Cytology 244First Term of year

1432-1433Nuha AL-Abdulhadi

lab 8

1-Some of the other components such as:A - Chromosomes.B - Fatty dropletsC - Glycogen granules.

 2- The mitosis .

Chromosomes.

Chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, and other nucleotide sequences. Chromosomes Chromosomes are the essential unit for cellular division and must be replicated, divided, and passed successfully to their daughter cells so as to ensure the genetic diversity and survival of their progeny

The sister chromatids of a mitotic pair compactly folded into the chromosome.

Fatty droplets

-In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. -It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. - Adipose tissue is derived from lipoblasts. Its main role is to store energy in the form of lipids, although it also cushions and insulates the body. Far from hormonally inert, adipose tissue has in recent years been recognized as a major endocrine organ[1], as it produces hormones such as leptin

Glycogen granules.

-Glycogen is : a molecule that serves as the secondary long-term energy storage in animal and fungal cells, with the primary energy stores being held in adipose tissue. Glycogen is made primarily by the liver and the muscles, but can also be made by glycogenesis within the brain and stomach.

-Glycogen is found in the form of granules in the cytosol/cytoplasm in many cell types, and plays an important role in the glucose cycle. Glycogen forms an energy reserve that can be quickly mobilized to meet a sudden need for glucose, but one that is less than the energy reserves of lipids.

-In the liver hepatocytes, glycogen can compose up to eight percent of the fresh weight (100–120 g in an adult) soon after a meal.

- Only the glycogen stored in the liver can be made accessible to other organs. In the muscles, glycogen is found in a low concentration (one to two percent of the muscle mass). However, the amount of glycogen stored in the body—especially within the muscles, liver, and red blood the cells mostly depends on physical training, basal metabolic rate, and eating habits such as intermittent fasting. Small amounts of glycogen are found in the kidneys, and even smaller amounts in certain glial cells in the brain and white blood cells. The uterus also stores glycogen during pregnancy to nourish the embryo( Why ? ) .

- Mitosis :is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly equal shares of these cellular components.

Mitosis : is when the parent cell divides to make 2 new cells, or daughter cells. This cell division is used for growth and repair.Mitosis has 5 different stages:1-Interphase2-Prophase3-Metaphase4-Anaphase5-Telaphase

- The process of mitosis is fast and highly complex. The sequence of events is divided into stages to the completion of one set of activities and the start of the next. These stages are: interphase, prophase, metaphase, anaphase and telophase.During mitosis the pairs of chromatids condense and attach to fibers that pull the sister chromatids to opposite sides of the cell. The cell then divides in cytokinesis, to produce two identical daughter cells which are still diploid cells (2n) .

1- Interphase During interphase, cellular organelles double in number, the DNA replicates, and protein synthesis occurs. The chromosomes are not visible and the DNA appears as uncoiled chromatin. 

2- Prophase: During the first stage of mitosis, prophase, the chromatin condenses and the chromosomes become visible. Also the nucleolus disappears, the nuclear membrane fragments, and spindle fibers are assembled

3- Metaphase :During metaphase, the nuclear membrane fragmention is complete and the duplicated chromosomes line up along the cell's equator

4- Anaphase :During anaphase, diploid sets of daughter chromosomes move toward opposite poles of the cell and cytokinesis (cytoplasmic cleavage) begins

  5- Telophase :During telophase, the nuclear membrane and nucleoli reform, cytokinesis is nearly complete, and the chromosomes eventually uncoil to chromatin.  

NUHA