Genetics Compendium # 2

Let’s talk genes and not the kind that you wear!
DNA + chromosomes = Genes It is that simple! (see pic #7)
DNA is made up of a double stranded helix that are held together by hydrogen bonds. It looks like a spiral staircase. Each strand in the DNA contains all these tiny little molecules called nucleotides. These guys are made up of three even smaller molecules that are joined together by covalent bonds and they form what is called polynucleotide chains and they are held in place by the glue in cell life called hydrogen bonds. DNA has two special ingredients called purines and pyrimidines. In the DNA a coupling occurs when two complementary bases come together and that is called complementary base pairing. This action helps a great deal in the replication of DNA it makes sure that the right genetic information gets to the right place during cell division. During DNA replication the DNA untwirls itself and then lays flat so a template can be made for more DNA strands. Before a cell splits it has to make a two copies of itself that way it can divide into two identical cells. So in order for cells to duplicate themselves they have to wiggle loose the hydrogen bonds that are holding the double helix together with the complementary bases. So when the double helix strands pull apart it exposes the polynucleotide chains. So now they can make their own complementary nucleotides in the nucleus. With the help of an enzyme called DNA polymerase goes down the strand one nucleotide at a time and binds them together being careful to line them up perfectly with its complementary nucleotide. After all the matching and aligning is complete then the DNA synthesis is finished and each one of the DNA molecules has its own double helix. One with a new strand of DNA and the other with an old strand of DNA. When thinking about RNA just remember that there are three types of RNA that are involved in protein synthesis. First is ribosomal RNA (rRNA) , messenger RNA (mRNA) and transfer RNA (tRNA). Each one has an important job to perform during protein synthesis. What makes DNA different from RNA is that DNA has what is called a nucleotide called deoxyribose and RNA has a sugar ribose. The DNA is in the nucleus and the RNA is primarly in the cytoplasm. The messenger RNA is just that a messenger to the nucleus to take genetic information that is needed to make proteins. The transfer RNA is what binds specific amino acids and takes them to the messenger and puts them in the right location on the messenger and ribosomal RNA is just the component of the ribosome. RNA synthesis takes place on the DNA template in the nuclei of the cells. When the work is being done on the template of the DNA that is called transcription. This happens when the cell is going through the interphase cycle. When the DNA untwirls itself and comes apart this creates a template by which the RNA can be made. During RNA synthesis an enzyme called polymerase helps in aligning nucleotides and catalyzing the formation of the covalent bonds coming together to form a polynucleotide chain. This is when the RNA is complete. Then the DNA lets go of the RNA and seals the double helix back together. Then the RNA leaves the nucleus. The only difference between RNA and DNA protein synthesis is the adenine pairs with uracil on the DNA template.
Genetic expression controlled at four different levels. One to control chromosome level, two to control transcription, three to control after translation but before translation takes place and lastly to control translation. By controlling at the chromosomal level that means happens by coiling and uncoiling of chromatin. By controlling transcription that is done by repression induction enhancement. After transcription but before translation when this is happening there is a removal of introns and rearrangement of exons and lastly by controlling translation it means RNA is being masked. In translation mRNA is transferred to the cytoplasm and it hoards them and then spills them out during protein synthesis.

