Chapter 6: Proteins Flashcards
amino acids
The building blocks of proteins. Each contains central carbon atom, an amino group, an acid group, and a side chain.
essential amino acids
Cannot be synthesized by the body in sufficient amounts to meet the needs and therefore must be included in the diet.
nonessential amino acids
Can be synthesized y the human body in sufficient amounts to meet their needs.
Transamination
The process by which an amino group from one amino acid is transferred to a carbon compound to form a new amino acid.
conditionally essential amino acids
amino acids that are essential in the diet only under certain conditions or a certain times of life. (ex. only if there is enough phenylalanine in the diet is there going to be enough tyrosine)
dipeptide
Two amino acids linked by a peptide bonds.
tripeptide
3 amino acids linked by peptide bonds
polypeptide
A chain of 3+ amino acids linked by peptide bonds
primary structure
Linear sequence of amino acids
secondary structure
Shapes within parts of a protein (e.g. beta-pleated sheet, helical, linear)
tertiary structure
Final 3D Structure
-Multiple polypeptide chains linked together (a protein) create a specific 3D shape to perform a specific task. If the shape is altered in any way the protein will NOT work the same way.
denaturation
the alteration of protein’s 3D structure. This can be caused by certain changes in the environment such as an increased temperature of pH.
Why is protein important? (5)
- Regulating body processes
- Growth and Repair of Tissues
- Immune Deficiency
- Transportation
- Energy (as a last resort if the body has not fat or CHO
amino acid pool
All of the amino acids in body tissues and fluids that are available for use by the body.
deamination
the removal of the amino acid group from an amino acid
amino acid pool allows for… (3)
- Energy production
- Synthesis of glucose or fatty acids
- Synthesis of nonprotein molecules that contain nitrogen
protein turnover
the continuous synthesis and breakdown of body proteins
gene
a length of DNA containing the information need to synthesize RNA or a polypeptide
transcription
the process of copying the information in DNA to a molecule of mRNA
translation
the process of translation mRNA code into the amino acid sequence of a polypeptide chain
limiting amino acid
the essential amino acid that is available in the lowest concentration in relation to the body’s needs
gene expression
the events of protein synthesis in which the information coded in a gene is used to synthesize a product, either a protein or a molecule of RNA
neurotransmitters
molecules that function to transfer signals between the cells of the nervous system and can stimulate or inhibit a signal
urea
a nitrogen-containing waste product formed from the breakdown of amino acids that is excreted in the urine
antibodies
proteins produced by the bodes immune system that recognize foreign substances in the body and help to destroy them
protein-energy malnutrition (PEM)
a condition characterized by wasting and an increased susceptibility to infection that results from the long-term consumption of insufficient amounts of energy and protein to meet needs
kwashiorkor
a form of protein-energy malnutrition in which only protein is deficient
marasmus
a form of protein-energy malnutrition in which a deficiency of energy in the diet causes severe body wasting
protein excess causes (4)
- Hydration and kidney function (if kidneys do not work well already extra stress is added to them)
- Bone health (excess calcium is lost in the urine)
- Kidney stones (in creased risk)
- Heart disease and cancer risk (high protein = high animal products = high risk CHD)
phenylketonuria (PKU)
an inherited disease in which the body cannot metabolize the amino acid phenylalanine. If the disease is untreated, toxic by-products called phenylketones accumulate in the blood and interfere with brain development
celiac disease
a disorder that causes damage to the intestines when the protein gluten is eaten
nitrogen balance
the amount of nitrogen consumed in the diet compared with the amount excreted by the body over a given period of time
negative nitrogen balance
nitrogen intake < nitrogen output
the total body protein decreases
e.g. when severely burned
positive nitrogen balance
nitrogen intake > nitrogen output
total body protein increases
e.g. when pregnant
High protein needs
pregnant and lactating women, the ill, those who exercise, and children
protein quality
a measure of how efficiently a protein in the diet can be used to make body proteins
complete dietary protein
protein that provides essential amino acids in the proportions needed to support protein synthesis
incomplete dietary protein
protein that is deficient in one or more essential amino acids relative to body needs
chemical or amino acid score
a measure of protein quality determined by comparing the essential amino acid content of the protein in a food with that in a reference protein. The lowest amino acid ratio calculated is the chemical score
protein digestibility-corrected amino acid score (PDCAAS)
a measure of protein quality that reflects a protein’s digestibility as well as the proportions of amnio acids it provides
protein efficiency ratio
A measure of protein quality determined by comparing the weight gain of a laboratory animal fed a test protein wit the wight gain of an animal fed a reference protein
net protein utilization
a measure of protein quality determined by comparing the amount of nitrogen retained in the body with the amount eaten in the diet
biological value
a measure of protein quality determined by comparing the amount of nitrogen retained in the body with the amount absorbed from the diet
protein complementation
the process of combining proteins from different sources so that they collectively provide the proportions of amino acids required to meet needs
vegetarianism
a pattern of food intake that eliminates some or all animal products
vegan
a pattern of food intake that eliminates all animal products
risks of missing animal products
lack of B vitamins, calcium, vitamin D, iron, zinc, DHA, and EPA
