Qualitative Reaction of Proteins (Lab) Flashcards
are macromolecules that are made from one or more chains of polypeptides
proteins
are linear polymers making up proteins
polypeptides
Polypeptides are linear polymers made up from smaller molecules called
amino acids
Polypeptides
are formed when amino acids are joined together via typical ___bonds that forms between
amino group of one amino acid and carboxyl group
peptide
Proteins are the structural building blocks of almost all major cellular components and
structures, such as
enzymes
ribosomes
cytoskeleton
centrosomes
proteasomes
There are more than _
different amino acids found in biological organisms
20
Amino acids have characteristic chemical and
structural features
amino group (-NH2)
carboxyl group (-COOH)
They have an amino group (-NH2) plus a carboxyl group (-COOH) as functional
groups which are covalently attached to the
first (a) carbon atom
Proteins can be visualized and be tested with the help of series of unique dyes, such as
biuret reagent
coomasie blue (lowry reagent)
Amino acids can be visualized and be tested for with the help of a
chemical reagent called
ninhydrin
However, a simple and relatively quick qualitative test for the
presence of amino acids in solution is the
Whatman filter paper spotting test
is performed to analyze proteins in solid samples
ninhydrin test
samples for protein qualitative analysis
egg albumin
diluted honey
potato starch
milk
egg yolk
glucose
amino acid
meat (pork,fish)
egg white
cooked rich
biuret reagent
sodium hydroxide
copper (II) sulfate
potassium sodium tartate
very poisonous
ninhydrin
inhaling the fumes of ___ is not advisable
ninhydrin
amino acid common structure (3)
amino group
carboxyl group
variable side chain (R group)
gives the amino acid its unique chemical properties.
R group
The specific sequence of amino acids in a protein is the
primary structure
This structure may be recited by naming each amino acid beginning on the _-terminus.
N terminus
Proteins twist, turn, and fold into complex three dimensional shapes.
what structure
tertiary structure
These twists and turns are possible because there is ____ of the bonds around the α-carbon of each amino acid.
free rotation
sequence of amino acids in a polypaptide chain, similar to the sequence of letters that spell out a specific word
what structure
primary structure
the corkscrew like twists or pleated folds formed by hydrogen bonds between amino acids in the polypeptide chain
what structure
secondary structure
the complex three dimensional shape formed by multiple twists and bends in the polypeptide chain, based on the side chains interactions with each other and the aqueous solvent
tertiary structure
two or more polypeptide chians bonded together
what structure
quaternary structure
positive test for biuret indicates
protein is present
biuret positive test
purple
In the presence of alpha (α)-amino acids what is observed in ninhydrin test
blue to blue violet color
ninhydrin reagent
ninhydrin in 10ml of either ethanol or acetone.
deep purple positive for ninhydrin means
For ammonia, primary/secondary amines, and amino acids
yellow positive for ninhydrin means
hydroxyproline and proline
brown positive for ninhydrin means
asparagine
organic macromolecules containing C,H,O,N
proteins
examples of proteins
enzymes
body tissues
many immune system cells
monomers of proteins
amino acid
amino acids joint to form small protein polymers called
peptides
long protein polymers are called
polypeptides
its characteristic that is critical to function
folded
sources of protein
beans
grams
lentils
peas
soya beans
eggs
paneer
fish
meat
milk
are macromolecules that are made from one or more chains of polypeptides
proteins
linear polymers made up from smaller molecules
polypeptides
polypeptides are formed when amino acids are joined together via typical ___ bonds
peptide bonds
amino acid common core structure
amino group (-NH2)
carboxyl group (COOH)
R group
functional group which are covalently attached to the first (a) carbon atom
carboxyl group
part that gives the amino acid its unique chemical properties
R group
basic functional group
amino group
side chains;
wild card structure
R groups
acidic functional group
carbonyl group
polar in nature
carbonyl group
essential amino acids
Phenylalanine
Valine
Tryptophan
Threonine
Isoleucine
Methionine
Histidine
Leucine
Lysine
conditionally essential amino acid
arginine
cysteine
proline
tyrosine
glutamine
glycine
nonessential amino acids
alanine
asparagine
aspartic acid
glutamic acid
serine
arrangement of amino acids
what structure
primary structure
protein structure levels that has hydrogen bonds
secondary structure
protein structure levels that has alpha helix and beta-pleated sheet
secondary structure
protein structure levels that has R group interactions
tertiary structure
proteins with more than 1 polypeptide subunit
quaternary structure
specific sequence of amino acids in a protein is the
primary structure
which starting terminus a protein can be recited by naming each amino acid
N-terminus
twist, turn, and fold into complex three dimensional shapes
proteins
why is twists and turns possible in protein
free-rotation of the bonds around the a-carbon of each amino acid
which sample is used for biuret test
egg albumin
diluted honey
potato
starch
milk
egg yolk
glucose
amino acid
filter paper test samplpe
amino acids
ninhydrin test sample
meat (pork,fish)
egg white
cooked rice
biuret test procedures
pipette 2ml of the solutions (distilled water, egg albumin, diluted honey, potato starch, glucose solution, egg yolk, amino acid)
add one dropperful of Biuret reagent into each of the test tubes and gently mix
place the tubes back into the rack and incubate contents for about 2 minutes at your work bench
specific for peptide bond
biuret test
substances containing not less than two peptide linkages give this test
biuret test
principle of biuret test
when proteins and peptides treated with an alkaline solution of dilute copper sulfate, a violet color is formed
what characteristic of biuret test result is proportional to the amount of proteins present
color density
biuret agent is what kind of solution
alkaline copper sulfate
chemical reation to detect existence of amino acids
ninhydrin reaction
used for liquid samples
filter paper test
indicate that there is an amino acid in the spot solution
purple stians
gives a yellow colour because it is a secondary amine
proline
how many sample is used for ninhydrin test
2 mg
how much to boil test mixture in ninhydrin test
15-20 seconds
what is observed when there is alpha amino acid in ninhydrin test
blue-violet color
result of distilled water in biuret test
negative result
biuret test result of egg albumin
violet/purple color (+)
biuret test result of diluted honey
yellow (-)
biuret test result of potato starch
negative (-)
biuret test result of glucose solution
-
biuret test result of egg yolk
positive (+)
result of amino acids in biuret test
Tyrosine
Proline
Tryptophan
Asparagine
All positive but proline will be yellow in color instead of purple
ninhydrin test result of distilled water
negative
ninhydrin test result of asparagine
positive (blue or purple color)
ninhydrin test result of proline
positive (yellow color)
ninhydrin test result of tryptophan
purple (+)
ninhydrin test result of tyrosine
purple (+)
ninhydrin test result of pork meat
positive (+)
ninhydrin test result of salmon
positive (+)
ninhydrin test result of egg white
(+)
ninhydrin test result of cooked rice
(+)
- In the test for proteins, which structure in the proteins does the Biuret reagent reacts with?
The Biuret reagent reacts with the peptide bonds in proteins. Peptide bonds are the chemical links between amino acids that form the primary structure of a protein. When the Biuret reagent, which contains copper sulfate, interacts with these peptide bonds, it forms a violet-colored complex. This color change indicates the presence of proteins.
- Which amino acid solutions resulted positive with the Ninhydrin Test? Explain.
all but proline will be yellow since it has a secondary amine group
