Week 4 Flashcards
What is the difference between essential and non-essential amino acids
Non-essential: Can be produced by the body via transamination of dietary amino acids at the required rate
Essential: Must be provided by the diet as the body is unable to produce these, or not a sufficient rate to meet demand
There are 8 essential amino acids for adults
What is amino acids are conditionally essential amino acid?
Tyrosine, histidine, Glutamine and arginine
What is amino acid Essentiality determined by?
Essentiality is determined on the basis of the inability of the human body to make the essential amino acids (EAA) because:
- Cells cannot make the carbon skeleton of EAA
- Cells lack the enzymes to attach the amine group to the carbon skeleton to form the EAA
- Cells cannot achieve the manufacture of EAA at a fast enough pace to meet requirements
When is gastrin produce?
in response to food exposure
what is the function of gastrin?
signals HCL production and pepsinogen secretions
What do secretin and CKK stimulate?
Secretin and CKK stimulate the pancreas to release proteases:
trypsin, chymotrypsin and carboxypeptidase into the duodenum
What digests short peptides into amino acids?
peptidases
What do proteases trypsin, chymotrypsin and carboxypeptidase, do?
These enzymes breakdown polypeptides into shorter peptides and into amino acids for absorption
Once absorbed, amino acids taken to liver via portal vein to constitute the amino acid pool for:
1) protein synthesis; or
2) for energy production after deamination; or
3) in gluconeogenesis after deamination
What is deamination?
when amino acids are to bec onverted to pyruvate, acetyl CoA, intermediates of the CAC, or to oxaloacetate for gluconeogenesis
What happens in deamination?
- Removal of the amine group from an amino acid (vitamin B6 is required)
- Amine group converted to ammonia
- Ammonia converted to urea in the urea cycle (in liver)
- Urea filtered in the kidney and excreted via urine
What do the Carbon skeleton of ketogenic amino acids form?
What does the product do
acetyl CoA: enter the CAC for energy production
fat production when in excess
What do Carbon skeleton of glucogenic amino acids forrm?
what does the product do?
Form pyruvate to fuel energy production or the oxaloacetate pool
– Enter the CAC to form various intermediates to fuel energy production
– Form oxaloacetate for gluconeogenesis pathway (in fasted state; in liver and kidney)
What is transamination? where does it occur?
when additional non-essential amino acids are required in the AA pool. Occurs principally in the liver
Transfer of an amine group from one AA to a carbon skeleton to form a new AA
What are the enzymes and cofactors required for transamination?
Enzymes and cofactors are required:
– Transaminases:
• Alanine aminotransferase (ALT)
• Aspartate aminotransferase (AST) – Vitamin B6
What are the two main phases of gene expression?
1- DNA transcription phase:
• DNA code copied and transferred from the nucleus to the cytosol via messenger RNA (mRNA)
2- mRNA translation phase:
• Amino acids (coming from the AA pool)are linked by peptide bonds to form proteins and have a physiological function
Define transcription
making a complementary copy of DNA = messenger RNA in nucleus
What does tRNA do?
tRNA’s present the adequate AA to the ribosome to be attached to the previous AA by peptide bond
What is a peptide bond?
Peptide bond = covalent bond between the carboxyl acid group of one amino acid and the amine group of another amino acid
(C-N)
Define the 4 protein structures?
primary, secondary, tertiary, quaternary
Primary: a simple sequence of amino acids in the chain
Secondary: the shape of the protein molecule caused by weak hydrogen bonding between C=O and N-H groups within the chain. E.g. alpha helix, beta-sheet
Tertiary: 3 D folding from the interaction between R- groups determining the overall shape and function of the protein
Quaternary: interactions between 2 or more polypeptide chains. The result is a protein classified as fibrous, globular or conjugated
What are prosthetic groups in quaternary structures?
Inorganic substances may be incorporated into the
molecule
heme is the prosthetic group in hemoglobin. Allows for the binding of iron for oxygen transport (= hemoglobin function
what happens due to denaturation of protein?
cause can cause it to occur?
