Mutations & Genetic Recombination - PowerPoint Presentation

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Mutations & Genetic RecombinationSlide2

Mutation

Permanent change in the genetic material of an organismAll mutations in gametes are inheritable because they are copied during DNA replicationSlide3

Somatic cell mutations occur in body cellsGerm cell mutations occur in reproductive cells

These are passed on from one generation to the nextSlide4

Types of mutations

Point mutationsChemical change that affects just one or a few nucleotidesMay involve substitution of one nucleotide for anotherOr the insertion or deletion of one or more nucleotidesSlide5

Point mutations

Minor effect on cellChange in coding sequence does not always result in a different polypeptide Ex. GGA  GGG both code for the amino acid, glycineSlide6

Even if the aa is substituted for another, it may not have a significant function in the final structureThis is called a

silent mutationExample: UAU and UAC Mis-sense mutationResults in an altered proteinEx sickle cell disease is a point mutation that is very harmfulSlide7

Nonsense mutation

Deletes a start signal or results in a premature stop signalA nucleotide substitution that affects the regulatory sequence may result in a cell being unable to produce a functional proteinSlide8

Frameshift

When an insertion or a deletion the codon reading frame is shifted and each codon is read incorrectly.

AAU GGU GCC

AAU GGU

G

GCCSlide9

Chromosomal Mutations

Crossing overLoss or duplication of portions of DNA during DNA replicationChange to structural or regulatory DNA sequencesSlide10

Causes of mutations

Spontaneous mutationsCaused by naturally occurring molecular interactionsEx. Incorrect base pairing InducedCaused by agents outside the cellMutagens increase the rate of mutation Slide11

Physical Mutagens

Cause physical changes to the structure of DNAEx. X-rays and gamma rays are the most damaging form of mutagen knownAlso UV rays cause chemical reactions to form between adjacent A and T bases, interfering with replicationA single sunburn doubles the chance of getting skin cancer (melanoma) Slide12

Chemical Mutagens

A molecule that can enter the nucleus of the cell and induce mutations by reacting chemically with DNA Can insert themselves and cause substitution or a frameshift mutationEx. Nitrates (a food preservative), gasoline fumes, 50 different compounds of cigarette smoke.Slide13

CarcinogenicChemical mutagens associated with one or more forms of cancer

Cancer is uncontrolled cell divisionThe result of somatic cells that disrupt the expression of genes involved in regulation of the cell cycleSlide14

Mutations and Genetic Variation

Single mutation has little or no effect on an organism

However, a series of mutations developed over time can be more serious.

Mutations accumulate within a cell

Different mutations over time help shed light on genetic variationSlide15

Tracing ancestry through mitochondrial DNA

Mitochondria and chloroplasts have there own DNA (which replicates, transcribes, and translates separately from nucleic DNA.Evidence suggests that these organelles were once independent prokaryotic cellsEndosymbiont theory proposes that eukaryotes arose when one prokaryote was engulfed by another Slide16

Mitochodrial DNA (mtDNA)

Recall, the cytoplasm of the fertilized egg (zygote) is donated by the ovum.All of your mtDNA is identical to your mothersMutations in mtDNA provide information about the evolutionary path of animals and plant species Slide17

The process of creating recombinant DNA involves 2 types of enzymes:

Restriction Enzymes – (DNA scissors) cut the DNA strand at specific sites -palindromes- and often creates sticky ends Slide18

2. The now unpaired segments can be paired with complimentary nucleotides from a different strand of DNA

3. DNA ligase – is genetic glue that puts DNA strands back together.rDNASlide19
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Application

Insulin used to be harvested from pigs, but some individuals did not tolerate it. we are now able to use bacteria to produce human insulin in large quantities. is tolerated much better by patients. This procedure was first marketed in Canada in 1983!Slide21
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Other Aspects of Biotechnology

Gene sequencing –determining the specific location and composition of specific genes. The Human Genome Project -1990 2000: mapped our 30 000 genes (3 billion nucleotides)NOVA Online | Cracking the Code of Life | Sequence for YourselfSlide23
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RFLP – restriction

fragment length polymorphism –cut DNA into piecesGel Electrophoresis – separate the DNA pieces by size. Slide25

DNA fingerprinting identify an individual based on their unique genetic code.

homologous segments of DNA are similar but contain unique patterns of nitrogen bases identify individuals involved in crimes, paternity Slide26

DNA FingerprintingSlide27

Misc. TechnologyPolymerase chain reaction –making billions of copies of a piece of DNA-

PCR AnimationPaternity Testing - Paternity TestingGene Gun - Genegun1Slide28
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Recombinant DNA

Genetic engineeringManipulating genetic material to alter genes and blend plant, animal, and bacteria DNA together.DNA that includes outside source is called recombinant DNA. Rapidly growing fieldEg peppersSlide30

Restriction EndonucleasesRestriction enzymes

cut DNA at specific nucleotide sequencesRestriction endonucleases cuts within the interior of a DNA molecule (rather than at ends)It recognizes a target sequence (short sequence of nucleotides) and cuts within it at the restriction site.Slide31

Two characteristicsSpecificity: cuts are specific and predictable

Meaning the same enzyme will cut the same target sequences producing the same set of DNA fragments called restriction fragments Slide32

Staggered cuts: leave a few unpaired nucleotides on a single strand at each restriction fragment called

sticky ends.Sticky ends can pair with a complementary sticky end cut by he same restriction endonuclease from a different strand of DNADNA ligase Spliced the paired sticky ends together resulting in a stable recombinant DNA molecule.Slide33

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