Nutriton Amino Acids Unit 6
The IOM does not set different RDAs for protein intakes for athletes, but the AND, the American College of Sports Medicine, and Dietitians of Canada have the following position statements:
"Nitrogen balance studies suggest that dietary protein intake necessary to support nitrogen balance in endurance athletes ranges from 1.2 to 1.4 grams per kilogram of body weight per day." "Recommended protein intakes for strength-trained athletes range from approximately 1.2 to 1.7 grams per kilogram of weight per day" (
Generally, "normal" people need around ____ grams of protein per kilogram of healthy body weight
0.8 gm of protein per kilogram of a healthy body weight. For example, if a moderately active person weighing 154 pounds were convert their weight to kilograms (154#/2.2 kg/lb) that would give them a weight of 70 kg. If you take that 70 kg x 0.8 g protein/kg healthy body weight, you get 56 g protein per day.
here are over ____different proteins in the human body.
100,000 Different proteins are produced because there are twenty types of naturally occurring amino acids that are combined in unique sequences.
collagen
6 percent of total body weight. Collagen makes up 30 percent of bone tissue and comprises large amounts of tendons, ligaments, cartilage, skin, and muscle. Collagen is a strong, fibrous protein made up of mostly glycine and proline amino acids. Within its quaternary structure three protein strands twist around each other like a rope and then these collagen ropes overlap with others. This highly ordered structure is even stronger than steel fibers of the same size. Collagen makes bones strong, but flexible. Collagen fibers in the skin's dermis provide it with structure, and the accompanying elastin protein fibrils make it flexible. Pinch the skin on your hand and then let go; the collagen and elastin proteins in skin allow it to go back to its original shape.
Considering that a single ounce of meat or ½ cup of beans gives around. _____ ounce of protein during the day
7 ounces of protein each, it is easy to get adequate protein during the day—even for vegetarians! In fact, the only food group that doesn't contain any protein is the fruit group. Even vegetables and whole grains contain some protein with the protein group (obviously) and the dairy group containing the most.
in endurance athlete who weighs 170 pounds should take in ______ grams of protein per day On a 3,000-kilocalorie diet, that amount is between ________percent of total kilocalories and within the AMDR. There is general scientific agreement that endurance and strength athletes should consume protein from high-quality sources, such as
93 to 108 grams (170 ÷ 2.2) × 1.2 and (170 ÷ 2.2) × 1.4). 12 and 14 dairy, eggs, lean meats, or soy; however eating an excessive amount of protein at one time does not further stimulate muscle-protein synthesis.
keratin
Another strong, fibrous protein is keratin, which is what skin, hair, and nails are made of.
why is maintaining PH balance in the body important
Blood pH is maintained between 7.35 and 7.45, which is slightly basic. Even a slight change in blood pH can affect body functions. Recall that acidic conditions can cause protein denaturation, which stops proteins from functioning.
other protein sources
Cells are made up of proteins which are continuously replaced. Proteins build most enzymes. . Enzymes, not only aid in digestion, but build substances, such as bone, and transform one substance into another. They act as catalysts, remain unchanged by the chemical processes which they help, and can make multiple chemical processes happen. Proteins form hormones & other important compounds: neurotransmitters : norepinephrine, epinephrine, seratonin relay nervous system messages throughout the body; melanin : forms pigments in our skin, hair, and eyes; thyroxin : regulates the metabolic rate; and n iacin : protein (the amino acid tryptophan) serves a precursor to the vitamin niacin.
Our ______ tells our body how to make proteins
DNA
how does proteins help with fluid balance in the blood
Fluid balance refers to maintaining the distribution of water in the body. If too much water in the blood suddenly moves into a tissue, the results are swelling and, potentially, cell death. Water always flows from an area of high concentration to one of a low concentration. As a result, water moves toward areas that have higher concentrations of other solutes, such as proteins and glucose. To keep the water evenly distributed between blood and cells, proteins continuously circulate at high concentrations in the blood.
