). After reaching the form of the blastula, cell mass increase still continues with the mitotic division.

Neurula

After the gastrula is formed, the embryo will differentiate, namely the change of cells that have not been specialized into cells that have a special structure and function. This means changes in physical properties and function of cells as cells multiply from the embryo to form different body structures.

Organogenesis

After neurulation, the embryo begins to reorganize to form a more perfect embryo through several stages, namely:

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Embryogenesis

several phases

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Class: College

Subject: Biology

Keyword: embryo, phases, cells

mountains can affect the climate of nearby lands. in some areas, mountains block rain, so that one side of a mountain range may be rainy and the other side may be a desert. much of airborne moisture falls as rain on the windward side of mountains.

explanation:

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.