3.1/2 APPLIED LEC Flashcards
(17 cards)
do all humans have ability to digest lactose?
other than lactose intolerant individuals, all babies have high expression of lactase enzyme genes to process lactose into glucose and galactose as milk in there food source
how does lactose become fuel for our cells
ingested lactose travels to sm intestine, lactase enzymes are in apical surfaces of microvilli enterocyte cells and grab passing lactose, cleaving it into glucose and galactose. Glucose and galactose are taken up into the bloodstream through transport channels
How glucose and galactose provide energy
glucose enters glycolysis and cellular respiration processes produce atp
galactose needs to become glucose: 3 enzymes facilitate this process
galactokinase adds a phosphate to galactose, making it galactose-1-P
galactose uridyltransferase and UDP galactose epimerase take galactose-1-P and convert it into glucose-1-P which can enter atp cycle
is lactose a regulated or housekeeping gene
a regulated gene
how does diet influence gene expression
diets diversified from lactose=drop in lactase enzyme transcription
in humans, 65% of people experience a drop in transcription of the lactase enzyme
ancestor diets also influence gene expression of lactase enzyme as we age (if ancestors 1000s of years ago diversified from lactose, or were pasturizers or cattle farmers, etc)
what is weaning and why is it important to gene regulation
amount of lactase proteins produced decreases significantly as mammals are weaned off milk being their only food source
what happens in the population where lactase enzyme transcription doesn’t drop?
This 35% of the population has a mutation in the mcm6 regulatory gene that regulates level of lactase enzyme
what is lactase non-persistance
a decreased expression of the lactase enzyme resulting in a lower tolerance to digesting lactose. these individuals have some lactase and can digest varying levels of lactose with no discomfort
what is lactose intolerance?
inability to transcribe lactase enzyme gene and connot digest lactose (congenital lactase deficiency)
what causes the physiological symptoms associated with lactose intolerance?
lactose cannot be digested in small intestine, moves through to large instestine where bacteria can break down lactose, however produce gas as a side effect (gas, bloating, cramps)
additionally, the high concentration of lactose within the large intestine has an osmolarity effect of the water in other organs, as water is sucked into the cell (this attributes to diarrhea)
what mutations attribute to congenial lactase deficiency
mutations of the LCT gene coding for lactase including single amino acid mutations and polypeptides that are too short. These mutations cause lactase to improperly fold, having a different shape and inhibited function
what is galactosemia
genetic mutation in the code of enzymes that turn galactose into glucose-1-P
Type I: mutation in uridyltransferase coding gene
Type 2: mutation in galactokinase coding gene
Type 3: mutation in UDP gal epimerase
galactose levels accumulate in the body which is toxic
has same symptoms as lactose intolerance, except babies experience jaundice as well
treated by omitting galactose, nearly impossible
how lactose can be depleted in dairy products
many dairy products contain bacteria like lactobacillus that break lactose into galactose and glucose and produce lactic acid as a by-product, which can curdle substances (creating thick yogurt, cheese, etc)
Lactose intolerance dietary aids
lactaid: harness lactase from yeast and fungi in high concentration for tablets. Tablets reach small intestine in 35-40 minutes and can break lactose down. Glucose and galactose can enter blood stream through their respective channels as normal
lactase drops
help lactose intolerant people as they are put in milk and let sit to digest lactose in milk and make it lactose free
lactose free milk
milk containing lactose is filtered through biochambers with lactase enzyme coated beads wich grab onto lactose and break down 40 percent of lactose in milk. Lactase is then stirred into milk and by the time milk reaches shelf, all lactose is digested. The lactase enzymes will be killed in the stomach
