Summary Grade 12 Biology: Protein Synthesis

PROTEIN SYNTHESIS
 Transcription- where, polymerase
 Translation – amino acids, where
 Codon and anticodon
 How abberations occur: frameshift mutations: insertion, deletion, substitution.
 Mutations can be caused by mutagens and chance

Replication
Replication: the process of making a new DNA molecule that is identical to the original
molecule.
Where:
 In the nucleus during interphase
Why:
 To ensure that the genetic code is passed on to each new daughter cell formed
during cell division
How:
1. The process is catalysed by the
enzyme DNA polymerase
2. The double helix unwinds
3. The weak hydrogen bonds holding
the base pairs together break,
allowing the two strands to part
(like a zip unwinding)
4. Each single chain base is exposed
5. Free nucleotides in the
nucleoplasm become attached to
their matching, exposed base
partners


The fact that only A=T and G=C makes sure that the sequence of bases in the daughter DNA
is exactly the same as the parent DNA. One DNA double helix therefore becomes two
identical double helices.

Protein synthesis:
Proteins: (which include enzymes) are the workhorses of all living systems
Types of RNA:
 Messenger RNA: mRNA
 Transfer RNS: tRNA