what is meant by the amino acid sequence of a protein?

# what is meant by the amino acid sequence of a protein?

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What element is found in proteins, but not in Carbohydrates and fats?nitrogen
In comparison to the composition of carbohydrates and fats, which element found in proteins makes them unique?nitrogen
What is the primary factor that differentiates one amino acid from another?the side group
Which of the following elements is found in certain amino acids?sulfur
Which of the following terms is NOT used to classify amino acids in the diet?partially essential
How many different kinds of amino acids make up proteins?20
Which of the following is NOT contained in an amino acid?An aldehyde group
Approximately how many different amino acids are used in the synthesis of body proteins?20
What is the simplest amino acid?Glycine
Which of the following is NOT an essential amino acid in human nutrition?Proline
What amino acid is classified as conditionally essential when dietary intake of phenylalanine is insufficient or the body cannot normally metabolize phenylalanine?Tyrosine
Which of the following is a feature of an essential amino acid?It must be supplied by the diet
What type of reaction is required to bind two molecules of glycine together and release a molecule of water?Condensation
When two amino acids are chemically joined together, the resulting structure is called adipeptide.
What is the composition of a tripeptide?Three amino acids bonded together
What is meant by the amino acid sequence of a protein?Order of amino acids in the peptide chain
A dispensable amino acid is one thatcan be synthesized by the body.
In comparison to the well-defined structure of starch, which is the most important factor that allows for the synthesis of thousands of different proteins?Number of different amino acids
Which of the following would be classified as a polypeptide?20 amino acids bonded together
The following amino acids are linked together: glycine-lysine-valine. This compound is atripeptide.
The weak electrical attractions within polypeptide chains account for the protein'ssecondary structure.
Which of the following is a feature of hemoglobin?It is constructed of 4 polypeptide chains
An example of a protein with quaternary polypeptide structures ishemoglobin.
What is the process by which heat or acidity disrupts the normal shape of a protein chain?Denaturation
The application of heat or acid to a protein that causes its shape to change is known asdenaturation.
What process results in the hardening of an egg when it is exposed to heat?Denaturation
After a hamburger is eaten, in what organ is the hydrolysis of its proteins initiated?Stomach
What is the name of the inactive form of the protein-splitting enzyme in the stomach?Pepsinogen
In what organ is pepsin active?Stomach
What digestive enzyme would be most affected in people who are unable to produce hydrochloric acid?Pepsin
Protein-hydrolyzing enzymes are commonly known asproteases.
The function of a protease is tohydrolyze proteins.
What is the chief function of pepsin?Cleaves proteins into smaller polypeptides
What percentage of dietary protein is hydrolyzed in the mouth?0
After digestion of proteins, what products are absorbed into the circulation?Free amino acids, and a few dipeptides and tripeptides
What is the usual fate of orally ingested enzyme supplements?Digested by gastrointestinal proteases
What is NOT characteristic of enzymes?They are involved in synthesis reactions only
Which of the following describes the structure of pepsin?Protein
Of the following sources of amino acids, which would be best absorbed in normal, healthy people?Whole proteins
Your cousin Wanda was born with a genetic defect affecting her digestion, namely, a lack of intestinal villus tripeptidases and dipeptidases. Which digestive processes would NOT take place?Peptides amino acids
Which of the following describes a process in protein synthesis?The code to make a protein is carried by a strand of messenger RNA
Which of the following is a characteristic of protein synthesis?Messenger RNA is constructed from a DNA template to carry instructions
The process whereby messenger RNA is made from a DNA template istranscription.
What is a ribosome?A structure upon which proteins are assembled
Which does NOT describe a feature of protein in nutrition?Most of the body's thousands of proteins have been studied thoroughly
Your college dormitory roommate, James, told you that he's had anemia for quite some time and that it's from having abnormally-shaped hemoglobin. What type of anemia does James have?Sickle-cell anemia
A common genetic variation which causes a change in the amino acid sequence in the structure of hemoglobin leads to the diseasesickle-cell anemia.
