Proteins Flashcards
What are proteins made up of?
Polymers made up of many amino acids
Proteins are also known as polypeptides.
What is a polypeptide?
A polymer made up of many amino acids
What are the three groups contained in all amino acids?
- Carboxyl group
- Amino group
- Variable (R) group
How many different amino acids are there?
20
What do R-groups change in amino acids?
The properties of the amino acid
What type of bond joins adjacent amino acids?
Peptide bonds
What is a dipeptide?
Two amino acids joined together
How is a dipeptide formed?
During a condensation reaction forming a peptide bond
What are the four different levels of protein structure?
- Primary
- Secondary
- Tertiary
- Quaternary
What does the primary structure of a protein refer to?
The order of amino acids in a polypeptide
What types of structures are included in the secondary structure of proteins?
- α-helix
- β-pleated sheet
How do secondary structures form?
Via hydrogen bonds
What defines the tertiary structure of a protein?
The final 3D structure of a polypeptide caused by further folding
What interactions contribute to the tertiary structure?
- Hydrogen bonds (polar groups)
- Ionic bonds (charged groups)
- Disulfide bridges (groups containing S)
- Hydrophobic regions
What is the quaternary structure of a protein?
The joining of multiple polypeptides together
What are prosthetic groups?
Non-protein groups associated with conjugated proteins
What determines a protein’s function?
Its tertiary or quaternary structure
True or False: A change in a protein’s structure can affect its function.
True
What genetic mutation causes sickle cell disease?
A mutation in the gene for haemoglobin
What amino acid change occurs in sickle cell disease?
Glutamine is swapped for valine
How does the mutation in sickle cell disease affect protein structure?
It causes a change in the primary structure, which alters the tertiary structure
What is the biochemical test for proteins?
Biuret test
What is the procedure for the Biuret test?
Add NaOH to sample, then add a few drops of dilute CuSO4
What color change indicates the presence of proteins in the Biuret test?
Blue to purple
whats the test for proteins?
- add a few drops of biuret reagent to food sample in a test tube.
- shake solution and wait a few minutes.
- if protein is present turns blue to purple
