What is DNA? • Deoxyribonucleic Acid • DNA, the molecule that holds genetic information, makes an exact copy of itself whenever a cell divides. • DNA stores the instructions for protein synthesis and is contained in chromosomes
Deoxyribose • 5-Carbon Sugar • Makes up part of the backbone of DNA
Phosphate Group • Makes up other part of the backbone of DNA
DNA Sugar-Phosphate Backbone • DNA Backbone • Double Helix-2 strands • Made up of the sugar and phosphate group
Nitrogenous Base • Four kinds on nitrogenous bases: • Thymine (T) • Adenine (A) • Cytosine (C) • Guanine (G) • Held together by a hydrogen bond
Chargaff’s Rules • Rules of Base Pairing: • A and T always go together • C and G always go together
Nucleotides • Unit made of: • 5-carbon sugar • Phosphate Group • Nitrogenous Base
3 Main steps in chromosome formation • Step 1: Replication • Pulls apart (1 double 2 single) original strand • Step 2: Transcription • Copies of an original single strand to formation of new strand • Step 3: Translation • Creation of final strand
Step 1: DNA Replication • Because of the Double Helix design and base-pairing, each strand has all the information needed to reconstruct the other half. • Before a cell divides, it duplicates its DNA-called replication • During replication, the DNA separates into 2 strands which can then reconstruct a new strand.
Unzipping • Unzips in hundreds of places. • Each spot of unzipping forms a “fork” • Hydrogen bonds are broken by an enzyme • DNA Polymerase-enzymethat helps in replication of DNA- “Proofreads”
Why RNA & DNA? • DNA is the coded instructions for making protein. • RNA actually does the job of decoding the DNA’s instructions and then makes protein.
RNA Structure • Like DNA-it’s long chain of nucleotides has: • 5-Carbon sugar • Phosphate group • Nitrogenous base • Unlike DNA, RNA has: • A different sugar: ribonucleic acid • Only one strand (sugar-phosphate backbone) • Has Uracil in place of Thymine
RNA Structure • It’s a disposable copy of a segment of DNA. • It’s a working copy of a single gene. • The DNA sequence makes it possible for a single gene to produce hundreds or thousands of RNA molecules.
Step 2: Transcription • Process of copying part of the DNA nucleotide sequence to make mRNA. • RNA Polymerase binds to the DNA and separates the strands. • Then, RNA Polymerase copies the strand of template DNA and assembles a strand of mRNA. • Template DNA: Strand that is being copied • First type: mRNA: Opposite copy of template DNA to make future copies
Transcription • Notice in the mRNA (messenger RNA: to be copied) strand, all Thymine become Uracil
Transcription Check-up • In your notes, write down this DNA sequence and transcribe it into mRNA: • A • C • T • G • G • C • A • T • C • A U G A C C G U A G U
Step 3: Translation Transcription Complete! Next:
Step 3: Translation • Translation is protein synthesis (make the final strand) • Uses mRNA to make proteins inside the rRNA. • rRNA: Ribosomal RNA • Occurs in the cytoplasm.
Types of RNA • Second type of RNA: • 1. Ribosomal RNA -This is where proteins are assembled. -Like a factory ** Called Translation
Types of RNA • Third type of RNA: • 3. Transfer RNA -Transfers amino acids to the ribosome where proteins are made.
tRNA • Anti-Codon (tRNA) -Matches with the codon (mRNA) to deliver the amino acid that makes the protein Codon Anti- Codon Protein Chain Amino Acid
Genetic Code • Is the language of mRNA instructions. • Every 3 nucleotides of mRNA is a codon. • UCU- GCA- AUG- CAU • Each codon “Codes” for an amino acid. • A chain of amino acids make a protein
Step 3: Translation • Starts (AUG) and stops with a “start” or “stop” codon. (like a sentence) • When a “stop” codon is reached, the protein is complete.
What is that codon? • HISTIDINE • STOP • START OR METHIONINE • GLYCINE • ALANINE • ASPARAGINE • ARGININE • STOP • PROLINE • VALINE • CAU • UAG • AUG • GGU • GCU • AAC • CGU • UGA • CCG • GUU
In Conclusion Genes contain nothing more than directions for assembling proteins. • Fun Video