Chromosome>>to>>Gene>>during transcription>>mRNA>>during translation>>to>>Protein

During mitosis at the prophase stage the chromosomes condense and the nuclear envelop vanishes. The centrioles begin to divide and move to the opposite poles of the dividing cells. The spindle forms then start to form and attach to chromosomes. The next stage of cell cycle is the metaphase. During this phase the chromosomes line up at the equatorial plate of the dividing cell. The next phase is where the chromosomes begin to separate. The telephase takes place when the chromosomes being to move or pulled to the opposite poles. At this point a new nuclear envelope forms and the chromosomes uncoil. Then in the last bit of mitosis it is called cytokinesis. During this phase a cleavage furrow forms and deepens and the cytoplasm divides. That is nuclear division in a nut shell. (See pic # 8)
When mentioning genetic engineering and biotechnology start thinking about cloning. This is the ability to replicate an existing or extinct organism. Jurassic Park is not too far from the truth. An positive example of this being done was with the sheep Dolly. In recombinant DNA technology geneticists take away and move parts of the DNA from an organism and use an enzyme called restriction endonuclease. Then after the moving of the DNA another enzyme kicks into high gear called DNA ligase. This enzyme is used to seal it in place and that is what it takes to form an recombinant DNA molecule. This then contains DNA from two different organisms. In bacteria there are tiny circular strands of DNA called plasmids. Genes that are from another source considered to be foreign can be spliced into plasmids and then the plasmids carry the foreign gene can be put back into bacteria in the culture. When cells divide, the plasmids copy themselves and make many copies of genes and then they are cloned. Cloning produces many copies of foreign genes which can be helpful to genetic study especially with hormones. In reverse transcriptase geneticists can make many copies of DNA by taking mRNA from the cells making it into DNA. Gene multiplication can be done in many ways but the most popular way to do it by polymerase chain reaction. This happens when the DNA double helix is heated and then cools off. The enzymes are added to catalyze the formation of complementary DNA molecules. There are many ways that recombinant DNA has been used. The most important uses of recombinant DNA, in my opinion is in the making of vaccines. But by putting this technique many things can be mass produced like hormones and other proteins that can be used to treat a variety of disorders. One example of this at work is with mass producing from bacteria to aid crop growth or to cure diseases. Gene splicing is another use of recombinant technology and it is used to move genes from one organism to another making transgenetic organisms. They don’t look much different maybe just a bit bigger. This is being done in the plants arena. This helps in producing larger plants that produce more nutritious foods that are resistant to pesky pests and herbicides. In gene therapy, this type of technology could be used to even cure genetic diseases or abnormalities by inserting normal healthy human genes. Another way of using this type of technology are with DNA probes. DNA probes are small segments of genes that bind to same base pairs of small samples of DNA. Like those taken from various crimes scenes.
Human genome mapping is extremely important in to the future of science. This is the mapping and recording of chromosomes that is done to help in aid of finding out which genetic material is on what chromosome.
Cancer is a serious disease not to be taken likely. It is frightening to think that one out of every three people will contract the disease and one out of every four will die from it. It is a proven fact that 20% to 40% of cancers are contracted by pollutants at work or in the environment and the remaining 60% to 80% of cancers are contracted by smoking, diet, or natural causes. Cancer is a disease in which the cells uncontrollably multiply and divide often moving into other parts of the body. Malignant tumors are tumors that continue to grow and spread throughout the body and destroy organs. The spread of cells from one place to another from one organ to another is called metastasis. One group of mutations called the proto-oncogenes and that controls the functions related to cell replication. The other group of mutations is the tumor suppressor genes. These inhibit the growth of cells. Precancerous cells are those that are released partially from normal growth controls and many times they stay dormant or a long time. There are chemicals that are released by tissues to aid in this suppression they are called tissue factors.
There are many cancer treatments that re available to people. Some tumors can be removed through surgery and then be treated with chemotherapy and radiation treatments. But a lot of times it is dependent on where it tumor is located and whether or not the secondary tumors were found and removed. Secondary tumors are tumors that are found in different areas of the body sometimes in the lymph nodes or other places that might be difficult to find or surgically remove. There are many new treatments for cancer. Anticancer vaccines are given to people to in an effort help the body build antibodies and T cells to help attack tumors and eliminate existing tumors. Microspheres is another type of treatment it is where they take liposomes that contain cancer-killing chemicals or antibodies that are attached to chemotherapy and are used to attack the cancer at its source. It is like a dart throwing approach to hitting the bulls eye. Another type of treatment that is promising is attacking cancer by reducing the blood vessel development in the tumors which in turn stop the growth of the cancer. The formation of new blood vessels is called angiogenesis. These new blood vessels carry nutrients and growth factors necessary for the tumor to grow. Another way to help kill cancer cells is by blocking genes involved in cell respiration. Oncogenes are a mutated version of genes that regulate cell growth. Lastly treating cancer by light or lasers with a combination of drugs seems to be an effective treatment with come kinds of cancers. The most obvious way to help in treating cancer is by being checked by a doctor at the first signs or inclination that you might be thinking that there may be something wrong. Survival is highly likely outcome the earlier the treatments can begin. (see pic #9)
When talking about human reproduction there are two important components that are necessary in order to reproduce. The first one I am going to go over is the male reproduction system. (see pic #10)
The testes consists of two gonads. The testes are hanging from what is called the scrotum which a sack of skin that is attached to the body that helps maintain the right temperature of the testes. The testes produce sperm and male sex steroids. The epididymes is where the sperm is held until ejaculation. Ejaculation is a reflex control that is stimulated by neurons in the spinal cord. The vas deferntia move the sperm through the urethra. The sex accessory glands produce seminal fluid that nourish the sperm. The urethra is used to excrete the wastes and sperm to the outside of the body. The penis is an organ that is used for copulation. It contains erectile tissue and during intercourse or sexual arousal it fills with blood that makes it rigid. The most of the fluids that make up semen is produced by the accessory glands. Sperm is formed in seminiferous tubulos. Interstitial cells produce male sex steroids and primary testosterone. They also produce male hormones and can be found in spaces lying between the seminiferous tubules. Interstitial cells are large clumps of cells found in these tubules and they produce sex steroid hormones called androgens. The most important one in male reproduction is called testosterone. Testosterone stimulates sperm formation and it is also flowing through the bloodstream that can stimulate cellular growth in bones and muscles. It also is what stimulates facial hair growth, as well as body hair, and voice changing among men.
