Week 5 Flashcards
What are the roles of proteins?
- associated with stregnth and muscle
- wound healing
- structural role (matrix in bones) and functional role in cells (immune system)
What can excess meat result in?
high saturated fat intakes, as meat is one of the main sources of saturated fats
Sources of protein?
- milk
- eggs
- legumes
- many whole grains
- vegetables.
- fruit has almost NO protein
emphasis on protein, mainly meat, can be at the expense of other foods
What are proteins that are working molecules?
- enzymes
- antibodies
- transport vehicles (ex. hemoglobin is made up of a cluster of 4 proteins)
- hormones (ex. insulin)
- cellular “pumps” (what goes in and out of cell)
- oxygen carriers
Are all hormones proteins?
no
Where are proteins present for structure?
- tendons
- ligaments
- scars
- fibres of muscles
- cores of bones and teeth
- filaments of hair
- materials of nails
What is in a protein?
- made of carbon, hydrogen, and oxygen
- contain nitrogen
- some amino acids also contain sulphur
like fat and carbohydrates, they are made of carbon and hydrgogen and oxygen, but what differentiates them is that it contains nitrogen (makes different from the energy yielding ones)
What are proteins composed of (general)?
amino acids
How many amino acids make up most of the proteins of living tissue?
20
What is the structure of amino acids (the general one)?
- an amine group at one end -nitrogen containing part
- an acid group at the other end
- a distinctive side chain (side group) attached to the carbon at the center of the backbone (this is what gives the identity and chemical nature of each amino acid)
What are the side chains of amino acids?
- make the amino acids differ in size, shape, electrical charge
- some are negative, positive, some with no cahrge
- the charge will contribute to the shape of the protein
- long strands of amino acids form large protein molecules
- the side chains help to determine the molecules shape and behaviours
What are essential amino acids?
- amino acids that can not be synthesized at all by the body or can not be synthesized in sufficient amounts
- can’t make, comes from the diet
- can only be replenshed from foods
- body can not make proteins it needs to work without the essential amino acids
What are non essential amnio acids?
- can be made by the body
- can make it from fragements derived from carbohydrate or fat to form the backbones
- nitrogen from other sources
What are the essential amino acids?
- histidine
- isoleucine
- leucine
- lysine
- methionine
- phenylananine
- threonine
- trypotophan
- valine
What are conditionally indispensable/essential amino acids?
- amino acid that is normally nonessential
- when the need exceed’s the body’s ability to produce it, must be supplied by the diet
Where is aspertaine made from?
- amino acids
- what makes it differ from sugar is becuase is 200x sweeter than sugar
How does the body recycle amino acids?
- body breaks down proteins to reuse those amino acids
- protein turnover is about 300-400 g/day
- recycling system provides access to amino acids for energy when needed
How can cells use amino acids for energy when needed?
- tissues can break d own their own proteins in times of fuel or glucose deprivation
- working proteins are sacrificed
- most dispensible proteins used first
- structural proteins of certain organs are gaurded until t heir use is forced by dire need
What is a peptide bond?
- connects one amino acid to another
- formed between the amino of one amino acid and thr acid group of the next amino acid
- a condensation reaction
- forms a chain of amino acids with side chains bristling out from the backbone
What is the primary structure of a protein?
the chain of amino acids
what is the secondary structure of a protein?
- determined by weak electrical attractions within the chain
- positively charged hydrogens attracts nearby negatively charged oxygen
- selections of the chain may twist into a helix or fold into a pleated sheet giving proteins strength and stability
What is the tertiary structure of a protein?
- long peptide chains twist and fold into shapes
- side groups may attract or repel each other
- side groups may be hydrophillic or hydrophobic so chains fold accordingly
- hydrophillic: side groups are on the surface near water
- hydrophobic: side groups are hidden in the middle
- disulfide bridges also determine tertiary structure
- shape gives characteristics
What is the quaternary structures of a protein?