Altering the protein’s 3 dimensional structure Acid alkaline (pH), heat, enzymes, HCl can modify the structure
What are the 10 functions of proteins?
- DNA expresses enzymes
- helps give rigid structure and assist in contractions
- transport of nutrients
- hormones and neurotransmitters
- keeps acid base balance
- DNA production and formation
- helps in immune function, antibodies
- helps keep fluid balance
- forms glucose
- provides energy
How do proteins help keep fluid balance?
fluid is forced into the interstitial space by blood pressure generated by the pumping action of the heart
fluid is drawn into the bloodstream by the proteins as blood pressure declines in the capillary bed
Define incomplete protein
Doesn’t contain all essential amino acids
usually plant proteins
define complete protein?
contains all essential amino acids
usually animal proteins
How do you measure protein quality?
- biological value (BV) of protein
- Protein effeciency ratio (PER)
- Chemical Score (CS)
- protein digestability corrected amino acid score (PDCAAS)
What is biological value?
How efficiently the protein from a food is converted to body tissue protein. If all 8 (9) AA are present, the body can use this protein more efficiently
How is biological value determined?
Nitrogen retained (g) / Nitrogen absorbed (g) x 100 Measure takes into account urinary % and fecal nitrogen excretion
What is the difference between high and low biological value?
High BV = Foods that provide amino acids in amounts consistent with body’s needs (e.g. similar AA profile). The body will retain much of the absorbed nitrogen, especially if consumption does not exceed requirement
Low BV = Foods that provide the amino acids in amounts not consistent with body’s needs (e.g. different AA profile). The body will not retain all of the nitrogen absorbed.
What is there protein effeciency ratio?
Compares weight gain of a laboratory animal consuming a tested protein with the weight gain of an animal consuming a protein of reference
How is protein effeciency ration calculated?
PER= Weight gain (g) /protein consumed
How is chemical score calculated?
mg of limiting amino acid in 1 gram of the test food
divided by
mg of that amino acid in 1 gram of the reference food
How is protein digestibility corrected amino acid score (PDCAAS) calculated?
PDCAAS= chemical score x digestability
How is protein digestability determined?
Protein digestibility = amount of amino acids absorbed. This is the amino acid profile able to support growth and maintenance
What is a “limiting” amino acids?
The “limiting” amino acids are the essential AA missing in the profile of a protein food
What is “the” limiting amino acid?
Limits the amount of protein a body can make
What is are Complementary” proteins
the protein foods that can be combined to supply all limiting AA’s
What is the aim of the NRV’s?
Maintaining sustenance and preventing deficiencies in the population
what is the AMDR for protein?
15-25%
what is gluten?
general term to describe a variety of proteins found in wheat, barley, rye, oats.
Gluten proteins are made of 2 groups of proteins: what are they?
glutelins (glutenin in wheat) and prolamines (gliadin in wheat)
What is Coeliac disease
Coeliac disease is an auto-immune gluten allergy disease
What happens to the body in coeliac disease?
the villi become inflammed and merge together decreasing the surface area
What is the difference between Kwashiorkor and Marasmus protein health concerns
Kwashiorkor
protein malnutrition specifically
Minimal amounts of protein intake but
moderate energy deficit
Marasmus
Protein + energy malnutrition
Minimal amounts of energy, protein and micronutrients intake
What happens when a protein is eaten that someone is allergic to?
Proteins (allergens) in food cause hypersensitivity reactions and trigger an immune response:
Stimulate white blood cells to produce antibodies, mostly immunoglobulin E (IgE)
Anaphylaxis is a life-threatening condition: what happens to the body when this occurs?
- Decreased blood pressure
- Respiratory distress
- Death with out medical treatment
What are the advantages of a high protein diet?
- Greater thermic effect post prandial=increased EE: good for weight balance or weight loss programs
- Appetite control
- Advantage im sparing muscle mass loss with ageing (sarcopenia)
- Advantage in mental well being: precursors of neurotransmitters
What are the disadvantages to a high protein diet?
- over burden on the kidneys
- increase urinary bone calcium loss
- may relpace other food groups with meat and loose good vitamins and minerals
