Examples of lactose in the following topics:
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- Lactose intolerance is the inability to digest lactose, a sugar found in milk, due to a lack of the enzyme lactase.
- Lactose intolerant individuals have insufficient levels of lactase, the enzyme that metabolizes lactose into glucose and galactose, in their digestive system .
- However, those living among societies that are largely lactose-tolerant may find lactose intolerance troublesome.
- About 44% of lactose intolerant women regain the ability to digest lactose during pregnancy.
- Individuals who suffer from lactose intolerance have insufficient levels of lactase to break down the lactose in milk and dairy products.
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- The lac operon is an inducible operon that utilizes lactose as an energy source and is activated when glucose is low and lactose is present.
- One such sugar source is lactose.
- Only lacZ and lacY appear to be necessary for lactose catabolism.
- Second, lactose must be present.
- The cell can use lactose as an energy source by producing the enzyme b-galactosidase to digest that lactose into glucose and galactose.
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- Although the sugar and lactose metabolizes to galactose, galactosemia is not related to and should not be confused with lactose intolerance.
- Lactose in food (such as dairy products) is broken down by the enzyme lactase into glucose and galactose.
- The only treatment for classic galactosemia is eliminating lactose and galactose from the diet.
- Infants with classic galactosemia cannot be breast-fed due to lactose in human breast milk and are usually fed a soy-based formula.
- Galactosemia is sometimes confused with lactose intolerance, but galactosemia is a more serious condition.
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- Traditionally, MacConkey agar has been used to distinguish those bacteria that ferment lactose from those that do not.
- Gut bacteria, such as Escherichia coli, can typically ferment lactose; important gut pathogens including Salmonella enterica and most shigellas are unable to ferment lactose.
- Shigella sonnei can ferment lactose, but only after prolonged incubation; it is referred to as a late-lactose fermenter.
- Those bacteria unable to ferment lactose, often referred to as nonlactose fermenters (NLFs) metabolize the peptone in the medium.
- In sorbitol MacConkey agar, lactose is replaced by sorbitol.
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- Lactose, also known as milk sugar, is a galactose-glucose compound joined as a beta-glycoside.
- Many adults, particularly those from regions where milk is not a dietary staple, have a metabolic intolerance for lactose.
- Infants have a digestive enzyme which cleaves the beta-glycoside bond in lactose, but production of this enzyme stops with weaning.
- Cheese is less subject to the lactose intolerance problem, since most of the lactose is removed with the whey.
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- This type of process can be seen in the lac operon which is turned on in the presence of lactose and absence of glucose.
- This opens up the DNA molecule, allowing RNA polymerase to bind and transcribe the genes involved in lactose catabolism.
- As cAMP-CAP is required for transcription of the lac operon, this requirement reflects the greater simplicity with which glucose may be metabolized in comparison to lactose.
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- Lactase is an enzyme that breaks down the disaccharide lactose into its component parts, glucose and galactose, which can also be absorbed by the small intestine.
- This condition is commonly known as lactose intolerance.
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- Researchers then discovered that lactose malabsorption is actually the norm for most populations in the world.
- Lactase deficiency, which prevents the breakdown of lactose, is a common cause of malabsorption.
- For example, patients may be put on a gluten-free diet for celiac disease or taught lactose avoidance for lactose intolerance.
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- For instance, prior to about 4000 BCE, most humans did not produce a protein that allowed them to digest lactose after being weaned.
- After Europeans began to drink the milk of domesticated animals, the genetic adaptation favoring lactose consumptions spread rapidly throughout the continent.
- This is an example in which cultural shifts (the domestication of animals) can lead to changes in behavior that affect biology (genetic adaptation to process lactose).
- People began domesticating cattle many years before they developed the genes for lactose tolerance.
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- Streptococcuseosin methylene blue (EMB), which is differential for lactose and sucrose fermentation.
- MacConkey (MCK), which is differential for lactose fermentationmannitol salt agar (MSA), which is differential for mannitol fermentation.