Which of the following is characteristic of sickle-cell anemia?The abnormal structure of the hemoglobin alters the shape of the red blood cell
What is the structure of an enzyme?Protein
What protein is intimately involved in the formation of scar tissue in wound healing?Collagen
What type of protein would the body make in order to heal a wound?Collagen
What term signifies when a cell makes a protein under the directions of a gene?Gene expression
Which of the following is a characteristic of hormones?Act as messenger molecules
Which does NOT function as a transport protein?Collagen
What is the relationship between body proteins and water?Proteins attract water
The conditions known as acidosis and alkalosis refer to a disruption of the body'spH balance.
Tissue swelling that results from water accumulating between cells is known asedema.
Proteins, because they attract hydrogen ions, can act asbuffers.
What function does a buffer perform?Helps maintain a constant pH
Which of the following processes is regulated primarily by the buffering action of proteins?pH balance
How do sodium and potassium travel into and out of cells?There are transport proteins within the cell membrane that pick up and release the minerals across the membrane
What is opsin?A light-sensitive protein
Which of the following proteins inactivates foreign bacteria and viruses?Antibodies
The body's usual response to detection of antigens is to synthesizeantibodies.
Which of the following describes the structure of an antibody?Huge protein molecule
Which of the following is involved in the clotting of blood?Fibrin
Given that protein is 16% nitrogen, how many grams of nitrogen are contained in a 2500-kcalorie diet that provides 15% of the energy as protein?15
Which of the following may be used to determine protein utilization?Nitrogen balance
When nitrogen taken into the body exceeds nitrogen losses, we say the person is inpositive nitrogen balance.
Which of the following defines protein turnover?The sum of protein synthesis and degradation
What is the amino acid pool?A mix of essential and nonessential amino acids derived from protein breakdown and dietary protein intake
Which of the following describes the state of nitrogen balance for a normal, healthy 35-year-old person who weighs 60 kg and consumes a diet that provides 75 g of protein and adequate energy?Equilibrium
The body's amino acid pool consists ofboth essential and nonessential amino acids.
What is the nitrogen balance of a person who consumed a 3500-kcalorie diet containing 10% protein and excreted a total of 12 grams of nitrogen? (Protein is 16% nitrogen.)+2 g
Which of the following would describe the state of nitrogen balance of a person who ingested 16 g of food nitrogen and lost 19 g of nitrogen?Negative balance
What is the usual state of nitrogen balance for healthy infants, children, and pregnant women?Positive
What amino acid is used to synthesize the neurotransmitter serotonin and the vitamin niacin?Tryptophan
What is meant by protein turnover?The synthesis and degradation of body proteins
What is the fate of excess dietary protein?After absorption, the extra amino acids will be rapidly degraded
When amino acids are deaminated, the immediate products are ammonia and often aketo acid.
Protein sparing in the body is best achieved when a person ingestsadequate levels of carbohydrate and fat.
A person who is starving is losingglycogen, protein, and fat.
Which of the following illustrates a deamination reaction?Removal of the amino group from an amino acid
Approximately how much urea (g) can be produced daily by the average adult?250 g
Which of the following is the most likely side effect of a high-protein, low-carbohydrate diet?Increased thirst
Which compound does NOT contain nitrogen?Cholesterol
Which of the following is a consequence of excess protein intake?Increased production and excretion of urea
Which of the following are precursors of urea synthesis?All amino acids
What is the process whereby an amino group is combined with a keto acid to form an amino acid?Transamination
In the metabolism of amino acids for energy, what is the fate of the amino group?Excreted as urea
The body's need for water increases on a diet high inprotein.
What is the most likely reason for a person to have abnormally high blood ammonia levels?Liver dysfunction
Jason is 35 years old and was recently diagnosed with 2 failing kidneys. He was advised to decrease the amount of protein he consumes. If Jason cheats by eating an 8-ounce steak for dinner tonight, shortly thereafter there would most likely be an increase in the urea levels of hisblood.
What is the most likely reason for having an abnormally high blood urea level?Kidney dysfunction
A prominent result of transamination reactions is the synthesis ofnonessential amino acids.
Your father, who has a high blood ammonia concentration, most likely has a poorly functioningliver.
Your mother, who has a high blood urea content, most likely has a poorly functioningkidney.
