DNA RNA and protein

• DNA stands for deoxyribonucleic acid and is the genetic material of all cells
• DNA has a sugar-phosphate backbone with nucleic acid bases: thymine, adenine, cytosine, guanine
• The nucleic acid bases form hydrogen bonds with each other and are very specific about which base they will bond with
• Adenine bonds with thymine, guanine bonds with cytosine
• Two nucleic acid bases held together by hydrogen bonds are called a base-pair
• DNA is typically found double-stranded, with complementary strands held together by base-pairs
• DNA replication involves separating the strands and using each strand as a template to add a complementary strand
• The process of DNA to RNA to protein leads to the expression of traits
• RNA stands for ribonucleic acid and is typically single-stranded
• RNA has a different sugar than DNA and contains uracil instead of thymine
• Messenger RNA (mRNA) carries the protein blueprint from DNA to ribosomes
• Transfer RNA (tRNA) carries amino acids to ribosomes
• Ribosomal RNA (rRNA) with certain proteins makes up ribosomes
• Each tRNA has a specific anticodon and carries a specific amino acid
• Transcription is the process of copying a sequence from DNA onto RNA
• Translation uses the RNA sequence to direct the production of a protein
• RNA processing in eukaryotic cells includes adding a cap and tail to protect the RNA, removing introns, and leaving exons that code for proteins
• Mutation is any change in DNA

  • Mutations may also be the result of errors in DNA replication
• Gene regulation is crucial for controlling gene expression, with negative and positive control mechanisms
• DNA polymerase is an enzyme that brings nucleotides and adds complementary pairs
• DNA polymerase can only build the new strand in the 5' to 3' direction, moving along the old template strand in the 3' to 5' direction
• Ligase glues DNA together
• DNA strands are anti-parallel, meaning one strand runs 5' to 3' while the other runs 3' to 5'
• Substitution: one base is substituted for another

  Insertion: one or more nucleotides are inserted into DNA

  Deletion: one or more nucleotides are deleted from DNA

  Mutagen: something that causes mutation

  • Insertion and deletion have potential to be especially dangerous
• • Codon: A sequence of three nucleotides that codes for a specific amino acid. It is located on the mRNA molecule.
  • Anticodon: The complementary base that matches the codon, and it is located in the tRNA molecule.
• • Start codon marks the beginning of translation
  • Stop codon signals for the termination of translation
• Transcription:

  • Initiation: RNA polymerase binds to DNA at a promoter, DNA strands are separated here.
  • Elongation: RNA polymerase incorporates RNA nucleotides into a strand that is complementary to the DNA template, DNA strands separate only long enough for this to occur.
  • Termination: RNA polymerase is released from the DNA at the terminator, DNA is double-stranded again.
• Translation:

  • Initiation: The small and large ribosomal subunits form a ribosome around tRNA with an amino acid on the start codon.
  • Elongation: The next three bases exposed by the ribosome form a codon, tRNA with the complementary anticodon fits into the ribosome and the amino acid it is carrying is added to the chain.
  • Termination: When the ribosome exposes a stop codon a release factor fits in, resulting in the ribosomal subunits falling off and the chain of amino acids (protein) being released.
• A silent mutation is a mutation that does not change the amino acid sequence of a protein.
• Mutations occur at random, however there can be factors that make mutations more likely to occur
• Not all genes code for proteins and not all genes are turned "on"either
• A frameshift mutation in a gene refers to the insertion or deletion of nucleotide bases in numbers that are not in multiples of three
• Cells must replicate their DNA before they can divide.