Nonpolar amino acids.
Nonpolar amino acids include alanine (Ala), leucine (Leu), isoleucine (Ile), proline (Pro), tryptophan (Trp), valine (Val), phenylalanine (Phe), and methionine (Met). The side chains of these amino acids are long carbon chains or carbon rings, making them bulky. They are hydrophobic, meaning they repel water.
Protein is also essential in maintaining proper pH balance (the measure of how acidic or basic a substance is) in the blood.
One of these is the circulating albumin. Albumin is slightly acidic, and because it is negatively charged it balances the many positively charged molecules, such as hydrogen protons (H+), calcium, potassium, and magnesium which are also circulating in the blood. Albumin acts as a buffer against abrupt changes in the concentrations of these molecules, thereby balancing blood pH and maintaining the status quo. The protein hemoglobin also participates in acid-base balance by binding hydrogen protons.
Some of the amino acids in proteins can be disassembled and used to make energy.
Only about 10 percent of dietary proteins are catabolized each day to make cellular energy. The liver is able to break down amino acids to the carbon skeleton, which can then be fed into the citric acid cycle. This is similar to the way that glucose is used to make ATP. If a person's diet does not contain enough carbohydrates and fats their body will use more amino acids to make energy, which compromises the synthesis of new proteins and destroys muscle proteins. Alternatively, if a person's diet contains more protein than the body needs, the extra amino acids will be broken down and transformed into fat.
essential and nonessential amino acids
Our bodies can synthesize some of these amino acids, the eleven nonessential amino acids. But nine of them, known as essential amino acids, we must metabolize from proteins in the foods we eat.
Even though [the majority of] plant-based proteins aren't complete (unless you combine them, which is pretty easy to do), they do offer additional benefits beyond animal protein.
Plant-based proteins usually have minimal saturated fat and no cholesterol. They can be high in fiber and phytochemicals. Lean meats, poultry, and pork are good sources of complete proteins and are generally well-absorbed sources of the minerals zinc and iron which are critical for health.
Polar amino acids.
Polar amino acids are glycine (Gly), serine (Ser), threonine (Thr), cysteine (Cys), tyrosine (Tyr), asparagine (Asn), and glutamine (Gln). The side chains of polar amino acids make them hydrophilic, meaning they are water-soluble.
Nitrogen balance is a clinical way of judging the adequacy of and use of protein in our bodies. This is not a test you can just run to doctor for, it's quite expensive and only used in research. However, it's been studied enough that it helps us know how much protein a person generally needs depending on the condition of their health.
Positive nitrogen balance occurs when protein intake exceeds what is excreted, such as during periods of growth, recovery from illness, and pregnancy. Nitrogen balance equilibrium occurs when there is a balance of protein synthesis and protein breakdown. Negative nitrogen balance is the condition by which the body is breaking down more protein than it is producing, such as during a time of illness or injury.]
how do proteins help
Protein makes up approximately 20 percent of the human body and is present in every single cell. Proteins are called the workhorses of life as they provide the body with structure and perform a vast array of functions. You can stand, walk, run, skate, swim, and more because of your protein-rich muscles. Protein is necessary for proper immune system function, digestion, and hair and nail growth, and is involved in numerous other body functions
structure of proteins
Proteins are long, chain-like structures of amino acids, which are bound together in different sequences by a chemical bond known as a peptide bond. Amino acids are structured similarly. Each comprises a central carbon atom connected to an amine group, an acid group, and a hydrogen atom. What gives each amino acid its unique properties and behaviors is its side chain.
hormones
Proteins are responsible for hormone synthesis. hormones are the chemical messages produced by the endocrine glands. When an endocrine gland is stimulated, it releases a hormone. The hormone is then transported in the blood to its target cell, where it communicates a message to initiate a specific reaction or cellular process. A major function of hormones is to turn enzymes on and off, so some proteins can even regulate the actions of other proteins. While not all hormones are made from proteins, many of them are.
The first step in digesting the dietary proteins found in the sandwich begins by mechanical digestion in the mouth.