What is the percent digestibility of most plant proteins?70-90
What is the percent digestibility of most animal proteins?90-99
Which of the following food proteins has the best assortment of essential amino acids for the human body?Egg
Which of the following is related to the quality of a food protein?Essential amino acid balance
What primary factor governs the quality of a food protein?Essential amino acid content
In the study of protein nutrition, what term describes the amount of amino acids absorbed from a given amount of protein consumed?Digestibility
Which of the following animal-derived proteins is classified as a poor-quality protein?Gelatin
If the diet is lacking an essential amino acid, what will be the course of action?Protein synthesis will be limited
What is a "limiting" amino acid in a protein?An essential amino acid present in insufficient quantity for body protein synthesis to take place
Gelatin is a poor-quality protein because itlacks tryptophan.
Alberta is a 20 year old who has been a vegetarian for 3 years. She comes to you for advice after reading some material online by the Meat Promoters of America organization. One of their statements is: "...vegetarians are at risk for protein deficiency because they cannot consume all of the essential amino acids necessary for healthy individuals." How should Alberta be advised?Although many foods don't provide all the essential amino acids individually, she could consume complementary proteins throughout the day, which would provide all the essential amino acids she needs
Which of the following is characteristic of protein nutrition in vegetarians?Most vegetarians eating a variety of foods need not balance essential amino acid intake at each meal
What is the Daily Value for protein based on a 2000-kcalorie intake?50 g
What is complementary protein nutrition?A strategy that combines plant proteins in the same day to improve the balance of essential amino acids
In general, the protein quality in grains would be most improved by the addition of a plant protein rich inlysine.
In general, the protein quality of legumes would be most improved by the addition of a plant protein rich inmethionine.
Relative to animal proteins, which of the following amino acids is present in lesser amounts in proteins of legumes?Tryptophan
Excessive amounts of homocysteine in the blood are thought to increase the risk forheart disease.
Which of the amino acids has been reported to lower blood pressure and reduce homocysteine levels?Arginine
Which of the following is a feature of homocysteine?It is increased in the blood of coffee drinkers
Which of the following describes a relationship between protein/amino acids and heart disease?Elevated blood homocysteine levels are associated with smoking cigarettes and drinking alcohol
What ratio (mg:g) of calcium to protein intake is believed to promote optimal bone health?20:1
Which of the following describes an association between protein intake and kidney function?Restricting protein intake may slow the progression of kidney disease
Based on the range of protein intake as a percentage of energy intake, what would be the highest safe level of protein intake for a 60-kg adult ingesting 2500 kcalories?219 g
Which of the following describes a relationship between protein intake and calcium metabolism?Calcium excretion rises with increasing intake of animal-derived proteins
What is the RDA for protein for a 48-kg woman?38 g
What is the actual ratio of calcium to protein intake (mg to g) for most U.S. women?9:1
What would be the primary principle of wise diet planning as related to protein nutrition?Moderation
Which of the following is a feature of the protein RDA?The recommendations are generous
If protein needs are expressed per kilogram of body weight, which of the following describes the requirements of infants?Greater than adults
What is the range of daily protein intake, in g/kg, recommended for athletes by fitness authorities?1.2-1.7
Your friend Jill has just joined her community college soccer team. How much protein should she consume each day?1.2-1.7 g/kg
Which is an assumption made in the formulation of the RDA for protein?Dietary carbohydrate and fat intakes are adequate
Which is a feature of protein nutrition?The protein RDA assumes that dietary protein is from a mix of low- and high-quality sources
What is the percentage of total energy derived from protein in a diet containing 50 grams of protein and 2000 kcalories?10
If a person consumes 65 grams of protein and a total of 2700 kcalories per day, approximately what percentage of energy would be derived from protein?10
Approximately how many grams of protein are found in one quart of milk?32
Which of the following is a feature of whey protein?It is a waste product of cheese production
Jim, a college baseball player, tells you that he has started to take glutamine supplements. How would you advise him?Since single amino acids do not occur naturally in foods, they offer no benefit to the body and may even be harmful
Which of the following is a feature of the branched-chain amino acids?They may be helpful in treatment of advanced liver failure
What amino acid has been linked to the development of the rare blood disorder eosinophilia-myalgia syndrome in people who took it as a supplement?Tryptophan
What amino acid supplement has been advertised in the popular media for treating herpes infections?Lysine
The disease phenylketonuria is related chiefly to abnormal metabolism ofa certain amino acid.
