Compendium # 2- Genetics

Topics

1. Mitosis-cell division

2. DNA/chromosomes

3. DNA Technology

4. Cancer

5. Roles of Genes

Once again our internal lives are constantly changing, reproducing and full of detailed processes. During this section, I have found DNA to be quite interesting. It seems as though DNA is similar to a green light, if it's green, cells are going to keep going through their required processes to full fill the duties. DNA is very useful source of information. It helps detect diseases, helps to improve the agriculture, research family inheritance, and used to investigate criminals. There are so many interesting concepts in the Genetic section, I will discuss the main topics mentioned above.

Each little cell in our body goes through, MITOSIS, the process of nuclei division. More important it is an identical process that copies the genetic information. During the process of division, two identical daughter cells are formed, having the same number and type of chromosomes. During the duplication stage, the two exact chromosomes, are known as sister chromatids. (which are connected by a centromere(a little ball connecting the two)) After they split from the centromere, the sister chromatids become chromosomes(diploid). These chromosomes are distributed equally and are eventually genetically identical. Mitosis is a constant function within the body. There are four stages that are important in Mitosis. Prophase is when the chromosomes are noticeable: like worms bunched together. Centromeres have duplicated and are awake pushing their bodies towards different ends of the cell(poles). They develop spindle fibers(resemble little tails) to help move the chromosomes(worms) throughout the nucleus. During metaphase, the chromosomes are lined up (like little soldiers) at the center of the cell where the spindle fibers have attached to the sister chromatids at each end of the cell. Anaphase: The centromere of each sister chromatid snaps apart, moving them to opposite sides of the pole (spindle fiber). The split becomes daughter chromosomes. During this process of mitosis, genetic division occurs! Telophase: the worms (chromosomes) wiggle back toward the poles. This creates two identical daughter nuclei, since the worms and their tails eventually resemble that of a cell. There are a few basic reasons why cells constantly divide. 1. Growth, which is an on going process 2. Replacement: blood, sperm, skin get worn out, and eventually can no longer function 3. Repair: when you fall and skin your knee, the tissues need rebuilding/repairments to function to its fullest.

DNA/CHROMOSOMES: DNA is the heart of the nucleus, which is mainly found inside of the chromosomes. The structure of a DNA is easily described as a ladder. The "double helix" often talked about is two strands that inter twine each other. The sides of the ladder are made up of the nucleotides: phosphate(phosphoric acid) and sugar(deoxyribose). The steps of the ladder (paired bases) are made up of hydrogen bonds: Adenine(A)-Thymine(T) and Guanine(G)-Cytosine(C). During cell division, each new cell receives an exact replica of the genetic DNA. A good comparison I read through researching was picture the DNA replication as unzipping. Imagine unzipping a jacket, as the zipper moves down, the pieces stay in their original places(the original DNA strand). Then, during re-zipping, the zipper brings a new piece, intertwining it with the original strand. "DNA provides the cell with a blueprint for synthesizing proteins (Mader 447). The mRNA is like a letter carrier, it carries the blueprint information into the cytoplasm. These proteins help figure out what type of function and form the cell will have. There are two processes: transcription and translation. Transcription is "a segment of the DNA serves as a template for the production of an RNA molecule" (Mader 449). The book also describes it as, "mRNA is a faithful copy of the sequence of bases in DNA" (449). Translation described in the book as, "putting information into a different language" (448). It deals with the base as an amino acid. These two forms are explained well in the book.

DNA TECHNOLOGY. DNA was first discovered by a scientist by the name of, Friedrich Miescher, in the year 1869. He came across DNA under a microscope while looking at old/used surgical bandages (Wikimedia). This world is becoming a world full of wonder! What could possibly happen next, with all the technology that researchers, scientists, doctors, and all individuals have available to them. The book begins this section with cloning. Recombinant DNA, "contains DNA from two or more different sources, allows genes to be clone" (Mader 458). Plasmids are typically used in this process, they are found in bacteria and are little circles of DNA. To the right is an example of the Recombinant DNA. The fish are class of zebra fish, which were injected with a fluorescent protein into their genome. The array of fluorescent colors capture this scene! (Wikimedia). Another interesting form used is genetic engineering which is when, "bacteria can be selected for their ability to degrade a particular substance" (Mader 460). Both of the technologies mentioned above typically occur outside of the organisms reproductive process. The purpose is to reintroduce the DNA into the cells/organism with a different characteristic. Or it may try to enhance the previous attribute. These experiments are not always proven to work, complications arise.

CANCER. Cancer is a wide spread disease: there are many different forms, developments, cures, preventions, and characteristics. The book begins this section by describing a cancer cell versus a normal cell. 1. Abnormal Nuclei. Which tend to be enlarged, with abnormal amounts of chromosomes. 2. Unlimited Cell Replication. Cancerous cells continue dividing. 3. Tumors form. When normal cells stop dividing when they come across another cell, cancerous cells don't recognize a neighboring cell. It's like a domino effect, they pile up on each other, forming a wall(tumor). 4. Cancer cells are unable to recognize signals to stop dividing. Carcinoma is a cancer that affects the epithelial cells, such as, skin, breast(shown to the right), lung, prostate, and pancreas. Sarcomas are found in the muscles/connective tissue, such as, bone. Leukemia is cancer of the blood, such as, lymphatic tissue. Causes of cancer can be passed on from genetics and environmental factors. There are many resources are available and screenings used to test for cancer. With the technology available some cancers are treatable, but are not guaranteed to be completely cured.

ROLES OF GENES. The two important concepts in genetics is genotype(genes/inherited characteristic) and phenotype (physical appearance). Allele is the same characteristic on a pair of chromosomes, affecting the same trait. It is usually described using a letter. Dominant allele is a capital letter, and recessive allele is lower case letter. If you see a set of twins that are identical, you assume all their physical (phenotype) features are exactly alike, but they are actually different. The genotypes are actually the same. Family are more capable of distinguishing the two apart. There are many traits that are inherited and used as an example of the above roles, but the lab on this section describes these roles in detail with examples. Punnet square, mono hybrid crosses, traits, dihybrid crosses are examples that are used to figure out dominant genes. Many genetic disorders are genetically dominant genes.

Works Cited:

Love, Jaime Dr. Principles of Genetics. www.synapses.co.uk/genetics/gintro.html. 12 June 2007. (pictures)- DNA

Mader, Sylvia S. Human Biology. Boston: McGrawHill Companies, Inc. 2008

(quotes)

http://en.wikipedia.org/wiki/DNA and genetic engineering.

pictures- fish- cancer picture

www.2.dpi.qld.gov.au/beef/3128.html.

picture- mitosis

black/white flower- my picture