Proteins in foods are chewed, crushed, and moistened with saliva to ease swallowing and to increase their surface area for more efficient digestion. Chemical digestion of proteins does not occur in the mouth but rather in the stomach.
conditionally essential amino acids.
Sometimes during infancy, growth, and in diseased states the body cannot synthesize enough of some of the nonessential amino acids and more of them are required in the diet.
limiting amino acids. complete protein
The amino acid that is in the shortest supply in an incomplete protein is known as the limiting amino acids. Since the presence of essential amino acids varies depending on the plant, combining different plant-based foods together (example: beans & rice) creates a complete protein.
Furthermore, a protein is organized into four different structural levels.
The first level is the one-dimensional sequence of amino acids that are held together by peptide bonds.
Additionally, proteins come in many different sizes.
The hormone insulin, which regulates blood glucose, is composed of only fifty-one amino acids; whereas collagen, a protein that acts like glue between cells, consists of more than one thousand amino acids. Titin is the largest known protein. It accounts for the elasticity of muscles, and consists of more than twenty-five thousand amino acids!
how many enzymes does the liver have substrate and enzymes nearly all chemical reactions require a ____ enzyme
The liver alone contains over one thousand enzyme systems. Enzymes are specific and will use only particular substrates that fit into their active site, similar to the way a lock can be opened only with a specific key. Nearly every chemical reaction requires a specific enzyme. Fortunately, an enzyme can fulfill its role as a catalyst over and over again, although eventually it is destroyed and rebuilt. All bodily functions, including the breakdown of nutrients in the stomach and small intestine, the transformation of nutrients into molecules a cell can use, and building all macromolecules, including protein itself, involve enzymes resulting in muscle contraction.
R group
The side chain of an amino acid, sometimes called the "R" group, can be as simple as one hydrogen bonded to the carbon center, or as complex as a six-carbon ring bonded to the carbon center.
Although each side chain of the twenty amino acids is unique, there are some chemical likenesses among them. Therefore, they can be classified into four different groups.
These are nonpolar, polar, acidic, and basic.
UREA
] amino acids are degraded & their nitrogen-containing amine groups are removed. The nitrogen generates ammonia (NH3) which is converted to urea and excreted in the urine. When protein is broken down for energy, a by-product is ammonia: NH3, which is toxic. Therefore, the body adds carbon dioxide to turn it into urea which is less toxic. When we say less toxic, it means that it's still toxic, only less so than ammonia. Because urea is still toxic to body tissues, it still has to be released from the body. Since the liver is busy converting amino acids into energy, it releases the urea into the blood stream where the kidneys then filter it out.
In the metabolism of amino acids for energy, what is the fate of the amino group (the part of the molecule that contains the nitrogen)? a. It is excreted as urea through the kidneys. b. It is burned off for energy. c. It is stored in the liver. d. It is converted into glucose and stored as glycogen.
a correct Right! Good job! Unless we're making other proteins, the NH3 group on an amino acid is useless to the human body. NH3 is ammonia and very toxic to tissues so the liver converts it into a slightly less toxic compound called urea which is then excreted by the kidneys into the urine (there's a reason those two names sound very similar). If someone's liver is failing, you can detect elevated levels of ammonia in their blood and if someone's kidneys are failing, you can detect excess levels of urea in the blood. Both are toxic.
The function of a protease is to a. break down proteins. b. make proteins. c. break down ribosomes. d. make ribosomes.
a correct Right! Good job! Whenever you read about something whose name ends in -ase, that means you're reading about a digestive enzymes. Proteases are enzymes that digest protein.
What is the relationship between body proteins and water? a. Proteins attract water b. Water attracts proteins c. Water degrades proteins d. Proteins form polymers of water
a correct Right! Good job! Water is attracted to protein.Proteins help maintain fluid balance by ensuring that your body fluids are evenly dispersed in your blood, inside & outside your cells.
