Page 119 - General Biochemistry

Denaturation of proteins:
When a protein loses its higher-order structure, but not its primary sequence,
it is said to be denatured.
Denatured proteins are usually non-functional
Protein synthesis:
It occurs in 2 steps: transcription and translation
1) Transcription:

▪ It is copying the genetic information from DNA to RNA.
▪ Since the genetic code for the protein is on the DNA that is found

in the nucleus, since proteins are made by the ribosomes that are
found in the cytoplasm and since the DNA is too large to leave the
nucleus (double stranded), but RNA can leave the nucleus (single
stranded) easily therefore, DNA should be transcribed to RNA that
will go to the cytoplasm to be translated to protein
▪ The first step is unwinding of the DNA and is used as a template to
assemble complementary nucleotides into messenger RNA
(mRNA). Then mRNA goes through the pores of the nucleus with
the DNA code and attaches to the ribosome
2) Translation
▪ It is the decoding of mRNA into a protein
▪ Transfer RNA (tRNA) carries amino acids from the cytoplasm to
the ribosome.
▪ Every three adjacent bases in an mRNA molecule codes for a
specific amino acid—called a codon.
▪ Each tRNA has 3 nucleotides that are complementary to the codon
in mRNA and each tRNA codes for a different amino acid.

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