In every cell there are three main parts: the nucleus, the cytoplasm, and the cell membrane. The nucleus is a spherical body usually located near the center of the cell that contains the genetic code of the cell and its purpose is to serve as the control center. Cytoplasm is the fluid medium for the many molecules and organelles the cell has. The cell membrane is the outer layer that separates the cell from its environment and controls what enters and leaves the cell.
DNA has a massive job of keeping you alive. In essence, a microscopic strand of genes support your entire body and life. There are many smaller jobs protein has to accomplish that combine to accomplish the main job of supporting life. To start, DNA codes for proteins and every protein provide an essential biological function. Also, cells make up tissues, organs, and body systems.
The fertilization may be internal or external. It depends on organism and its environment in which that animal live. In external fertilization many invertebrates simply release their gametes into water in which they live and allow them to fertilize (e.g. sponges and corals), while in some other invertebrates utilize internal fertilization to transfer sperm
Transfection: One of the methods of gene transfer where the genetic material is deliberately introduced into the animal cell in view of studying various functions of proteins and the gene. This mode of gene transfer involves creation of pores on the cell membrane enabling the cell to receive the foreign genetic material. Transfection can be carried out using calcium phosphate (i.e. tricalcium phosphate), by electroporation, by cell squeezing or by mixing a cationic lipid with the material to produce liposomes which fuse with the cell membrane and deposit their cargo inside. The choice of methods of DNA transfer depends upon the target cells in which transformation will be performed. It also depends upon the objectives of gene manipulation.
First and foremost, what is epigenetics? Epigenetics is described as the study of gene expression changes without involving the changes in DNA sequence. The word “epigenetics” originates from the theory of epigenesis. The theory of epigenesis states that an embryo develops progressively from an undifferentiated egg cell. Epigenetics is a mechanism for mediating gene activity independent of DNA sequence determining which genes are turned on and which genes are turned off.
Mechanism of meiotic recombination The Meiotic recombination is an integral part of the meiotic division in most eukaryotes. It can lead to either crossovers (reciprocal exchange of genetic material between homologous chromosomes), or non-crossovers (non-reciprocal exchange of the genetic material). In eukaryotes, only a small percentage of meiotic DSBs result in crossover products (Sung et al., 2003; Youds and Boulton, 2011). In contrast, repair of DSBs in the mitotic cells happen mostly through the non-crossover recombination pathway, via the sister chromatids.
These move from the outer portion of the seminiferous tubule to a more central location and attach themselves around the sertoli cells. The primary sperm cells then develop somewhat by increasing the amount of cytoplasm and organelles within the cytoplasm. After a resting phase the primary cells divide into a form called a secondary sperm cell. During this cell division there is a splitting of the nuclear material. In the nucleus of the primary sperm cells there are 46 chromosomes; in each of the secondary sperm cells there are only 23 chromosomes, asthere are in the egg.
7- Granular cell tumors They are never cancers, start in primitive nerve cells, rarely found in the breast, can be felt as a firm mobile lump, but some may be attached to the skin or chest wall, they are usually about ½ to 1 inch across and most often are in the upper, inner part of the breast. (39) Fig.8. Granular cell tumor shows a well circumscribed tumor with lobular nested architecture. High power shows nests of cells with small nuclei and abundant granular eosinophilic cytoplasm.
1.Telomerase Telomeres play a crucial role in cellular replication, with the loss of telomeres cell is unable to divide. Replicative senescence which is cell incapability to divide was first defined by Hayflick (Hayflick,2000). Hayflick observed that after a several number of cell divisions cells in culture ceased to propagate. 1.1 Telomerase maintenance Cells can attain immortality by two telomere maintenance mechanisms, the first pathway includes an action of ribonucleoprotein enzyme complex telomerase. Telomerase helps in the elongation of telomeres through nucleotide addition by catalyzing the de novo synthesis of TTAGGG repeats, thereby counteract shortening, of telomeres and allow indefinite cell proliferation.
5. How do the processes of meiosis and fertilization produce genetic variety? During the meiosis stage of crossing over, the maternal and paternal homologous chromosome segments are being exchanged. During independent assortment, different genes independently separate from one another.
Chromosome #2 with locus TPOX with a length of 248 base pairs was only found in the parent sample A. None of the chromosomes from sample b matched the chromosomes from A, C, or D+E except for maternal TPOX chromosome from B and the paternal TPOX from C. 3. Would this exercise still work properly if you had chosen any combination of maternal and paternal chromosomes for chromosomes 2, 5, 7, and 13 from samples D & E? Yes because the maternal and parental chromosomes would still be put on the electrophoresis table. The parents turn out different based on DNA combos that are chosen. 4.
During the first cycle of replication in meiosis, Prophase is the same but crossing over occurs along side of the nuclear membrane dissolving, chromosomes developing, and the spindle fibers forming. Crossing over is the process in which homologous chromosomes from both parents pair up and exchange DNA. Also during metaphase and anaphase homologous chromosomes are separated and pulled to opposite sides. During this second cycle of replication the cells grows through Prophase II, Metaphase II, Anaphase II, Telophase II, and its final cycle of cytokinesis which is the exact same as during mitosis. I will play a quick review of this process.
What comes to people’s mind when they hear the word “animal’? Most people will picture a furry creature with four legs such as a dog or a cat in their mind, but none will picture a sand dollar even though it’s an animal. Most people would find it’s difficult to label a sand dollar as an animal. To begin with, it doesn’t even look like a living thing; it looks like a flat piece of rock. Secondly, sand dollar looks nothing like a typical animal that people see daily; it doesn’t seem to have animal-like characteristics.