Lecture 7: Proteins Flashcards
What happens to a protein when it is exposed to different environments, such as increased temperature
it unfolds into a single strand of amino acids, the normal protein becomes a denatured protein
What two major pancreatic enzymes digest protein?
Chymotrypsin and trypsin
Protein turnover
The process where all cells in the body continually break down proteins and build new ones
What is the most abundant structural protein?
Collagen
Enzymes
proteins that conduct specific chemical reactions, catalyst
Hormones
proteins responsible for hormone synthesis, chemical messages produced by endocrine glands
basic structure of amino acids
-Hydrogen
-Amino Group, N terminal (H2N)
-Acid Group, C terminal (C=O, C-OH)
-Side Chain, R group, unique to each
amino acid
How are amino acids classified
20 amino acids –> 9 essential, 11 essential
Structures of protein
Primary: Sequence of a chain of amino acids
Secondary: Hydrogen bonding of the peptide backbone causes the amino acids to fold into a repeating pattern
Tertiary: Three-dimensional folding pattern of a protein due to side chain interactions
Quaternary: Protein consisting of more than one amino acid chain
Process of gene expression
- Transcription: genetic information copied using mRNA
- mRNA leaves nucleus travels to cytoplasm
- binds to ribosome, code is translated for specific order of amino acids
- amino acids are added to growing chain and eventually produce a specific protein
protein synthesis
translating the genetic information contained in mRNA into a functional protein. This process occurs in the cytoplasm of the cell
Transamination
how your body converts non-essential amino acids to essential amino acids through transferring the amine group from an essential amino acid to a different acid group and side chain
Food sources of protein
meat, poultry, legumes
Role of protein in health
cell growth, repair, maintenance, fluid and electrolyte balance, acid-base balance
AMDR for protein
10-35%, limit to 2g/kg BW
Nutritional Implications of vegetarian diets
lower fat and energy intake, nutrient deficiencies
Genetic conditions related to protein synthesis
PKU, sickle cell anemia, cystic fibrosis
Marasmus vs. kwashiorkor
marasmus: low energy & protein intake, wasting of muscles, cannot be reversed, stunted physical & brain development, infants
kwashiorkor: food consumption but almost no protein intake, edema (water retention in belly), linked to early weaning, fatty liver, slow growth & development, toddlers, can be reversed
What begins protein digestion in the stomach?
HCL & pepsin which dentures/unfolds protein
What are polypeptides broken down into in the SI
amino acids, dipeptides, tripeptides
Transport proteins
move products from protein digestion into mucosal cell
How are amino acids absorbed?
Through mucosal cell that travels into the blood, to the liver which regulates distribution of amino acids
Conditionally essential amino acid
Non-essential amino acid becomes essential.
For example, in patients with phenylketonuria (PKU), tyrosine must be provided by
the diet.
What are proteins made up of?
amino acids, carbon, hydrogen, oxygen, nitrogen, some contain sulphur
Gene
segment of deoxyribonucleic acid (DNA) that serves as a template for the synthesis (expression) of a particular protein
Incomplete protein vs. complete protein
Incomplete protein (low quality):
-Generally plant based
-Lack at least one essential amino acid
-Lower digestibility
Complete Protein (high quality):
-Generally animal based
-Have 9 essential amino acids
-High digestibility
Free radicals
unstable molecules that damages cell at DNA level which can lead to cancer
High protein diets (consuming animal protein-rich diet)
contribute to calcium loss/bone loss, may increase blood acidity, progression of kidney disease and liver malfunction
Consuming more plants can potentially reduce
cancer by neutralizing free radicals
