DNA, genes and chromosomes

• DNA is instructions for protein synthesis
• DNA instructs the synthesis of both structural and functional proteins
• Each set of 3 bases/ nucleotides codes for 1 amino acid
• DNA cannot leave the nucleus
• transcription- the process of making another copy of DNA but in the form of RNA
• DNA can be made into mRNA to be transported outside the nucleus
• mRNA- messenger RNA

  tRNA- transfer RNA

  rRNA- ribosomal RNA
• tRNA has 3 prongs that reads the 3 bases at the same time
• if the tRNA reads the correct anticodon, it will release the amino acid it is carrying
• if the tRNA does not read the anticodon that corresponds with its amino acid, it will move on
• The script codes for the amino acid NOT the mRNA
• tRNA is looking for the complimentary bases to the amino acid it is carrying
• A gene is a sequence of 3 nucleotide bases that come together to code for an amino acid
• 64 different triplet codes exist
• Most amino acids have more than 1 triplet code
• STOP codes are the end of the coding for a polypeptide
• Introns are part of the DNA that is non-coding
• Exons are part of the DNA that are coding
• The genetic code is:

  • Degenerate
  • Non-overlapping
  • Universal
• Diploid- a full set of DNA
• Haploid- half a set of DNA, found in sperm and egg cells
• DNA can also exists as plasmids and circular DNA
• Plasmids are small and circular, found in bacteria
• Circular DNA can be found in chloroplasts (cpDNA) and mitochondria (mtDNA)
• mtDNA is always passed down from the mother