Module 6 - Proteins Flashcards
How much of the human body is protein?
15%
Protein deficiency is common in Canada: T or F?
False. Protein deficiency is rare in Canada. Most people have more then the AMDR recommends.
About what percent of Canadians consume over 10% AMDR of protein?
> 97%
What is the AMDR for Protein for adults?
10-35%
On average, how much of total kcal is from protein?
15%
What are the pros and cons of protein from animal sources?
Pros: Great source of B vitamins and minerals (iron, zinc, calcium)
Cons: Low in Fibre, usually high in SFA and cholesterol
What are the pros and cons of protein from plant sources?
Pros: Good source of most B vitamins and minerals (iron, zinc, calcium) contains fibre, unsaturated fats
Cons: Less absorbable forms of iron, zinc, calcium present
Name Similarities and Differences between Proteins and Carbohydrates, Fats
Similarities:
- Made in body and consumed in various forms
Differences:
- proteins are made according to instructions from DNA
- proteins contain N along with CHO
What are amino acids?
nitrogen containing molecules
that combine to form proteins
What are proteins?
Chains of amino acids in different sequences
How long is a Dipeptide?
2 amino acids
how long is a Tripeptide?
3 amino acids
How long is a oligopeptide?
4-9 amino acids
How long is a polypeptide?
10+ (many peptide bonds)
How many amino acids in a protein?
more than 50 amino acids
How many amino acids typically in a protein?
between 100-10,000 amino acids in a sequence
What processes synthesize and break down proteins?
Synthesize: Condensation
Break down: Hydrolysis
What are peptide bonds?
chemical bond between carboxyl group of one amino acid and amine group of another amino acid
What parts of the amino acids bind together in condensation?
amine group and carboxyl group (acid group)
How many unique amino acids are there?
20
What are the components of an amino acid?
Central carbon
Hydrogen
Acid/Carboxyl Group (COOH)
Amino Group (NH2)
Unique Side Group (R)
By combining the 20 amino acids in various lengths and sequences, the body is able to make
10,000 - 50,000 unique proteins
How many of the 20 amino acids are “essential”/”indispensable”?
9
How many of the 20 amino acids are “non-essential”/”dispensable” or conditionally essential?
11
Non-essential amino acids are less important then essential amino acids: T or F?
False. non essential AAs are just as important as essential AAs, however our body makes non-essential AAs so they are of less concern in diet
What are essential Amino Acids?
amino acids that body does not make
what are conditionally essential amino acids?
amino acids that are not synthesized at a rate to meet body’s needs
How are non-essential and conditionally essential amino acids synthesized in the body?
Transamination: involves transfer of amino group to a compound which creates new amino acid
What are the characteristics that differentiate amino acid chains?
- Number of amino acids
- Proportion of each amino acid
- Order of amino acids
Chains of amino acids fold into specific way, giving each protein a unique 3D shape that is essential to its function: T or F?
True. Proteins can fold due to bonds linking amino acids together and become 3D. Structure = Function.
Is insulin a protein?
Yes! Discovered by Canadian Frederick Banting and produced in the pancreas by Beta cells to regulate high blood sugar.
How is protein structure formed?
polypeptide chains fold and may bind together. The structure determines the function.
How does the structure of hemoglobin protein determine its function?
spherical shape allows for places for heme (a non protein portion of hemoglobin) to hold and transport iron
What are ways in which the structure and therfore function of proteins are changed?
- Mutation
- Denaturation
What is mutation?
alteration of gene sequence that codes for specific proteins
What is an example of mutation in protein?
sickle cell anemia, changes shape of blood cell to “sickle”, changing function
The polypeptide protein chains found in hemoglobin of sickle cell anemic individual will be different then someone without sickle cell anemia: T or F?
True. They are mutated, as a single AA is altered, causing protein molecules to bind together in long chains. This causes a distorted shape, unlike the normal disc shape of RBC. Alters ability to release and carry 02, dangerous.
What is Denaturation? How does it occur?
uncoiling of proteins which causes loss of shape. Occurs when protein exposed to heat, acids, bases, heavy metals, alcohol etc.
What is an example of protein denaturation?
stiffening of egg whites
salt on meat, denatures the protein to make juicer meat
Denaturation of proteins in digestion allows…
for breakdown into amino acids and absorption
How does digestion in the mouth differ for proteins compared to CHO and lipids?
no enzymatic digestion for proteins in mouth (CHO have salivary amylase to break them down and fats are broken down by lingual lipase)
Explain how protein digestion begins in the stomach?
HCL and pepsin begin chemical digestion of protein in the stomach
What cells secrete pepsinogen in the stomach?
