PROTEINS Flashcards
A ______ is a naturally occurring, unbranched polymer in
which the monomer units are _____ _______
Proteins, amino acids
________, the oxygen-transporting protein of blood,
contains iron.
Hemoglobin
An amino acid is an organic compound that contains both
an amino (-NH) group and a carboxyl (-COOH) group. True or False?
FALSE, (-NH2) group and (-COOH)
The amino acids found in proteins are always b-amino acids. True or False?
FALSE, a-amino acids
What is α-amino acid?
an amino acid in which the amino group and the carboxyl group are attached to the α-amino.
Amino acid that contains one amino group, one carboxyl group, and a nonpolar side chain.
Nonpolar amino acid
There are _____ nonpolar amino acids.
9
The only nonpolar amino acid that has a propyl group on its side chain which is bonded to both the α-carbon atom and the amino nitrogen atom, giving a cyclic chain.
Proline
Some textbooks list this amino acid as a polar neutral amino acid because water can weakly interact through hydrogen bonding with the NH ring location on this side-chain ring structure, although it is non polar.
Tryptophan
Such amino acids are hydrophilic. True or False?
FALSE, hydrophobic
The nine nonpolar amino acids:
Glycine, Alanine, Valine, Leucine, Isoleucine, Proline, Phenylalanine, Methionine, Tryptophan
side chain of a polar neutral amino acid is neither acidic nor basic, because the side chain is
polar but neutral
Which of the following are not part of the group:
Serine, Arginine, Cysteine, Threonine, Asparagine, Glycine, Glutamine, Tyrosine
Arginine and Glycine
If Arginine and Glycine are the amino acids that do not belong to the group of Polar Neutral amino acids, what group do they belong to?
Arginine = Polar Basic Amino Acids, Glycine = Non Polar Amino Acids
An amino acid that contains one amino group, one carboxyl group, and a side chain that is polar but neutral.
Polar neutral amino acid
The side chain of the group of this amino acid bears a negative charge
polar acidic amino acid
polar acidic amino acid is an amino acid that contains one amino group and _____ carboxyl groups
2
The second carboxyl group of a polar acidic amino acid is where to be seen?
part of the side chain.
There are two polar acidic amino acids:
Glutamic Acid and Aspartic Acid
polar basic amino acid is an amino acid that contains two amino groups and two carboxyl groups. True or False?
FALSE, polar basic amino acid has TWO AMINO GROUP and ONE CARBOXYL GROUP only
the side chain of a polar basic amino acid bears a ________ charge
positive
Draw the structure of the three polar basic amino acids and the two polar acidic amino acids.
Tignan nyo sa libro/ppt kung tama kayo
How many essential amino acids are there? Name them all
9: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine
Is Arginine not an essential amino acid? If so, explain your answer
It is essential, but for CHILDREN only because of the fact that it is required for their growth. It is not essential for adults,
These amino acids which are called “essential amino acids”, must be obtained from?
DIetary proteins
What is dietary proteins?
Dietary proteins are essential nutrients that our bodies need to build and repair tissues, produce enzymes, hormones, and antibodies, and transport nutrients.
Not a question, but rather a review, click to see
Serotonin is a tryptophan derivative, while both Dopamine and Norepinephrine is a tyrosine derivative
A standard amino acid needed for protein synthesis that must be obtained from dietary sources because the human body cannot synthesize it in adequate amounts from other substances. What amino acid is being described in the sentence?
Essential Amino Acid
A __________ __________ _________ is a protein that contains all of the essential amino acids in the same relative amounts in which the body needs them
complete dietary protein
An incomplete dietary protein is a protein that does not contain adequate amounts relative to the body’s needs, of one or more of the essential amino acids. Is the statement true or false?
True
An essential amino acid that is missing, or present in inadequate amounts, in an incomplete dietary protein
Limiting amino acid
Proteins from animal sources is usually a incomplete dietary protein, while proteins from plants sources tends to be complete dietary protein. Is the statement true or false?
FALSE, they are opposite. Proteins from animals = complete dietary protein, Proteins from plants = incomplete dietary protein
_____________ _____________ _____________ are two or more incomplete dietary proteins that when combined, provide and adequate amount of all essential amino acids relative to the body’s needs
COMPLEMENTARY dietary proteins
What is the simplest standard amino acid?
Glycine
Is glycine achiral or chiral?
Glycine is achiral, all of the standard amino acids are chiral
Isoleucine and threonine possess 3 chiral centers. Is this true or false?
FALSE, it only has 2 chiral centers for both isoleucine and threonine
What are the rules for drawing Fischer Projection for amino acids?
1.) The COOH group is put at the top of the projection formula, R group at the bottom. This positions the carbon chain vertically
2.) The -NH2 group is in a horizontal position. Positioning it on the left denotes the L isomer, and positioning it on the right denotes the D isomer.
In pure form, what is the color of amino acids?
White crystalline solids
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 neutral solution, carboxyl group have a tendency to lose protons (H+), producing a ________ charged species
negatively
In neutral solution, amino group have a tendency to accept protons (H+), producing a ________ charged species
positively
Is the amino group of an amino acid (H2N or NH2) structure basic or acidic?
basic
Is the carboxyl group of an amino acid (COOH) structure basic or acidic?
acidic
In solution and also in the solid state, α-amino acids exist as zwitterions. True or False?
TRUE
the net charge on a zwitterion is _____ even though parts of the molecule carry charges.
zero
The pH at which an amino acid exits primarily in its zwitterion form is called the ________ _________
isoelectric point
Cysteine is the only standard amino acid that has a side chain that
contains a ______________ group.
sulfhydryl
An unbranched chain of amino acids
peptide
What is the difference between oligopeptide and polypeptide?
