T3A1

Question 1

Lactose

Answer 1

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

Question 2

Lactase role

Answer 2

B-galactosidase hydrolyzes lactose to the monosaccharides glucose and galactose

Question 3

Lactase present on

Answer 3

apical surface of absorptive intestinal enterocyte cells

Question 4

Galactose gets converted into

Answer 4

glucose 6 phosphate

Question 5

Galactokinase

Answer 5

enzyme that adds phosphate group to proteins

Question 6

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

Answer 6

Galactose to glucose enzymes

Question 7

Weaning

Answer 7

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

Question 8

Mutations that keep lactase gene permanently on common in

Answer 8

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

Question 9

Lactase mutations arose in what gene?

Answer 9

MCM6 (enhances lactase gene transcription through lifetime)

Question 10

90% lactase gene expression through whole life populations

Answer 10

Swedes, Danes, pastoralist African

Question 11

50% lactase gene expression through whole life populations

Answer 11

Spanish, French, Pastoralist Arab

Question 12

Low in lactase gene expression through whole life populations

Answer 12

non-pastoralist Asian and African

Question 13

Lactose intolerance

Answer 13

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

Question 14

Lactose intolerance results

Answer 14

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

Question 15

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

Answer 15

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

Question 16

Galactosemia

Answer 16

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

Question 17

Galactosemia type I gene

Answer 17

GALT gene (Galactose-1-phosphate uridylyltransferase)

Question 18

Galactosemia type II gene

Answer 18

GALK1 gene (Galactokinase)

Question 19

Galactosemia type III gene

Answer 19

UDP-Gal Epimerase

Question 20

Galactosemia mutations in what genes?

Answer 20

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

Question 21

Galactosemia effects

Answer 21

toxic accumulation of galactose. Cataracts, kidneys, liver affected

Question 22

Galactosemia clinical landmark

Answer 22

jaundice

Question 23

Lactose intolerance treatment

Answer 23

• omitting lactose
• pretreating milk with purified lactase

Question 24

Galactosemia treatment

Answer 24

omitting galactose consumption

Question 25

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

Answer 25

Elie Metchnikoff

Question 26

Elie Metchnikoff observed

Answer 26

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

Question 27

Milk fermented with lactic acid producing bacteria inhibits

Answer 27

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

Question 28

Lactic acid producing bacteria

Answer 28

Lactobacillus Lactococcus Bfidobacteria

Question 29

What does lactic acid producing bacteria do?

Answer 29

ferment carbs in milk (lactose>glucose and galactose)

Question 30

Microbial B-galactosidase in yogurt is present

Answer 30

in active forms in duodenum

Question 31

B-galactosidase enhances

Answer 31

lactose metabolism in lactase deficient individuals

Question 32

Low pH environments reduce

Answer 32

enzyme activity (irreversible denaturing)

Question 33

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

Answer 33

protection by bacterial cell membrane buffering capacity of yogurt

Question 34

pH of stomach while yogurt passing through

Answer 34

4

Question 35

Can lactase enzyme supplement help people experiment

Answer 35

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

Question 36

Can lactase enzyme supplement help people results

Answer 36

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