DNA and Biotech

1
DNA and Biotech
2
DNA Sequencing for 1,000 soon?

• Companies doing nanopore DNA sequencing
• Oxford Nanopore (Dr. Hagan Bayley) Illumina
• IBM 454 Life Sciences (div. Roche) artificial
  nanopores (Stanislav Polonsky)
• NabSys (from Brown U in Rhode Island)
• University of PA (Marija Drndic)

3
(No Transcript)
4
Biotechnology
5
Key Points

• Genes are a set of instructions encoded by the
  DNA sequence
• DNA is a Large polymer made from 4 different
  subunits (adenine, thymine, guanine, and
  cytosine)
• DNA structure allows it to code for RNA
  proteins and be copied easily

6
Key Points

• Mutation occur spontaneously at low rates some
  mutations make no difference, some change the
  cells or organisms vastly
• The Human Genome project analyzed all of the DNA
  in a human and will advance our understanding of
  DNA
• New technology allows us to look at genes and
  changes in the genes
• This will revolutionize medicine

7
How do we know DNA is the Genetic Material?

• Griffiths Transformation Experiment

8
How do we know DNA is the Genetic Material?

• Hershey and Chase
• Used radioactive labeling to trace DNA and
  Protein
• Viral DNA was injected into the cell
• DNA is the genetic material
• Animation http//highered.mcgraw-hill.com/olc/dl/
  120076/bio21.swf

9
DNA is made of

• Nucleotides
• 5 Carbon Sugar
• 1 Phosphate
• 1 Nitrogenous Base

10
The Bases
11
Watson and Crick

• 1953 ? Built a model of the double helix
• Two outside strands of alternating deoxyribose
  and phosphate
• Cytosine and guanine bases pair to each other by
  three hydrogen bonds
• Thymine and adenine bases pair to each other by
  two hydrogen bonds

12
Structure of DNA

• Twisted ladder
• Rails of the ladder are represented by the
  alternating deoxyribose and phosphate
• The pairs of bases (C-G or T-A) form the steps

13
Chromosome Structure

• DNA ? Chromatin ? Chromosomes

14
Prokaryotic and Eukaryotic DNA

• Prokaryotes What are they?
• 1 large circular DNA strand
• Some very small plasmids (also circular)
• Eukaryotes What are they?
• Many chromosomes
• All are linear

15
DNA ReplicationSemi Conservative Replication

• Parental strands of DNA separate and each become
  the template for the new strand

16
DNA ReplicationSemi-Conservative Replication

• Helicase unwinds DNA
• Yields 2 strands (leading and lagging)
• DNA polymerase attaches and adds nucleotides to
  the 3 end of the growing strand
• Nucleotides added by complementary base pairing
  with template strand
• DNA synthesis on the leading strand (5 ? 3 end)
  is continuous
• Lagging strand also grows in the 5-to-3
  direction
• DNA synthesis on the lagging strand is
  discontinuous
• DNA is added as short fragments (Okasaki
  fragments) that are later attached by ligase

17
DNA ReplicationSemi-Conservative Replication
18
The Central Dogma of Biology
19
Central Dogma

• Cells are governed by a cellular chain of command
• DNA ??RNA ??protein
• Transcription
• Is the synthesis of RNA
• Produces messenger RNA (mRNA)
• Translation
• Is the actual synthesis of a polypeptide
  (protein)
• Occurs on ribosomes

20
Transcription

• Stages
• Initiation
• Elongation
• Termination

21
TranscriptionStep 1 Initiation

• Promoter regions signal the initiation of RNA
  synthesis
• Key to RNA polymerase to attach to DNA

22
TranscriptionStep 2 Elongation

• RNA polymerase synthesizes a single strand of RNA
  against the DNA template strand
• RNA polymerase moves down DNA
• Untwists the double helix exposing about 10 to 20
  DNA bases at a time
• mRNA is formed

23
TranscriptionStep 3 Termination

• Specific sequences in the DNA signal termination
  of transcription
• When DNA polymerase meets termination sequence ?
  mRNA is released from the DNA
• Double helix can zip up again