What cells secrete HCL in the stomach?
Chief cells secrete pepsinogen
Parietal cells secrete HCL
Explain the denaturation of proteins in the stomach through parietal cells and chief cells?
Parietal cells release HCL which begin denaturation of proteins, they also activate the pepsinogen from chief cells to become pepsin, a protein that breaks peptide bonds
Explain the role of the pancreas in digesting proteins?
Pancreas releases protein digesting enzymes into duodenum (mixing bowl) of the small intestine which breakdown amino acids
What enzymes are released by pancreas into small intestine for protein digestion?
Trypsin and Chymotrypsin
Trypsin activates chymotrypsin and they both can cleave peptide bonds
A lot of protein is lost in feces: true or false?
FALSE, very little protein is lost in feces, most is absorbed in the duodenum and jejunum of the small intestine.
Where do amino acids go after entering mucosal cell and proceeding to blood?
To the liver, which distributes to the rest of the body.
Where is most of protein absorbed?
Small intestine, by the pancreatic enzymes trypsin, chymotrypsin and brush border enzymes
What is role of pepsin in stomach protein digestion?
breaks protein apart
Proteins are absorbed in the form of ___ ___ through specific carriers
amino acids
Explain the co-transport of amino acids, dipeptides or tripeptides across intestinal epithelial cell
1 Na+ is required in co-transport of each amino acid, dipeptide or tripeptide through to the blood stream and eventually the liver
Food allergies are triggered when…
a whole protein is absorbed without being digested
A rapid, severe allergic reaction is called…
Anaphylaxis
Why are people with GI disease prone to allergic reactions?
Their damaged intestines allow for the digestion of whole proteins
Amino acids in body tissues and fluids are referred to collectively as the
amino acid pool
What accessory organ is in charge of distribution of amino acids throughout the body
Liver
Proteins required for synthesis come from…
amino acid pool
Where are instructions for specific proteins contained?
DNA
Chromosomes contain ___ that stores ___ for protein synthesis
DNA
Genetic instructions
Genetic information flows through the central dogma which is…
DNA > RNA > Protein
What process turns DNA into RNA?
Transcription
What process turns RNA into Protein?
Translation
Explain Protein Turnover
Fact that proteins are always being degraded and synthesized
Do structural proteins (eg. collagen) have slower or faster rates of protein turnover?
Slower
What is an example of quick Protein Turnover?
Insulin, can be increased in amount rapidly by increasing synthesis and decreasing degradation, and decreased by doing the reverse.
If the protein to be made requires more of a certain amino acid then is available, said amino acid is a…
limiting amino acid (as it limits protein synthesis)
What is transamination?
process used to synthesize nonessential amino acids (transfer of amine group)
What is Deamination?
Removal of amine group to synthesize other nitrogen containing compounds
Nitrogen from amino acids can be removed (in deamination) to form other nitrogen-containing compounds such as:
Neurotransmitters
Phosphatidylcholine (lecithin)
Hormones
Deamination produces 3-carbon molecules that can be used to…
synthesize glucose
Deamination produces 2-carbon molecules that form
acetyl-CoA for ATP production
When protein and energy are excess, amino acids converted to acetyl-CoA via deamination are used to…
synthesize fat for storage
Deamination is…
the removal of amino group (NH2) from amino acid
What is the toxic waste product formed by Deamination?
Ammonia
What happens to ammonia (toxic waste product) formed by Deamination?
Liver combines ammonia with CO2 to form Urea which is released into bloodstream and filtered by kidney for excretion in urine (UREA is URINATED)
Kidneys need water to excrete Urea, if there is no water, what happens?
Water is taken from body water
Excess urea (or ammonia) in blood does what?
changes PH
What does the process of deamination and its production of toxic waste product mean for high protein diet?
When on high protein diet, water intake must be increased drastically or else you will risk dehydration. More protein intake means more Ammonia from deamination which along with CO2 takes the form of Urea and therefore more urination.
What is hyperammonemia?
Too much ammonia, toxic, occurs through deamination
As nitrogen is secreted via Urea (there is nitrogen in Ammonia), we can use the balance of N in the body to assess protein intake: State the equation for N balance
N balance: N (g) intake - N (g) output
If N balance is + then…
Protein synthesis > breakdown
If N balance is - then…
Protein breakdown > synthesis
Name at least 3 ways Nitrogen can be lost in the body
Urine (Urea, Ammonia) - major way
Feces - major way
Dermal (skin debris, sweat) - minor way
Hair, Nails - minor way
If Dietary N intake > N loss/excretion then..
there is enough nitrogen to support growth and repair
How/when does a positive N balance happen?
