Nutrition Chapter 6

What is the DRI for protein?

.8 g of protein per kg of weight

Compare the advantages and disadvantages of a vegetarian diet and a meat eater's diet.

A well-planned vegetarian diet is associated with lower rates of chronic diseases, such as obesity, heart disease, hypertension, cancer, and diabetes. Protein sources from meat have optimal digestibility and availability to the body compared to most plant-based protein sources. Compared to the meat eater's diet, a vegetarian diet is more environmentally sustainable since it requires less land, water, fuel and other resources to produce than diets high on meats.

Outline the processes of protein digestion and absorption of amino acids.

Digestion of protein involves denaturation by stomach acid and enzymatic digestion in the stomach and small intestine to amino acids, dipeptides, and tripeptides. The cells of the small intestine complete digestion, absorb amino acids and some larger peptides, and release them into the bloodstream for use by the body's cells.

The roles of protein in the body include which of the following? balance of acids and bases thinning of blood providing energy transport of substances in the bloodstream cell structure

I,III,IV and V

List the potential health problems that are caused by eating patterns that are either too low or too high in protein.

Most U.S. protein intakes fall within the DRI recommended protein intake range of 10 to 35 percent of calories. No Tolerable Upper Intake Level exists for protein, but health risks may accompany the overconsumption of protein-rich foods. Gluten-free diets often relieve symptoms of celiac disease, non-celiac gluten sensitivity, or gluten allergy, but no evidence supports claims that they cure other ills

________ is/are important for the control of protein synthesis.

RNA

What is required for legumes to "fix" nitrogen?

bacteria

Protein functions as the body's ___________ helping maintain normal pH.

buffers

Eating a variety of protein foods from plants so that amino acids that are low in some foods will be supplied by the others are:

complementary proteins

Heat, radiation, alcohol, acids, bases, and the salts of heavy metals causes a protein to unfold and inactivate itself, which is called

denaturation

Protein digestibility is highest for which foods?

eggs

The most easily digestible form of protein can be found in which of the following foods?

eggs

A(n) _________ is a substance that speeds the rate of a chemical reaction without itself being permanently altered in the process.

enzyme

Which amino acids cannot be made by the body or made in quantities great enough to meet the body's needs?

essential amino acids

Proteins can be denatured by all of the following except

freezing

The roles of protein in the body include all but _________

gas exchange

___________ is a protein that forms in grain foods, is best known for providing a pleasing stretchy texture to yeast breads.

gluten

What advice would you give to a friend who has started a gluten-free diet to lose weight?

gluten free weight loss diets offer no advantages over other low-calorie diets

Problems with consuming too much protein include all the following EXCEPT:

increase in electrolytes from fluid retention seen with high protein intakes

Which of the following is NOT a consequence of protein deficiency?

increased nutrient absorption from the digestive tract

Heavy use of soy products in place of meat can inhibit absorption of what nutrient?

iron

What is an important function of the amino acid tyrosine?

it is used to make the brown pigment melanin

What protects the stomach from digesting itself?

mucus lining of stomach

The ___________ of the protein's side group determines the protein's function.

shape

The variable part of an amino acid is the _____________

side chain

Insufficient dietary protein can cause

slowed protein synthesis

Protein digestion and denaturing begins in the __________.

stomach

When amino acids are consumed in excess of what is needed, all the following are possible fates of the excess amino acids EXCEPT:

stored in muscle tissue

The process of protein turnover involves the ________

use of amino acids that have been conserved from the breakdown of old cells

Which statement regarding digestion and absorption of proteins is true?

Cells in the small intestine possess different sites for absorbing different types of amino acids, which causes competition among amino acids at the absorption sites.

Would you recommend an amino acid supplement to a friend who is recovering from illness and wants to promote muscle mass gain? Why or why not?

No; whole protein is better handled by the digestive system and will promote muscle mass gain better than amino acid supplements

Identify the benefits and drawbacks of protein-rich foods in the diet.

Protein is critical in nutrition, but too many protein-rich foods can displace other important foods from the diet. In addition, many protein-rich foods such as meat are high in calories, and overconsumption can contribute to obesity. Protein-rich foods often carry with them a characteristic array of vitamins and minerals, such as vitamin B and iron, but they lack others—vitamin C and folate, for example.

Describe the nature of proteins and amino acids.

Proteins are unique among the energy nutrients in that they possess nitrogen-containing amine groups and are composed of 20 different amino acid units. Of the 20 amino acids, nine are essential amino acids. Under special circumstances, a nonessential amino acid can become essential. Amino acids link into long strands that make a wide variety of different proteins. Each type of protein has a distinctive sequence of amino acids and so has great functional specificity. Certain proteins are common to all cells. In addition, specialized cells synthesize specific proteins that enable them to do distinct jobs. Nutrients do not alter genes, but they powerfully influence genetic expression. Proteins can be denatured by heat, acids, bases, alcohol, the salts of heavy metals, or other agents. Denaturation begins the process of digesting food protein and can also destroy body proteins.

Identify the roles of proteins and amino acids in the body.

The body needs dietary amino acids to grow new cells and to replace old or damaged ones. Proteins help regulate gene expression; provide structure and movement; serve as enzymes, hormones, and antibodies; provide molecular transport; help regulate fluid and electrolyte balance; buffer the blood; contribute to blood clotting; and provide energy. Amino acids can be used as fuel or converted to glucose or fat. No storage form of protein exists in the body. Amino acids can be metabolized to protein, nitrogen plus energy, glucose, or fat. Amino acids will be metabolized to protein only if sufficient energy is present from other sources. When energy is lacking, the nitrogen part is removed from each amino acid, and the resulting fragment is oxidized for energy.

List the factors that determine the daily protein needs of an individual.

The protein intake recommendation depends on size and stage of growth. The DRI for adults is 0.8 grams of protein per kilogram of body weight. Factors concerning both the body and food sources modify an individual's protein need. Protein recommendations are based on nitrogen balance studies, which compare nitrogen excreted from the body with nitrogen ingested in food. Digestibility of protein varies from food to food, and cooking can improve or impair it. A protein's amino acid assortment greatly influences its usefulness to the body. Low-quality food proteins lack essential amino acids and so can be used to build body structures only if those amino acids are present from other sources. Low-quality food proteins lack essential amino acids and so can be used to build body structures only if the missing amino acids are supplied by other sources. The more severely food supplies are limited, the more important protein quality becomes.

Who would benefit most from eating a variety of protein foods so that amino acids that are low in some foods will be supplied by the others?

a vegan

Which protein-rich food would be a good source of calcium for vegetarians?

almonds

___________ are the building block of protein

amino acids

Amino acids are linked together to form a protein strand by _____________

peptide bonds

All the following are functions of protein EXCEPT:

primary energy source

What is NOT one of the beneficial characteristics of a vegetarian diet?

provides more saturated fat

Proteins play several important roles in the body. What is NOT one of these?

providing an unlimited supply of energy