Wonderful Genetics!!

This is a picture representing homozygous and heterozygous genes given off by the mom fish and the dad fish and the different gametes that are possible.

  













    
   The Idea of genetics is amazing!!! There is so many things that you can think of when you think about genetics. In class we have been learning about genetics, and we did a baby lab to represent the outcome of what you and yours partner's baby would look like. There are many different terms that is involved with genetics. When someone is Homozygous they have two of the same copies of a gene. For example, AA and HH. When someone is Heterozygous, it is the complete opposite they have two different copies. For example, Aa and Ff. Gametes are reproductive cells that have haploid chromosomes. A dominant trait is a trait that shows up in the offspring if one of the parents contributes it. A recessive gene is hidden, it has identical alleles for a single trait.  A gene is DNA region for one trait. An allele is a form of a certain gene. Phenotypes are visible traits, it's what the baby is going to look like. Genotypes are the genes that are present. A chromosome is an organized structure of DNA and protein that is found in cells. The difference between a diploid and a haploid is that a diploid are two copies of each chromosome and a haploid is one copy of each chromosome. In meiosis when mom and dad's chromosomes are separated this is called segregation. If a mom is homozygous for free earlobes and marries a man who doesn't have free earlobes,what are the possible genotypes and phenotypes of their children? Well, the genotypes would be Ff, and ff. The phenotypes would be free earlobes and not free earlobes.

Independent Assortment is when there are as many combinations as possible. According to Mendel's second law alleles of two or more different gene pairs inherit two different alleles. They assort independently of each other during meiosis. A random combination of the genes from each pair end up in the gametes. For example, Ss and Yy assort independently because when the S and s alleles segregate from each other during meiosis, each one is most likely to land in the same gamete with the big Y allele and with the little y allele. The reason why idependent assortment occurs is because there are many ways that chromosomes are placed in metaphase one of meiosis. Two genes must reside on different chromosomes or on the same chromosome in order to assort independently. They must be located far apart from each other along the chromosomes arms. Genetics is involved everywhere in our world, and it plays a major role. It determines what you look like, like if you get more traits from your mom or dad. Sometimes, you can look more like family members in your family's history from generations ago. I have a good understanding about genetics, and how we get the traits that we do.

Meiosis/Reproduction

This is a diagram of meiosis. 



The division of meiosis. 



























Meiosis is the type of cell division by which eggs and sperm are produced. In meiosis I, the chromosomes in a diploid cell resegregate, which produces four haploid daughter cells.  This step in meiosis generates genetic diversity. It occurs in humans, fungi, plants, and animals. Each human cell contains a full set of 46 chromosomes. When meiosis begins, each chromosome is attracted to its special homologous partner. The two number one chromosomes; one from the paternal set and one from the maternal set, wrap tightly with each other in a process called synapsis. Then, a tetrad of four chromosomes is created. Each homologous pair forms its own tetrad, which happens with the other chromosomes. All of the tetrads arrange themselves on the spindle. The chromosomes are pulled apart, and divisions happen. The four chromosomes are separated into two's and then into ones of each tetrad. 


Meiosis II is very similar to mitosis. However, there is no S phase. The chromatids of each chromosome are no longer identical because of recombination. Meiosis II separates the chromatids producing two daughter cells, each with 23 chromosomes and each chromosome has only one chromatid. Homologous chromosomes pair forming bivalents until anaphase I in chromosome behavior. In genetic identity of progeny during meiosis the chromatids are not identical. The daughter cells have a new assortment of parental chromosomes. Meiosis can only happen if the nucleus contains an even number of chromosomes. 


In class we watched the movie Life's Greatest Miracle in which it was about the long processes it takes to have a baby. It was interesting to learn about how a baby is formed by how the process has to be done  right on time. In which, there has to be enough sperm that is developed and the egg can't die. But, the process of having a baby is all about meiosis. This movie really taught me a lot of information about how meiosis is very important, it was gross though watching the live birth of a baby. Meiosis produces different sperm and egg.  In conclusion, I understand about the processes of meiosis and how it is different from mitosis. 

The Idea of Stem Cells

This is a diagram of Pluripotent Stem Cells. 

   Cells develop into many different cell types in our bodies during early life and growth. When a stem cell divides, each new cell has the capability to either remain a stem cell or become another type of cell with a more important function; such as a muscle cell, a red blood cell, or a brain cell. There are two important characteristics that stem cells are distinguished from other cells. The first characteristic is that  they are unspecialized cells that are capable of renewing themselves through cell division, sometimes after long periods of inactivity. Another characteristic is that under certain experimental conditions, the cells can become tissue or organ-specific cells with special functions. Stem cells regularly divide to repair and replace worn out or damaged tissues, in some organs such as the gut and bone marrow. Stem cells only divide under special conditions, in organs such as the pancreas and the heart.