Protein digestion in the stomach takes (time)
a longer time than carbohydrate digestion, but a shorter time than fat digestion. Eating a high-protein meal increases the amount of time required to sufficiently break down the meal in the stomach. Food remains in the stomach longer, making you feel full longer.
collagen
a ropelike, fibrous protein used for structure, is the most abundant protein in your body. Even bones are made with a collagen foundation filled in with calcium and other minerals
The most abundant protein in blood is the butterfly-shaped protein known as
albumin. Albumin's presence in the blood makes the protein concentration in the blood similar to that in cells. Therefore, fluid exchange between the blood and cells is not in the extreme, but rather is minimized to preserve the status quo.
Recall that amino acids contain nitrogen, so further catabolism of amino acids releases nitrogen-containing
ammonia. Because ammonia is toxic, the liver transforms it into urea, which is then transported to the kidney and excreted in the urine. Urea is a molecule that contains two nitrogens and is highly soluble in water. This makes it a good choice for transporting excess nitrogen out of the body.
complementary proteins
and is how vegans ensure adequate protein intake. If we do not consume the essential amino acids, then proteins that require those amino acids cannot be produced Most plant-based foods are deficient in at least one essential amino acid and therefore are incomplete protein sources. For example, grains are usually deficient in the amino acid lysine, and legumes do not contain methionine or tryptophan. Because grains and legumes are not deficient in the same amino acids they can complement each other in a diet.
What function does a buffer perform? a. Helps emulsify fats b. Helps maintain a constant pH c. Facilitates chemical reactions d. Helps protect against plaque buildup
b correct Right! Good job! . Proteins help maintain acid-base balance by acting as buffers. Buffers are substances that help maintain the proper pH in a solution by attracting or donating hydrogen ions. A drop in pH will cause your body fluids to become too acidic (thus breaking apart protein structures), whereas a rise in pH can make your body too basic.
In what organ of digestion is the enzyme pepsin active? a. Mouth b. Stomach c. Small intestine d. Large intestine
b correct Right! Good job! Pepsin is a special enzyme. Not only can it survive the acidic environment of the stomach, but that is the environment where it works best.
Which of the following is a characteristic of hormones? a. Inactivate bacteria b. Act as messenger molecules c. Coordinate visual response d. Act as buffers in the bloodstream
b correct Right! Good job! Some hormones are made from protein and others from lipids. Hormones are part of our endocrine system and act as messengers. When a condition of the body changes (such as food enters the stomach) the body's cells experiencing the change release hormones which then tell another part of the body to also make a change (the release of gastric acid and proteases in the stomach).
Which of the following elements does protein NOT have in common with carbohydrates & fats? a. Oxygen b. Nitrogen c. Carbon d. Hydrogen
b correct Right! Good job! The base of an amino acid also contains nitrogen.
protein found how much energy do they provide/gram what are proteins used for in our bodies
body structure of animals is based on proteins. Proteins are a macronutrient indicator in our diets and provide four calories per gram. However, their least important function in our diets as an energy source. Proteins in our diets are sources of amino acids which our body then uses to build proteins (based on our DNA). Proteins are responsible for much of the structure and function of our bodies. ]
Proteins make up our body's
building materials and make up the majority of our body tissues ( tissue maintenance and repair) . Proteins provide structural and mechanical support and help maintain body tissues.
What is meant by protein turnover? a. Nitrogen equilibrium b. The antibody-antigen complex c. The synthesis and degradation of body proteins d. The secondary structure of proteins that initiates folding
c correct Right! Good job! Protein turnover is the name for the body's process of constantly creating and breaking down proteins to meet its needs
Denaturation of a protein results in a. the removal of amino acids. b. tighter folding of the protein. c. alterations in the protein's function. d. binding of amino acids.
c correct Right! Good job! A protein's structure is absolutely critical to its function. Without it, it does not work anymore.
