Dietary Protein

Question 1

Summarize the major steps in protein digestion.

Answer 1

• Enzymes mediate hydrolysis of proteins into single AA’s that can be absorbed
• in the stomach, pepsin is the major proteolytic enzyme
• in the small intestines, substances secreted by the pancreas further break down the partially digested material from the stomach.
• bicarbonate neutralizes the stomach acid. This raises the pH for optimal range for digestive enzymes.
• enteropeptidase cleaves typsinogen»>trypsin
• trypsin then cleaves other zymogens

Question 2

Summarize the major steps in protein absorption.

Answer 2

Specific transport proteins transfer AAs into the intestinal cells where some are used and the rest are transported via the blood to the liver.

Question 3

Describe the conversion of digestive zymogens to their active form.

Answer 3

slide

Question 4

What is an essential amino acid? List them.

Answer 4

An amino acid that the body cannot make at all or cannot make in sufficient quantities to meet its needs.

Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine

Question 5

What is the recommended protein intake?

Answer 5

50% carbohydrate
20% fats
30% proteins

Question 6

Where is the major source of Amino acid metabolism?

Answer 6

liver

Question 7

Other than soybeans, plant sources do not provide all the essential amino acids. Give an example of plant combinations that do.

Answer 7

beans + corn

beans + rice

Question 8

How many calories are in a gram of protein?

Answer 8

4 calories

Question 9

Unlike carbohydrate and fat, protein does not have a specialized form of ?

Answer 9

storage

Question 10

If not supplied by diet, protein will be acquired from?

Answer 10

working and structural components of the cells and tissues

Question 11

What does starvation always cause?

Answer 11

wasting of lean body tissue in addition to fat loss

Question 12

How do you spare proteins from being used for energy and allow them to perform their unique and important roles?

Answer 12

Take in adequate carbohydrate and fat

Question 13

In what form is pepsin secreted? Where is the zymogen stored? How is it changed?

Answer 13

Produced and secreted by gastric cells as pepsinogen.

HCl produced by parietal cells induces conformational change that causes pepsinogen to be cleaved to active pepsin.

Question 14

What cleaves trypsinogen?

Answer 14

enteropeptidase

Question 15

Where is enteropeptidase released?

Answer 15

small intestines

Question 16

What would happen if enteropeptidase malfunctioned?

Answer 16

• trypsin would not be produced
• chymotrypsin would not be produced
• elastase would not be produced
• carboxypeptidase would not be produced

**failure to thrive, diarrhea, hypoproteinemia

Question 17

Where is chymotrypsinogen synthesized?

Answer 17

pancreas

Question 18

Where is proelastase synthesized?

Answer 18

pancreas

Question 19

Where is procarboxypeptidase synthesized?

Answer 19

pancreas

Question 20

If the patient was unable to produce HCl, what would the patient experience?

Answer 20

• deficiencies in protein digestion and absorption

- malnourishment

Question 21

What is the first step in the use of protein for energy production?

Answer 21

deamination (removal of N-containing amino group)

Question 22

What two products result from deamination?

Answer 22

ammonia (NH3)

keto acid

Question 23

Because ammonia is toxic, what does the liver do?

Answer 23

combines ammonia with carbon dioxide to produce urea and water

Question 24

At what protein consumption level does the maximum urea production occur?

Answer 24

250 grams/day

Question 25

How would you diagnose disease of liver?

Answer 25

blood ammonia is high

Question 26

How would you diagnose kidney disease?

Answer 26

blood urea is high

Question 27

How much water should a person drink if they are on a high protein diet?

Answer 27

>100 grams/day

Question 28

What is chronic protein-energy malnutrition called? What are the symptoms?

Answer 28

Marasmus - infancy (<2) - develops slowly - severe weight loss - severe muscle wasting - no detectable edema - no fatty liver - skin is dry, thin and easily wrinkles

Question 29

What is acute protein-energy malnutrition called? What are the symptoms?

Answer 29

Kwashiorkor - older infants and young children (1-3 years) - rapid onset - some weight loss - some muscle wasting - edema - fatty liver - loss of appetite - skin develops lesions

Question 30

Why would you see edema in Kwashiorkor?

Answer 30

decreased plasma protein in circulation

Question 31

What 2 tests could you perform to confirm Kwashiorkor?

Answer 31

BUN (Blood urea nitrogen) | Creatinine clearance tests

Question 32

What results would confirm Kwashiokor from the BUN test?

Answer 32

lower than normal levels (<6 mg/dL) are seen in low protein diet or malnutrition

Question 33

What does the BUN test measure?

Answer 33

the amount of urea nitrogen in the blood Urea nitrogen is what is formed when protein breaks down

Question 34

What does the creatinine clearance test measure?

Answer 34

compares the creatinine level in the urine with the creatinine level in the blood. Higher levels indicate muscle breakdown **In elderly patients, creatinine clearance appears to decrease with age**

Question 35

What results would confirm Kwashiokor from the creatinine clearance test?

Answer 35

higher than normal levels indicate breakdown of muscle Male: 97-137 ml/min Female 88-128 ml/min

Question 36

Why do Kwashiorkor patients have increased infections?

Answer 36

damaged immune system due to the body breaking down antibodies

Question 37

What enzyme is lacking in patients with PKU?

Answer 37

phenylalanine hydroxylase (PAH)

Question 38

What inheritance type is PKU?

Answer 38

autosomal recessive

Question 39

In addition to light pigmentation, what other symptoms may be present in PKU?

Answer 39

- delayed mental and social skills - small head size - hyperactivity - jerking movements - seizures - skin rashes

Question 40

What are some foods that contain phenylalanine? What supplements should be added to the diet?

Answer 40

aspartame Supplements: - fish oil -iron

Question 41

What amino acids are not able to be broken down by Maple Syrup Urine Disease patients?

Answer 41

branched chain amino acids | BCAA

Question 42

What inheritance type is MSUD?

Answer 42

autosomal recessive

Question 43

Which four genes can mutate to result in MSUD?

Answer 43

BCKDHA BCKDHB DBT DLD - genes form a complex to catabolize branched chain amino acids (BCAAs)

Question 44

What is the name of the MSUD complex?

Answer 44

BCKD - mutation in BCKD is the most common reason for MSUD

Question 45

What symptoms appear with MSUD?

Answer 45

poor feeding vomiting lethargy developmental delay

Question 46

What treatment is available for MSUD?

Answer 46

diet low in branched chain amino acids (Val, Leu, Ile) fish oil supplements iron supplements some patients pursue a liver transplant

Question 47

An infant with PKU would be expected to be deficient in what non-essential amino acid?

Answer 47

tyrosine

Question 48

A mother is informed that products containing aspartame could be detrimental to her child's health. What is the likely genetic disorder?

Answer 48

PKU