Chapter 4 Proteins Flashcards
What are the building blocks that make up our proteins?
amino acids
Does each protein have the same sequence of amino acid chains?
no
How is the amino acid pool created?
when protein foods are eaten and broken down
What can we use amino acids for?
building new protein
what is in the amino group in an amino acid?
NH2
how many amino acids do we need to make every protein in our body?
20
what makes each amino acid different?
the unique side off the central C changes. the top part stays the same
How is a protein made?
Take two amino acids, dehydrate them. Extract OH from one and H from another, which causes a bond between the C and N.
What is the bond between C and N called when joining two amino acids?
peptide bond.
What are amino acids that cannot be manufactured in our body and must be consumed in food called?
indispensable (essential)
what are amino acids called that we have the ability to produce (synthesize)?
dispensable (non essential)
what amino acids can normally be made in the body but in certain conditions, we may require temporary dietary intake it in the diet?
conditionally indispensable amino acids
Normally, is intake and output of protein equal (in equilibrium)?
yes
What is it called when we take proteins in and break them down or break them down from tissues in the body?
catabolism
What is it called when we take amino acids and use them to build new proteins?
anabolism
Explain deamination
amino acids break down and remove the Nitrogen group. The N makes urea and then is excreted through the urine.
The remaining O and H are called residue and they can convert to carbohydrates and fats
What are the three contributors to the amino acid pool?
dietary protein
protein from breaking down tissue (catabalism)
plasma proteins
What four things can the amino acid pool create?
Nitrogen via deanimation
Fats/Carbs via deanimation
Creating tissue
plasma proteins
What can we look at to determine our protein balance?
nitrogen balance
What does looking at our nitrogen balance indicate?
how well our tissues are maintained
What measure determines nitrogen balance? How much nitrogen excreted per level of intake.
1 g of nitrogen is excreted for every 6.25g of nitrogen from the diet and metabolism
What is positive nitrogen balance?
When in life does it normally occur?
stores more nitrogen than it excretes
rapid growth, pregnancy, lactation, following illness
What is negative nitrogen balance?
Why does it happen and what does our body do in response?
body takes in less nitrogen than it excretes
results from inadequate protein intake
body will break down tissue to supply amino acids
What are the 6 functions of protein?
build tissue
water balance
pH balance
metabolism
body defense system
energy (4 kcal/g)
How does the amino acid act as a buffering agent to regulate pH?
The amino acid can let go of the H in the carboxyl group when we are too alkaline. H ions make us acidic, which would help balance the pH
If we are too acidic, the NH2 group can act as a base and accept extra H from the blood, raising the pH to become more alkaline
What is the term for when the amino acid has the ability to act as an acid and a base?
amphoteric
What are most enzymes in our body made of?
proteins
How many indispensable (essential) amino acids are there?
9
What complete protein sources supply the 9 indispensable (essential) amino acids?
eggs, milk, cheese, meat, fish, poultry, soy
What are sources of incomplete indispensable (non essential) amino acids?
grains, legumes, nuts, seeds, fruits, vegetables
How do vegetarian diets consume all amino acids if the 9 complete essential amino acids come from animals?
they have to heat the right variety of plant based foods to get all the amino acids
List the types of vegetarian diets
lacto-vegetarian (dairy)
ovo-vegetarian (eggs)
lacto-ovo vegetarian (dairy and eggs)
vegan (no animal foods)
Benefits of vegetarian diets
decreased fat and cholesterol, obesity, CVD, diabetes, cancer risk
improved lipid panels
Explain digestive process of proteins
Mouth - mechanical digestion
Stomach - stomach secretes pepsinogen (inactive form of protein enzyme) which is activated by hydrocholoric acid from the stomach, and creates pepsin. Pepsin breaks proteins into smaller proteins. Makes chyme and polypeptides.
Small intestine - polypeptides come in contact with pancreatic and intestinal proteases, which breaks down proteins into dipeptides and amino acids. Pancreatic enzymes trypsin, chymotrypsin, and carboxyypeptidase assist with hydrolysis.
Peptides aminopeptidase and dipeptidase break it all down into amino acids.
What are the three pancreatic enzymes used in protein digestion?
trypsin
chymotrypsin
carboxypeptidase
What activates trypsinogen to turn into trypsin?
enterokinase
What does the pancreatic enzyme trypsin do?
digests large polypeptides into small dipeptides
what does trypsin activate that gets converted to chymotrypsin?
chymotrypsinogen
what activates the pancreatic enzyem carboxypeptidase to be released and break down proteins into small peptides and amino acids?
trypsin
What does aminopeptidase that is secreted from the small intesting in protein digestion do?
produce small peptides and amino acids
what does dipeptidase that is secreted from the small intestine in protein digestion do?
splits dipeptides into amino acids
