dna chapter 10 the code of life. history griffith hershey and chase chargaff linus pauling maurice...
TRANSCRIPT
DNA Chapter 10
The Code of Life
HistoryGriffithHershey and ChaseChargaffLinus Pauling Maurice WilkinsRosalind FranklinFrancis CrickJames Watson
ModelDouble HelixBuilding Blocks-NucleotidesSugar-DeoxyribosePhosphateNitrogen Base
Types of Nitrogen Bases
Pyrimidines and Purines
•DNA has four kinds of bases, A, T, C, and G
thymine cytosine adenine guanine
pyrm
Hydrogen bonds between bases hold the strands together
Each base pairs with a complementary partner
A pairs with TG pairs with C
DNA stands for_____________.Describe the structure and replication of DNA.Describe Transcription.Describe Translation.
DNA is made up of building blocks called nucleotides. A nucleotide consists of a phosphate, a sugar (deoxyribose) and a nitrogen base.
There are two kinds of bases-purines(adenine and guanine) and pyrimidines(cytosine and thymine). Purines have a double ringed structure and pyrimidines have a single ringed structure.
A pairs with T and they join with a double hydrogen bond and C pairs with G and they join with a triple bond. DNA is anti-parallel. Its structure is called a double helix.
In DNA replication, the strands separate.Enzymes use each strand as a template to assemble the new strands
DNA replication begins at specific sites
Each strand of the double helix is oriented in the opposite direction
DNA Replication
Where? NucleusWhen? before cell division so that each cell can have a complete set of instructionsWhat? DNA, free nucleotides, enzymes and energyEnzymes (helicases) unwind the DNA. Then it unzips beginning in the middle-points of origin.Free DNA nucleotides come in and join with complimentary base on each strand.
Enzymes join the sides of the new DNA strands.Each strand is half old and half new. Thus this process is semi-conservative.
RNA vs DNARibose-deoxyriboseRNA is single stranded and DNA is double strandedUracil instead of thymine
A specific gene specifies a polypeptide
The “words” of the DNA “language” are triplets of bases called codons.The codons in a gene specify the amino acid sequence of a polypeptide.
Virtually all organisms share the same genetic code
Transcription
Where? NucleusWhy? DNA wants to send out a message.What? DNA, free RNA nucleotides, enzymes and energyFirst, a section (gene) of DNA unzips.Then RNA nucleotides come in and join with the template side of the DNA.Enzymes join the RNA nucleotides and the RNA pulls away and leaves the nucleus.DNA zips back up.
mRNA Editing
Exons-left inIntrons-cut out
Noncoding segments called introns are spliced outA cap and a tail are added to the ends
Translation (Protein Synthesis)
Where? At a ribosome in the cytoplasmWhat? enzymes and energy, mRNA, tRNA, rRNA, amino acids
Transfer RNA molecules serve as interpreters during translation
In the cytoplasm, a ribosome attaches to the mRNA and translates its message into a polypeptideThe process is aided by transfer RNAs
Each tRNA molecule has a triplet anticodon on one end and an amino acid attachment site on the other
Ribosomes (rRNA)
mRNA, a specific tRNA, and the ribosome subunits assemble during initiation
Translation
First a small ribosomal subunit joins mRNA at a start codon-AUG. The appropriate tRNA comes to join the mRNA. Large ribosomal sub unit joins.
Another tRNA comes bringing the correct amino acid with it. A peptide bond forms between the amino acids, and the 1st tRNA leaves.
Translation
First a small ribosomal subunit joins mRNA at a start codon-AUG.
The appropriate tRNA comes to join the mRNA. Large ribosomal sub unit joins.
Another tRNA comes bringing the correct amino acid with it. A peptide bond forms between the amino acids, and the 1st tRNA leaves.
This continues until a stop codon (UGA, UAG, UAA) is reached. Then all break apart and a polypeptide is released.
Mutations
Good, bad, or who cares?Substitution-redundancyDeletion or InsertionFrameshift
SpontaneousMutagensHigh energy radiation
X rays, UV lightChemicals
Viruses-DNA or RNA in a protein coat
RNA viruses-retrovirusesReverse transcriptaseLytic cycleLysogenic
Viruses of concern
EbolaHantaHIVAvian (Bird) fluInfluenza 203AIDS 205
Differentiation
Cancer results from mutations in genes that control cell division.
OncogenesProto-oncogenes
Colon Cancer
Recombinant Genetics
Gel Electrophoresis
Separates fragments by their size