Chapter 6 The Proteins and Amino Acids Flashcards
How is protein digested and absorbed?
- Begins in the stomach where HCl denatures the protein in food and other enzymes attack the peptide bonds
- Further broken down and absorbed in the small intestine
- Dipeptides and tripeptides are broken down into single amino acids on the surface on intestinal cells and absorbed
- Proteins enter the bloodstream and get sent to the liver
- Liver processes them and sends them out to the body
What is the fate of amino acids and proteins in the body?
for cellular use we build protein, a needed compound, and dismantling amino acids for component parts
wasting of amino acids
What four conditions satisfy the wasting of amino acids?
- Body lacks energy from other sources
- The diet supplies more protein than the body needs
- Too much of a single amino acid
- Diet = low quality protein
What is the role of amino acids and proteins in the body?
- regulation of gene expression
- providing structure and movement through muscle tissue (40% of body protein exist here) and other structural proteins (confer shape and strength to bones, teeth, skin, tendons, cartilage, blood vessels)
- building enzymes, hormones, and other compounds
- building antibodies used to destroy one specific invader
- transporting substances like hemoglobin and lipoproteins
- maintaining fluid and electrolyte balance through buffers preventing acidosis and alkalosis
- blood clotting
- providing energy and glucose under conditions of inadequate carbs
*Each day, a quarter of the body’s amino acids are “irretrievably used”
How is protein stored?
- no storage compound for protein
- excess amino acids have amine groups removed and remaining residues converted to glucose and used to either meet immediate energy needs or be stored as glycogen
*note that stripped amine group (nitrogen) is incorporated into urea by the liver and sent to the kidney for excretion
Are protein supplements effective?
Not really. They don’t improve performance, aren’t effective for weight loss and most of the time are not necessary since we meet our protein needs
keep in mind that Fat-free Greek yogurt offers just as much protein as protein shakes
How much protein does an average adult need a day?athlete?how is requirement determined?
Average: 0.8 g/kg/day
Athletic: 1.2-1.7 g/kg/day
Requirement does depend on the body’s health
what are some conditions that happen to the body that require an increased need for protein?
Cachexia and trauma (due to illness or burns) are states in which the body has an increased need for protein
rank proteins sources by digestibility?
Protein from animal sources = ~90% digestible
Legumes ~80% digestible
grains/other plant sources = ~70-90% digestible
What is nitrogen balance?
Nitrogen balance is the ratio of nitrogen excreted compared to nitrogen consumed
what is nitrogen equilibrium?
Equilibrium: Nin = Nout
e.g. – Normal, healthy people
what is negative nitrogen balance?
Negative: Nin < Nout
Here, muscle and other protein tissues are broken down or lost to make up remainder
e.g. – Astronauts or severely ill individuals
what is positive nitrogen balance?
Positive: Nin > Nout
e.g. – Children, pregnant women, weight lifters, etc.
what are the different forms/types protein can take?
Globular – They’re…globular…and water soluble
ex. Proteins of the blood
Hollow – Carry and store materials
Long, rod-like structures – Insoluble in water and very strong
ex. Tendons
what are the disorders associated with protein deficiency?
Kwashiorkor (often seen in children)
Impacts stature, lean body mass, and fluid balance
what are the disorders associated with energy deficiency?
marasmus
what is the term used to describe the condition that develops when the diet delivers too little protein, too little energy, or both?
protein energy malnutrition
what are some effects of protein excess?
weight loss dieting heart disease kidney disease adult bone loss cancer
in terms of protein excess, how does weight loss develop as a result of?
consuming more protein (upwards to 65% of calories) preserves the body’s working lean tissues (liver and muscle), may help control appetite, may cost extra energy for its metabolism
in terms of protein excess, how does weight loss lead to kidney disease?
Excess doesn’t CAUSE damage, but does speed up kidney decline in already afflicted kidneys
what is the affect on calcium due to excess protein?
Excess protein encourages excretion of Ca2+
What are the macronutrient distribution ranges?
Fats: 20-35%
Protein: 10-35%
Carbs: 45-65%
How much energy are we getting from each macronutrient?
proteins carbs fats alcohol vitamins and minerals
- Proteins = 4 cal/g
- Carbs = 4 cal/g
- Fats = 9 cal/g
- Alcohol = 7 cal/g (not a nutrient)
- Vitamins and minerals = No energy, but are essential
How is RDA established for carbohydrates, fats, and protein?
Carbs – Based on what our brain needs each day
Fats – There is no RDA for fat (unless you’re <1 year old, then it’s based on fat in breast milk)
Protein – Based on nitrogen balance
What is the difference between essential and non-essential amino acids?
Essential amino acids are those that our body cannot produce on its own and must be consumed in the diet
What are the essential amino acids?
PVT TIM HLL
Tryptophan; Valine; Phenylalanine; Isoleucine; Leucine; Methionine; Threonine; Histidine; Lysine
which of the amino acids is the most needed?
leucine
Which amino acid is the most abundant free amino acid in the human body?
glutamine
A patient presents to her primary care physician with significant hair loss and brittle nail formation. In addition to lysine, arginine, and methionine, what other essential amino acid should the patient incorporate into her diet?
cysteine
Are partially completed proteins held for completion for when the diet improves?
No, they are dismantled and the amino acids are returned to circulation for other cells
What are some nutrients that vegetarians need to make sure they’re getting in their diet?
Vitamin B12, iron, zinc, calcium, and vitamin D
Fortified cereals can generally give all of these nutrients
What are the effects of body mass loss?
If we lose 10% body mass = impaired healing
20% = spontaneous wounds
30% = death
common functions and deficiency symptoms for tyrosine?
- Used in the production of epinephrine and norepinephrine (catecholamine pathway)
- Used to treat phenylketonuria (PKU)
- Also used in the production of melanin and the thyroid hormone
common functions and deficiency symptoms for alanine?
- Balances glucose and nitrogen
- Has cholesterol reducing effect
- Together with histidine, beta-alanine creates carnosine (stored in skeletal muscle) which reduces lactic acid accumulation in muscles during exercise, thus improving athletic performance.
common functions and deficiency symptoms for histidine?
- Rich in animal meat, eggs, and dairy
- Precursor to hemoglobin, histamine, and glutamate
- Histidine deficiency could cause eczema
common functions and deficiency symptoms for arginine?
Involved in vasodilation through nitric oxide
common functions and deficiency symptoms for cysteine?
Responsible for stability of keratin
common functions and deficiency symptoms for glutamine?
Most abundant amino acid in the body
common functions and deficiency symptoms for valine?
- Replaces glutamate in hemoglobin amino acid sequence and creates sickle cell
- Is a branch-chained amino acid
- -BCAAs account for 35% of essential amino acids in muscle protein
- -Used in the treatment of burn patients
common functions and deficiency symptoms for lysine?
o Alleviates and prevents spread of herpes
o Aids in production of collagen
