Download 3.6.4 Define denaturation 3.6.5 Explain the use of lactase in the

3.6.4 Define denaturation
•A change in the shape of a protein. Shape is everything to an
enzyme. Change the shape, and the enzyme doesn’t work.
(Enzymes are specific to a substrate and the active site has a
distinct shape.)
–Temperatures or pH changes affect the shape of an enzyme
3.6.5 Explain the use of lactase in the
production of lactose-free milk
•World-wide, 70% of adults are lactose intolerant. Normally,
Lactose  glucose +galactose. Dairy industry can add
Lactase to milk and convert all of the lactose.

Bonnie Blair accomplishments
Digestion
Section by section!
(The underlined
Words are very
Important)
Oral Cavity/Mouth
1. Food broken mechanically by teeth.
(Mastication)
2. Salivary amylase in saliva breaks down starch.
David J. (’04) did a spit/raw potato enzyme lab
that was messy yet effective…
3. ‘Food ball’ named ‘bolus’.
Pharynx to esophagus
1. Epiglottis closes over the
larynx. So that food does
not get into the lungs
2. Bolus travels down the
esophagus by paristalsis.
To the stomach
1. Bolus goes through the cardiac sphincter (sphincter near
the heart –leaky sphincter here gives you heartburn!
Because it lets gastric juice burns the esophagus.)
2. Gastric juice (made of pepsin and hydrochloric acid)
hydrolyzes protein –breaks down protein.
3. ‘Bolus’ name changes to ‘chyme’
Review:
• What gets digested in the mouth? What is
the enzyme that does it? Carbohydrate, amylase
• What gets digested in the stomach? What is
the enzyme that does it? Protein, pepsin
To the small intestines!
1. Chyme leaves the stomach through the
pyloric sphincter.
2. Three hormones are secreted depending
on the type of chyme:
1. Secretin stimulates the release of sodium
bicarbonate from the pancreas. (makes the pH
rise! Why is this important?)
2. Cholesystokinin stimulates the release of bile
from the liver. Bile breaks up fats.
3. Enterogastrone slows the rate of digestion
if there is a lot of fat or protein in the diet.
LE 21-11a
Liver
Bile
Gallbladder
Stomach
Bile
Acid chyme
Intestinal enzymes
Duodenum of
small intestine
Pancreatic
juice
Pancreas
Review:
• What hormone gets secreted after a high fat
meal? Cholesystokinin –stimulates the liver to secrete bile
• What hormone gets secreted if the chyme is
full of acid? secretin
• What hormone gets secreted if the meal is
large and full of protein or fat? (Slows
digestion…) Enterogasterone
In the Duodenum of the Small
Intestine
1. Bile is secreted from the liver/gall bladder to emulsify
fat…
2. Pancreatic amylase is secreted from the pancreas (for
carbohydrates.)
3. Trypsin, chymotrypsin, carboxypeptidase are secreted
from the pancreas for protein digestion.
4. Lipase is also secreted by the pancreas for lipid
digestion.
Review of stuff secreted into the small
intestine:
lipase
• _______________
secreted by __________
pancreas
to digest lipid
• ______,___________,______________
Trypsin, chymotrypsin,
carboxypeptidase
pancreas
secreted by _________
to digest protein
pancreas
• _____________
Pancreatic amylase secreted by the _________
to digest carbohydrate
bile
Liver/gall bladder
• _____________
secreted by the _________
to emulsify fat
Look at these important organs that
secrete into the small intestine!
Jejunum and Ilium of the small intestine:
• This is where absorption takes place.
• Villi and microvilli increase the surface area so that
more absorption can take place.
NOTE: Each villus is made for absorption!
(lots of surface area!)
Muscle
layers
Large
circular folds
Blood
capillaries
Nutrient
absorption
Lacteal
Also in the Villus:
• Each villus has a capillary bed and a lacteal. The capillaries
get food to the circulatory system, but they are leaky!
• Lacteals collect FAT and fluid that leaks out of the
capillaries.
elephantiasis
LE 21-13a
Small
intestine
Small
intestine
Stomach
Cecum
Colon
(large
Intestine)
Carnivore
Herbivore
Large Intestine
1.
2.
3.
4.
DOES NOT DIGEST
Water gets reabsorbed here.
Feces forms
E-coli bacteria digest fiber and give off gas. That
is why you give off gas.
5. E-coli bacteria also produce vitamin K from this.
6. Peristalsis occurs when the stomach expands…
leads to defecation.
Problems of the large intestine
• Constipation: Hard, dry feces. Happens when the
feces is left in the large intestine too long and too
much water is reabsorbed.
• Diarrhea: watery feces. Happens when there is
too much peristaltic activity (infection, emotional
stress, physical stress…)
• Ulcerative colitis: Ulcers resulting in constant
diarrhea.
• Colon cancer: tumors of the colon.
The End