Proteins Flashcards
_____________ are the major structural and functional components of all cells in the body, and act to facilitate biochemical reactions among the most abundant biological macromolecules and are extremely versatile in their functions.
Proteins
Proteins play a crucial role in a healthy, balanced diet. For example, without sufficient protein nutrition, we would not be able to form ________, and the body’s ability to repair and generate cells would be affected.
enzymes
____________ percent of the human body is made up of proteins.
Twenty
A typical human cell contains about __________ different kinds of proteins, and the human body contains about ________ different proteins.
9000, 100 000
All proteins contain the elements _______, _________, __________, and __________; most also contain ______.
carbon, hydrogen, oxygen, nitrogen, sulfur
Proteins are composed of ___________ carbon.
50-55%
Proteins are composed of ___________ carbon.
Proteins are composed of ___________ oxygen.
19-24%
Proteins are composed of ___________ nitrogen.
13-19%
Proteins are composed of ___________ sulfur.
0-4%
The building blocks for Proteins
Amino acids
It is a molecule that has both negative and positive charges
Zwitterion
Amino acids are _____________ (able to react both as
a base and as an acid.)
amphoteric
Amino acids naturally occur in ___ form
L
It is a molecule that has a positive charge on
one atom and a negative charge on another atom, but
which has no net charge.
Zwitterion
In an acidic solution, the zwitterion accepts a _________ to form a positively charged ion.
proton (H+
)
In basic solution, the -NH3 of the zwitterion _______ a proton,
and a negatively charged species is formed.
loses
___________ are the best-known examples of zwitterions.
Amino acids
Classification of Amino Acids based on Side Chain (R groups)
- Non polar aliphatic amino acids
2.Amino acids with Uncharged (neutral) side chain - Acidic amino acids
4.Amino acids with basic side chain
Classification of Amino Acids Based on Capacity of the Body to Synthesize Them
- Essential Amino acids
- Non-essential amino acids
There are _____ essential amino acids
nine
There are ________ essential amino acids
eleven
They cannot be synthesized in the body and, therefore, must be present in the diet in order for protein synthesis to occur.
Essential amino acids
It is required for growth in children but is not an essential amino acids for adults
Arginine
These amino acids can be synthesized in the body itself and hence not necessarily needed to be acquired through diet
Non-essential Amino Acids
Amino acids are linked together in proteins by a special kind of bond
Peptide bonds
Small Peptide Hormones
o Vasopressin
o Oxytocin
Small Peptide Neurotransmitters
Enkephalins
Small Peptide Antioxidants
Glutathione
___________ regulates the excretion of water by the kidneys; it also affects blood pressure
Vasopressin
Another name for vasopressin is _________________
antidiuretic hormone (ADH)
It is produced by the pituitary gland, and stimulates uterine contractions in labor.
Oxytocin
It was the first naturally-occurring hormone to be produced in a laboratory.
Oxytocin
Pentapeptide neutrotransmitters produced by the brain itself that bind at the receptor sites in the brain to reduce pain.
ENKEPHALINS
Is present in significant concentrations in most cells and have physiological importance as a regulator of oxidation-reduction reactions. As anti-oxidants. Protecting cells contents form the oxidizing agents such as peroxides and superoxides.
Glutathione
They are examples of chemical signaling peptides. They are natural painkillers that are produced in the body. They interact with receptors in the brain to inhibit the transmission of pain signals.
Endorphins
___________ is a naturally occurring, extremely complex substance that consists of amino acid residues joined by peptide bonds
Protein
4 PROTEIN STRUCTURAL LEVELS
•PRIMARY STRUCTURE
•SECONDARY STRUCTURE
•TERTIARY STRUCTURE
•QUATERNARY STRUCTURE
Is the order in which amino acids are linked together in a protein.
Primary Structure
The hormone that regulates blood
glucose levels
Insulin
Is the arrangement in a space adopted by the backbone portion of protein.
Secondary structure
The polypeptide chain is coiled tightly in the fashion of a spring
Alpha helix
In this structure, individual protein chains are aligned side-by-side with every other protein chain aligned in an opposite direction.
The protein chains are held together by intermolecular hydrogen bonding, that is hydrogen bonding between amide groups of two separate chains.
Beta pleated sheets
Is the overall three dimensional structure shape of the protein that result from the interaction between amino acid side chains (R Groups).
Tertiary structure
it is the strongest of the tertiary structure interactions result from the –SH groups. Of two cysteine residues interacting with each other forming
Covalent Disulfide
Involves the interactions between the acidic side Groups and basic R group. The acidic being negative
–COOH becomes –COO-
The basic being positive –NH2 becomes NH3 +
Electrostatic interactions called salt
bridges
This can occur between amino acids with polar R groups.
Hydrogen bonds
Results when 2 non polar amino acids are close with each other.
HYDROPHOBIC INTERACTIONS
Highest level of protein organization. It is only found in multimeric proteins. Describes the
interactions of the subunits in an oligomeric protein. Present also
the electrostatic
interactions
Hydrogen bonds
Quaternary structure
The sequence of amino acids present in a protein’s peptide chain or chains
Primary Structure
The regularly repeating ordered spatial arrangements of amino acids near each other in the protein chain, which result from hydrogen bonds between carbonyl oxygen atoms and amino hydrogen atoms
Secondary structure
The overall three-dimensional shape that results from the attractive forces between amino acid side chains (R groups) that are not near each other in the protein chain
Tertiary structure
The three-dimensional shape of a protein consisting of two or more independent peptide chains, which results from noncovalent interactions between R groups
Quaternary structure
3 Main types of proteins
Fibrous, Globular, and Conjugated
It is a protein whose molecules have an elongated shape with one dimension much longer than the others. They tend to have simple, regular, linear structures.
Fibrous proteins
A __________ is a protein whose molecules have peptide chains that are folded into spherical or globular shapes.
globular protein
These are simple proteins combined with some non-protein material in the body.
Conjugated proteins
____________ is a structural change in a protein that results in the loss (usually permanent) of its biological properties
Denaturation
Temperatures at which proteins denature may vary, but most human proteins function optimally at body temperature (~37ºC).
True
