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44 Cards in this Set

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Describe the structure of amino acids.
Amino acids are the building blocks of protein. The structure of amino acids consists of a central C atom, bonded to one carboxylic acid group, one amino group, and a side group. It is the side group that gives the amino acid its uniquness, affecting its properties, like shape, size, composition, pH, and charge. (The side group only has H or H's and C's).
Explain how their sequence in proteins affects the proteins' shapes.
Joined to another AA by a peptide bond via condensation reaction (releases H2O) in the cytoplasm, the amino acid sequence determines a protein's primary structure. The interactions along those AAs determines its S(hydrogen bonding), T(weak interactions among side groups and fluid environment), and structures. This 3D shape determines its function and interaction w/ other molecules.
What are the essential and nonessential amino acids?
They essential AA (9) are the ones that the body cannot make and must get in the diet. The nonessential AA (11) can be manufactured in the body, if given a source of N, C, O, H.
What is meant by conditionally essential amino acids?
These are nonessential AAs that become essential under certain circumstances. Ex: Tyrosine. In PKU, no enzyme is present to convert phenylaanline to Tyrosine, so it is needed in diet. Glutamine-becomes essential after taruma or illness.
How does the chemical compoition of proteins differ from that of carbohydrates and fats?
They contain N or N group. They are more diverse because of their unique #D shape.
What happens when proteins are denatured?
They unfold and lose their shape, which also affects its ability to function. It is the FIRST step in protein digestion. It is caused by acidity, alkalinity, heat, alcohol, oxidation, and agitation.
Describe each of the functions of proteins in the human body: STRUCTURE
They provide structure to different tissues. It gives bone its elastic strenght via collagen and gives keratin to hair and nail. Motor proteins, like in the muscle, transport energy into mechanical movement.
Describe each of the functions of proteins in the human body: ENZYMES
Some proteins are enzymes and catalyze reactions without being used up. Those reactions include catabolism, release energy from nutrients, and anabolism. They are denatured in stomach.
Describe each of the functions of proteins in the human body: HORMONES
They are chemical messengers with important regulatory functions. Ex: Insulin and thyroxine.
Describe each of the functions of proteins in the human body: IMMUNITY
The immunity function depends on proteins. Antibodies are blood proteins that attack and inactivate bacteria and viruses that cause infection. Each Anti-B is unique to each infection.
Describe each of the functions of proteins in the human body: BLOOD CLOTTING
Body produces protein (fibrin) tht causes blood clotting in injury.
Describe each of the functions of proteins in the human body: VISION OR VISUAL CYCLE
Opsin, a protein, is essential to normal vision.
Describe each of the functions of proteins in the human body: TRANSPORT
They form channels and pumps (require E). They also act as carriers, transporting substances for delivery in the bloodstream. Ex: lipoproteins and hemoglobin
Describe each of the functions of proteins in the human body: FLUID BALANCE
The interior and exterior fluid levels must stay in balance or body processes to operate properly. For example, protein in capillaries are to large to be excreted. So when the fluid leaves, it attracts more fluid. Otherwise, swelling or edema occurs.
Describe each of the functions of proteins in the human body: ACID BASE BALANCE
The body works hard to keep the pH of the blood 7.4, or nearly neutral. Proteins maintain stable pH levels by serving as buffers, where they pick up H when acidic and donate H when basic.
Describe each of the functions of proteins in the human body: SOURCE OF ENERGY AND GLUCOSE
Because of so many functions, proteins are spared to do other functions. This only happens in cases of starvation. Body gets energy via deamination and makes energy or glucose with the carbon skeleton.
Describe the differences between enzymes and hormones.
Hormones are made in one part of the body but act on cells in other parts of the body whereas enzymes assist chemical reactions. Enzymes do not have a regulatory purpose.
Describe the process of protein synthesis.
A specific lenght of DNA, called a gene, makes mRNA. The mRNA leaves the nucleus with the code and attaches itself to ribosomes. Many specific tRNA brings their own amino acids and protein synthesizes occurs by direction of rRNA. Genetic defects in DNA can cause coding problems. Ex: Valine replace glutamic acid to make sickle cells.
Describe the concept of protein turnover.
Proteins are constantly being synthesized and being broken down, which gives us a constant amino acid pool. This recycling capacity is the reason we need so little protein in our diet. They can be used for many purposes: Carbon skeleton is used as energy, to make glucose or body fat. Nitrogen is used to make another AA, converted to urea for excretion, or made into other molecules.
Define nitrogen balance.
Nitrogen balance related intake of N to output. Intake is via digested protein whereas output comes from urine. Nitrogen equilibrium in when intake = output, a characteristic of healthy adults. When NH2 is broken of AA, it converts to NH3, then urea in liver, and then is excreted. As N is excreted s proteins are recycled or used, the balance of N helps evalutate whether the body is getting enough protein. It is defined as NB = Intake - Output.
What conditions are associated with zero, positive, and negative balance.
With PB, intake > output. This is only desirable for growth or recovery. With NB, intake < output either thorough low intake or increasing output with ilness. ZB is N eqauilibring, which is adequate to maintain and repair tissue. Side note: Breakdown of protein provides 2/3 of protein in AA pool.
What is the RDA (g/day) for protein for adults. Be able to calculate a protein RDA for a sample individual.
RDA's are set to meet the nutritional needs of most ppl, so some ppl require less. The RDA is 0.8 grams per kilogram of body weight. For average adult male, its 56g and average femake, its 46g.
