After duplication the cell is ready to begin mitosis. More, cells undergo prophase, Prophase is the first phase of mitosis. The DNA and proteins start to condense. The two centrioles move toward the opposite end of the cell as the chromosomes become visible. The nuclear envelope and nucleolus also start to break up.
You will not see it in this phase. The nuclear envelope is not destroyed but is re-used in telophase. -the breakdown of the nuclear envelope allows the microtubules from the mitotic spindle to access the chromosomes. -microtubules attach to kinetochore proteins. Kinetochores are the protein area of the centromere on each sister chromatid.
4 – Dismantles debris B. 6 – Protein synthesis C. 2 – Houses DNA D. 1 – Lipid synthesis E. 7 – Processes secretions F. 3 – Energy extraction G. 5 – Detoxification 2) Explain the functions of the following proteins: A. Tubulin and Actin – Tubulin forms microtubules, while actin forms microfilaments. B. Caspases – Caspases are responsible for apoptosis. C. Cyclins and kinases – The interaction of cyclins and kinases trigger mitosis from the inside. D. Checkpoint proteins – Checkpoint proteins are responsible for regulating the cell cycle.
Crossing over contributes to the genetic variation of sexual reproduction. While all this is occurring, the nuclear envelope and nucleoli begin to disappear. Spindle fibers attach to the chromosomes and begin moving them to the equatorial plate. Metaphase I: Homologous chromosomes, in a pair-wise fashion, have lined up
Transgenesis and Cloning Transgenesis is the process of inserting a gene from one source into a living organism that would not normally contain the inserted gene. The gene can come from the same species (called Cisgenesis) or from a different species entirely. To facilitate the transfer of genes from one organism to another, often a Transgenic Organism with Recombinant DNA is created: -The first step in creating an organism capable of carrying out the transformation process is to isolate the required gene. This is done so using Restriction Enzymes, which target a specific gene sequence. The gene is often cut with staggered ends, called “Sticky Ends” which only allow specific and complementary gene sequences bond by base pairing.
Each genome contains the information needed to maintain and create the organism. The process of genetic engineering involves extracting of a small piece of cellular DNA, called a plasmid, from the bacteria if organism involved in the manipulation. A very small section of the circular plasmid is then cut out by the restriction enzymes which act as molecular scissors. The gene from the organism being modified is then inserted into this space and the plasmid is therefore modified. The genetically modified plasmid is now inserted and introduces into a new organism which starts divides rapidly.
B cell enters the germinal center and undergoes rapid division. Introduces mutations around VDJ gene. Each B cell expresses slightly diff antibody, one with greatest affinity will bind to antigen on dendritic cell. The rest will die via apoptosis. Interaction with T cell causes class switching of IgM on naïve B cell.
The enzyme used in this step is unique to the mitochondria and therefore can be used as a marker for the presence of mitochondrial contamination in a sample of cell fraction. We can use cellular fractionation to separate the cellular components and test them for the presence of certain enzymes or chemicals (Hames). Cellular fractionation involves two steps. Firsty, we must lyse the cells from a homogenous cell population to obtain a homogenate of subcellular components. Since different cellular components vary in size and weight, we can centrifuge them at different speeds and durations to obtain pellets containing these cell fractions (Ardell).
B lymphocytes perform the role of antigen presenting cells (APC’s) and eventually develop into memory B cells after activation by antigen interaction. T helper cells activate the b cells to form a large clone of plasma cells, b effector cells that produce antibodies. In humans, immature b cells are formed in bone marrow before birth. After reaching the immature stage in the bone marrow they migrate to the spleen, where they are called transitional b cells. Some of these cells terminally differentiate into mature b lymphocytes.
Growth 2 (G2) G2, in which the cell ensures that its chromosomes and organelles are ready for mitosis. The proteins necessary for cell division are also made. For example, the proteins needed for the microtubules to form the spindle fibres. Duration is variable and depends on the function of the cell. Some human cells divide every 24 hours; in this case interphase takes about 22 hours and mitosis the remaining 2.