Animal sources of protein...
- 1 egg = 7g of protein
- 1 cup milk = 8g protein
- 3oz meat = 20g protein
- 1/2 cup legumes = 6 to 10 g protein
- 1/4 nuts = 5 to 10 g protein
- slice of whole wheat bread, 1/2 cup rice or pasta = 2 to 3 g protein
Animal vs. plant nutrients...
Food from animals have lots of B Vitamins and iron, zinc, and calcium as well as protein. BUT! Animal based food is also high in sat. fat and cholesterol.
Food from plants have lots of fiber, phytochemicals, unsat. fats. BUT! don't have as absorbable forms of the minerals found in meat.
What is an amino acid?
A molecule that has a C atom with: an amino group ( NH2 ), a H atom, an acid group ( COOH ), and a side chain with variable make up all attached to it.
Amino acids connected to each other by linking acid groups to amino groups along a chain make up a protein.
What are nonessential amino acids?
Amino acids that the body can easily make in sufficient quantities.
There are 11 nonessential amino acids.
What are essential amino acids?
Amino acids that the body cannot synthesize itself in large enough amounts or at all.
There are 9 essential amino acids.
What is transamination?
Transfer - amine.
The amine group from one amino acid is transfered to another molecule that is one amine group shy of being an amino acid. In this way the body can make new amino acids.
What is deamination?
The removal of an amine group ( NH2 ) from an amino acid.
What is a conditionaly essential amino acid?
The body can make some amino acids out of other amino acids. Phenyalanine can be broken down and made into tyrosine instead.
However, if there is not enough Phenylalanine in the body to make into tyrosine then the body must get it from food instead.
So if there is enough Phenylalanine then Tyrosine is nonessential, the body can synthesize it. If there is not enough Phenylalanine to make Tyrosine then Tyrosine is essential - it must be gotten from food. In this way it is a conditionally essential amino acid.
What is a peptide bond?
It is the bond formed between two amino acids. The acid group of one amino acid ( COOH ) loses an OH and the amine group ( NH2 ) of another acid loses an H, making a water molecule H2O and joining the two amino acids where they lost OH and H.
What are dipeptides, tripeptides, polypeptides?
Dipeptides are two amino acids bound by a peptide bond, tripeptides are three amino acids bound by peptide bonds, polypeptides are more than thee amino acids bound by peptide bonds.
What is a protein, difference between protein and polypeptide?
A polypeptide is kind of a long string of amino acids joined together by polypeptide bonds.
A protein is formed from the polypeptide when different parts of the polypeptide chain are attracted to each other and the polypeptide bends and twists into a folded sheet or spiral shape or a big glob. After it's folded it's considered a protein.
What is denaturation ( "denatured" )? What can cause denaturation?
It's simply when the shape of a protein is changed for some reason.
- What can cause a protein to be denatured?
- Heat, change in pH of the protein's environment, heavy metals with strong + or - charges can change the shape of a protein. Physical force can change the shape of some proteins, too.
Eggs have loads of protein, cook them up and the heat causes the proteins to change shape and the egg becomes more solid.
Cream has a lot of protein, whip it up and it and the physical force changes the shape of the proteins and it becomes more solid.
Milk has protein, add lemon juice ( acidic, change in pH ) and it separates into solid and liquid portions because the proteins have changed shape.
In each case the proteins are denatured.
How does the body digest proteins?
- Where does protein digestion begin?
- The stomach -
- Stomach acid ( HCl ) denatures proteins.
- Stomach acid signals enzyme pepsin ( made in stomach ) to release and break down protein into polypeptides.
- Small intestine - in SI
- amino-, and dipepsidase ( made in SI )
and trypsin, chymotripsin, and carboxypeptidase ( made in pancreas )
break down polypepties into tri- and dipeptides ( groups of 3 and 2 amino acids ) and all the way down to individual amino acids.
How does the body absorb amino acids in small intestines?
Small intestines are lined with what's called the brush border where villi ( small, fingerlike projections ) and microvilli ( tiny, hairlike projections ) increase surface area of the small intestines.
Cells that make up this surface area have special proteins imbedded in them called transport proteins that amino acids attach to and the transport proteins pull into the cell. There the cell will process the amino acid in different ways and send it off in different forms to different places in the body.
How do proteins from fiid cause allergies?
When the protein is absorbed by the body before it is completely broken down.
What is anaphylaxis, anaphylactic shock?
