Certain human populations have developed the ability to digest the nutrients found in milk throughout their life spans. As newborns, mammals rely solely on milk for their nutritional needs, and, thus, have the necessary enzymes to digest milk and its nutrients. However, all mammals, besides select populations of humans, lose the ability to digest the main carbohydrate in milk, lactose, after weaning (Ingram et. al, 2008). Lactase is the small intestinal enzyme responsible for breaking down lacrosse into the absorbable monosaccharides glucose and galactose. The presence or absence of lactase is a genetic polymorphism; individual are either lactase persistent or lactase nonpersistent. Individuals who are lactase nonpersistent do not absorb lactase in the intestines, so it travels to the colon, where it is metabolized by bacteria. This results in fermentation and excess gas, which causes abdominal symptoms such as bloating, cramps, nausea, diarrhea, and vomiting. On the other hand, those who display lactase persistence are able to breakdown lactase throughout the course of their lives. Lactase persistence started with the domestication of animals, which lead to dairying. Dairying and human adult milk consumption provided a selective pressure that lead certain human populations to evolve lactase persistence, allowing them to digest the beneficial nutrients of milk products throughout their lifetime.
Lactase Persistence Frequencies and Origin in Human Populations
It was thought for a long time that most humans had high lactase activities as adults, most likely due to that fact that early research was conducted in countries where lactase persistence was the norm (Swallow, 2003). However, lactase nonpersistence is actually more ...
... middle of paper ...
...ons have high frequencies of lactase persistence and low frequencies of the T-13910 allele. Two SNP have been lined to lactase persistence in Saudi population, T/C-3712 and T/G-13915 (Enattah et. al, 2008). Both have been show to increase transcription of lactase in vitro (Enattah et. al, 2008).
Conclusion
Lactase persistence in humans has been one of the most prominent examples of natural selection in humans. It is an example of convergent evolution, as the phenotype lactase persistence developed independently in different human populations. Although the single nucleotide polymorphism, -T 13910,is highly associated with lactase persistence in Europeans populations, there is more variants in SNPs that control lactase persistence in Middle Eastern and African populations. More research is needed to fully understand the evolution of lactase persistence worldwide.
We actually saw this change occur by watching the RER values increase. At the 2:30 mark Kerbi was using 100% fats as her fuel source with an RER of .75. One minute later, at an RER of .80 she was using 50% fat and 50% carbohydrates. In between minutes 6:30 with and RER of .99 and less than the 7:00 mark with an RER of 1.04 she was using primarily 100% carbohydrates as her fuel source. Lactate began accumulating in Kerbi’s blood at the 7:00 mark with an RER of 1.04, a speed of 3.4 and a grade of 14. I know this because her RER was above the 100% carbohydrate level of 1.00, and this is also the time at which she felt uncomfortable to the point that the test
Data table 1 Well plate Contents Glucose concentration A 3 drops 5% sucrose + 3 drops distilled water Negative B 3 drops milk+3 drops distilled water Negative C 3 drops 5% sucrose +3 drops lactase Negative D 3 drops milk +3 drops lactase 15+ E 3 drops 20% glucose +3 drops distilled water 110 ++ Questions B. In this exercise, five reactions were performed. Of those reactions, two were negative controls and one was a positive control.
One of the most primitive actions known is the consumption of lactose, (milk), from the mother after birth. Mammals have an innate predisposition towards this consumption, as it is their main source of energy. Most mammals lose the ability to digest lactose shortly after their birth. The ability to digest lactose is determined by the presence of an enzyme called lactase, which is found in the lining of the small intestine. An enzyme is a small molecule or group of molecules that act as a catalyst (catalyst being defined as a molecule that binds to the original reactant and lowers the amount of energy needed to break apart the original molecule to obtain energy) in breaking apart the lactose molecule. In mammals, the lactase enzyme is present
The affects of pH, temperature, and salt concentration on the enzyme lactase were all expected to have an effect on enzymatic activity, compared to an untreated 25oC control. The reactions incubated at 37oC were hypothesized to increase the enzymatic activity, because it is normal human body temperature. This hypothesis was supported by the results. The reaction incubated to 60oC was expected to decrease the enzymatic activity, because it is much higher than normal body temperature, however this hypothesis was not supported. When incubated to 0oC, the reaction rate was hypothesized to decrease, and according to the results the hypothesis was supported. Both in low and high pH, the reaction rate was hypothesized to decrease, which was also supported by the results. Lastly, the reaction rate was hypothesized to decrease in a higher salt concentration, which was also supported by the results.
