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DNA Technology a Dr. Production. DNA Coiling:. Replication: DNA  DNA. Occurs during S phase of mitosis in reproducing cells only DNA template is copied complimentarily and semi conservatively

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replication dna dna
Replication: DNADNA
  • Occurs during S phase of mitosis in reproducing cells only
  • DNA template is copied complimentarily and semi conservatively
  • Multiple oris (in eukaryotes) and replication forks form in both directions, producing a leading and lagging strand as DNA is elongated to the 3’ end
complimentary antiparallel
Complimentary & Antiparallel
  • DNA end with the phosphate attached to the #5 carbon = 5’ end
  • DNA end with the OH group attached to the #3 carbon is the 3’end
  • Synthesis of a n.a. chain always proceeds 5’ to 3’
okazaki fragments
Okazaki Fragments
  • Fragments of DNA 1000-2000bp long
  • Produced on the lagging strand
  • Must be joined with ligase

Replication:

DNA Replication Fork & Nucleotide Addition Videos:

enzymes
Enzymes
  • DNA polymerase1:exonuclease activity, 2: DNA repair, 3:primary replication enzyme)
  • Ligasejoins nucleic acid pieces
  • Primase joins RNA primer to DNA strand
  • Helicaseunwinds the DNA
  • Nuclease cuts DNA
  • Endonuclease cuts DNA internally vs at the ends
  • Telomerasecatalyzes lengthening of telomeres
  • Topoisomerasealters the degree of supercoiling nucleic acids but cutting and rejoining strands
mistakes mutations
Mistakes/Mutations
  • Mutation any permanent alteration in the sequence of DNA bases
  • Point mutations can result in frameshifts in the reading frame
  • Chromosomal mutations can result in translocations
slide10

Chromosomal Mutations

Base-pairing (substitution/ deletion-addition) Mutations

mistakes mutations11
Mistakes/Mutations
  • Silent mutation change in nt sequence, but no change in product
  • Nonsense mutation insertion of stop codon into sequence
  • Missense mutation swapping of aa (sickle cell anemia, PKU)
types of dna
Types of DNA

Coding DNA

Less than 5% of the human genome actually codes for genes

slide13
Simple Sequence DNA

20-30% human DNA

Short sequence of 5-10 bp repeat.

Half of the DNA in a species of crab has ATATATATA

Fruit fly has ACAAACT 12 million times

slide14
Intermediate-Repeat

150-300bp scattered throughout genome, some have known functions and code for histones and rRNA

Huntington’s disease CAG repeats 6-35/38-180bp (also various dystrophies)

junk dna
Junk DNA ?

More than 95 percent of all DNA, was called "Junk DNA" by molecular biologists, because they were unable to ascribe any function to it. However that category is becoming smaller as scientists identify non-coding DNA as introns, transposable elements, pseudogenes, VNTRs (variable number tandem repeats and “junk”.

Chromosome #11 Flyover

slide16
Extraneous DNA

proviruswhen the DNA of a virus incorporates its self into an eukaryotic cell. Can move around in the genome

reverse transcriptase enzyme that allows RNA strand to be a template of DNA

transposons “jumping genes”

where did it come from
Where did it come from?

One hypothesis about the junk is that these chromosomal regions are trash heaps of defunct genes, sometimes known as pseudogenes, which have been cast aside and fragmented during evolution.

Evidence for a related hypothesis suggests that the junk represents the accumulated DNA of failed viruses.

Yet another hypothesis is that the junk DNA provides a reservoir of sequences from which potentially advantageous new genes can emerge. (Junk vs trash)

As with most things in science, time and technology will tell…

types of rna
Types of RNA
  • mRNA “messenger RNA” Transcribe DNA to RNA
  • rRNA “ribosomal RNA’ used in the building of ribosomes
  • tRNA “transfer RNA” carry a.a. to ribosome during translation
  • snRNA “small nuclear RNA” Mediate the processing of DNA transcripts for mRNA, rRNA, and tRNA
  • snoRNA “small nucleolar RNA”RNAs within the nucleolus have several functions
  • miRNA“micro RNA” tiny (~22 nts) RNA molecules that appear to regulate the expression of mRNA
  • XIST RNA. inactivate one of the two X chromosomes in female vertebrates.
  • gRNA “guide RNA” found in mitochondrial DNA
  • sl RNA “splice leader RNA” 5’mRNA cap
  • hnRNA “heterogenous nuclear RNA” nonspliced or immature RNA
isolating dna
Isolating DNA