- interactions between 2 or more polypeptides
- some polypeptides work together in large complexes
- an example of this is hemoglobin
What is hemoglobin in regards to a polypeptide
- a large globular protein that carries oxygen is made up of four polypeptide chains
What are globular proteins?
water soluble, such as some proteins of blood
what are proteins that form hollow balls?
carry and store materials in their interior
What type of proteins are much longer than they are wide?
proteins of tendons
What is collagen?
- a protein from which connective tissues are made
- acts like glue between cells
- ex. tendons, ligaments, scars, and the foundations of bone and teeth
what is insulin?
helps regulate blood sugar
what is an enzyme?
- protein catalysts
What is sickle cell disease?
- inherited variation in amino acid sequence
- abnormal hemoglobin
- one amino acid in a critical position has been replaced by a different one
- it changes shape, so it changes the function of the protein
- there was an insertion of an amino acid that changes the shape of the protein and the function of it
- alters the protein so it is unable to carry oxygen
- red blood cells collapse from the normal disk shape into crescent shapes resulting in bad stuff
True or False: every human cell nucleus contains the DNA for making every human protein, but cells do not make every protein
true
What is denaturation?
- irreversible change in a protein’s shape
- can be caused by heat, acids, bases, alcohols
- important to the digestion of food protein
What do stomach acids do to a proteins structure?
open up a proteins structure (denaturation), this allows digestive enzymes to make contact with the peptide bonds and cleave them
What happens between digestion and proteins?
- certain acid tolerant proteins (many of which are enzymes), digest proteins from food that have been denatured by acid
- the coating of mucus secreted by the stomach wall proteins its proteins from attack by either acids or enzymes
- we also have pepsin in stomach for protein digestion
what is the usual acidity of the stomach?
2
What role does the stomach play in protein digestion?
- acid helps to uncoil the protein’s tsngled strands so that the stomach’s protein digesting enzyme can attack the peptide bonds
- pepsin works best in an acidic environment
- pepsin cleaves amino acid strands into polypeptides and a few amino acids
- lining is protected from acid and enzymes from mucus coating stomach cells
What is the role of the small intestine in protein digestion?
- recieves small denatured pieces of protein from the stomach
- most are polypeptides
- a few are single amino acids
- alkaline juices from pancreas enutralize the acid delivered by the stomach, pH to 7
- protein digesting enzymes (proteases) from the pancreas and small intestine continue breaking down the protein until nearly all that is left is dipeptides, tripeptides, or single amino acids
True or false: people need to eat enzymes to properly digest their food
most people produce enzymes that they wouldn’t need any help to digest our food
What happens to amino acids in the bloodstream?
- carried to the liver
- used by the liver or released into the blood to be taken up by other cells
for the liver
* used in protein synthesis
* used for energy
* used in the synthesis of a nonessential amino acid and released into bloodstream for cells
the cells
* use amino acids to make proteins for their own use
* make proteins that are released into the lymph or blood for other uses
* when needed, body cells can use amino acids for energy
What are the roles of proteins in the body (must know)?
- supporting growth and maintenance
- building enzymes, hormonens, and other compounds
- maintaining fluid and electrolyte balance
- maintaining acid base balance
What is the proteins role of supporting growth and maintenance?
- amino acids must be continuously available to build the proteins of new tissue
- protein helps replace worn out cells and cell structures
What is the proteins role of building enzymes, hormones, and other compounds?
- enzymes- thousands of enzymes reside inside a single cell
hormones
* chemical messengers secreted by a number of body organs in response to conditions that need regulation
* each hormone affects a specific organ or tissue and elicit a specific response
* some are made from amino acids
- amino acids
- antibodies
What is protein turnover?
the continuous breakdown and synthesis of body proteins involving the recycling of amino acids (300-400/day)
What is maintaining fluid and electrolyte balance for proteins roles?
- too much fluid in a cell and it ruptures
- too little fluid in a cell the cell is unable to function
- water can diffuse freely into and out of cells
- proteins can not diffuse freely
- fluid is kept within blood bessels by proteins that are too large ti freely move across capillary walls
- edema: failure of any part ofthe fluid balance system
what is acidosis?
