Table of Contents
- 1 How can one protein have more than one polypeptide chain?
- 2 How can a functional protein contain one or more polypeptides?
- 3 Can more than one copy of a polypeptide be made?
- 4 How does a polypeptide chain become a protein?
- 5 How does polypeptide become protein?
- 6 How can a single gene encode more than one polypeptide?
How can one protein have more than one polypeptide chain?
Many proteins are formed from more than one polypeptide chain. The quaternary structure describes the way in which the different subunits are packed together to form the overall structure of the protein. For example, the human hemoglobin molecule shown below is made of four subunits.
How can a functional protein contain one or more polypeptides?
A functional protein may contain one or more polypeptides. The role of hydrogen bonds, ionic bonds and disulfide bridges in the structure of proteins.
What type of protein has more than one polypeptide?
Three-Dimensional Structure of Proteins Quaternary structure exists in proteins consisting of two or more identical or different polypeptide chains ( subunits ). These proteins are called oligomers because they have two or more subunits.
How many polypeptides can be in a protein?
Since each of the 20 amino acids is chemically distinct and each can, in principle, occur at any position in a protein chain, there are 20 × 20 × 20 × 20 = 160,000 different possible polypeptide chains four amino acids long, or 20n different possible polypeptide chains n amino acids long.
Can more than one copy of a polypeptide be made?
How is it possible for a single gene to encode more than one polypeptide? Exons in mRNA can be spliced together in different combinations. In translation, tRNA molecules bring amino acids to the ribosome.
How does a polypeptide chain become a protein?
Proteins are formed from one or more polypeptides joined together. In fact, some researchers use the term peptide to refer specifically to oligopeptides, or otherwise relatively short amino acid chains, with the term polypeptide being used to describe proteins, or chains of 50 or more amino acids.
How many polypeptide chains do trimeric proteins consist of?
Assembled human PCNA (PDB 1AXC), a sliding DNA clamp protein that is part of the DNA replication complex and serves as a processivity factor for DNA polymerase. The three individual polypeptide chains that make up the trimer are shown.
How many polypeptide chains are in proteins with a quaternary structure?
two
To be considered to have quaternary structure, a protein must have two or more peptide chains forming subunits. The subunits can be different or identical, and in most cases they are arranged symmetrically.
How does polypeptide become protein?
To form polypeptides and proteins, amino acids are joined together by peptide bonds, in which the amino or NH2 of one amino acid bonds to the carboxyl (acid) or COOH group of another amino acid.
How can a single gene encode more than one polypeptide?
How is it possible for a single gene to encode more than one polypeptide? Exons in mRNA can be spliced together in different combinations. When the ribosome encounters a stop codon, the translation complex dissociates, and the newly made polypeptide is released into the cell.