When you eat more protein then required for body’s maintenance
How/when does a negative N balance happen?
Inadequate protein intake
Name at least 3 functions of proteins
Structure
Enzymes
Hormones
Transport
Contraction
Water balance
Buffering
Protection & Defense
Detoxification
Source of energy & glucose
How does protein provide structure in the body?
Eg. Collagen holds together cells and forms protein framework of bones and teeth, also forms ligaments and tendons
How are proteins involved as enzymes in the body?
protein enzymes speed up metabolic reactions
How are proteins involved in hormones in the body?
some hormones are made of amino acids, they are called peptide hormones (insulin and glucagon)
How are protein hormones different then steroid hormones?
Peptide hormones bind to protein receptors on surface of cell membrane while steroid hormones diffuse through cell membrane to enter cell
How are proteins involved in transport in the body?
Proteins transport substances all over the body, and sometimes even in and out of cells. Eg. Glucose is transported by carrier proteins across cell membrane
Another Eg. Hemoglobin transports oxygen from lung to tissues
How is protein involved in contraction?
proteins in muscles allow for contractions
How does protein play a role in water balance in the body?
protein exerts oncotic pressure (pushes water into blood from intercellular space)
- when blood protein is low, more water is pushed into intercellular spaces and fluid accumulates leading to edema
How does protein play the role of a buffer in the body?
some amino acids can resist change of pH due to acid, maintaining balance by donation and acceptance of H+
Normal blood pH is 7.4
pH<7.35 acidosis sets in and can cause coma
pH>7.45 alkalosis can result in convulsions
How does protein protect and defend the body?
- it is the main component of skin
- when foreign particles enter, proteins called antibodies are formed to eliminate foreign particle
adequate protein is important for these AA to function
How does protein detoxify the body?
Liver enzymes (which are proteins) detoxify toxins
inadequate protein reduces ability to detoxify such compounds
How is protein a source of energy and glucose?
protein can be sacrificed to produce energy and glucose (gluconeogenesis) in absence of CHO and fat
What two factors determine the quality of a protein?
- amino acid composition
- digestibility
What is a complete protein?
dietary protein which contains all 9 essential amino acids in adequate amounts for human use
Where can you get complete proteins?
all animal products (except gelatin) are complete
What is an incomplete protein?
dietary protein which lacks or contains limited amounts of essential amino acids; could not support growth if sole source of protein
What are complimentary proteins?
2 or more proteins that together allow you to have each essential amino acid (but individually they do not have each essential amino acid)
What is an example of complimentary protein?
black beans and rice
What is the purpose of the DIAAS %?
it shows how much of the amino acids in a certain food will actually be absorbed
What products typically score well on DIAAS and PDCAA rankings?
animal products like chicken, eggs, meat and milk
What is the AMDR for protein in a day?
10-35% of total energy
What is the RDA for protein for adults?
0.8g protein/kg of body mass
Is there a UL for protein?
No, but caution against consuming additional AA above what is found in food
What life stages would require more protein?
Elderly (due to age related muscle loss)
Pregnant woman
Children
How much muscle do we lose each year after age 40?
about 1% of our muscle each year (sarcopenia)
The RDA for protein of 0.8g/kg of body weight is a great guideline for everyone regardless of age, lifestyle, to use: true or false?
False, based on studies over 50 years ago for healthy young adults
What are the possible negative effects of excess protein?
obesity, heart disease, cancer and osteoporosis (calcium excretion associated with high protein)
Diets higher in protein are also usually higher in ___
saturated fats and cholesterol (dietary cholesterol has little effect on blood cholesterol)
Why can amino acid supplements such as protein powder be dangerous?
they could lead to imbalance of AA and overload of some AA while others are neglected
What is the problem with being especially high in some AAs?
amino acids compete to go through same protein channels sometimes, so more abundant amino acid will become more present in cell while other amino acid is less present
DIAAS vs PCDAAS
DIAAS: samples protein from ileum
PCDAAS: samples proteins from feces (assumes if AA is not there it was digested)
DIAAS is better and more accurate representation of amino acid digestion in humans
Are smaller peptides and amino acids absorbed into mucosal cell with active or passive transport?
Active
AMINO ACIDS can be used to provide energy: true or false?
True, but it is not the first choice of energy of the body.
High protein diets increase production of ___
Urea and other waste products (which can cause dehydration), increase Ca+ loss, can be high in saturated fats or cholesterol
To meet protein needs you should:
have N balance, AMDR of 10-35%, have a variety of animal and plant proteins
Loss of calcium is linked to
osteoporosis