The study of how food interacts with genes is known asnutritional genomics.
The study of how environmental factors influence the expression of genes without altering the DNA is known asepigenetics.
The cell's proteome consists ofall the protein in the cell.
The cell process of silencing or activating genes is in part accomplished byDNA methylation.
Approximately what percentage of a person's genes are similar to those of an unrelated person?99.9
What dispensable amino acid becomes essential in people with PKU?Tyrosine
The incidence of PKU in infants in the United States is one in every15,000 births.
Dietary restriction of phenylalanine combined with adequate tyrosine is the usual treatment for people born with the disorderPKU.
A variation in a single nucleotide of a DNA strand is called a(n)single nucleotide polymorphism.
proteinscompounds composed of carbon, hydrogen, oxygen and nitrogen atoms, arranged into amino acids linked in a chain
amino acidsbuilding blocks of proteins
nonessential amino acidsones that the body can synthesize (make) itself
essential amino acidsamino acids that the body cannot synthesize in amounts sufficient to meet physiological needs
conditionally essential amino acidone that is normally nonessential, but must be supplied by the diet in special circumstances when the need for it exceeds the body's ability to produce it
peptide bonda bond that connects the acid end of one amino acid with the amino end of another, forming a link in a protein chain
dipeptidetwo amino acids bonded together
tripeptidethree amino acids bonded together
polypeptidemany (10 or more) amino acids bonded together
hemoglobinthe globular protein of the red blood cells that carries oxygen from the lungs to the cells throughout the body
pepsina gastric enzyme that hydrolyzes protein. Secreted in an inactive form, pepsinogen, which is activated by hydrochloric acid in the stomach
proteasesenzymes that hydrolyze protein
peptidasea digestive enzyme that hydrolyzes peptide bonds.
transcriptionthe process of messenger RNA being made from a template of DNA
translationthe process of messenger RNA directing the sequence of amino acids and synthesis of proteins
gene expressionthe process by which a cell converts the genetic code into RNA and protein
matrixthe basic substance that gives form to a developing structure
collagenthe structure protein from which connective tissues such as scars, tendons, ligaments, and the foundations of bones and teeth are made
acidscompounds that release hydrogen ions in a solution
basescompounds that accept hydrogen ions in a solution
bufferscompounds that keep a solution's PH constant when acids or bases are added
acidosishigher-than-normal activity in the blood and body fluids
alkalosishigher-than-normal alkalinity (base) in the blood and body fluids
antigenssubstances that elicit the formation of antibodies or an inflammation reaction from the immune system.
antibodieslarge proteins of the blood and body fluids, produced by the immune system in response to the invasion of the body by foreign molecules.
protein turnoverthe degradation and synthesis of protein
amino acid poolthe supply of amino acids derived from either food proteins or the body proteins that collect in the cells and circulating blood and stand ready to be incorporated in proteins and other compounds or used for energy
nitrogen balancethe amount of nitrogen consumed (N in) as compared with the amount of nitrogen excreted (N out) in a given period of time
neurotransmitterschemicals that are released at the end of a nerve cell when a nerve impulse arrives there.
serotonina neurotransmitter important in sleep regulation, appetite control, and sensory perception, among other roles.
deaminationremoval of the amino (NH2) group from a compound such as an amino acid
ammoniaa compound with the chemical formula NH3 produced during the deamination of amino acids
keto acidan organic acid that contains a carbonyl group
transaminationthe transfer of an amino group from one amino acid to a keto acid, producing a new nonessential amino acid and a new keto acid
limiting amino acidthe essential amino acid found in the shortest supply relative to the amounts needed for protein synthesis in the body. 4 amino acids are most likely to be limiting: lysine, methionine, threonine, tryptophan
branched-chain amino acidsthe essential amino acids leucine, isoleucine, and valine, which are present in large amounts in skeletal muscle tissue
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