Advertisement Upgrade to remove ads

nutrients can only be absorbed when broken down

to their monomers

enzymes

large protein molecule produced by body cells. biological catalysts that increase the rate of a chemical reaction without themselves become part of the product

the digestive enzymes are what type of enzymes?

hydrolases

hydrolases

break down organic food molecules by adding water to the molecular bonds, cleaving the bonds between the subunits or the monomers

the various hydrolytic enzymes are

highly specific in their action

each enzyme hydrolyses only

1 or a small group of substrate molecules and specific environmental conditions are necessary for it to function optimally

digestive enzymes actually function where?

outside the body cells in the digestive tract, so their hydrolytic activity can also be studied in a test tube - in vitro

carbohydrate digestion:

what is the enzyme that breaks down STARCH and what site of action does it take place in?

enzyme / source = salivary amylase
site of action = mouth

when starch is broken down by salivary amylase, what is it broken down to?

dextrin + disaccharides

carbohydrate digestion:

what is the enzyme that breaks down dextrin + disaccharides and what site of action does it take place in?

enzyme / source = pancreatic amylase
site of action = small intestine

when dextrin + disaccharides is broken down by pancreatic amylase, what is it broken down to?

disaccharides

the 3 enzymes of the small intestine (maltase, lactase and sucrase) break the disaccharides down to what 3 things?

lactose
maltose
sucrose

lactose is broken down to what 2 substances?

galactose
glucose

maltose is broken down to what substance?

glucose

sucrose is broken down to what 2 substances?

fructrose
glucose

galactose, glucose, and fructose are considered

monosaccarides

the monosaccharides are absorbed into the intestinal vili and transported via the

hepatic portal vein in the liver

Salivary Amylase

the enzyme produced by salivary glands and secreted into the mouth

Experiment A. Starch DIgestion by Salivary Amylase

we investigated the hydrolysis of starch to maltose by salivary amylase to determine to what extent the enzymatic activity occurred.

what does the following equation suggest?

starch + water + amylase --->
maltose (units) + amylase

starch decreases and sugar increases as digestion occurs

Experiment A. Starch DIgestion by Salivary Amylase

procedure - IKI TEST

added 3 drops of each indicated substance and placed the tubes in a water bath for 1 hour. then we marked a spot plate A for amylase and made 6 depressions

added a drop of the sample from each of the tubes with a drop of IKI solution

what color would indicate a positive starch test? (indicating the presence of starch) - IKI TEST

a blue black color

what color would indicate a NEGATIVE starch test? (indicating that starch is not present) - IKI TEST

the mixture will not turn blue

Experiment A. Starch DIgestion by Salivary Amylase

procedure - Benedict's Test

into the remaining mixture in each tube, we placed 3 drops of benedict's solution and put each tube into a beaker of boiling water for 5 minutes.

what color would indicate a POSITIVE sugar test? (indicating that maltose is present) - Benedict's Test

green-to-orange precipitate

what color would indicate a NEGATIVE sugar test? (indicating that maltose is not present) - Benedict's Test

no color change

protein digestion by

Trypsin

protein digestion:

what is the enzyme that breaks down PROTEIN and what site of action does it take place in?

enzyme = pepsin in the presence of HCl

site of action = stomach

what does the breakdown of protein lead to?

proteases and peptones

protein digestion:

what is the enzyme that breaks down proteases & peptones
and what site of action does it take place in?

enzyme = pancreatic enzymes (trypsin, chymotrypsin and carboxypeptidase)

site of action = small intestine

what does the breakdown of proteases & peptones lead to?

small peptides

protein digestion:

what is the enzyme that breaks down small peptides
and what site of action does it take place in?

enzyme = small intestine enzymes (aminopeptidases and dipeptidases)

sit of action = small intestine

amino acids are absorbed into the intestinal vili and transported via

the hepatic portal vein in the liver

trypsin, an enzyme is produced by what digestive organ?

pancreas

what does trypsin do?

it hydrolyzes proteins to small fragments (proteases, peptones and peptides).

BAPNA

used to test for protein hydrolysis, which was indicated by a yellow color

the appearance of yellow color indicates what with the BAPNA dye?

the presence and activity of an enzyme that is capable of peptide bond hydrolysis

Experiment B: Protein DIgestion by Trypsin

procedure

5 test tubes, and added 3 drops of trypsin and 3 drops of BAPNA, placed the tubes in a 1 hour water bath and observed the color results

what color indicates a positive hydrolysis test?

yellow
the dye molecule has been cleaved from the amino acid

what happens when no detectable hydrolysis has occurred?

the sample mixture remains clear

fat digestion:

what are the 2 enzyme that break down unemulsified fats?

and what site of action does it take place in?

enzymes = emulsified by bile salts from liver, stored in the gall bladder

& pancreatic lipases

site of action = small intestine

what 2 substances does the breakdown of unemulsified fats lead to?

1. monoglycerides & fatty acids
2. glycerol & fatty acids

lipids are absorbed mainly by what?

lacteals in the villi and into lymphatic circulation, eventually into circulation

the treatment that fats and oils go through during digestion in the small intestine is a bit more complicated than carbs and proteins, why is this so?

because pre-treatment with bile to physically emulsify the fats is required.

what 2 reactions occur in fat digestion?

First - fats and oils are emulsified in the presence of bile salts to produce minute droplets.

