Central Dogma

Semiconservative Replication = each strand has 1 parent and 1 new strand

Replication DNA Helicase unzips DNA RNA Primers bind to DNA strands DNA Polymerase adds nucleotides to DNA Leading – continuous adding of bases Lagging – Okazaki fragments DNA Ligase fills in gaps

DNA Replication Two strands open forming Replication Forks (Y-shaped region) New strands grow at the forks Replication Fork Parental DNA Molecule 3’ 5’

Unwinding DNA Helicase unwinds/unzips DNA strand Hydrogen bonds are broken

Base Pairing Steps DNA Polymerase adds nucleotides only adds to the 3’ end of the DNA NEW strand is built in a 5’ to 3’ direction Adds a 5’ Q: Will the strands be identical? Parental DNA Molecule 3’ 5’

Leading Strand Replicated as the DNA unwinds New nucleotides are added continuously

Lagging Strand Replicated away from replication fork Create fragments - Okazaki Fragment Fragments later connected

Joining DNA Ligase – links two sections of DNA together

Replication DNA Helicase unzips DNA RNA Primers bind to DNA strands DNA Polymerase adds nucleotides to DNA Leading – continuous adding of bases Lagging – Okazaki fragments DNA Ligase fills in gaps

Prokaryote vs. Eukaryote Prokaryotes 1 origin Eukaryote Many origins

DNA Info DNA in the nucleus is safe But DNA in the cytoplasm can be destroyed

RNA – Ribonucleic Acid Copy of DNA that goes into cytoplasm DNA RNA guides synthesis of proteins DNA RNA # of strands 2 Strands 1 Strand Type of Sugar Deoxyribose sugar Ribose Sugar Nucleotide Base pairs A-T C-G A-U

3 types of RNA Messenger RNA (mRNA) – complementary to DNA C=G, A=U Travel from nucleus to ribosome Direct synthesis of protein Ribosomal RNA (rRNA) –forms ribosomes Transfer RNA (tRNA) – brings amino acids

Transcription RNA is made from 1 strand of DNA Specifically mRNA is made DNA safe in the nucleus To send a message to the cytoplasm Uses mRNA

Transcription Unzip DNA (helicase) RNA Polymerase binds to synthesize RNA Match up bases to one strand of DNA Uracil instead of thymine mRNA gets modified mRNA moves out of nucleus and into cytoplasm

Transcription happens in the nucleus. An RNA copy of a gene is made. Then the mRNA that has been made moves out of the nucleus into the cytoplasm Once in the cytoplasm, the mRNA is used to make a protein Cytoplasm of cell Nucleus DNA mRNA

A little more about RNA DNA is interrupted by short sequences that are not in the final mRNA Called introns Exons = RNA kept in the final sequence

The Code Every 3 bases codes for amino acid sequence Three base code is called a codon All but 3 codons code for an amino acid AUG = start codon

Anticodon - 3 base sequence at the bottom Ribosomes 2 subunits – only together during translation Attaches to mRNA strand tRNA Anticodon - 3 base sequence at the bottom Matches the codon on mRNA strand

Translation mRNA attaches to ribosomes tRNA moves into ribosome Anticodon matches with mRNA strand and adds an amino acid tRNA leaves ribosome Stop codon is reached & amino acid chain (polypeptide) detaches from ribosome Folds and creates a protein

Proteins Chains of amino acids fold into a specific 3-D shape to perform their biological function Shape depends on interactions among amino acids Hydrogen bonding

What would be the complementary DNA strand for the following DNA sequence? Which direction (right to left or left to right) DNA 5’-CGTATG-3’

Translate mRNA Write the Amino Acid Sequence for the following mRNA UUG CAG CGC AUG Would you make a complete protein? Explain. Transcribe and translate the following DNA sequence. Draw a line separating each codon: A T C G T C C A A

DNA vs. RNA DNA RNA 2 Strands 1 Strand Deoxyribose sugar Ribose Sugar A-T C-G A-U

SWEET VID!! https://www.youtube.com/watch?v=TEQMeP9GG6M

Questions: put on a separate sheet of paper. 1. Replicate this strand of DNA: ATGCAGTCGATG TACGTCAGCTAC 2. If a DNA strand were to replicate, would they be the same or different? Why? 3. How does the structure of a DNA molecule help account for the great variety of life that exists on earth?

Transcribe DNA 1. If a DNA strand read AAC GTC GCG TAC, what would the mRNA strand be? 2. Does the mRNA model more closely resemble the DNA strand from which it was transcribed or the complementary strand that wasn’t used? Explain 3. Explain how the structure of DNA enables the molecule to be easily transcribed. Why is this important for genetic information? 4. Why is RNA important to the cell? How does an mRNA molecule carry information from DNA?

https://www.youtube.com/watch?v=itsb2SqR-R0