Proteins Flashcards
What do proteins contain?
Carbon, hydrogen, oxygen and nitrogen
What monomers are proteins made up of?
Amino acids
What two other elements do some proteins contain?
Sulphur and phosphorus
How many amino acids are there that are commonly found in tissues and cells?
20
What is denaturing?
The permanent loss of specific 3D shape of a protein molecule
What 4 components make up the structure of an amino acid?
R group, amino group, carboxyl group and hydrogen
What group in amino acids is variable?
R group
What does Zwitterion mean?
Amino acids can be both positive and negative charged as they have acid and base properties
How do peptide bonds form?
Condensation reaction between 2 amino acids
What two groups does a peptide bond form between?
Carboxyl and amino group
How do you test for proteins?
Add sodium hydroxide and very dilute copper II sulfate and mix gently
What colour change indicates a protein is present?
Blue to purple due to the presence of peptide bonds
What four structures are there of proteins?
Primary, secondary, tertiary and quaternary
What two things does the order and sequence of amino acids determine?
Shape and function
What is the primary structure of a protein?
Sequence of amino acids found in a polypeptide chain
What bonds are found in the primary structure?
Peptide bonds
What is the secondary structure of a protein?
Polypeptide bonds form an alpha helix shape due to hydrogen bonding although pleated sheets can also occur
What bonds occur in the secondary structure?
Peptide and hydrogen bonds
What is the tertiary structure of a protein?
Bending and twisting of the polypeptide helix into a compact structure
What bonds are there in the tertiary structure?
Peptide, hydrogen, ionic and disulphide bonds
What is the quaternary structure of a protein?
Combination of a number of different polypeptide chains into a large 3D shape
What bonds are found in the quaternary structure?
Peptide, hydrogen, ionic and disulphide bonds
What effect does temperature have on proteins?
Breaks the hydrogen bonds destroying the 3D structure and denaturing the protein
What effect does alcohol have on proteins?
Break the hydrogen bonds and alters the hydrophobic interactions ruining the 3D shape and denaturing the protein
What is the effect of acid on a protein?
Hydrogen and ionic bonds break unravelling the structure so the inside parts of the structure are exposed to dorm bonds with other protein molecules that stick together and become insoluble.
What are the two typed of proteins?
Globular and fibrous proteins
What is an example of a globular protein?
Enzymes and haemoglobin
What is an example of a fibrous protein?
Collagen
What is the difference in function between a globular and fibrous protein?
Globular have metabolic functions
Fibrous have structural functions
What is the structure of a fibrous protein?
Form long chains that are parallel they are linked by cross bridges to form very stable molecules
What type of structure does collagen have?
Rope like
How is collagen prevented from being weak at one point?
The points where the molecules start and end are spread throughout
Where is collagen found?
In tendons
Why is collagens structure good for its function?
It has long rope like chains which are strong but can also be stretched when a muscle contracts
How does cross linkages increase the stability and strength of collagen?
Prevent the polypeptide chains from sliding past each other instead they work as one large molecule
