Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
39 Cards in this Set
- Front
- Back
Amino Acids
|
-building blocks of proteins
-each amino acid contains amine group (NH2) and acid (COOH) -the side chains are what differentiates the 20 different amino acids -amino acids connect to each other by peptide bonds |
|
Specificity of proteins
|
-proteins are often composed of 500 or more amino acids
-the sequence of the amino acids determines a proteins shape and thus its function |
|
Composition of insulin
|
-composed of 2 chains of 51 amino acids, connected by sulfur
|
|
Protein as an energy source:
|
-generally the body uses carbohydrates and fat for energy
-if the body is not supplied with enough energy, protein can be utilized -like carbs, it gives 4 calories per gram -the body can use amino acids to form glucose but can't do the reverse -the use of protein as an energy source compromises its other functions -excess dietary protein can be stored as fat |
|
Uses of protein:
|
-makes and repairs tissues (muscles, blood, internal organs, skin, hair, nails, and bones)
-essential for growth -important to maintain body fluid balance (and electrolyte balance) -acid-base balance - |
|
Some examples of proteins:
|
-enzymes
-antibodies -transport vehicles -hormones -tendons -muscles -ligaments -core of bones and teeth -filaments of hair -the material of nails |
|
effect of alkalosis or acidosis on proteins
|
-if pH balance is not maintained, individual may develop acidosis or alkalosis and denature proteins in the body, rendering them unable to function
|
|
Inborn errors of metabolism:
|
-the sequence of amino acids needed to form specific proteins is encoded in the DNA in the cell nucleus
-some genetic diseases result in an error in protein production (cystic fibrosis, sickle-cell anemia) -an incorrect order of amino acids can lead to an altered shape of a protein, changing its function |
|
Sickle-cell anemia
|
-In the disease sickle cell anemia, the hemoglobin molecule that carries oxygen or carbon dioxide throughout the body is altered.
-Due to a single amino acid error of valine replacing glutamic acid in the polypeptide sequence of hemoglobin, the red blood cell has a sickle shape instead of the normal disc shape. -This altered shape hinders oxygen transport |
|
Protein denaturation:
|
-can be denatured by:
1. heat (think of cooking eggs) 2. Acids and Bases 3. Toxins (such as heavy metals mercury or silver) -we use denaturation for protein digestion (stomach hydrochloric acid). the proteins are unfolded so enzymes can get to the peptide bonds to break them down -no bonds are broken in protein denaturation (amino acid content is unchanged) |
|
Protein breakdown and re-synthesis:
|
-Proteins in food are broken down into amino acids during digestion, which are then absorbed and used to make new proteins in the body.
-Once the amino acids are absorbed into the bloodstream, they can be used directly to resynthesize proteins -To use dietary proteins for protein synthesis, we must consume adequate energy. If we do not consume enough energy, our body will break down dietary protein for energy -Proteins in the body are being constantly broken down and resynthesized. (The process of re-synthesizing your body’s proteins is not 100% efficient and so we require daily protein to replace the amount of protein that was not completely re-synthesized.) |
|
Nitrogen balance:
|
-amount of nitrogen we excrete can let us know how much protein we are using
-ex. after surgery, body is under stress and uses a lot of protein and we will lose a lot of nitrogen to indicate this use (negative nitrogen balance). -the nitrogen balance should be zero -if you are trying to build muscle, if you are growing as a child, or if you are pregnant; you need a positive nitrogen balance |
|
Recommended protein intake:
|
-10-35% of daily calories
-RDA = 0.8g of protein per kg body weight -The RNI takes into account that our diets are generally a mix of poorer quality vegetable proteins (2/3) and higher quality animal proteins (1/3). |
|
Protein Quality:
|
measured by:
-amino acids -how well it supports growth -digestibility *animal proteins are of a higher protein quality than vegetable proteins |
|
Essential amino acids:
|
-there are 9 a.a. that our body cannot produce (must obtain them from diet)
|
|
High- Intermediate- and Low-quality proteins
|
-high: egg, milk, beef, fish
-intermediate: soy, flour, sunflower seed, rice, oats -low quality: peas, cornmeal, cassava gelatin |
|
limiting amino acid
|
the amino acid in shortest supply (most plant proteins are lacking or short in supply of at least one amino acid, this is a limiting amino acid)
|
|
Protein Efficiency Ratio:
|
-PER= gain in body weight divided by weight of protein consumed
-used to judge the quality of protein in infant formulas and baby food Examples: -whey: 3.6 -milk protein: 3.1 -casein: 2.9 -soy: 2.1 *any protein that has PER of 2.7 or higher is considered an excellent quality of protein |
|
athletes require more..