Food allergies can cause different reactions: difficulty breathing, digestive trouble, drop in blood pressure, rash.
Anaphylaxis is a severe ( sometimes life threatening ) and immediate reaction to an allergen.
What is the amino acid pool?
The pool of amino acids available in body tissues and fluids that the body can make use of to make energy or build proteins out of.
What is protein turnover?
The body breaks proteins from food down into amino acids and then makes those amino acids into new proteins, then breaks down some of those proteins into amino acids then uses those amino acids to make more proteins.
What is an example of protein turnover?
Insulin. The body can make lots of insulin protein to deal with a large amount of sugar in the system. When there is less sugar in the system the excess insulin can be broken back down into amino acids and added to the amino acid pool.
What is the proces the body uses to synthesize proteins?
It happens in idividual cells.
DNA strands in the cell nucleus unwind and open up to be read.
Messenger RNA ( mRNA ) comes into the nucleus and reads the open DNA to get instructions on what protein is needed and how to build it.
mRNA takes the instructions to a Ribosome.
Ribosome reads the instructions.
Transfer RNA ( tRNA ) goes and grabs some amino acids that correspond to the instructions the ribosome has read and brings them to the ribosome.
Ribosome then builds the protein out of the amino acids the tRNA brought to it.
What is gene expression?
When a particular gene is "turned on" and is able to be read. When a gene is expressed it can be read and the protein it has instructions for can be made.
The genes exist in all cells but are not expressed in all cells. Instructions for insulin production might exist in cells making up the liver but they are not expressed in the liver. They are only expressed in the pancreas.
What are limiting amino acids?
A limiting amino acid is not a process but a particular amino acid.
Proteins are made from many individual amino acids. If a protein is made from amino acids A, B, and C and you have plenty of A and B amino acids but only a small amount of C amino acids then C is the limiting amino acid. You can only make as much of the protein as C amino acids you have available in the amino acid pool.
What are different ways the body can use amino acids after deamination?
Carbon from deaminated amino acid can be synthesized into glucose by liver - process is called gluconeogenesis.
Carbon structure of deaminated amino acid can be made in to acytly-CoA which is used in the citric acid cycle ( which makes ATP which produces energy ).
Other compounds from deaminated amino acids can go straight into part of the citric acid cycle.
What is a potentially negative effect of deamination? How does the body prevent this negative effect?
Amonia ( NH3 ) is toxic to the body.
When NH2 is pulled off of amino acids during deamination, toxic ammonia is formed. The liver will attach CO2 to the ammonia to make urea which is processed in the kidney and expressed in urine.
How does the body use amino acids to deal with a defecit of energy?
The body can break down amino acids to make energy ( liver makes glucose ). But if energy is low ( starvation ) the amino acids can come from the proteins that make up the body's own tissue. Protein making up muscles, heart, lungs can be taken from these organs and broken down into amino acids which are used to synthesize glucose in the liver.
If the proces continues and 30% or more of the body's proteins are used in this way then the organs that have lost proteins will not function as well as they did. If this continues death will be an ultimate result.
How does the body use amino acids to deal with an excess of energy?
If the body has plenty of proteins then amino acids taken in ( in protein form ) can be broken down to produce more energy in the form of ATP.
If there is already plent of protein -and- plenty of energy in the body then amino acids can be broken down to form fatty acids which are stores as triglycerides in adipose tissue.
What are structural proteins?
Proteins that make up structures in the body. Examples of these structures include hair, skin, muscle, ligaments, bones, etc.
What are enzyme proteins?
Proteins that make up enzymes.
What are transport proteins?
Proteins imbedded in cell membranes that different things can attach to and be pulled into the cell by the transport protein itself.
Skin protects the inside of the body and is made from protein. Antibodies attach to forein bodies in the body ( bacteria, viruses ) so that other parts of the immune system ( WBCs ) can recognize them and attack them.
Contractile proteins -
Proteins that make up muscle cells and allow for muscle contractions.
Protein hormones -
Hormones made from proteins.
Proteins help regulate fluid balance -
Proteins make up cells that make up blood vessels. These cells keep fluid in the blood in the blood vessels. Without enough protein the cells in blood vessels don't do a very good job keeping fluid in them and it can leak out and end up in the abdomen.
Proteins regulate they body's pH.
Proteins in the blood and in cells in kidneys and lungs regulate acidity by attracting or releasing Hydrogen atoms.
What is protein-energy malnutrition?
Malnutrition due to not enough protein and energy in a diet.