The female reproductive system is made up of two key features the reproductive tract and the external genitalia. (see pic # 11) The reproductive tract consists of 4 parts. The uterus which is used for the cradling of embryos or a fetus. There are also two uterine tubes or oviducts which transport sperm to the ova and then transport the fertilized ova to the uterus. The two ovaries produce ova or female gamete during ovulation and female sex steroids. The vagina is the primary place for sperm drop off and it is also called the birth canal. The external genitalia is made of two flaps of skin on each side of the vaginal opening that is referred to as the labia. The labia majora are the larger folds outside of the vaginal opening and the labia minora are the inner flaps right by the vaginal opening. Where the two flaps meet is called the clitoris. This is a very sensitive organ that when sexual arousal takes place it can become aroused and filled with blood. Almost like a miniature penis. Each month a woman after puberty with have what is called a menstrual cycle which is a series of changes in the ovaries, hormone levels, uterus, and endocrine system. This cycle on the average is about 28 days but it varies from woman to woman. The first half of the menstrual cycle is called the follicular phase and during this time the body starts to produce follicle growth and estrogen production. As the estrogen levels rise this causes the body to ovulate. The oocyte is expelled out and the follicle collapses into a corpus luteum (CL) and produces more estrogen and progesterone. (see pic # 12) If fertilization takes place then the CL breaks down but if the fertilization does happen then the embryo will stay there for about 6 months. During the menstrual cycle the uterine wall thickens preparing itself for a embryo and if that does not happen then the walls slough off the lining which is what is known as menstruation. Estrogen is like testosterone as it promotes the growth of genitalia, body hair growth, fat pockets in the areas of the breasts, hips and butt. Thanks. Some women have a problem with premenstrual syndrome or otherwise known as PMS. Later on in life women between the ages of 45 and 55 will stop ovulating, producing so much progesterone, and menstruating this is called menopause. Some of the symptoms of menopause occur because of the breakdown and lack of estrogen in the body. Some things that women might experience during this time are night sweats, irritability, depression, and hot flashes. Sounds like tons of fun to me! Sign me up!
There are many types of birth control that are available to people for both men and women. Basically it is any method that prevents the ability for the body to reproduce. There are two categories and they are contraception, and induced abortion. Of course there is the oldie but goodie which is abstinence that is a sure fire way to stay safe. There is surgical sterilization which is done by a tubule ligation which is where they cut the tubes that transport the ova which is on women only and then there is the vasectomy which is for the men and that is the cutting of the vas deferens. Women can also get matchstick size capsules implanted under the skin and they release a steady stream of progesterone that blocks the ovulation for months. Next is the birth control pills these pills tricks the body into thinking that it is pregnant. The least effective way of preventing pregnancy is by using the withdraw method which is removing the penis just before ejaculation. Lastly, there is the barrier birth control options for men and women which are the diaphragm, the condom, and the vaginal sponge. Of course abortion is an option for those who may become pregnant and not want to continue on with the pregnancy. This is a surgical termination of the pregnancy. There is also a pill that can be taken called the “morning after pill” and this pill prevents implantation.
Infertility is the inability to get pregnant. Lots of things can contribute to this problem. It could be a lack of sex, low sperm count, or the obstruction of the uterine tubes.
So from genetics to reproduction without the microscope and countless hours that scientists, doctors, and geneticists have spend pondering over the human body known of the information would be available today. With each day that passes the medical field is becoming more and more knowledgable about the diseases of the past, the flus of the future, the cures of tomorrow, and babies of yeaterday. Maybe with enough hard work and diligence maybe just maybe a push for a cure for some of the most heartbreaking of diseases can be found. Here is to tomorrows yesterday, and yesterdays future.