The two major pancreatic enzymes that digest proteins are The cells that line the small intestine release The muscle contractions of the small intestine In the lower parts of the small intestine, the amino acids are
chymotrypsin and trypsin. additional enzymes that finally break apart the smaller protein fragments into the individual amino acids. mix and propel the digested proteins to the absorption sites. transported from the intestinal lumen through the intestinal cells to the blood. This movement of individual amino acids requires special transport proteins and the cellular energy molecule, adenosine triphosphate (ATP)
The average adult, age 19 and older, should consume _______grams of protein for each kilogram of body weight.
correct 0.8 Right! Good job! Generally, "normal" people need around 0.8 gm of protein per kilogram of a healthy body weight.
The body structure of plants is based primarily on____ whereas the body structure of animals is based on_____ .
correct carbohydrate correct protein Right! Good job! The body structure of plants is based on carbohydrate and lipid whereas the body structure of animals is based on proteins.
A person who was recently severely injured in a car accident would be in _______ nitrogen balance.
correct negative Right! Good job! Negative nitrogen balance indicates a person is using more protein that what they've been eating. Body tissues are being broken down to supply the deficiency of the diet.
A pregnant woman would typically be in _____ nitrogen balance.
correct positive Right! Good job! Positive nitrogen balance means that protein is being used to make new tissues, blood, bone, skin and muscles. This means that protein we're eating is being used as protein, not as energy or glucose.
The _____ of a protein determines its function.
correct structure Right! Good job! The structure of a protein is so important that if it loses that structure, it no longer does its correct job.
What protein is intimately involved in the formation of scar tissue in wound healing? a. Albumin b. Thrombin c. Hydroxyproline d. Collagen
d correct Right! Good job! Collagen is an important structural protein and has a critical role in wound healing.
deamination
deamination removes an amino group from an amino acid. the amino group is converted to ammonia and then to urea. It is released by the kidneys. this process leaves behind a carbon Skelton the structure of the carbon skelton shows where it will enter the energy pathway.
Before a protein from food can be absorbed, it must be Denaturation can also happen in our bodies-
denatured during the digestion process. Denaturing is the opposite of the structural process described in the previous section. When you affect the structure of a protein—through cooking, marinade, tenderizing, etc.—you start the denaturing process that helps our digestive tract break down the proteins in foods to individual amino acids for absorption. -which is dangerous! Very high fever or an altered pH balance can cause proteins working in our bodies to denature and stop functioning. This is why these conditions can lead to death
How much protein you need also depends on protein quality . A high quality protein is considered one that is easily
digestible and contains all the essential amino acids. The digestibility of a protein can be affected by its source. For example, cooked animal proteins are very accessible to our digestive tract. Plant proteins on the other hand can often be encased within cell walls (fiber) and less easy to digest. However, cooking of plant proteins (like legumes) makes the protein within more available to digestive enzymes. Plant proteins are generally incomplete , meaning they don't contain all of the nine essential amino acids.
animal protein and vegetable protein probably have the same
effects on health. It's the protein package that's likely to make a difference Simply put, different protein sources differ in their additional components, so it is necessary to pay attention to the whole nutrient "package."
Although proteins are found in the greatest amounts in connective tissues such as bone, their most extraordinary function is as
enzymes. Enzymes are proteins that conduct specific chemical reactions. An enzyme's job is to provide a site for a chemical reaction and to lower the amount of energy and time it takes for that chemical reaction to happen (this is known as "catalysis"). On average, more than one hundred chemical reactions occur in cells every single second and most of them require enzymes.
A common myth is that protein intake directly supports muscle growth and development. The only thing that does that is
exercise—specifically strength training! A key for skeletal muscle growth is that protein synthesis must exceed breakdown, but increased protein intake (above needs) does not increase net protein balance, so increasing protein intake to maximize growth won't do anyone any good
People who meet the 2008 Physical Activity Guidelines for Americans have higher protein needs than sedentary people. True False
f correct Right! Good job! Physically active, non-athletes can use the DRI for protein which is 0.8 g/kg of body weight per day.
