Topic 3: Protein Synthesis Flashcards
Definition of Protein Synthesis
the process in which cells make proteins through transcription and translation
Role of DNA polymerase
an enzyme that synthesises new strands of DNA by adding nucleotides to a pre-existing strand of DNA
Definition of RNA polymerase
an enzyme responsible for synthesising RNA from a DNA template strand in transcription.
what are the TWO main steps in protein synthesis?
- Transcription
- Translation
What occurs in Initiation (1)
- the RNA polymerase binds to a region of a gene called a promoter
- this signals DNA to unwind so the enzyme can “read” the bases on the template strand
What occurs in Elongation (2)
- the RNA polymerase reads the unwound DNA and builds the mRNA molecule using complementary base pairs.
What occurs in Termination (3)
- occurs when the RNA polymerase crosses a termination sequence in the gene
- mRNA stand is complete and detaches from DNA
Briefly explain steps in Translation
- mRNA moves from the nucleus to the cytoplasm and attaches to a ribosome.
- The ribosome reads the mRNA three nucleotides (codon) at a time, starting at the START codon.
- tRNA brings amino acids to the ribosome, matching its anticodon with the mRNA codon.
- Peptide bonds form between amino acids, creating a polypeptide chain.
- Protein synthesis stops at the STOP codon, and the mRNA detaches from the ribosome.
Define anti-codon
three nucleotide sequences found on the tRNA that bind with the mRNA sequence
Define codon
three nucleotides found on the mRNA that codes for a specific amino-acid.
Role of the ribosome
to translate the genetic code transcribed in mRNA into an amino-acid sequence
What is a polypeptide chain?
a string of amino acids connected by peptide bonds. They are the building blocks for proteins or amino acids.
How are polypeptide chains and proteins different?
A polypeptide is a chain of amino acids linked together by peptide bonds. Whereas the protein is made up of one or more polypeptide chains folded to a specific three-dimensional structure, in which determines its functions.
How is mRNA paired with DNA?
through transcription - the enzyme (RNA polymerase) binds to a promoter and unwinds the DNA helix. It then reads the template strand one nucleotide at a time until crosses termination sequence
what is mRNA? what is the role of mRNA?
a single-stranded RNA that is involved in protein synthesis.
its main role is to act as a messenger carrying genetic information from DNA to the ribosome, where proteins are synthesized.
