BIO.B.1 Cell Growth and Reproduction
Topic Summary for Protein Synthesis:
A specific sequence of bases in DNA carries the directions for forming a polypeptide, a chain of amino acids. The types and order of amino acids in a polypeptide determine the properties of the protein. The sequence of bases in mRNA is the genetic code. The four bases, A, C, G, and U, act as “letters.”
The code is read three “letters” at a time, so that each “word” is three bases long and corresponds to a single amino acid. Each three-letter “word” in mRNA is known as a codon.
Some codons serve as “start” and “stop” signals for protein synthesis.
Translation
Ribosomes use the sequence of codons in mRNA to assemble amino acids into polypeptide chains. The process of decoding of an mRNA message into a protein is translation.
Messenger RNA is transcribed in the nucleus and then enters the cytoplasm.
On the ribosome, translation begins at the start codon. Each codon attracts an anticodon, the complementary sequence of bases on tRNA.
Each tRNA carries one kind of amino acid. The match between the codon and anticodon ensures that the correct amino acid is added to the growing chain.
The amino acids bond together, each in turn. The ribosome moves along the mRNA, exposing codons that attract still more tRNAs with their attached amino acids.
The process concludes when a “stop code” is reached. The newly formed polypeptide and the mRNA molecule are released from the ribosome.
Molecular biology seeks to explain living organisms by studying them at the molecular level, using molecules like DNA and RNA.
The central dogma of molecular biology is that information is transferred from DNA to RNA to protein.
Gene expression is the way in which DNA, RNA, and proteins are involved in putting genetic information into action in living cells.
The genetic code is generally the same in all organisms.
Topic Summary for Protein Synthesis:
A specific sequence of bases in DNA carries the directions for forming a polypeptide, a chain of amino acids. The types and order of amino acids in a polypeptide determine the properties of the protein. The sequence of bases in mRNA is the genetic code. The four bases, A, C, G, and U, act as “letters.”
The code is read three “letters” at a time, so that each “word” is three bases long and corresponds to a single amino acid. Each three-letter “word” in mRNA is known as a codon.
Some codons serve as “start” and “stop” signals for protein synthesis.
Translation
Ribosomes use the sequence of codons in mRNA to assemble amino acids into polypeptide chains. The process of decoding of an mRNA message into a protein is translation.
Messenger RNA is transcribed in the nucleus and then enters the cytoplasm.
On the ribosome, translation begins at the start codon. Each codon attracts an anticodon, the complementary sequence of bases on tRNA.
Each tRNA carries one kind of amino acid. The match between the codon and anticodon ensures that the correct amino acid is added to the growing chain.
The amino acids bond together, each in turn. The ribosome moves along the mRNA, exposing codons that attract still more tRNAs with their attached amino acids.
The process concludes when a “stop code” is reached. The newly formed polypeptide and the mRNA molecule are released from the ribosome.
Molecular biology seeks to explain living organisms by studying them at the molecular level, using molecules like DNA and RNA.
The central dogma of molecular biology is that information is transferred from DNA to RNA to protein.
Gene expression is the way in which DNA, RNA, and proteins are involved in putting genetic information into action in living cells.
The genetic code is generally the same in all organisms.