If the body needs additional protein, it can take fat from our fat stores & use it to make new proteins. True False
f correct Right! Good job! Once carbohydrate or protein gets converted to fat there is no going back. Protein can get converted into carbohydrate and carbohydrate skeletons can be converted into non-essential amino acids if there's nitrogen available, but fat can only become fat or the molecule acetyl CoA which is involved in energy metabolism.
Denaturing a protein alters its sequence of amino acids. True False
f correct Right! Good job! The sequence of amino acids in the primary structure of a protein is determined by the DNA of the animal or plant that made it. Denaturation doesn't change this sequence, but does affect the tertiary and quaternary structures.
A denatured protein is still able to function as long as its amino acids are intact. True False
f correct Right! Good job! A good example of this is eggs. If you take an (fertilized) egg from a chicken, boil it, and then put it back under the chicken, can you still get a chick? Nope. The application of heat denatured all the proteins critical for that chick's life so the egg is no longer viable. It is, however, more edible to humans because cooking eggs releases important nutrients like biotin.
proteins help with immune system
immune system's attack and destroy functions are dependent on enzymes and antibodies, which are also proteins. An enzyme called lysozyme is secreted in the saliva and attacks the walls of bacteria, causing them to rupture. Certain proteins circulating in the blood can be directed to build a molecular knife that stabs the cellular membranes of foreign invaders. The antibodies secreted by the white blood cells survey the entire circulatory system looking for harmful bacteria and viruses to surround and destroy. Antibodies also trigger other factors in the immune system to seek and destroy unwanted intruders
Our digestive system breaks down those proteins into Dietary proteins are digested in the During digestion of protein, small intestines
individual amino acids and then our DNA uses those amino acids to build new proteins. stomach and small intestine and absorbed in the small intestine. gastric acid in the stomach denatures proteins by beginning the process of uncoiling them from their original structures. Then, the enzyme pepsin will break the polypeptide chains into small chains. In the small intestine, polypeptides are broken down into individual amino acids and then absorbed across the wall of the small intestine to enter the blood stream for transport to the liver and processing.]
Proteins are involved in all aspects of wound healing, a process that takes place in three phases:
inflammatory, proliferative, and remodeling. For example, if you were sewing and pricked your finger with a needle, your flesh would turn red and become inflamed. Within a few seconds bleeding would stop. The healing process begins with proteins such as bradykinin, which dilate blood vessels at the site of injury. An additional protein called fibrin helps to secure platelets that form a clot to stop the bleeding. Next, in the proliferative phase, cells move in and mend the injured tissue by installing newly made collagen fibers. The collagen fibers help pull the wound edges together. In the remodeling phase, more collagen is deposited, forming a scar. Scar tissue is only about 80 percent as functional as normal uninjured tissue. If a diet is insufficient in protein, the process of wound healing is markedly slowed.
The fourth level of structure (also known as its "quaternary" structure)
is achieved when protein fragments called peptides combine to make one larger functional protein. [ These subunits are bound together by numerous weak interactions and it is this structure that is most critical for protein function. The sites at which protein action occurs is based on the juxtaposing of the different amino acid functional groups. The protein hemoglobin is an example of a protein that has quaternary structure. It is composed of four peptides that bond together to form a functional oxygen carrier.
Once the amino acids are in the blood, they are transported to the
liver. As with other macronutrients, the liver is the checkpoint for amino acid distribution and any further breakdown of amino acids, which is very minimal.
Someone who has a low-protein diet may also be in Positive nitrogen balance occurs when a person excretes less At these times the body requires more protein to build new tissues, so more of what gets consumed gets used up and less nitrogen is excreted. (example)
negative nitrogen balance as they are taking in less protein than what they actually need. nitrogen than what is taken in by the diet, such as during child growth or pregnancy. A person healing from a severe wound may also be in positive nitrogen balance because protein is being used up to repair tissues.
amino acids are recycled to make
new proteins. All cells in the body continually break down proteins and build new ones, a process referred to as protein turnover. Every day over 250 grams of protein in your body are dismantled and 250 grams of new protein are built. To form these new proteins, amino acids from food and those from protein destruction are placed into a "pool."
