Tuesday, November 29, 2011

Tuesday Novermber 29, 2011

This is the process of DNA becoming tRNA.

  1. DNA Replication- Before a cell divides, it must first duplicate its DNA- replication

  2. Transcription- A molecule of DNA is copied into a complementary strand of mRNA

  3. Translation- tRNA anticodons (3 nucleotides) complement the mRNA and bring in the corresponding amino acids

  4. Protein Synthesis- Amino acid are bonded together to form a polypeptide

RNA has-

  1. ribose sugar

  2. 1 strand

  3. Uracil instead of Thymine

  4. smaller size than DNA- can go inside/outside nucleus

  5. 3 types- messenger- mRNA, transfer- tRNA, ribosomal- rRNA(its the one that form ribosomes)

Steps of Transcription

1. Initiation- RNA polmerase attaches to the DNA promoter nucleotide sequence on DNA. RNA is synthesized

2. RNA elongation- RNA grows longer, peels away from DNA, DNA strands come back together (uses DNA as a template)

3. Termination- RNA polymerase reaches the terminator- end of the gene. polymerase molecule detaches from RNA molecule and the gene

Processing RNA

in prokaryotes, RNA is ready(mRNA)

in eukaryotes, it needs to process it, add extra nucleotides

  • cap and tail protect RNA from enzymes and help ribosomes recognize it as mRNA

  • introns-non coding regions (useless junk)

  • exons-are the coding regions

introns are removed before RNA leaves the nucleus=RNA splicing

  • mRNA is now ready

Steps of Translation

  1. initiation-
  • a mRNA binds to small ribosomal subunit. tRNA with attached amino acid (Met) (UAC) binds to start codon, AUG on mRNA

  • large ribosomal subunit binds to small one, creating a functional ribosome

2. elongation- amino acids are added one by one to the first amino acid

3. a stop codon (UGA, UAG, UAA) does not code for an amino acid. tells translation to stop. Polypeptide is freed ( several hundred amino acid) ribosome splits into its subunits


DNA->RNA->Protein. genes determine the protein, which makes your appearance and your cell capabilities

  1. Mutations
  • change in nucleotide sequence of DNA-a. base substitution- replacement of one base for another. no change, or critical, bad or good~b. base insertion or deletions- adding or subtracting nucleotides. often disastrous results- can disrupt entire sequences of triple pairing (insertions are always bad)

  • mutagens- physical and chemical agents, such as UV light, x-rays, chemicals, carcinogens. can cause mutations. Can also lead to diversity. DNA errors are also due to unknown causes.

next scribe Dana


  1. The pictures are kind of blurry but it was a good idea to include that kind of visual.

  2. A lot of helpful information... I liked how you included the characteristics of RNA, but you could have also reviewed the characteristics of DNA.

  3. I like how you used the pictures we used in class as pictures. Although it is a little blurry. The information is well done, although it was a little messy and unorganized but overall well done.