24
End Result of TranscriptionMessenger RNA
What happens next?Translation

• mRNA leaves the nucleus to go to the ribosome
• Translation has three stages
• Initiation
• Elongation
• Termination

25
TranslationStep 1 Initiation

• mRNA meets transfer RNA (tRNA)
• mRNA is read as single bases by a tRNA until
  AUG start codon is recognized
• Codon 3 base pairs

26
TranslationStep 2 Elongation

• mRNA is decoded by tRNA, which transports
  specific amino acids to the growing chain
• mRNA is read 3 base pairs at a time (codon)
• Direction 5 ? 3

27
TranslationStep 3 Termination

• Translation ends when a stop codon (UAA, UAG,
  UGA) is reached
• mRNA and protein chain are released

28
The Code

• DNA code is 3-base code
• 3 base code in mRNA is a codon
• We can code DNA or mRNA into Protein
• AUGUUCAGACACGAC

29
DNA code to Protein
30
Mutations

• A permanent change to the DNA is called a
  mutation
• Types of Mutation
• Point mutation
• Insertion
• Deletion
• Mutations to somatic (body) cells are not passed
  to the next generation
• Mutations to the sex cells are passed to the
  offspring

31
Types of Mutations

• 1. Point mutation - replacement of one DNA
  nucleotide with another.
• missense mutation - point mutation that changes a
  codon so that a different amino acid is
  specified.
• Ex. sickle cell anemia

32
(No Transcript)
33
Biotechnology and Applied Genetics
34
Selective Breeding

• Desired traits of plants and animals are selected
  and passed onto the offspring
• Often results in inbreeding

Saint Bernard Rescue dog
Husky Sled dog
German Shepherd dog Herding/ service dog
35
(No Transcript)
36
Artificial Selection
37
The Latest Research

• Siberian geneticists have been breeding silver
  foxes
• They have discovered that there are specific
  traits that are related to fox-human connections
• Size, floppier ears, tail bone length, fur color
  pattern and behavior like tail wagging.
• After only 9 generations they have fox that
  connect with humans the same way as dogs
  domestication is in their genes
• Each generation is tamer (unlike tigers)

38
Inbreeding

• Two closely related organisms are bred to have
  desired traits and eliminate undesired traits
• Pure breeds are maintained by inbreeding
• A disadvantage is that harmful recessive traits
  can be passed along
• German Sheppard- hip dysplasia
• Dalmatian- deafness
• Boxers- high rate of cancer

39
Another Example Hemophilia in the English Royal
Family

• Aka - "Royal Disease" because was prominent in
  the history of European royalty in the 19th and
  20th centuries
• Specifically haemophilia B

40
Gene Engineering

• Technology that involves manipulating the DNA of
  one organism and inserting it into another
• Look it glows green!!
• Used virus

41
Why do we genetically engineer organisms?

• To study the expression of a gene
• To study the cells
• To study the development of diseases
• Find traits that might be beneficial to humans

42
(No Transcript)
43
Gel electrophoresis

• Separates DNA based on size
• DNA is negatively charged
• Animation http//learn.genetics.utah.edu/content/
  labs/gel/

44
DNA Tools

• A genome is all of the DNA in the nucleus of the
  cell
• DNA tools and manipulate DNA and isolate genes
  from the rest of the genome

45
Biotechnology

• Genetically engineered organisms that have a gene
  from another organism are called transgenic
  organisms
• Used for research- mice and fruit flies
• Crops- Round-up Ready soybeans
• Health- insert functioning genes into a virus or
  bacteria and infect the host
• Bioterrorism- super anthrax

46
Specific ExamplesPlants

• Genetically engineered cotton resist boll weevil
  infestation
• Golden Rice- has more vitamin A
• Many plants- (corn, soy and coca)- are Round-up
  ready and resistant to a common herbicide

47
Human Genome Project

• Sequenced all 3 billion nucleotides in a human
• 20,000-25,000 genes
• 2 of the nucleotides codes for protein
• We are still trying to find out what the rest does

• DNA Fingerprinting
• Long stretches of noncoding regions are unique to
  each individual
• We can look at these fragments and observe
  patterns