Recall that there are twenty different amino acids, and we require all of them to make the many different proteins found throughout the body Eleven of these are called However,9 amino acids because we
nonessential amino acids because the body can synthesize them. [ They are synthesized other amino acids or by adding nitrogen to carbon-containing structures from glucose metabolism]. cannot synthesize them either at all or in sufficient amounts. These must be obtained from the diet.
Nutrition experts also recommend that athletes consume some protein within______ hrs after exercise to enhance muscle tissue repair during the recovery phase, but some carbohydrates and water should be consumed as well. The recommended ratio from nutrition experts for exercise-recovery foods is
one hour 4 grams of carbohydrates to 1 gram of protein.
RNA is chemically similar to DNA, but has two differences;
one is that its backbone uses the sugar ribose and not deoxyribose; and two, it contains the nucleotide base uracil, and not thymidine. The RNA that is transcribed from a given piece of DNA contains the same information as that DNA, but it is now in a form that can be read by the cellular protein manufacturer known as the ribosome. Next, the RNA instructs the cells to gather all the necessary amino acids and add them to the growing protein chain in a very specific order. This process is referred to as translation. The decoding of genetic information to synthesize a protein is the central foundation of modern biology.
Denaturation refers to the
physical changes that take place in a protein exposed to abnormal conditions in the environment. Heat, acid, high salt concentrations, alcohol, and mechanical agitation can cause proteins to denature. When a protein denatures, its complicated folded structure unravels, and it becomes just a long strand of amino acids again. Weak chemical forces that hold tertiary and secondary protein structures together are broken when a protein is exposed to unnatural conditions.
Proteins are similar to carbohydrates and lipids in that they are in contrast to carbohydrates,
polymers of simple repeating units; however, proteins are much more structurally complex. which have identical repeating units, proteins are made up of amino acids that are different from one another.
Intense exercise, such as strength training, stresses muscle tissue so that afterward, the body adapts by building bigger, stronger, and healthier muscle tissue. The body requires protein
post-exercise to accomplish this.
The food's protein quality is then ranked against the foods highest in examples
protein quality. Milk protein, egg whites, whey, and soy all have a ranking of one, the highest ranking.
The appropriate amount of protein in a person's diet is that which maintains a balance between what is The RDAs for protein were determined by assessing Remember that when the liver breaks down amino acids, it produces Most nitrogen is lost as
taken in and what is used. nitrogen balance. Nitrogen is one of the four basic elements contained in all amino acids. When proteins are broken down and amino acids are catabolized, nitrogen is released. ammonia, which is rapidly converted to nontoxic, nitrogen-containing urea, which is then transported to the kidneys for excretion. urea in the urine, but urea is also excreted in the feces. Proteins are also lost in sweat and as hair and nails grow
Once in the small intestine,
the polypeptides encounter protein enzymes, known as proteases, secreted from the pancreas and the small intestine. These proteases split the polypeptides into single amino acids. The complex proteins in the sandwich you ate, now digested into single amino acids, are absorbed through the intestinal cell and transported to the liver to be dispersed throughout the body. These proteases split the polypeptides into single amino acids. The complex proteins in the sandwich you ate, now digested into single amino acids, are absorbed through the intestinal cell and transported to the liver to be dispersed throughout the body.
2nd level
the two-dimensional level of protein structure is dependent on the chemical interactions between amino acids, which cause the protein to fold into a specific shape, such as a helix (like a coiled spring) or sheet. [ Folding is accomplished through hydrogen bonding, ionic bonding; and hydrophobic and other interactions between individual R groups (side chains) on the amino acids.]
The third level of protein structure is
three-dimensional. As the different side chains of amino acids chemically interact, they either repel or attract each other, resulting in the coiled structure. [ For example, one R (side chain) group can have a negative charge which is attracted to the positive charge of a R group on another amino acid.]
