This is the process of DNA becoming tRNA.
- DNA Replication- Before a cell divides, it must first duplicate its DNA- replication
- Transcription- A molecule of DNA is copied into a complementary strand of mRNA
- Translation- tRNA anticodons (3 nucleotides) complement the mRNA and bring in the corresponding amino acids
- Protein Synthesis- Amino acid are bonded together to form a polypeptide
- ribose sugar
- 1 strand
- Uracil instead of Thymine
- smaller size than DNA- can go inside/outside nucleus
- 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
- 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
- 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
