Lecture

Question 0

Digestion in stomach

Answer 0

Gastric parietal cells release HCL: disrupts protein structure and concerts pepsinogen to pepsin.

Question 1

Protein sources

Answer 1

1. Exogenous: Animal (meat, poultry, fish, dairy products) and plant (gains, legumes, vegetable)
2. Endogenous: desquamated mucosal cells and digestive enzymes and glycoproteins

Question 2

Pepsin function

Answer 2

Cleve’s peptide bonds within and distant from the ends of a polypeptide chain to form large polypeptide and oligopeptides.

Question 3

Digestion in small intestine

Answer 3

CCK and secretin: synthesized in duodenum in response to acid chyme and trigger pancreatic acrobat cells to secrete bicarbonate, electrolytes, water and digestive proenzymes (trypsinogen, chymitrypsinogen, procarboxypeptidase).

Question 4

Digestive enzyme activation

Answer 4

1. Trypsinogen (enteropeptidase) trypsin
2. Procarboxypeotidase (trypsin) carboxypeptidase.
3. Chymotrypsinogen (trypsin) chymotrypsin

Question 5

End products of protein disgestion

Answer 5

Protein to large polypeptides to AA, dipeptides and tripeptides.

Question 6

Complete protein

Answer 6

Meat, poultry, fish, eggs, milk, cheese, yogurt.

Question 7

Incomplete protein

Answer 7

Plants, legumes, grains, nuts, seeds, vegetables.

Question 8

Essential AA

Answer 8

TV TILL PM and histidine

Question 9

Non essential AA

Answer 9

Also get from diet
Synthesized in vivo if nitrogen sufficient
Met to cyt and phe to tyr

Question 10

Protein absorption

Answer 10

AA absorbed in proximal small intestine: paracellular transport and AA transporters.

Peptides absorbed via PEPT1: more rapid than AA transporter and primary system for AA absorption.

Question 11

Supplementation with individual AA

Answer 11

Supplemental free AA may impair the absorption of AA in diet.

Question 12

RDA

Answer 12

0.8g

Question 13

Protein in body

Answer 13

Skeletal muscle

50% of protein in body represented by only 4 proteins: myosin, actin, collagen, hemoglobin.

Question 14

Functions

Answer 14

Major functional and structural component of every cell in the body: enzymes, transport proteins, hair, fingernails, keratin, collagen.

Large part is amino nitrogen.

Question 15

AA metabolism

Answer 15

AA to peptides to excretion as urea or oxidation in TCA cycle.

Question 16

Protein metabolism and vitamins

Answer 16

Numerous vitamins needed for protein/AA met.
For AA oxidation: b6, b12, biotin
AA interconversions: b6, b12, folate.
For collagen formation: ascorbate

Question 17

Protein requirements: exercise

Answer 17

Increased protein with regular heavy resistance exercise can enhance muscle development.
Should take 1.8g but not over 2.4g

Question 18

Endurance exercise

Answer 18

Does not develop muscle mass to same extent and resistance exercise.
Protein metabolism does change: increased AA oxidation
RDA: 1.4g

Question 19

Supplements caution

Answer 19

Individual AA are a concern.

Toxic symptoms and death like tryptophan.

Question 20

Requirement for elderly

Answer 20

1g

Some may have higher intake