- the condition of excess acid in the blood
- indicated by a below normal pH
What is the maintaining acid base balance role of proteins?
acids: compounds that release hydrogen
base: compounds that accept hydrogens
- blood proteins act as buffers to maintain the blood’s pH
- protein buffers pick up hydrogens when there are too many in bloodstream
- protein buffers release hydrogens when there are too few in the bloodstream
what is alkalosis?
- the condition of excess base in the blood
- indicated by a above normal pH
True or false: both acidosis and alkalosis can cause coma or death?
true
what is gluconeogenesis?
What are the ways that an amino acid that arrives at a cell can be used?
- used to build a part of a growing protein
- altered to make another needed compound
- dismanteled to use its amine group to build another amino acid
What happens if the cell is starved for energy and lacking glucuose and fatty acids?
- the amine group will be removed and the remainder used for energy
- the amine group will ultimately be excreted as urine
what happens if the body has a surplus of amino acids and energy?
- the amino group will be excreted
- the remainder can be used for: energy or converted to glucose or fat for storage
What happens with “wasted amino acids”? (amino acids not used to build protein or make other nitrogen containing compounds)
- the body does not have enough energy from other sources
- has more protein than it needs
- has too much of any single amino acid, such as from a supplement
- the diet supplies protein of low quality, with too few essential amino acids
How do you prevent wasting of dietary protein and permit the synthesis of needed body protein?
- dietary protein must bbe adequate in quality
- the diet must supply all of the essential amino acids in the proper amounts
- enough energy yielding carbohydrates and fat must be present, as they have a protein sparing effect
Why would malnutrition (undernutrition) and infection may greatly increase need for proteins?
undernutiriton
* secretion of digestive enzymes slows as the tract’s lining degenerates
infection: extra protein is needed for enhanced immune function
What are the easily absorbed sources of protein? How does the digestibility of a protein vary from food to food?
- animal sources are more easily digested and absorbed than plant sources
- animal sources: 90%+ digested and absorbed
- legumes: 80-90% are digested and absorbed
- grains and other plant foods: 70-90% digested and absorbed
What are high quality proteins?
dietary proteins containing all of the essential amino acids in relatively the same amounts that humans requires, may also contain nonessential amino acids
What is the amino acid pool?
- amino acids dissolved in the body’s fluids that provide cells with ready raw materials from which to build new proteins or other molecules
What happens if the diet fails to supply enough of an essential amino acid?
- cells adjust their activities
- limit breakdown of working proteins
- reduce their use of amino acids for fuel
What can limiting amino acids also limit?
protein synthesis
What happens if there is a chronic deficiency of an essential amino acid?
- cells begin to break down their protein making machinery
- cells function less and less efficiently
What are complementary proteins?
- 2 or more proteins whose amino acid assortments complement each other in such a way that the essential amino acids missing from one are supplied by the other
- don’t need to be in the same meal
What is mutual supplementation?
the strategy of combining 2 incomplete protein sources so that the amino acids in one food make up for those lacking in the other food
What is the DRI committee recommendations regarding protein?
- larger people have a higher protein need
- Adults: 0.8g/kg body weight per day (RDA)
- 10%-35% of total calories (AMDR)
- athletes may need more
What is nitrogen balance?
the amount of nitrogen consumed compared with the amount excreted in a given time period
normal circumstances
* healthy adults are in nitrogen equilibrium= zero balance (nitrogen in=nitrogen out)
positive nitrogen balance or positive nitrogen status
* nitrogen in greater than nitrogen out
negative nitrogen balance or negative nitrogen status
* nitrogen in less than nitrogen out
What is a positive nitrogen balance mean?
- more protein is synthesized by the body than what is degraded
- nitrogen intake exceeds excretion
What does a negative nitrogen balance mean?