Oligopeptide = peptides with 10-20 amino acid
Polypeptide = a long unbranched chain of amino acid
A peptide bond is a noncovalent bond between the carboxyl
group of one amino acid and the amino group of another
amino acid. True or False?
FALSE, covalent bond NOT NONcovalent
this refers to the backbone of the peptide
These are the repeating sequence of peptide bonds and a-carbon –CH groups in a peptide (tignan ang page 126 para mas magets)
Peptides that contain the same amino acids but in
different order are different molecules (constitutional
isomers) with different properties is called?
Isometric Peptides
An amino acid residue is the portion of an amino acid
structure that remains, after the release of H2O. True or false?
TRUE
Give the Three Biochemically Important Peptides
Small Peptide Hormones
Small Peptide Neurotransmitters
Small Peptide Antioxidants
two best-known peptide hormones, both produced by the pituitary gland,
oxytocin and vasopressin.
Enkephaline is a type of Small Peptide Neurotransmitters. Define Enkephaline
pentapeptide neurotransmitters produced by the brain itself
that bind at receptor sites in the brain to reduce pain.
________ functions as an antioxidant, protecting cellular contents from
oxidizing agents such as peroxides and superoxides
glutathione
- A simple protein is a protein in which only amino acid
residues are present. - A conjugated protein is a protein that has one or more
nonamino acid entities present in its structure in addition to
one or more peptide chains.
A. Both statements are true
B. Both statements are false
C. First statement is TRUE, Second statement is FALSE
D. First statement is FALSE, Second statement is TRUE
A
These non-amino acid components, which may be organic or inorganic, are called
prosthetic groups. True or False?
TRUE
non-amino acid group present in a conjugated protein.
prosthetic group
- Primary protein structure is the order in which amino acids
are linked together in a protein. - Secondary protein structure is the arrangement in space
adopted by the backbone portion of a protein.
A. Both statements are true
B. Both statements are false
C. First statement is TRUE, Second statement is FALSE
D. First statement is FALSE, Second statement is TRUE
A
The two most common types of secondary structure of protein
alpha helix (α helix) and the beta pleated sheet (β pleated sheet)
How does the α helix and β pleated sheet differs?
▪An alpha helix structure is a protein secondary structure in
which a single protein chain adopts a shape that resembles
a coiled spring (helix), with the coil configuration
maintained by hydrogen bonds.
▪A beta pleated sheet structure is a protein secondary structure in
which two fully extended protein chain segments in the same or
different molecules are held together by hydrogen bonds.
Identify what is being described in the sentence.
the overall three-dimensional shape of a protein that results from the interactions between amino acid side chains (R groups) that are widely separated from each other within a peptide chain.
Tertiary protein structure
(take note of the letter t in “three-dimensional, it refers to t of tertiary protein structure)
A protein secondary structure that is neither an a-helix nor a B-pleated sheet.
Unstructured Protein Segment
Give the classification of proteins based on shape
▪ fibrous protein
▪ globular protein
▪ membrane protein
This proteins tend to have simple, regular, linear structures.
fibrous protein
A protein that is found associated with a membrane
system of a cell.
membrane protein
A protein whose molecules have peptide chains that
are folded into spherical or globular shapes.
globular protein
globular proteins are water insoluble substances. True or False
FALSE, globular proteins are water SOLUBLE substances
How many and name the classification of proteins based on function
12:
▪ Catalytic proteins.
▪ Defense proteins.
▪ Transport proteins.
▪ Messenger proteins.
▪ Contractile proteins.
▪ Structural proteins.
▪Transmembrane proteins.
▪ Storage proteins.
▪ Regulatory proteins.
▪ Nutrient proteins.
▪ Buffer proteins.
▪ Fluid-Balance proteins.
These proteins bind (and store) small molecules for future
use. An example of this protein is Myoglobin
Storage proteins.
(remember that Myoglobin is an oxygen-
storage protein present in muscle; the oxygen so stored is a reserve oxygen
source for working muscle.)
“Many such proteins have channels through which molecules can enter and exit a
cell”. What type of protein base on function is being described?
Transmembrane proteins
(remember membrane transport, TRANSmembrane)
“Proteins with the role of biochemical catalyst are called enzymes”. What type of protein base on function is being described?
Catalytic proteins
(take note of the word catalyst)
These proteins, also called immunoglobulins are central to the functioning of the
body’s immune system.
Defense proteins
(they are part of the immune system, ‘cause it DEFENDS)
Example of this protein is Hemoglobin and Transferrin
Transport proteins
(remember hemoglobin as which carries oxygen
from the lungs to other organs and tissues, and transferrin which carries iron from
the liver to the bone marrow)
These proteins confer stiffness and rigidity to otherwise fluid like
biochemical systems. Collagen is an example of this protein
Structural proteins
(they provides STRUCTURE. Remember that Collagen is
a component of cartilage and a keratin gives mechanical
strength as well as protective covering to hair, fingernails,
feathers, hooves, and some animal shells)
These proteins transmit signals to coordinate biochemical processes between different cells, tissues, and organs.
Messenger proteins.
(take note of the word “transmits”)
These proteins are necessary for all forms of movement. Sperm can “swim” because of long flagella made up of _________ proteins
Contractile proteins.
These proteins are particularly important in the early stages of life, from embryo to infant. Casein, found in milk, and ovalbumin, found in egg white, are two examples of such proteins.
Nutrient proteins
These proteins are often found “embedded” in the exterior
surface of cell membranes. These proteins are often the molecules
that bind to enzymes (catalytic proteins), thereby turning them “on” and “off,” and thus controlling enzymatic action.
Regulatory proteins (‘cause they regulate the channels)
__________ __________ involves the loss of the protein’s three dimensional structure.
Protein Denaturation
