4-Proteins Flashcards
Which are the protein sources for human’s body?
- Liver where protein production takes place
- Food which contains proteins
How many different proteins are needed to carry out body’s activities?
Around 50,000
Where are the half of the proteins been located?
In the muscles
Which is the most abudant protein in human’s body and where is it found?
Collagen and is present in all connective tissues
Name some protein functions
- Some proteins play primarily a structural role (muscles contain about half of the body’s protein)
- All hormones are proteins
- Transport proteins can shuttle chemical elements, such as oxygen(e.g haemogoblin) or store minerals, such as iron( e.g. ferritin)
- Proteins can also help maintain base-acid balance by acting as buffers to minimize changes in pH.
- Proteins contribute to a healthy immune system through the formation of antibodies
Protein malnutrition might increase infection risk - Proteins can also provide energy to the body (however the main role is for tissue building)
What kind of molecules are hormones?
They are proteins.
What is the function of enzymes?
Enzymes serve as chemical catalysts, speeding up chemical reactions
Name a protein for each category: Structural Transport and binding Enzymes Regulation Protection pH regulation
Collagen Haemogoblin, ferritin Pepsin Insulin IgA antibodies Silain
From where is the word amino acid derived?
From the presence of both amino and acid group to the central group
How proteins differ fromcarbohydrates and fats?
Due to the existence of the amino groups
What do proteins contain?
Carbon
hydrogen
suplur
nitrogen
What determines the properties / function of an amino acid?
ONLY the R-group
Through which procedure do the petide bonds be formed?, are they strong?, how these bonds are destroyed?
They are formed by enzymatic reaction
They are very strong
They are destroyed through hydrolysis only by enzymes during digestion or these ones that are present in lysosomes.
How can peptide chains be categorises by their lenght?
Dipeptides Tripepeptides Short- polypeptides(10-40aa) Large polypeptides(proteins) (more than 40aa) Large proteins (dystrophin=3648aa)
How many amino acids are needed from our body in order to built all the proteins
20 amino acids
How proteins differ each another?
number of amino acids
order/sequencing
types of amino acids (polar/non-polar)
Where can proteins be synthesized in our body?
In the liver
How can we say essential/ non-essential amino acids in other words?
indespensable/dispensable
How many levels has protein 3D structure and which are the characteristics of each one?
4 levels
1) Primary- sequence of aa in peptide chain
2) Secondary-Folding/ coiling of peptide chain (usually to a-helix or b-pleated sheet)
3) Tertiary-peptide chain folds upon itself
4) Quaternary-folded peptide chains join together
Can a protein be directly absorbed when eate?if not what procedures should happen?
When a protein is eaten as part of the diet, it is not absorbed directly, but must first be broken down into its component amino acids
Stage 1—Digestion in mouth
Digestion begins in the mouth with the moistening effect of saliva and the chewing by the teeth
Moistening the food creates a bolus, which can be more easily mix with acid and enzymes in the stomach.
2)Stage 2-Digestion in the Stomach
Hydrochloric acid (HCI) is secreted by parietal cells in the stomach lining in order to denature the protein and provide an appropriate environment for digestion
Chief cells in the stomach lining produce an inactive enzyme, pepsinogen
The acidic environment converts the pepsinogen to the active protease( protein-cleaving enzyme), pepsin.
Pepsin breaks the polypeptide chain at numerous sites, yielding:
intermediate- length polypeptides
small polypeptides
and some amino acids
Stage 3- Digestion And Absorption in the Small Intestine
Further breakdown of the polypeptides takes place in the small intestine
It involves cleavage by proteases produces by both the pancreas and the small intestine
A variety of proteases (e.g. amylopeptidase , carboxylpeptidase etc.) is needed to cleave peptide bonds associated with the full range of proteins
Amino acids and short peptides are absorbed by the small intestine
Can a protein be brokendownn to provide energy?
yes, but a samll percentage
What is the destination of amino acids when are inserted in the bloodstream?
the liver
What is protein turnover?
Is the dynamic process whereby proteins are continually synthesized and degraded
What is the average protein turnover in an adult?
The average protein turnover in an adult is 300-400g per day
Can amino acids released from protein degradation be re-incorporated into protein?
yes
In which food categories do we find protein?
in all food categories(plant & animal)
Why we need to recieve proteins?
- Tissue repair
- Replace the lost amino acids
Should a well-fed individual have high-protein diet?
No, it is wasteful
What happens if we recieve surplus amino acids in our body?
Surplus amino acids are rapidly catabolised & the nitrogen is excreted as urea in the urine
Importance of protein is OFTEN overestimated!!
What is the recommended protein intakefor adults?(UK recommendations) and what the current protein intakes males and females?
0.8g/kg body weight and no more than 1.5g/kg per day for adults
¬50-70g protein per day for adults
88g protein per day for men
64g protein per day for women
How the protein’s quality is defined?
Protein Quality is defined as the protein’s source ability to support growth
When can a protein be characterised as complete?
A complete protein has all the essential amino acids present in proper proportions to sustain growth
Info: Proteins derived from animal sources(meat,fish) as well as soy protein are complete (high biological value)
.
Info: Plant based proteins are incomplete proteins (low biological value)
.
What are the effects of protein defficiency?
- People that are chronically ill, institutionalised and elderly are at high risk of protein malnutrition muscle loss (sarcopenia)
- Protein -energy malnutrition might be serious concern for children in developing countries.
- Malnutrition affects hundred of millions of young children and leads to growth failure (stunted growth)
What are the effects of high protein intake?
- High-protein diets may have effects on calcium metabolism
- As protein increases in the diet, calcium excretion increases, which may be related to bone loss.
- Excessive intake ,may lead to deterioration of renal function in patients with chronic renal diseases (stages 1-4)