- the body degrades more protein than it synthesizes
- body loses nitrogen as it breaks down muscle and other body proteins
What is protein energy undernutrition (PEU, PEM)
- world’s most widespread malnutrition problem
- includes both marasmus, kwashiorkor, and states in which they overlap
marasums: chronic inadequate food intake
kwashiorkor: severe acute malnutrition
What is marasums?
a severe form of malnutrition — specifically, protein-energy undernutrition. It results from an overall lack of calories. Marasmus is a deficiency of all macronutrients: carbohydrates, fats, and protein.
without adequate nutrition
* muscles waste and weaken
* brain development stunted
* metabolism is slow, temperature messed up
* little or no fat under skin for insulation
* won’t even cry for food, no physical activity
* lots more bad stuff
What is kwashiorkor?
a disease marked by severe protein malnutrition and bilateral extremity swelling. It usually affects infants and children, most often around the age of weaning through age 5. The disease is seen in very severe cases of starvation and poverty-stricken regions worldwide.
What is PEU (PEM) like in canada?
- poverty or unaffordable food costs
- many elederly people
- unhoused children and adults
- anorexia nervosa
- infants, with over diluted formula
- toddlers with un-enriched milk
- wasting diseases (Ex. AIDS)
- addiction to drugs and alcohol
What is the maximum amount of calories recommended by the AMDR?
no more than 35%
Consequences of overconsumption of proteins?
- no health benefits
- may pose health risk for heart, kidneys, bones
What can animal protein sources be high in?
saturated fat
can lead to increased LDL cholesterol
How does a high protein diet effect kidney problems?
can worsen it and accelerate the decline of only mildly impaired kidney’s
What are the advantages and disadvantages of legumes?
Advantages
* many B vitamins
* iron
* calcium
disadvantages
* lack of vitamin A, C, B12
What is soybean protein comparable to?
meat
What does heavy use of soy products in place of meat inhibit?
iron absorption
What is texturized vegetable protein?
- soy protein
- can be formulated to look and taste like meat, fish, poultry
- fall short on nutritional content (processed)
What is the nutrition like in tofu?
- also known as bean curd
- rich in calcium
- variable fat content
- nutrients of soybeans also available. here
What is a lacto-ovo vegetarian?
includes dairy products and eggs, but excludes animal flesh and seafood
What is a lacto-vegetarian
includes dairy products but excludes eggs, animal flesh, and seafood
what is a ovo-vegetarian
includes eggs but excludes milk products, animal flesh, and seafood
what is a vegan
only food from plant sources ad excludes all food from animal sources, also called strict vegetarian
what is a flexitarian
includes primary plant based foods but animal products such as meat and fish are eaten occasionally
What are the positive health aspects of vegetarian diets?
- reduced incidences of chronic disease
- have more fibre, potassium, and good vitamins in their diet
- smoke less, use alcohol less, more physical activity (on average)
- die less often from heart disease and related illnesses
- lower in saturated fats and cholesterol
- increase phytochemical consumption
- lower blood pressure
- low rates of some cancers than general population comparison (ex. colon cancer)
What is lower body weight correlated with?
- high intakes of fibre
- low intakes of fat
- less meat consumption?
What is a heart benefit for when soy protein replaces animal protein?
reduced total blood cholesterol, LDL cholesterol, triglycerides, and blood pressure
What is the DRI intake recommendation for iron for vegetarians?
- increased to 1.8x the general iron RDA
- iron in plant foods is poorly absorbed
What is zinc in correlation with a vegetarian diet?
- meat is a rich zinc source
- zinc from plant sources not well absorbed
- soy interferes with zinc absorption
- can be a problem for growing children
Where are sig amounts of B12 found?
meat derived foods, vegans need to get B12 fortified foods
what type of omega fatty acid do vegetarians lack?
- omega 3 fatty acids
- have enough omega 6 fatty acids
- imbalance slows production of EPA and DHA
- without fish or eggs in diet, EPA and DHA production lacking
*
Why should a vegetarian’s diet include a good source of linolenic acid?
essential nutrient
