Transcription and Translation Flashcards
Transcription:
- the synthesis of mRNA copied from the DNA base sequences by RNA polymerase
- process by which an RNA sequence is produced from a DNA template
Process of Transcription (3 steps):
- The enzyme RNA polymerase binds to a site on the DNA at the start of a gene
- RNA polymerase separates the DNA strands and synthesises a complementary RNA copy
- Once the RNA sequence has been synthesised :
- -> RNA polymerase detaches from the DNA molecule
- -> RNA detaches from the DNA
- -> Double Helix reforms
Where does transcription occur?
in the nucleus and once made the mRNA moves to the cytoplasm
Translation:
- the synthesis of polypeptides on ribosomes
- the process of protein synthesis in which the genetic information encoded in mRNA is translated into a sequence of amino acids in a polypeptide chain
Ribosome:
- composed of two halves –> a large and small subunit
What are the roles of ribosomes?
- During translation ribosomal subunits assemble together like a sandwich on the strand of mRNA
- -> the small subunit binds to the mRNA
- -> the large subunit has binding sites for tRNAs and also catalyzes peptide bonds between amino acids
Exons:
a segment of a DNA or RNA molecule containing information coding for a protein or peptide sequence
Introns:
a segment of DNA or RNA molecule which does not code for proteins and interrupts the sequence of genes
Centromere:
the specialized DNA sequence of a chromosome that links a pair of sister chromatids
Telomere:
a region of repetitive nucleotide sequences at each end of a chromosome, which protects the ends of the chromosome
Codons:
a sequence of three DNA or RNA nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis
Gene regulation:
controls how much mRNA is produced
Factors regulating phenotypic expression:
proteins can bind to DNA and can work to enhance, and inhibit mRNA production, along with changing the shape of DNA
