Chapter 6: Protein Flashcards
Amino acid primary sequence
determined by the amino acid sequence
Polypeptide shapes- secondary structure
-determined by weak electrical attractions with chain
-results in twisting folding of protein
-provides strength and rigidity
polypeptide tangles - tertiary structure
-Complex structures
-due to side chain properties (hydrophillic)
-maintaining shape required to function
Multiple polypeptide Interactions
- interactions between polypeptide chains
Protein denaturation
- Disturbs their stability
-uncoil and lose their shape
-less functional ability
Causes of Protein Denaturation
- Heat
- Acid, Base
- Agitation
- Alcohol, Heavy Metals
-other agents
Mouth and Salivary Glands
Chewing and crushing moisten protein rich foods and mix them with saliva to be swallowed
Stomach
HCl uncoils protein stands and activates stsomach enzymes
Small Intestine and Pancreas
Pancreatic and small intestinal enzymes split polypeptides further,
then the enzymes on the surface of the small intestine cells hydrolyze these peptides and the cells absorb them
HCl
Denatures protein structure
activates pepsinogen to pepsin
Pepsin
Cleaves proteins to smaller polypeptides and some free amino acids
inhibits pepsinogen synthesis
Enteropeptidase
Converts pancreatic trypsinogen to trypsin
Trypsin
-Ihnhibists trypsinogen synthesis
-cleaves peptide bonds next tothe amino acids lysine and arginine
-converts pancreatic procarboxypeptides to carboxpeptidases
-Converts pancreatic chymotrypsinogen
Chrymotrypsin
Cleaves peptide bonds next to the amino acids phonylalnine tryosine, tryptophan, methionine, asparagine and histidines
Protein Absorption
Amino acids must transport into intestinal cells
-there are specific carries for amino acids and small peptides
Once amino acids are in intestinal cells
Used for energy
synthesis of other compounds
unused proteins are sent to the liver via the bloodstream
Roles of Proteins
-Building materials for growth and maintanece
- as enzyme to help facilitate or help a reaction to completion
- As hormones messesnger molecules, released in bloodstream to tissues and elicit appropriate responses
Regulators of fluid balance
Proteins attract water
-found in blood and plasma
-do not normally cross cell membranes, when they do this causes problems for the body
-fluid balance like edema
Acid-Base Regulators
-acceot and release H+ ions to maintain balance
-disruptions may cause acidosis or alkalosis, resulting in coma or death
As Transporters
Found in nlood, cell membranes
-carrt nutrients and other molecules
-act as a pump in cell membrane
antibodies
invading antigens are destroyed by antibodies
-each antigen = specific antibodies
-molecular memory is called immunity
As a source of energy and glucose
Proteins can be sacrificed when needed
-body tissues broken down into amino acids
-gluconerogenesis
Using amino acids
-To make other compounds
-for energy and glucose
-to make fat
- deamination reactions
creates annonia and C structure without amaino group
Converting ammonia to urea
Ammonia is toxic
-the liver combines ammonia with CO2 to make urea
-Urea is released inti the blood and passes through the kidneys
-direct relationship to dietary protein intake
-water is required
Nitrogen balance
nitrogen intake - nitrogen output
Conditionally essential amino acids
Tyrosine becomes an essential amino acid if the body doesn’t convert phenylanine or if diet it doesn’t supply it
Protein quality: digestibility
Animal protein- 90-99% soy and legume protein =less than 90%
Plant protein 70-90%
Amino acid composition
Must get all 9 essential amino acids
we do not make partial proteins
High quality proteins
animal derived foods and some plant derived foods
Complementary proteins A=
Achieved throughout the dayas opposed to each meal
measuring protein quality
0-100
100- egg whites, ground beef, chciken, skim milk, tuna
Recommendation intakes of protein RDA
0.8 g/kg of healthy body weight
increased for various population groups
DRI
10-35% daily intake from protein
must also ensure consumption of adequate energy daily
reasons we need dietary protein
obtain essential amino acids
to supply nitrogen to make other proteins
Protei Energy undernutrition
insufficient intake of protein, energy or both
most commone malnutrition
impact on children is poor growth
may impact certain adult population
Health effects of protein
Heart disease
cancer
osteoporosis
weight control
kidney disease
protein powders
Commonly whey protein
often used post-workout
not necessary but can be convenient
Amino Acid supplements
Single amino acids do not naturally exist in food s
-possibly harmful to the body
Difference between proteins and carbs/fats
Nitrogen group that is excreted as urea
they are much larger and can fold and configure themselves in unique ways
denatured proteins cannot preform functions but can’t happen to carbs/fats
Protein synthesis
DNA is the templater that determines the amino acid sequence of proteins
Translation
the process of mRNA directing the sequence of amino acids and synthesis of protein; the amino acids are collected by tRNA and brought to the ribosomes
Transcription
the process of making mRNA from the DNA template
Ribosomes
The part of the cell where translation happens and then the completed protein is released
DNA
packed with 46 chromosomes
segments of DNA are genes
genes can be translated into a protein
Gene expression
DNA- mRNA- tRNA -Protein
genes must be switched on and off
single gene disorders
Mutations inherited at birth
damage to the individual exerted early in life
Multigene disorders
Influence several genes
sensitive to interactions with the environment
single nucleotide polymorphosis
Clinical consideration
-genetic predisposition to specific diseases
-personalied therapies based on genetic profile
-creation of new medicine for genetic variations
-deeper understanding of nutrition and disease pathways
-currently look mostly at SNPs
