week 6 proteins Flashcards
what are proteins?
proteins are amino acids linked together end-to-end via peptide bonds
what is a peptide bond?
chemical bond formed between amine group end of one amino acid and the acid group of the next
what is a condensation reaction
joins amino acids together via removal of water
what is hydrolysis?
separation of amino acids via addition of water
when two amino acids are together what are they called? three? 10 or more?
two: dipeptide
three: tripeptide
10 or more: polypetide
what are the 4 kinds of protein structure?
primary
secondary
tertiary
quaternary
what is the primary structure?
amino acid sequence
what is the secondary sequence?
weak electrical attractions (e.g hydrogen bond between H and O)
what is the tertiary structure?
folding of the long AA chain - hydrophobic amino acids cluster on the inside while hydrophilic face the outside of the structure
what is the shape of the protein critical for?
their function
what is globular hemoglobin?
4 polypeptides combined at the quaternary-level and each carry O2 and Fe (iron)
what is denaturation?
- when subjected to heat, acid, or other conditions that disturb stability, proteins uncoil and lose their function
- does not change their “primary” shape or amino acid sequence, but will cause them to lsoe their shape, thus their function
what does an amino acid contain?
contain an amine group (N-containing), acid group (COOH), and side chain/group
what does the side chain do?
creates a unique chemical structure, differentiates one AA from another; makes AA differ in size/shape/electrical change
what are Essential Amino Acids
cannot be synthesized at all. must be supplied by diet
What are proteins made of?
Amino acids linked together via peptide bonds.
What is the process called that joins amino acids together?
Condensation.
What is the process that separates amino acids?
Hydrolysis.
What do you call two amino acids linked together?
Dipeptide.
What do you call three amino acids linked together?
Tripeptide.
What is the term for a chain of 10 or more amino acids?
Polypeptide.
What is the primary structure of a protein?
AA sequence.
What type of bonds are formed in the secondary structure of proteins?
Weak electrical attractions, such as hydrogen bonds.
In the tertiary structure of proteins, where do hydrophobic amino acids cluster?
On the inside of the structure.
What is the quaternary structure of proteins?
Multiple polypeptides interacting together.
What is the critical factor of a protein that determines its function?
Shape of the protein.
What are enzymes?
Proteins that act as catalysts.
What is hemoglobin composed of?
4 polypeptides combined at the quaternary level.
What happens to proteins during denaturation?
They uncoil and lose their function.
What are the 20 different kinds of amino acids known as?
Building blocks of protein.
What do essential amino acids (EAA) refer to?
Amino acids that cannot be synthesized or are insufficient in the diet.
How many essential amino acids are there?
Nine.
what are the nin essential amino acids?
- Histidine * Isoleucine * Leucine *lysine *methionine *phenylalanine *threonine *tryptophan *valine
What are dispensable amino acids?
Amino acids that can be synthesized by the body.
What are conditionally essential amino acids?
Normally non-essential but must be supplied by diet when the body cannot meet its needs.
What is the process of protein digestion that occurs in the stomach?
Hydrochloric acid denatures proteins and activates pepsin.
What enzyme initiates protein digestion in the stomach?
Pepsin.
What occurs in the small intestine during protein digestion?
Proteases hydrolyze polypeptides into tripeptides and dipeptides.
What is the primary function of proteins in the body?
Building blocks for growth and maintenance.
What is the process of protein synthesis?
Messenger RNA (mRNA) combines with ribosomes to make protein. using transfer RNA (tRNA) and amino acids
What is transcription in protein synthesis?
mRNA being made from a template of DNA.
What is translation in protein synthesis?
mRNA directing the sequence of amino acids to synthesize protein.
What is nitrogen balance?
The relationship between nitrogen intake and nitrogen output.
What is positive nitrogen balance?
Nitrogen intake is greater than nitrogen output.
what is negative nitrogen balance?
Nitrogen output is greater than nitrogen intake.
What can be made from tyrosine?
Norepinephrine, epinephrine, thyroxin, and melanin.
What is deamination?
Removal of the nitrogen-containing amino group from amino acids.
What is the purpose of converting ammonia to urea?
To prevent ammonia buildup, which negatively impacts blood pH.
What are high-quality proteins?
Proteins that provide all essential amino acids.
What is the Protein Digestibility-Corrected Amino Acid Score (PDCAAS)?
A method to evaluate the quality of food protein.
What is protein pairing?
Combining proteins with different amino acid compositions to improve quality.
What can lead to protein-related edema?
Excessive protein losses, inadequate protein synthesis, or inadequate protein intake.
What role do antibodies play in the body?
Combat antigens from viruses, toxins, bacteria, and allergens.
What is the effect of insufficient protein on immunity?
Insufficient protein leads to insufficient immunity.
What is typically lower in saturated fat in vegetarian diets?
CVD prevention
Vegetarian diets often include more MUFAs and PUFAs from nuts, seeds, and soy.
How does a vegetarian diet contribute to cancer defense?
Decreased consumption of red and processed meat and increased intake of fiber and fruits/vegetables
Antioxidants from fruits and vegetables play a significant role.
What is a common misconception about vegetarian diets?
Vegetarian does NOT always equate to healthy
Variety is essential for a balanced diet.
What are the macronutrients of concern in vegetarian diets?
Protein, Omega 3 fatty acids
Quality of protein and sources of Omega 3s are important.
What types of protein are considered complete versus incomplete?
Complete: animal sources, Incomplete: plant sources
Digestibility of protein also matters.
What are the micronutrients of concern for vegetarians?
Iron, Zinc, Calcium, Vitamin B12, Vitamin D
Heme iron is more absorbable from animal sources.
What is the RDA for protein for healthy adults?
0.8g/kg/d of healthy body weight
This varies for different age groups and conditions.
What is the AMDR for protein intake?
10-35% of daily calories from protein
This helps balance macronutrient intake.
What is the recommended protein intake for women and men?
46g/day for women, 56g/day for men
Higher recommendations exist for specific populations.
How do you calculate protein requirements?
Weight in kg x 0.8g
Example: 180lbs = 81.8kg, 81.8kg x 0.8g = 65g protein/day.
What can result from insufficient protein intake?
Slowed growth, impaired brain and kidney function, weakened immunity
Nutrient absorption can also be affected.
What is Protein-Energy Malnutrition (PEM)?
Most widespread form of malnutrition due to starvation and hunger
It affects overall health and development.
What is whey protein?
A by-product of cheese manufacturing, full array of essential amino acids
It is the most popular protein supplement.
What is the role of protein supplements?
To help individuals with higher protein needs or difficulty achieving intake
A “foods first” approach is often recommended.
Are single amino acid supplements advisable?
No, large intake can cause digestion issues and possible deficiencies
BCAAs may support muscle synthesis post-exercise.
Does excess protein increase muscle mass?
No
Muscle growth relies on physical training and adequate energy.
What is the relationship between protein and heart disease?
High consumption of animal-protein often linked to high saturated fats
This association raises concerns for CVD.
How does protein intake affect osteoporosis?
Higher protein intakes associated with increased calcium excretion
Calcium intake is crucial to mitigate this effect.