The first step in constructing a protein is the
transcription (copying) of the genetic information in double-stranded deoxyribonucleic acid (DNA) into the single-stranded, messenger macromolecule ribonucleic acid (RNA).
The building of a protein consists of a complex series of chemical reactions that can be summarized into three basic steps:
transcription, translation, and protein folding.
Muscle tissue is rich in protein composition and has a very high ____ rate During exercise, especially when it is performed for longer than two to three hours, muscle tissue is
turnover rate. broken down and some of the amino acids are catabolized to fuel muscle contraction. To avert excessive borrowing of amino acids from muscle tissue to synthesize energy during prolonged exercise, protein needs to be obtained from the diet.
When proteins reach the stomach they are
uncoiled by hydrochloric acid in a process called denaturation. The hydrochloric acid denatures, or uncoils, the strands of amino acids. This allows pepsin, a protein-digesting enzyme also released in the stomach, to hydrolyze proteins into shorter polypeptide chains and single amino acids. These shorter polypeptide chains then travel to the small intestine for further digestion and absorption.
great post workout snacks
whole grain cereal banana protein bar
Acidic amino acids. Basic amino acids .
Acidic amino acids are negatively charged, hydrophilic amino acids and include aspartic acid (Asp) and glutamic acid (Glu). Basic amino acids are positively charged, hydrophilic amino acids and include lysine (Lys), arginine (Arg), and histidine
protein helps transport
Albumin chemically binds to hormones, fatty acids, some vitamins, essential minerals, and drugs, and transports them throughout the circulatory system. Each red blood cell contains millions of hemoglobin molecules that bind oxygen in the lungs and transport it to all the tissues in the body. A cell's plasma membrane is usually not permeable to large polar molecules, so to get the required nutrients and molecules into the cell many transport proteins exist in the cell membrane. Some of these proteins are channels that allow particular molecules to move in and out of cells. Others act as one-way taxis and require energy to function
Amino acids
Amino acids form the foundation of any protein. All amino acids contain carbon, hydrogen, oxygen, and nitrogen (which makes them unique from carbohydrates and fat which both just contain carbon, hydrogen, and oxygen). Amino acids have the same general structure except for the "R" group which differentiates each amino acid.
how many different proteins exist in the body what does the protein word mean
In fact, it is estimated that more than one hundred thousand different proteins exist within the human body. The word protein is a Greek word, meaning "of utmost importance."
The second component of protein quality is digestibility, as not all protein sources are equally digested.
In general, animal-based proteins are completely broken down during the process of digestion, whereas plant-based proteins are not. This is because some proteins are contained in the plant's fibrous cell walls and these pass through the digestive tract unabsorbed by the body.
amino acid pool
It is critical to maintain amino acid levels within this cellular pool by consuming high-quality proteins in the diet, or the amino acids needed for building new proteins will be obtained by increasing protein destruction from other tissues within the body, especially muscle. This amino acid pool is less than one percent of total body-protein content. Thus, the body does not store protein as it does with carbohydrates (as glycogen in the muscles and liver) and lipids (as triglycerides in adipose tissue).
A protein's structure also influences its nutritional quality.
Large fibrous protein structures are more difficult to digest than smaller proteins and some, such as keratin, are indigestible. Because digestion of some fibrous proteins is incomplete, not all of the amino acids are absorbed and available for the body to utilize, thereby decreasing their nutritional value.
How do the proteins from foods, denatured or not, get processed into amino acids that cells can use to make new proteins?
When you eat food the body's digestive system breaks down the protein into the individual amino acids, which are absorbed and used by cells to build other proteins and a few other macromolecules, such as DNA.
do athletes need more protein?
Yes! Athletes need more protein than do non-athletes. Endurance athletes need 1.2-1.4 g/kg while resistance athletes (or any athlete whose sport involves very high energy, short bursts of strength) need up to 1.7 g/kg. Here's the rub, though, most Americans already consume this amount —without the addition of protein powders/shakes/supplements!]