Lactase is an enzyme found in the digestive system. It is essential to the complete digestion of sugar in whole milk and milk products. Lactase specifically breaks down lactose, a complex sugar. Lactase cannot be absorbed by the body unless it is broken down by lactase into glucose and galactose. According to webMD, “Lacking lactase in their intestines, a person consuming dairy products may experience the symptoms of lactose intolerance…Abdominal cramping, flatulence (gas) and diarrhea can occur when a lactose intolerant person consumes milk products.” ("Lactase Enzyme oral : Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD", n.d.) Lactase is not recommended for use in CHILDREN younger than 4 years of age. Safety and effectiveness in this age group have not been confirmed. (Kluwer, 2014)
2Gómez-Pérez L, Alfonso-Sánchez M.A., Sánchez D, García-Obregón S, Espinosa I, Martínez-Jarreta B, De Pancorbo M.M., Peña J.A. 2011. Alu Polymorphisms in the Waorani Tribe from the Ecuadorian Amazon Reflect the Effects of Isolation and Genetic Drift. American Journal of Human Biology Vol 23(6): pp 790-795
My research strives to answer the presence and degree of interbreeding between Neanderthal and Modern humans. Researchers use different comparisons of the fossil record, phylogenetic, morphological, and genetic methods to explore these questions in more detail. The literature provided many positive correlations to my hypothesis that Neandertals and Modern Humans interbred on a small-scale basis after the dispersal of modern humans from Africa. The literature also predicts a time frame of likely interbreeding. To explore this question it is important to research article’s explaining the statistical, genetic, and physical evidence associated with possible interbreeding.
-Reilly Philip. Is It In Your Genes. Cold Spring Harbor Laboratory Press. 2004: 223-228. Print
Pierron, D. Chang, I. Arachiche, A. et al. 2011. Mutation Rate Switch inside Eurasian Mitochondrial Haplogroups. Plos one 6(6): e21543.
Genetic Family History Assessment All nurses, no matter where they practice, need to have proper training in genomics and genetics to provide the best information to clients regarding recognition, prevention, and/or treatment of diseases (Thompson & Brooks, 2011). Genetic family history can help clients discover the unique patterns of health and illness within their family. In this paper, I will complete a Genetic/Genomic Nursing Assessment using the information found in Kaakinen, Coehlo, Steele, Tabacco, & Hanson’s text (2015) in Box 7-7 (p. 198). I will identify three generations of a family, analyze the genetic health risks, and consider nursing strategies for this family. The woman featured in my genetic assessment will be referred to as LG.
The Human Genome Project has brought to light the importance of single nucleotide polymorphism's (SNPs), which occur every 100 to 300 bases (1). A single nucleotide variation in the DNA sequence can have a major impact on how humans react to bacteria, viruses and drug therapy.
Is there any food on earth that can provide the PERFECT nutrition to a human? Yes, and it is breast milk. Breast milk is the perfect nutrition. This superior food contains hormones, live antibacterial and antiviral cells and essential fatty acids (What Makes Human Milk Special?, Mar-Apr 2006). All of which are helpful in protecting against any harm. Sicknesses in infants are lowered by the help that breast milk gives. Breastfed children are sick less often than children who aren’t breastfed (What Makes Human Milk Special?, Mar-Apr 2006). Breast milk contains all the nutrients that an infant needs as it continues to grow. When the child is brought into the world it has no way to fight off any d...
Belk. C., & Borden, V. (2009). Human biology. (pp. 96-99). San Francisco, CA: Benjamin Cummings.
This paper addresses a currently relevant topic of detection of associations of copy number polymorphism with traits and will be of interest to readers of Genetics Research.
U.S. Dept. of Energy. Understanding our Genetic Inheritance the U.S. Human Genome Project. "The first Five Years: Fiscal Years 1991-1995", Obtained from WWW 10/19/99:1/13/99: http://www.ornl.gov/hgmis/project/5yrplan/intro.html.