What is Kwashiorkor?
A disease that can affect children who have been weened off protein-rich breast milk and on to a diet that is very low in protein. There may be enough energy in their diet but deficiency in protein creates problems.
Symtoms include stunted growth, distended abdomen, changes in skin and hair color, poor immune system health.
Stunted growth - growing kids need a higher per cent of protein in their diet than grown adults, without enough protein they cannot grow well.
Distended belly - protein in the blood keeps fluid in the blood vessels, without enough of that protein the water diffuses from the blood vessels and into the abdomen. Protein used in lipoproteins can't be made without a protein source so fat gets stored in the liver rather than moved to other parts of the body.
Protein makes up melanin which colors hair and skin, without enough protein there is less melanin.
Protein makes up many aspects of the immune system and without enough protein the body is not well protected.
What is marasmus?
A disease that can affect someone of any age and causes them to "waste away".
Like kwashorkor there is insufficient protein in the diet but also insufficient energy, fat, and carbohydrate intake. Children with kwashorkor may have enough fat intake and fat stores for the body to use its fat as an energy source. In marasmus since fat intake is inadequate fat stores can quickly be used up leading to the child being emaciated. The same process can affect people with eating disorders.
Too much protein can affect kidney function.
As proteins are broken down in the body, urea is produced by the kidneys. With too much protein can come too much urea which needs to be flushed out in the urine. More water must be expelled to flush out the urea in the urine and this can lead to dehydration.
Too much calcium can lead to kidney stones.
Calcim in the body is usually stored in bones. If there is too much calcium in the body however it is expelled in urine. Along the way it can deposit the calcium in the kidney which builds up and forms kidney stones.
Kidney stones have been associated with very high protein diets.
High protein diets can lead to risk of heart diesease.
High protein diets are usually high in protein gained from animal products. Diets high in animal products are also usually high in cholesterol and low in fiber. Cholesterol builds up in arteries, clogs them, causes heart attack.
What is phenylketonuria ( PKU )?
In most people the amino acid phenylalanine is converted by the body into tyrosine by the enzyme phenylalanine hydrolase.
In some people the gene responsible for making phen. hydrolase is faulty and the phen. hydrolase they make doesn't function properly. Since phenylalanine cannot be converted to tyrosine in such people it gets converted into phenylketones instead. Phenylketones are toxic to the brain.
If phenylketones are present in infants in can prevent proper brain development and cause brain abnormalities and other birth defects.
What is celiac disease?
Gluten intolerance. It causes the immune system to attack the villi in the small intestine.
- What is gluten?
- A protein found in wheat, barley, rye, other grains.
Monosodium glutamate ( MSG ) is a flavor enhancer and food additive. It is the amino acid glutamate bound to sodium. People with a sensitivity to it can have various reactions including headaches, chest pain, rapid heartbeat, burning sensations, flushed face, etc. within an hour after eating it on an empty stomach.
What is nitrogen balance?
When the amount of nitrogen consumed ( as part of protein ) is equal to the amount of nitrogen flushed from the body in urine. This means that the body is taking in as much as it is pushing out and maintaining a balance.
Negative nitrogen balance occurs when the body excretes more nitrogen than it takes in, nitrogen is being lost.
Positive nitrogen balance occurs when the body excretes more nitrogen than it takes in. This suggests the body is using the nitrogen to make new body proteins, like during wound healing, muscle building, or pregnancy.
What is the RDA for protein for an adult?
0.8g of protein per kg of body weight per day.
What is the difference between complete and incomplete proteins?
Complete proteins contain all the amino acids necesarry for protein synthesis. Animal protein is complete protein.
Incomplete proteins either do not have all the amino acids necesarry for protein synthesis or are low in some amino acids.
What is a chemical, or, amino acid score?
It is a rating for a source of protein as compared to a reference protein know to be a complete protein. The testing looks at the limiting amino acid in the protein source ( the amino acid there is the least of in the protein ) and compares it to the limitin amino acid in the reference protein. The ratio is the protein's amino acid score.
What is the protein digestibility corrected amino acid score?
PDCAAS. Not all proteins are digestible, the PDCAAS takes into account a proteins digestibility. After all, if you cannot digest it it doesn't matter how great its amino acids are.
What is protein complementation?
Protein from rice will not have all the amino acids a body needs, neither will beans. But if you eat both rice and beans you will have all the amino acids you need. The two proteins complement each other, they are considered complementary proteins.