Stem cells are cells that divide by mitosis to form either two stem cells, thus increasing the size of the stem cell & 34;pool& 34;, or one daughter that goes on to differentiate, and one daughter that retains its stem-cell properties. How the choice is made is still unknown. However, several genes have been found whose activity prevents a daughter cell from differentiating.
Reorganization of Atoms That Form Different Substances A chemical reaction is a chemical change where matter (a reagent or reagents) becomes a new substance or substances (a product or products). Some reactions occur only under certain circumstances (eg heat supply, light or electricity).
Malaria or malaria, among other designations, is an acute or chronic infectious disease caused by parasitic protozoa of the genus Plasmodium, transmitted by the bite of the Anopheles mosquito. Malaria kills 3 million people a year, a rate comparable only to AIDS, and affects more than 500 million people every year.
These are diseases caused by viruses that attack a person's liver. Hepatitis B viruses are transmitted through sexual intercourse, transfusions with contaminated blood and from mother to child through the placenta. Symptoms of hepatitis B include jaundice, fever, headaches, nausea, vomiting and muscle aches.
Abstinence Avoid intercourse with penetration. Tabular Method (or calendar) It is a natural method that does not employ any material or medicine. It consists in not having sex in the fertile period, that is, in the period closest to ovulation. Therefore, it can only work for women who have a very regular menstrual cycle.
Biotechnology is the study and development of genetically modified organisms and their use for productive purposes. That is, technology based on biology, being used mainly in agriculture, food science and medicine. The following are some topics on subjects in this area.
It is an infectious disease caused by the bacteria Treponema pallidum. It manifests in three stages: primary, secondary and tertiary. The first two stages present the most striking characteristics of the infection, when the main symptoms are observed and when this STD is more transmissible. Then it disappears over a long period: the person feels nothing and has an apparent cure for the initial injuries, even in untreated individuals.
It is a disease that appears and disappears on its own from time to time, depending on factors such as stress, tiredness, overexertion, fever, sun exposure, trauma and menstruation. In women, herpes can also be localized to the internal parts of the body. Once infected with the Herpes Simplex virus, the person will remain with the virus in their body forever.
The causative agent of this STD is Chlamydia trachomatis, and its incubation period can be from 7 to 30 days. Signs and Symptoms Venereal lymphogranuloma is characterized by the appearance of a short-term genital lesion (three to five days) that presents as a wound or as a skin elevation.
IUDs are polyethylene artifacts, to which copper or hormones may be added, which are inserted into the uterine cavity exerting their contraceptive function. They act by preventing fertilization, making it difficult for sperm to pass through the female reproductive tract. The most common problems during IUD use are expulsion of the device, pelvic pain, dysmenorrhea (irregular bleeding in the early months) and increased risk of infection (acute infection without improvement or persistent infections imply removal of the IUD).
The vaginal ring containing etonogestrel and ethinyl estradiol is placed in the vagina on the 5th day of menstruation, remaining in this position for three weeks. The biggest advantage is that women will not have to take the pill every day nor will they forget. Another advantage is that hormones will be absorbed directly into the circulation, avoiding some unpleasant side effects of the oral pill.
Emergency contraception is an alternative use of oral hormonal contraception (taken before 72 hours after intercourse), avoiding pregnancy after unprotected sex. This method should only be used in emergency cases, ie when other contraceptive methods have not been adopted or have failed in any way, such as forgetfulness, condom breakage, diaphragm dislocation, table or coital failure. discontinued, forgetting to take the pill for two or more days in a cycle or in case of rape.
Earth's organisms do not live in isolation, interact with each other and the environment. By studying these interactions we call Ecology. The word ecology comes from two Greek words: Oikós which means house, and logos which means study. Ecology literally means Habitat Science.
The rainforest is situated in the intertropical region. The largest area is the Amazon, the second in the East Indies and the smallest in the Congo Basin (Africa). The energy supply is abundant and rainfall is regular and abundant, exceeding 3,000 mm per year. The main feature of the rainforest is its stratification.
It is a biome that is characterized by presenting a single stratum of vegetation. The number of species is very large, but represented by small number of individuals of each species. The location of the fields is very varied: Midwest United States, Mideast Eurasia, part of South America (Brazil, Argentina) and Australia.
Savannah is a name given to a type of vegetation cover usually consisting of grasses and sparse trees. The topography is generally flat with tropical climate, presenting two well defined seasons, one rainy and one dry. Savannas occur mainly in the intertropical zone of the planet, so it receives a huge amount of sunlight.
Plants require a number of elements other than those they obtain directly from the atmosphere (carbon and oxygen in the form of carbon dioxide) and from groundwater (hydrogen and oxygen). All but one of these elements comes from the disintegration of rocks and is captured by plants from the ground.
They occur between organisms of different species. They include protocooperation, mutualism, commensalism and teninism. It is an association in which one species - the diner - benefits, without causing benefit or harm to the other. The term diner has a more literal interpretation: "diner is one who eats at another's table."
The oxygen cycle is closely linked with the carbon cycle, since the flow of both is associated with the same phenomena: photosynthesis and respiration. Photosynthesis processes release oxygen into the atmosphere, while breathing and combustion processes consume it. Part of the stratosphere's O2 is transformed by the action of ultraviolet rays on ozone (O 3).
It is the set of all physical factors that can affect the communities of a certain region. These influence the growth, activity and characteristics that beings have, as well as their distribution in different places. These factors vary from location to location, determining a wide range of environments.