Transcription and Translation : Transcription and Translation Transcription : Transcription DNA to RNA The Genetic Code : The Genetic Code The sequence of nitrogen bases along a DNA strand that code for the synthesis of proteins.
There are 20 different amino acids ( the building blocks of proteins.) What is a Codon? : What is a Codon? 3 Nitrogen bases are paired together to code for each of the 20 amino acids.
The 3 nitrogen bases together are called a CODON Slide 6: There are 64 total different codons in the genetic code.
There are 61 codons to signal for amino acids.
There are 3 codons to signal the STOP of protein synthesis. Important Note : Important Note The order of the Nitrogen Bases on the DNA strand will determine the type and order of amino acids in a protein.
The genetic code is the SAME for every organism, which means the CODONS represent the same AMINO ACIDS in ALL organisms. Slide 8: A few review questions Q.What organelle is responsible for making proteins? A. ribosomes Q. Where are ribosomes found in the cell? A. in the cytoplasm Question… : Question… If DNA is found in the nucleus and has the genetic code, then how does it reach the ribosomes in the cytoplasm to make proteins?
Answer: RNA RNA Structure : RNA Structure RNA differs from DNA in 3 ways:
RNA is a single strand
RNA has the sugar ribose
RNA has the nitrogen base uracil instead of thymine. Types of RNA : Types of RNA Messenger (mRNA) Types of RNA (continued) : Types of RNA (continued) Transfer (tRNA)
Ribosomal (rRNA) Slide 13: And now…Transcription Page 319 figure 13.6 Slide 14: Transcription: The process An enzyme unzips DNA
As DNA uncoils, free RNA nucleotides combine with DNA nucleotides.
When base pairing is done, mRNA breaks away.
mRNA leaves the nucleus and enters the cytoplasm TRANSLATION(see page 322-323 figure 13.8) : TRANSLATION(see page 322-323 figure 13.8) RNA to PROTEIN Slide 17: Translation: The Process mRNA attaches to the ribosome.
The tRNA molecule with the correct anticodon attaches to the mRNA codon.
The enzyme releases the amino acid (attached to tRNA). Slide 18: 4. The mRNA slides through the ribosome to the next codon and another tRNA comes and attaches to mRNA.
5. The enzyme connects the amino acids to one another using a peptide bond.
**This process continues until a STOP codon is reached. Slide 19: Amino acid