Second - the minute fat/oil droplets are digested by lipase to free fatty acids and glycerides

pancreatin shows what?

used to describe the enzymatic product of the pancreas, which includes :
- protein
- carbohydrates
- nucleic acids
- fat digesting enzymes

pancreatin is used in the lab to investigate what?

the properties of pancreatic lipase

pancreatic lipase

hydrolyzes fats and oils to their component monoglycerides and 2 fatty acids
(and occasionally to glycerol and 3 fatty acids)

the benefit of the end products of fat digestion are being (fatty acids) that are organic acids that decrease the pH is that

they provide an easy way to recognize that digestion is ongoing to completed

what is the name of the pH indicator that can help you follow these changes?

litmus blue

what colors does litmus blue change from and to as the test tube contents become acid

blue to pink

Experiment C: Pancreatic Lipase DIgestion of Fats and the Action of Bile

to demonstrate the action of bile on fats

procedure

2 test tubes
10 drops of water with 2 drops of veggie oil in one tube

10 drops of water with 2 drops of veggie oil and pinch of bile salts in the 2nd tube

cover each tube, shake, allow tubes to stand at room temp

bile is a secretory product of the liver but it is not what?

why is it important to fat digestion

an enzyme

because of its emulsifying action (the physical breakdown of larger particles into smaller ones)
on fats.

emulsified fats provide a

larger surface area for enzymatic activity

Experiment C test results:

what happens if emulsification has not occurred?

the oil will be floating on the surface of the water

Experiment C test results:

what happens if emulsification has occurred?

the fat droplets will be suspended throughout the water, forming an emulsion

Lipid Digestion by Lipase experiment, how many drops did you add?

5 drops

lipase assay - what is the basis of this assay?

a pH change that is detected by a litmus powder indicator

what color will alkaline or neutral solutions containing litmus (which are blue) turn into in the presence of acid?

reddish

since fats are digested to fatty acids (organic acids) during hydrolysis, they do what to the pH of the sample they're in?

lower the pH

Litmus cream (fresh cream providing the fat substrate to which litmus powder was added) will turn from what color to what color if the solution is acid?

bluish color to pink

how did you prepare a color control?

added 0.1 N HCl drop by drop to tubes 1L and 2L until the cream turns pink

Mechanisms of Food Propulsion & Mixing

just about any time organs exhibit mobility, what are involved?

muscles and movements of the GI tract

what 2 types of muscle are involved in digestion?

skeletal and smooth muscle

swallowing aka

deglutition

swallowing aka deglutition is largely the result of what type of muscle activity?

skeletal muscle activity

swallowing occurs in what 2 phases?

1. buccal (mouth)
2. pharyngeal-esophageal

1. buccal (mouth) phase is voluntary or involuntary??

voluntary controlled and initiated by the tongue

2. pharyngeal-esophageal phase is voluntary or involuntary??

involuntary in the pharynx and esophagus

through peristalsis

resulting in the delivery of swallowed contents to the stomach

peristalsis

wave like muscular contractions that squeeze food through the esophagus into the stomach

Activity D - food propulsion and mixing

procedure

place stethoscope 1 inch below the xiphoid process and slightly to the left

listen to sounds as the partner consumed 2 or 3 swallows of water

determine time interval between two sounds

how many audible sounds should you have heard?

two sounds:

1 when the water splashes against the gastroesophageal sphincter

2. when the peristaltic wave of the esophagus arrives at the sphincter and the sphincter opens, allowing water to gurgle into the stomach

what does the time interval give an indication of?

the time it takes for the peristaltic wave to travel down the 10 inch esophagus

catalyst

increases the rate of a chemical reaction without becoming part of the product

control

provides a standard of comparison for test results

enzyme

biologic catalyst - protein in nature

substrate

substance on which a catalyst works

list at least 3 characteristics of enzymes

1. not used up in the reaction / does not change shape

2. used to speed up a reaction

3. will bind to a molecule if the enzyme-substrate complex can form

the enzymes of the digestive system are classified as hydrolases, what does this mean?

catalyze digestive hydrolysis reactions

1. organ that produces it
2. site of action
3. substrate

salivary amylase

1. salivary glands
2. mouth
3. starch

1. organ that produces it
2. site of action
3. substrate

trypsin

1. pancreas
2. small intestine
3. proteins

1. organ that produces it
2. site of action
3. substrate

lipase (pancreatic)

1. pancreas
2. small intestine
3. fats

name the end products of digestion for protein

amino acids

name the end products of digestion for carbohydrates

simple sugars

name the end products of digestion for fats

fatty acids and glycerol

why was 37 degrees the optimal incubation temperature?

because the body's enzymes work at their optimum temperature.

what happened to the tube in starch digestion that was incubated at 0 degrees rather than 37 degrees?

no starch digestion occurred

in the exercise concerning Trypsin function in the BAPNA test, why was an enzyme assay like Benedicts or IKI (which tests for the presence of a reaction product) not necessary?

because the color change from clear to yellow is direct evidence of hydrolysis, additional tests are not required when using BAPNA

what did you do to tube 1T

added water, trypsin and incubated at 37 degrees

trypsin is a protease similar to what?

pepsin

pepsin is

the protein digesting enzyme in the stomach

would trypsin work well in the stomach, why or why not?

no, the stomach is highly acidic while trypsin works well in the neutral/basic environment of the small intestine

int he procedure concerning pancreatic lipase digestion of fats, why did the litmus indicator change from blue to pink during fat hydrolysis

because the change of blue to pink indicates the presence of acids as is the case when fats is broken down into glycerol and fatty acids

BAPNA is used to test for?

protein hydrolysis

what color was the BAPNA test for protein hydrolysis indicated by?

yellow

Litmus is used to test for?

presence of fatty acids

what color change was Litmus test presence of fatty acids evidenced by?

blue to pink

IKI was used to test for the presence of what?

starch

what color was indicated by the IKI test presence of starch?

blue-black color

Benedict's solution was used to test for

presence of reducing sugars (maltose, sucrose, glucose)

Benedict's solution that was used to detect the presence of reducing sugars (maltose, sucrose, glucose) was indicated by what color?

a colored precipitate

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set