Restriction enzymes/ endonucleases cut at specific palindromic sequences

5’ G/AATT C 3’

3’ C TTAA/G 5’

cleavage leaves “sticky ends”

G AATTC

CTTAA G

Steps in Cloning a Gene

DNA Restriction Step by Step

recombination
Recombination
  • Recombinationprocess in which one or more nucleic acid molecules are rearranged or combined to produce a new nucleotide sequence
  • In eukaryotes, usually occurs as the result of crossing-over during meiosis
  • In prokaryotes, usually occurs as the result of plasmid DNA
    • Construction of a Plasmid Vector
    • Mechanism of Recombination
    • DNA Transformation
rflp analysis
RFLP Analysis
  • Restriction Fragments. Those are the fragments of DNA that were cut by restriction enzymes.
  • Length, and refers to the length of the restriction fragments.
  • Polymorphism, a Greek term that literally means "many shapes". The lengths of some of the restriction fragments differ greatly between individuals, thus there are many shapes, or lengths, of DNA possible.
  • Molecular biologists have identified regions of the human genome where restriction fragment lengths are highly variable between individuals. These regions are called RFLP markers.

VNTR Tutorial

electrophoresis
Electrophoresis
  • Move DNA through a matrix with a sieving effect
  • Agarose gels for DNA
  • PAGE for proteins
  • Single digest uses 1 enzyme
  • Double digest produces 2 restriction patterns

Interactive Animation, Simplified

blotting
Blotting
  • Goes from the gel to filter paper to make and autoradiograph
  • Southern blot: uses RNA to probe DNA strands (SB2)
  • Northern blot: uses DNA to probe RNA strands
  • Western blot: “immunoblotting” uses pp-antibody binding reaction
hybridization
Hybridization
  • These hybridization reactions can be used to detect and characterize nucleotide sequences using a particular nucleotide sequence as a probe.
  • used to find relatedness in n.a.
slide26

Polymerase Chain Reaction (PCR)

PCR2PCR3PCR4PCR Rap PCR Song

transcription dna mrna
Transcription: DNAmRNA
  • Occurs continually throughout the cell cycle
  • Occurs in the nucleus as messenger RNA copies DNA
  • cDNA
slide28
Operon=promoter + operator + TFs
  • Promoter region, upstream of gene, signals start of transcription
  • Transcription factors mediate binding of RNA polymerase
  • Operon is controlled by regulatory genes such as repressor genes

Control in Prokaryotes: http://trc.ucdavis.edu/biosci10v/bis10v/week6/08lacoperon.html

splicing of introns exons
Splicing of introns & exons
  • Non-coding regions (introns) of mRNA are spliced out of the mRNA strand before leaving the nucleus
  • 5’cap is methylated and 3’tail is polyadenylated to indicate orientation at the ribosome
translation mrna protein
Translation: mRNAprotein
  • Aamino acyl (initiation with Met.)
  • Ppeptide bond (elongation)
  • Eexit (termination with UAG, UAA, UGA)
regulatory proteins
Regulatory Proteins
  • Lac Operon
  • Lac Operon Induction
  • Regulatory Proteins: Repression
signal transduction
Signal Transduction
  • Signal Transduction Pathway
  • My Dog is Broken (A Case Study for Cell Signaling)
slide35
GMOs
  • Classical vs Transgenic Breeding
  • Harvest of Fear (What about this fish?)
  • Babies by Design?
  • Transgenic Mouse
resources
Resources
  • BioStudio Animations: http://www.biostudio.com/a_sitemap.htm
  • Biology Animations: http://science.nhmccd.edu/biol/ap1int.htm
  • Restriction Mapping Tutorial:
  • DNA Replication:
  • BioZone BioLinks: http://www.biozone.co.nz/CELL_BIOL_AND_BIOCHEM.html
  • Lac Operon Animation:
  • Lac Operon Induction:
  • Biointeractive Animations:
  • Animated Tutorials: Molecular Biology:
  • Processing of Gene Information Animation Prokaryotes vs Eukaryotes:
  • Learner’s TV:
  • Fundamentals of Molecular Diagnostic Links:
  • Gene Expression
  • DNA Technology Quiz