proteins Flashcards
what chemical elements are proteins made of
C,H,O,N and sometimes S
are proteins polymers
yes
whats the name of the monomers that make up proteins
amino acids
what is the name of polymers of proteins
polypeptides
what determines the function of a protein
its shape
what determines the shape of a protein
the sequence,type and number of amino acids within a protein/the amino acid sequence of a protein
name everything that proteins form
-enzymes
-cell membrane proteins
-transport proteins e.g haemoglobin
-immunoglobulins
-structural proteins like collagen, keratin
-hormones
-contractile proteins
state some functions of proteins
-cell growth
-repair of tissues and cell
-acts as carrier molecules r in cell membranes e.g hormones,antibodies,enzymes
-structurally important like collagen
what happens if a mutation occurs and the sequence of amino acids changes
the shape of the protein,its tertiary structure which will alter the function of the protein
how many amino acids exist in living organisms
20
draw the structure of an amino acid
what is the R group detrmine in an amino acid
-determines the chemical properties of an amino acids,it gives it its unique characteristics
what distinguishes one amino acid from another
the R group contained within each amino acid
what can the R group within an amino acid by
-polar/non-polar
-basic/acidic
-have sulfur
-have rings
-hydrophilic/hydrophobic
-positively charged/negatively charged
what determines whether an amino acid is polar or non-polar
the R group contained in the amino acid’s basic structure
what is the peptide bond
-a type of covalent bond that occurs between adjacent amino acids
-it forms in a condensation reaction
describe how a peptide bond forms
In a condensation reaction,a hydroxyl group within the carboxylic group of one amino acid interacts with the hydrogen atom of the amino group of another amino acid to release a molecule of water and form a peptide bond.
hoe does a dipeptide form
forms from the condensation reaction between 2 amino acids
draw the structure of a dipeptide
how does a polypeptide form
from the condensation reaction between more than 3 amino acids
how many polypeptide chains can a protein have
one or multiple polypeptide chains interacting with each other
describe how a peptide bond is broken
in a hydrolysis reaction a water molecule is added to break the peptide bond between amino acids resulting in the dipeptide/polypeptide being broken down into two separate amino acids
describe the primary structure of a protein
its the specific sequence of amino acids .bonded together by peptide bonds to form a polypeptide chain
what determines the primary sequence of a protein
dna determines the sequence of amino acids,carries information which codes for the primary structure of a protein
-instructs a cell to add certain amino acids in specific quantities,and sequence
what happens to the shape and function of a protein if the primary structure of the protein undergoes changes-What if a mutation occurs ?
the primary structure of a protein influences how a polypeptide folds into its tertiary structure which determines the shape of the protein.Thus any changes to the primary structure will result in a change in the shape of the protein and so will alter its function
describe the secondary structure of a protein
ist when hydrogen bonds occur between nearby amino acids in a polypeptide chain, making the polypeptide either coil into an alpha helix shape or fold into a beta-pleated sheet
where do the hydrogen bonds occur to form an alpha helix
-hydrogen bonds occur between amino acids within a polypeptide chain
-this pulls the polypeptide chain in,forcing it to coil into an alpha helix
where do the hydrogen bonds occur to form a beta-pleated sheet
-hydrogen bonds occur between the amino acids of parallel polypeptide chains, joining them together
-they then fold to form a beta-pleated sheet
describe the tertiary structure of a protein
its the folding of a protein into its final shape
-the tertiary structure determines the function of a protein
-The folding/coiling of the polypeptide chain into its secondary structure brings the R groups of different amino acids closer together
-Various bonds form between the R groups of different amino acids which stabilise and hold the tertiary structure of a protein together.
-The bonds that form cause the polypeptide chain to fold into its final shape
what do ionic bonds form between
-form between positively and negatively charged R groups-
-between oppositely charged R groups
what do hydrogen bonds form between
they form between slightly positive charges and slightly negatively charged R groups
what to disulphide bonds form between
-occur between R groups which contain sulfur
-strongest
what to weak hydrophobic/hydrophilic interactions form between
-occur between polar and non-polar R groups
which bonds holding the tertiary strcuture of a protein together are the strongest and which the weakest
disulphide bonds are the strongest, hydrogen bonds are the weakest
which is stronger ionic or hydrogen bonds
ionic
what is the most common bonds that form in a tertiary structure of a protein and which are rare
hydrogen bonds as can occur between wide range of R groups
-ionic,disulphide and hydrophobic, hydrophilic are not common
what breaks disulphide bonds
oxidation
what breaks ionic bonds
ph changes
describe the quaternary structure of a protein
its the 3d structure of protein,only present in proteins that have more than 1 polypeptide chain
-Multiple bonds interact with one another, and various of bonds form between the polypeptide chains -
the same as the bonds that form in tertiary structure but form between different polypeptide chains
-This causes a protein to fold into its final £D structure
what can subunits be
both identical or different
how many subunits does haemoglobin have
4 ,2 alpha and 2 beta subunits
what are different polypetide chains known as in quartenary structure
subunits
how many levels of structure does a protein with 1 polypeptide chain have
3
what is a negative result in the test
solution remains blue
describe the test for proteins
-use the biuret test to test for proteins
-first add sodium hydroxide to the sample to make the conditions slightly alkaline
-then add copper II sulfate to the sample which is blue
how many levels of structure does a protein with
more than 1 polypeptide chain have
4
what is a positive result in the test
colour change from blue to purple,might nee dto use a white tile as the colour change is very subtle
state limitation of the test
- if the sample contains amino acids or dipeptide the result will be negative as there must be at least 2 peptide bonds present to be detected
-test is qualitative and doesn’t give a quantitative value of how much protein is present in the sample
what is the name of the test used to test for proteins
biuret test
what detrmines how proteins fold into their teriatury structure
-hydrophobic and hydrophilic interaction
-proteins are assembled in an aqueous environment,in the cytoplasm
hydrophobic R groups clump together on the inside of the protein,away from the aqueous environment,while the hydrophilic R groups are pushed on the outside surface of the protein.
