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BIOLOGY 1A03 > T3A1 > Flashcards

T3A1 Flashcards

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1
Q

Lactose

A

a sugar that is common in milk and dairy products, can serve as a primary energy source

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2
Q

Lactase role

A

B-galactosidase hydrolyzes lactose to the monosaccharides glucose and galactose

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3
Q

Lactase present on

A

apical surface of absorptive intestinal enterocyte cells

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4
Q

Galactose gets converted into

A

glucose 6 phosphate

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5
Q

Galactokinase

A

enzyme that adds phosphate group to proteins

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6
Q

Gal-1-P Uridyltransferase and UDP-Gal Epimerase are

A

Galactose to glucose enzymes

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7
Q

Weaning

A
  • adult mammals other than humans lactase production decreases significantly (environmental factors)
  • 65% humans have reduced ability to digest lactose after weaning
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8
Q

Mutations that keep lactase gene permanently on common in

A

individuals whose ancestors has access to domesticated dairy animals
- 7500-9000 years ago in middle east and north africa, then brought to europe

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9
Q

Lactase mutations arose in what gene?

A

MCM6 (enhances lactase gene transcription through lifetime)

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10
Q

90% lactase gene expression through whole life populations

A

Swedes, Danes, pastoralist African

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11
Q

50% lactase gene expression through whole life populations

A

Spanish, French, Pastoralist Arab

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12
Q

Low in lactase gene expression through whole life populations

A

non-pastoralist Asian and African

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13
Q

Lactose intolerance

A

individuals born without the ability to express lactase gene that codes for lactase protein - congenital lactose deficiency

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14
Q

Lactose intolerance results

A

excessive lactose in intestine attracts water molecules, which prevents water from being properly absorbed into bloodstream. Bacteria ferments > bloating, diarrhea, dehydration

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15
Q

LCT gene on chromosome 2 codes for lactase enzyme > mutations in coding region

A

changes that alter single amino acids or lead to polypeptides that are too short

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16
Q

Galactosemia

A

galactose in the blood, individuals born without enzymes needed for galactose processing

17
Q

Galactosemia type I gene

A

GALT gene (Galactose-1-phosphate uridylyltransferase)

18
Q

Galactosemia type II gene

A

GALK1 gene (Galactokinase)

19
Q

Galactosemia type III gene

A

UDP-Gal Epimerase

20
Q

Galactosemia mutations in what genes?

A

GALT, GALE, GALK1 and genes on chromosome 9. Alter single amino acids or polypeptides too short

21
Q

Galactosemia effects

A

toxic accumulation of galactose. Cataracts, kidneys, liver affected

22
Q

Galactosemia clinical landmark

A

jaundice

23
Q

Lactose intolerance treatment

A
  • omitting lactose
  • pretreating milk with purified lactase
24
Q

Galactosemia treatment

A

omitting galactose consumption

25
Q

Who pioneered the original modern hypothesis of the positive role of certain bacteria

A

Elie Metchnikoff

26
Q

Elie Metchnikoff observed

A

populations in rural Europe that lived on fermented milk exceptionally long lived

27
Q

Milk fermented with lactic acid producing bacteria inhibits

A

growth of proteolytic bacteria due to low pH produced by fermentation of lactose

28
Q

Lactic acid producing bacteria

A

Lactobacillus
Lactococcus
Bfidobacteria

29
Q

What does lactic acid producing bacteria do?

A

ferment carbs in milk (lactose>glucose and galactose)

30
Q

Microbial B-galactosidase in yogurt is present

A

in active forms in duodenum

31
Q

B-galactosidase enhances

A

lactose metabolism in lactase deficient individuals

32
Q

Low pH environments reduce

A

enzyme activity (irreversible denaturing)

33
Q

How does enzyme retain function in duodenum after passing through stomach?

A

protection by bacterial cell membrane
buffering capacity of yogurt

34
Q

pH of stomach while yogurt passing through

A

4

35
Q

Can lactase enzyme supplement help people experiment

A

after 4 people were given treatments to modify intestine bacterial contents (yogurt, capsules, mix of bacterial strains), measured feces, bifidobacteria has made it through.

36
Q

Can lactase enzyme supplement help people results

A

supplementation with probiotics modified amount of bacteria and increased bgalac in feces of lactose intolerant subjects. probiotic cannot stimulate endogenous intestinal lactase enzyme activity in small intestine

BIOLOGY 1A03 (24 decks)

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