1.6 Proteins Flashcards
How is protein made?
Amino acids (monomers) > polypeptides (polymers) > protein
What elements does a protein contain?
- a central carbon
- amino group (—NH2) - a basic group
- carboxyl group (—COOH) - an acidic group
- hydrogen atoms
- R (side) group - a variety of different chemical groups
How many different amino acids are there?
20
What can be formed when combing two amino acid monomers?
A dipeptide
What is the process called when combining two amino acid monomers to form a dipeptide?
Condensation
How is water made when combining two amino acids?
By combining an —OH from the carboxyl group of one amino acid with an —H from another amino acid.
What bond is linking two amino acids?
A peptide bond
How can a peptide bond be broken down?
By hydrolysis (with addition of water)
What is the process called when many amino acid monomers are joined together?
Polymerisation
What is a polypeptide?
Condensation of many amino
acids
What does a functional protein contain?
One or more polypeptides
What levels of structure does protein have?
- primary structure
- secondary structure - pleated sheet (折片) or alpha helix
- tertiary structure
- quarternary structure
Why is it important that primary structures of proteins are correct?
Because the primary structure of protein determines all properties of a protein, so if the primary structure of protein goes wrong, the entire protein will go wrong.
Which level of protein structure are amino acids?
Primary structure
What bond is formed in a polypeptide chain?
Hydrogen bond
What does the hydrogen bond cause to the polypeptide chain?
To be twisted into a 3D shape
How is alpha helix formed?
They are formed as a result of hydrogen bonds forming between the —OH from the carboxyl group of one amino acid and the —H from another amino acid.
How is pleated sheet formed?
They are formed between sections of the same or different polypeptide chains.
How are tertiary structure of protein formed?
By twisting and folding the secondary protein structure even more to give a more complex 3D structure of protein.
What bonds are maintaining the tertiary structure of protein?
- disulfide bonds
- ionic bonds
- hydrogen bonds
Are disulfide bonds strong or weak?
Strong and not easily broken
How do ionic bonds form? Are they strong or weak?
They are formed between a carboxyl group and an amino group that are not involved in forming peptide bonds. They are weak and are easily broken by changes in pH.
How many hydrogen bonds are there in the tertiary structure of proteins? Are they strong or weak?
They are numerous (很多) but they are weak and easily broken.
Why are the tertiary structures of proteins important when it comes to the function of proteins?
Because it makes each proteins distinctive (獨特的) and allows it to be recognised.
