proteins and amino acids

Question 1

what are proteins ?

Answer 1

the predominant structural and functional materials in every cell, chains of amino acids bonded by peptide bonds

Question 2

what does protein contain ?

Answer 2

carbon, hydrogen, and oxygen

Question 3

an amino acid’s structure

Answer 3

a central carbon atom attached to a hydrogen, an acidic carboxyl group (COOH), an amino group (NH2), and an organic side chain (R group)

Question 4

what kind of sequences are proteins ?

Answer 4

polypeptide sequences, a polymer of amino acids joined together by peptide bonds

Question 5

what body parts digest and absorb protein ?

Answer 5

mouth, stomach, small intestine, pancreas, and liver

Question 6

how does the mouth digest and absorb protein ?

Answer 6

mechanical digestion of protein begins with chewing, tearing, and mixing food with salivary juices to form a bolus

Question 7

how does the stomach digest and absorb protein ?

Answer 7

hydrochloric acid denatures protein and activates pepsinogen to form pepsin; pepsin breaks the polypeptide chain into smaller polypeptides

Question 8

how does the small intestine digest and absorb protein ?

Answer 8

proteases continue to cleave peptide bonds, resulting in dipeptides, tripeptides, and single amino acids; tripeptidases and dipeptidases on the surface of the enterocytes finish the digestion to yield single amino acids, which can then be absorbed into the bloodstream and travel through the portal vein to the liver

Question 9

how does the pancreas digest and absorb protein ?

Answer 9

produces proteases that are released into the small intestine via the pancreatic duct

Question 10

how does the liver digest and absorb protein ?

Answer 10

uses some amino acids to make new proteins or converts them to glucose; most amino acids pass through the liver and return to the blood to be picked up and used by body cells

Question 11

describe the functions of protein in the body (7)

Answer 11

help maintain acid base balance, transport substances throughout the body, contribute to a healthy immune system, provide energy, improves satiety and appetite control, provide structural and mechanical support in tissues, and regulate fluid balance

Question 12

daily calories from protein (%)

Answer 12

10-35%

Question 13

daily protein needs

Answer 13

0.8 g of protein/kg of body weight, 1.4-1.7 for athletes

Question 14

healthy sources of protein in the diet

Answer 14

meat, fish, poultry, dried beans, peanut butter, nuts, foods that have all 9 essential amino acids

Question 15

health consequences of consuming too little protein

Answer 15

may lead to reduction of lean body mass, especially in older adults, risk of increased frailty, impaired healing, decreased immune function

Question 16

health consequences of consuming too much protein

Answer 16

may increase risk of heart disease, kidney stones, calcium loss from bones, can displace other nutrients and fiber rich foods associated with a reduced risk of chronic diseases (whole grains, fruits, and vegetables)

Question 17

benefits of a vegetarian diet

Answer 17

may reduce risk of heart disease, high blood pressure, diabetes, cancer, stroke, and obesity, vegetarian diet food staples are rich in fiber and low in saturated fat and cholesterol

Question 18

risks of a vegetarian diet

Answer 18

potential deficiencies of nutrients found in animal foods (protein, iron, zinc, calcium, vitamin D, riboflavin, vitamins B12 and A, omega 3 fatty acids)