8: Proteins Flashcards
what are proteins
Organic molecules composed of folded long chains of amino acids
how is protein an energy yielding nutrient?
promote tissue growth and repair
what are the effects of protein deficiencies?
can hinder a person’s ability to grow and thrive
what is the structure of amino acids?
Amino acids contain a nitrogen containing amine group, a carboxylic acid group, and a side chain (Rx)
how many amino acids are there and where can they be found?
21 amino acids found in foods/bodies, structurally identical expect their side chains
T/F: All amino acids are essential
False,
- Only nine amino acids are essential
- Some amino acids are essential from the diet, while others can be synthesized by the body from other amino acids
what does it mean when an amino acid is essential?
These are absolutely required from the diet because the body cannot make them itself
what is the process of Transamination?
the non-essential amino acids can be made by modifying other amino acids
what are conditionally essential amino acids and how many are there?
6 are considered conditionally essential, because they become essential when the body is not able to synthesize adequate amounts
what causes conditionally essential amino acids to occur?
certain disease states
how is a food considered a complete protein?
complete proteins are foods that have all 9 amino acids
T/F: All animal and plant products are complete proteins
False,
animal products are complete proteins, while plant products are typically incomplete proteins
how is a food considered an incomplete protein?
incomplete proteins are foods that are missing one or more essential amino acids called Limiting Amino Acids
what is the concept of complementing proteins or mutual complementation?
by eating lots of plant sources of protein, all essential amino acids can be consumed
give some food examples of complementing incomplete proteins
Rice and Beans,
Pita with Hummus,
Peanut Butter on Bread
what are the few plant products that are complete proteins
soy, tofu, quinoa and buckwheat
T/F: To become part of a fully functional protein, amino acids must bind together in a specific order
True,
Our DNA holds the instructions for the sequence of amino acids needed in order to build specific proteins
What is the amino acid pool
to build the sequence of amino acids, the body draws on the amino acid pool, a reservoir of amino acids that are available for making protein
what happens if the diet lacks a non-essential amino acid
the liver can make it from another one through transamination
what happens if the diet lacks an essential amino acid
it is not available for the amino acid chain and protein synthesis stops
what does the phrase “DNA has the blueprints for life”
DNA has the blueprints for making the various proteins that contribute to the structure and funcon of organisms, including humans
how to make a protein
1) RNA makes copy of DNA code for particular gene
2) RNA message has code that dictates sequence of amino acids needed to build specific protein. these amino acids are drawn from the amino acid pool
T/F: A polypeptide chain is not a functional protein
True,
A polypeptide chain is not a functional protein unless it folds in a specific way to form its secondary, tertiary and quaternary structure
how is the first level of protein structure started
adjacent amino acids bonding to each other
though a condensation reaction leading to the formation of a peptide bond
peptide bonds lead to the formation of what
peptide bonds help build the polypeptide chain
what factors determine how the protein folds to form its secondary, tertiary and quaternary structures and eventually the protein’s function?
The amino acid order in the polypeptide chain (which amino acids are located where) and the chain length
T/F: The primary structure is therefore critical to that protein’s role in the body
True
what is the secondary structure of a protein?
hydrogen bonds between non-adjacent amino acids lead to the formation of Alpha helices and beta-pleated sheets
what is the tertiary structure of a protein?
interactions between amino acid side chains leads to further folding of the polypeptide chain and may result in a functional protein
what are several bonds that can occur between tertiary structure side chains
salt bridges and disulfide bonds
what is the quaternary structure of a protein?
several proteins with a tertiary structure bind together to form the final protein
typically, how many protein subunits make up a quaternary protein?
Most quaternary proteins are made up of eight or less protein subunits, each contributing a specific structure and function to that protein
what are protein subunits?
tertiary structure proteins that make up the quaternary structure are typically referred to as protein subunits
when is a protein denatured?
A protein is denatured when it loses its folded three-dimensional structure - change in structure also alters the protein’s function
how does digestion denature protein?
acid in our stomachs unfolds protein units, allowing enzymes to work on the primary structure of a protein, separating off amino acids for absorption
what factors can denature protein and give examples
Heat, acid and agitation
Ex: cracking an egg on a heated frying pan, adding lemon juice to ceviche or beating egg whites
what is the protein digestion pathway in the body?
Mouth: no chemical digestion, only mechanical
Stomach: HCL acid denatures proteins; pepsin chemically digests protein
Pancreas: secretes pancreatic proteases (chymotrysin/trypsin)
Small Intestine: majority of digestion; pancreatic proteases chemically digest protein
Large Intestine: minimal protein digestion
the main site of protein digestion is the small intestine. what occurs here?
proteases trypsin and chymotrypsin, secreted by pancreas, act on remaining polypeptide structures. Proteases act on different amino acid sites to further break polypeptides into single, double (dipeptides) or triple (tripeptides) amino acids. All 3 are absorbed through active transport into centre of small intestine villus. Once amino acids enter villus, they pass into bloodstream via capillaries and proceed to liver. Amino acids that are not metabolized at liver are released into general blood circulation. Tissues can then pick up amino acids from blood and use them for various functions
what is the importance of protein to body structure?
bones, muscles, skin as well as every organ in the body contain protein
Key Structural Protein:
what is Collagen?
protein found in bone, skin and connective tissue; most abundant protein in humans and other mammals.
what does collagen do in bones?
collagen organizes itself into a rigid matrix that calcium and phosphate then harden
what does collagen do in skin?
collagen promotes firmness and strength
Key Structural Protein:
what is Elastin?
adds elasticity and can allow a structure to be slightly deformed and then resume its shape