How does the RDA for adults compare to that for infants? Why are they different?
Infatns need about 1.52 gram per kg of body weight. This is because of the demand for protein to support rapid growth and heal all the burns, fevers, and infections children get.
How does the protein RDA compare to current average protein intakes in the US?
Adults consume about 15% of their energy as program, which is ample for most protein since we need 10 to 25%. Average man comsumes 90 grams and woman comsumes 60 grams, above the 56 grams and 47 grams required for average adult.
Know the AMDR for protein (% of energy intake). Be able to use these numbers in calculations related to sample food intake or food labels.
AMDR for protein is 10 to 35%.
What factors affect the quality of dietary protein?
1. Does it provide the right balance of AA and the essential AAs?
2. Will it support protein synthesis, by providing enough other AA to serve as N sources for synthesis nonessential AA?
3. Is that protein digestible?
How is protein quality assessed?
It is assessed in many ways. All essess EAA content and digestibility. You have (1) different analytical/lab methods and the (2)PDCAAS. It accounts for both the AA composition of a food and the digestibility of that protein. It can be used to determine %DV. It is the chemical score X %digestibility of the protein. The answer ranges from 0 to 1. It is the official method for determining he protein quality of most food.
What is a complete and incomplete protein?
Complete, or high-quality proteins, supply all the essential AA and ALSO the right proportions. Animal food and soy are 2 examples. Incomplete, or low-quality proteins, lack one or more essential A. Plant proteins are incomplete.
What is a limiting amino acid?
The AA with the lowest score is the limitingAA, which means the AA is present in the smallest amt. relative to biological need. This is the AA in shortest supply during protein synthesis.
How do animal and plant proteins compare in terms of protein quality?
With plant protein, protein quality becomes an issue becuz they're incomplete. That is why we need to complement plant proteins or small amounts of animal foods.
What is meant by complementary proteins?
Completementary proteins are proteins that have an assortment of AA tht make up for, or complement each other's lack of speicifc EAA so that the sufficent amt. is provided. This means protein and energy intake are adequate.
What is the DV for protein (g/day)?
There is none. It is based on food's PDACAAS. Two different protein foods, whlle having the same amt. of grams, would provide differnt %DV values. The DV is 50 grams/day.
Why is %DV usually not listed on a food label?
It is not required.
What would a manufacturer need to do in order to list the %DV for protein on a label?
The manufactorer would have to do the protei quality assessment via the PDACAAS.
Describe the different types of vegetarian diets.
1. Semi-vegetarian - eliminates red meats or certain types of meants
2. Lacto-ovo vegetaranism - eliminate ALL meat products, but milk and eggs
3. Lactovegetarian - consumes meat, but no eggs
4. Vegan - Eliminates ALL meat, plus milk, eggs, and other dairy products and avoid cosmetics made from animals.
How do vegetarians meet their protein needs without eating meat?
If carefully planned, a diet can be nutritionally complete. They can eat variety of foods and use supplements. The more the limited the diet, the more likely the nutritional problems. Eat red meat for iron and zinc, chicken for B6, and animal foods for B12.
What are the advantages of different vegetarian diets?
Contain less fat, s. fat, and cholesterol
contain higher amoujnts of antioxidants, dietary fiber, phytochemicals
have lower blood cholesterollevels and are lower heart disease risk
weigh less for their height, no high BP
certain caners such as breast and colon cancers occur less frequently
Reduce food cost
What are the disadvantages of different vegetarian diets?
Vitamins and minerals are low
tend to have higher intakes of phytates, oxalates, and tannins - which bind to minerals and make them less absorbable
quire careful planning for periods of rapid growth
What are the health consequence of ingesting inadequate protein and energy?
If protein is lacking, malnutrition occurs. The body burns dietary protein for energy rather than use it to make other proteins. The symptoms can be mild or severe and acute or chronic. Marasmus and kwashiorkor are two severe types of protein-energy malnutrition.
Describe marasmus.
It develops from chronic PEM and is "normal." It develops more slowly and there is severe muscle wasting. Here, the growth slows or stops and children are SHORT and THIN. Muscle and fat are used up and metabolism slows and BTemp. drops. They are also apathetic. There is learning disabilities and can occur in adults during cancer and starvation.
Describe kwashiorkor
It develops from acute PEM and is "abnormal." Infections or toxins may trigger this type of development. It causes edema and produces a bloated belly, stunted weight and height, increased susceptibility to infection, dry and flaky skin, and sometiems skin sores, changes in skin color, and unnaturally blond hair. The muscle wastes and the ppl are withdrawn and apathetic. There are also some body fat stores left.
How are the two condiions different, and in what ways do they overlap?
What sets kwashiorkor aprt from marasmus is edema, or swelling of body tissue, usually in feet and legs. Energy deficient is not as severe in kwashiorkor and there is less muscle wasting. Also, kwashiorkor is sudden whereas marasmus is not. Also, kwashiorkor develops only in children, not adults and children like maramus.
How might protein excess, or the type of protein eaten, influence health?
It has been linked to heart disease, cancer, osteoporosis, kidney problems, and mineral losses. Also, it goes hand-in-hand w/ high intakes of s. fat and cholesterol.
Elaborate on those health risks.
KD - high intake puts train on kidneys and can cause dehydration
ML - high intake increases calcium excretion, so calcium needs to be increased
Obesity - high protein foods are also high in fat, also alters hormones
HD - Cuz they're high in fat
Cancer - increases if red meat is high