|
-sulfur amino-acids (methionine and cysteine) not for re-synthesis of hair, but for growing quality muscle fiber after an energy expenditure
|
|
Protein Digestibility Corrected Amino Acid Score:
|
-reflects the digestibility of a protein as well as the proportions of amino acids that it provides
-Protein PDCAAS: -whey: 1.00 -egg white: 1.00 -soy: 0.94 -beef: 0.92 -pea flour: 0.67 -rice: 0.47 -wheat flour: 0.40 -wheat gluten: 0.25 *pea flour + wheat gluten = 0.82 |
|
only plant source to offer complete protein?
|
-soy
-other plant proteins can be combined to get complete proteins (they are incomplete proteins by themselves) |
|
Effect of physical activity:
|
-decreased protein synthesis
-increased protein degradation -increased AA (alanine and glutamine) released from muscle -5-15% of energy expenditure depending on total energy supply and PA intensity -mainly in endurance exercise |
|
Use of protein as an energy source during exercise
|
-branched chain amino acids (isoleucine, leucine, and valine)
-provide energy directly to muscle -provide energy via carbohydrate produced in liver *endurance training increases the capacity of muscle to derive energy from the body's protein |
|
Effects after physical activity:
|
-increase in protein synthesis leading to positive protein balance
-further increase after resistance exercise -the anabolic effect of intense training is observed after a specific intensity threshold (70% of 1RM) |
|
Whey protein vs. Casein protein supplements:
|
-whey can be digested and absorbed faster
-casein is absorbed slower, so absorption is over a longer period of time |
|
When is it most beneficial to drink a protein shake?
|
-prior to workout (prevents protein deficit that occurs during training)
-after workout it is good to eat carbs to replenish glycogen stores. |
|
Amino acid supplements
|
-controversial, studies are contradictory and generally show no effect on performance
-Margin of Safety for Large Amino Acid and Protein Doses are not established -can cause amino acid imbalance and toxicity |
|
Creatine Supplements
|
-Nitrogen Containing Compound Known As an Amine, not AA
-found in meats -formed in liver from glycine and arginine -we would have to eat about 5kg of beef to get as much as we do from supplements -we eat about 1g/day and body produces about 2g/day -blood level is at about 50-100 micro moles per liter -with supplemetn spikes to 500-1000 micro moles per liter -brings water with it, so gives muscles "water weight" -effects more seen in the last reps or last set -May Enhance Performance in Repetitive, Short-term, High Intensity Tasks in Which the Body Does Not Move From Point to Point Such As Resistance Exercise -Can help when doing the final “sprint" during endurance exercise -Does Not Improve Performance Where the Body Has Moved Such As Swimming and Running -if you are a big meat eater you might not see the effects of creatine supplements |
|
Protein requirements for PA
|
-endurance athletes: 1.2-1.4 g per kg body weight
-strength athletes: 1.6-1.8 g per kg body weight |
|
Excessive intake of protein
|
DRI: no UL excessive protein intake
-extra protein may be converted to glucose or fat or excreted in the urine -can lead to calcium losses that compromise bone health -foods that are high in protein are also high in fats (CVD risk) -risk of kidney disease -may exceed liver's ability to convert excess nitrogen to urea 1. 200-400g 2. 5g/kg body weight 3. >35% of total energy |
|
High protein/low carb diets?
|
-forces body to obtain glucose from other sources
-results in a build up of ketone bodies -disrupts acid-base balance -disrupts fluid/electrolyte balance -normal breakdown of fat to energy is blocked -the body responds by breaking down protein which is supposed to be used for other duties -often rapid weight loss due to excessive water loss |
|
Positive aspects of vegetarian diets:
|
-promotes leaner body composition and lower blood pressure
-less sat. fat -provides more: vegetable protein, fiber, antioxidant nutrients, phytochemicals |
|
Negative aspects of vegetarian diets:
|
-have difficulty getting enough protein
-lack of omega-3 fatty acids in diet -risks of stunted growth -vitamin D, B12, calcium, iron, and zinc deficiencies |
|
Marasmus
|
-protein-energy deficient
-develops slowly in children under 2 years of age -severe weight loss, severe muscle wasting, hair loss, thin dry skin |
|
Kwashiorkor
|
-protein-deficient
-develops quickly in children 1-3 years of age -weight loss, muscle wasting, decreased growth rate, big swollen bellies |
|
Food allergies
|
-antibody IgE
-1-2 Percent of Adults and 3 Percent of Children Have Food Allergies -about 90% caused by: milk, egg, wheat, peanut, soy, tree nuts, fish, and shellfish |
|
Food intolerance
|
-An Adverse Effect of a Food or Food Additive Usually Not Involving the Immune System
-Ex. celiac disease, food poisoning |
|
Celiac Disease
|
Certain Peptides From Wheat Proteins (Gluten) Are Toxic to the Gut When They Are Not Broken Down During Digestion
|
|
Food Poisoning
|
caused by microorganisms in the food, not the food itself
|