  Scientists have worked with two kinds of stem cells from animals and humans which are embryonic stem cells and non-embryonic somatic stem cells. Scientists discovered ways to derive embryonic stem cells from early mouse embryos in 1981. Then in in 1998,  a method to derive stem cells from human embryos and grew the cells in the laboratory was developed. These cells are called human embryonic stem cells. The embryos used in these studies were created for reproductive purposes through procedures called invitro fertilization. Stem cells are important to living organisms for a lot of reasons. The inner cells give rise to the entire body of the organism in a blastocyst embryo which is a 3- to 5-day-old embryo. It includes many specialized cell types and organs such as the heart, lung, skin, sperm, eggs, and many other tissues. Some tissues that are in adults such as bone marrow and muscle generate replacements for cells that are lost through injury, diseases, and normal wear and tear. Stem Cells offer new ways for treating diseases like heart and diabetes. Scientists use stem cells in labs to test new drugs and to find the reasons that causes birth effects. 


The research about stem cells continue to advance about how an organism develops from a single cell and how healthy cells replace damaged cells in adult organisms. All stem cells have three properties which are how they are unspecialized, capable of renewing and dividing themselves for a long period of time, and how they can give a rise to specialized cell types. Information is difficult for scientists to be able to grow a large number of unspecialized stem cells in the lab for further experimenting. One of the main properties of a stem cell is that it does not have any tissue-specific structures that allow it to perform specialized functions. Stem cells can't carry oxygen molecules through the bloodstream. But, when stem cells give a rise to specialized cells, this process is called differentiation. The cell usually goes through several stages, while differentiating. There are many questions about the process of stem cell differentiation that still remains. 


I understand about the capabilities and the unique features about stem cells. It's interesting about how stem cells develop into many different cell types in our bodies. 

The Cell Cycle of Mitosis

In Class, we have been learning about the different stages of mitosis. The different stages are Interphase, Prophase, Metaphase, Anaphase, and Telophase. The biggest percentage of what the cells mostly spend there time in is Interphase, which is about 90% of the time. Cells rarely spend there time in Telophase which is about 2.7% of the time.






 Interphase: 

                                                                                                       

      Interphase is the period of the cell cycle in which the nucleus does not undergo division. It mainly occurs between mitotic or meiotic divisions. Its the resting stage between all cell divisions. It usually lasts between twelve to twenty-four hours in mammalian tissue. The cell is always synthesizing RNA during this period. Interphase can be divided into four steps which are Gap 0, Gap 1, synthesis phase, and Gap 2. In Gap 0 there are times when the cell may quit dividing. An example would be a cell that has reached an end stage of development and will no longer be able to divide. In Gap 1 the cells increase in size, producing synthesize and RNA protein. A cell cycle control mechanism is activated during this period and it makes sure that everything is ready for DNA synthesis. During the synthesis phase DNA replication occurs. This happens in order to produce two similar daughter cells. During Gap 2 between DNA synthesis and mitosis, the cell will continue to grow and produce proteins. At the end of the cycle it determines if the cell can proceed to enter mitosis and divide. 

                

  Prophase:     

Prophase is the first stage of mitosis in which the chromosomes join together and become visible. The nuclear membrane breaks down and the spindle apparatus forms at opposite poles of the cell. Two centrosomes, in which replicate independently of mitosis have microtubule-activity increased due to the recruitment of the y-tubulin. The interesting feature of prophase is the setup of the mitotic spindle, in which is used to maneuver the chromosomes about the cell. The spindle is formed by extra parts from the cytoskeleton. The cell's centioles are duplicated to form two two pairs of centrioles. In which, each pair becomes the part of the mitotic center which forms the focus for an array of microtubules. This procees is called the aster. Two asters lie next to each other close to the nuclear envelope. Towards the end of prophase the asters pull apart and the spindle is formed. 

                                                                        

                                                    

                Metaphase:

                                                 Metaphase is the stage that follows prophase and preceeds anaphase, in which the chromosomes are aligned along the metaphase plate.  The genetic material is condensed into chromosomes. The chromosomes therefore become visible. The nuclear disappears and the chromosomes appear in the cytoplasm of the cell. As metaphase continues the cells break into two daughter cells.   

                                                                  

              Anaphase:
During anaphase two events occur. Anaphase begins when the duplicated centromeres of each pair of sister chromatids separate, and the now-daughter chromosomes begin moving toward opposite poles of the cell, due to the action of the spindle. The kinetochores begin to move towards the poles. Then the polar fibers elongate, which spreads the poles farther away from each other . Anaphase follows as the separated chromatids move toward opposite spindle poles. Wherever the centromere is located along the chromosome, a characteristic shape appears during chromosome movement. Then, at the end of anaphase a complete set of chromosomes is collected at each pole of the cell.

         Telophase:
                                           In the last stage of mitosis, which is telophase there are two separate groups of chromosomes at each pole.  A nuclear envelope begins to form around each set of chromosomes to form two nuclei. It is temporarily in one cell. When the envelope reassembles RNA synthesis that begins to break down the chromosomes. This causes the nucleolus to reappear. The chromosomes of daughter cells are basically grouped in new nuclei. There are many changes that occur in telophase. Some of the changes is that the polar fibers continue to lengthen, nuclei begins to form at opposite poles, and the nuclear envelopes of these nuclei are formed from pieces of the parent cell's nuclear envelope, and from pieces of the endomembrane system. Also, nucleoli also starts to reappear. After these changes, the genetic contents of one cell has been divided equally into two.
 
   By learning about the different types of stages in mitosis I now have a good understanding about how each stage works. I understand how to classify which cell is in what stage during mitosis.