dna basics dna is a molecule located in the nucleus of a cell every cell in an organism contains the...
TRANSCRIPT
![Page 1: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/1.jpg)
DNA basics
• DNA is a molecule located in the nucleus of a cell
• Every cell in an organism contains the same DNA
• Characteristics of DNA varies between individuals within a species and between species
![Page 2: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/2.jpg)
What is DNA?
![Page 3: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/3.jpg)
DNA is contained in chromosomesChromosomes contain DNA and associated proteins (which allow the DNA to condense/wind up tightly)
![Page 4: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/4.jpg)
What is a chromosome?
Tightly packed DNA wrapped around histone proteins
![Page 5: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/5.jpg)
Chromosomes, DNA, genes, and nucleotides
gengenee
gengenee genegene
Chromosomes contain DNA
Genes are sequences of DNA nucleotides
Genes are located on chromosomes
Chromosomal regions in between genes contain
variable nucleotide sequences
![Page 6: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/6.jpg)
Forensic DNA analysis seeks nucleotide variation in DNA
• Point mutations from errors in DNA replication– RFLP (Restriction Fragment Length
Polymorphism) analysis
• Variable number tandem repeats (VNTRs)– STR (Short tandem repeat) analysis
![Page 7: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/7.jpg)
Why is there nucleotide variation between the DNA of individuals of the same species?
• All the DNA nucleotides in a cell must be copied (replicated) prior to cell division
• Random copying errors are made during DNA replication
![Page 8: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/8.jpg)
• Every human cell contains 3.4 billion nucleotide pairs
DNA replication copies DNA nucleotides
![Page 9: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/9.jpg)
DNA replication
![Page 10: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/10.jpg)
DNA polymerase & point mutations
• 1 mistake made every 10,000 replicated nucleotides
![Page 11: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/11.jpg)
Repair enzymes limit mutations to 1 in a billion replicated nucleotides
![Page 12: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/12.jpg)
Point mutations are a source of genetic diversity
![Page 13: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/13.jpg)
Point mutations & genetic variation
• Point mutations in the wild type gene result in new alleles
![Page 14: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/14.jpg)
Genetic variation• Alleles are differences (variation) in a gene
within a population of a species
• Genes determine phenotype (physical characteristic) of a structure, molecule, etc.
![Page 15: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/15.jpg)
Forensic DNA analysis and nucleotide variation
• Restriction endonucleases (enzymes) cut DNA at specific short palindromic nucleotide sequences
![Page 16: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/16.jpg)
Forensic DNA analysis & nucleotide variation
• RFLP (Restriction Fragment Length Polymorphism) analysis– Began in 1985
![Page 17: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/17.jpg)
Gel electrophoresis separates DNA fragments by size
![Page 18: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/18.jpg)
RFLPs are DNA “fingerprints”
![Page 19: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/19.jpg)
RFLP analysis and DNA probes
![Page 20: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/20.jpg)
Forensic RFLP analysis uses multiple DNA probes
• If each probe identifies an RFLP with a frequency of 1 in 100 persons, then 5 probes yields 1 in 10 billion
![Page 21: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/21.jpg)
Case Study - OJ Simpson
![Page 22: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/22.jpg)
Modern forensic DNA analysis
• Based on the Polymerase Chain Reaction (PCR)
![Page 23: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/23.jpg)
Polymerase chain reaction (PCR)
• 25-30 PCR cycles yield ~1 million copies of the DNA sample
• Can be used on trace quantities of DNA– Saliva, hair follicle,
trace dried blood
![Page 24: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/24.jpg)
PCR conducted in a thermal cycler
![Page 25: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/25.jpg)
Forensic PCR & VNTRs
• VNTR – variable number tandem repeat– Individuals vary in the number of repeats
![Page 26: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/26.jpg)
PCR, VNTRs and Paternity
![Page 27: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/27.jpg)
PCR and STRs (Short Tandem Repeats)
• STRs are short VNTRs
![Page 28: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/28.jpg)
STRs
• Repeats of 3-7 nucleotides– 5-20 repeats– 5-20 alleles per STR
• PCR amplifies fragments ~200-500 nucleotides in length
![Page 29: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/29.jpg)
STR primers flank the repeat region
• Penta D
![Page 31: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/31.jpg)
Analyzing STRs
• Capillary electrophoresis
![Page 32: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/32.jpg)
STR data
• Each peak identifies a different STR allele
![Page 33: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/33.jpg)
Multiplexing
• Using several VNTR/STR primer sets simultaneously
![Page 34: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/34.jpg)
![Page 35: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/35.jpg)
Gender identity in DNA typing
• Amelogenin gene (tooth pulp)– Located on both X and Y chromosomes– X chromosome amelogenin gene is shorter
by 6 nucleotides
![Page 36: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/36.jpg)
![Page 37: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/37.jpg)
Y chromosome specific STRs
![Page 38: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/38.jpg)
Mitochondrial DNA
![Page 39: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/39.jpg)
Mitochondrial DNA & forensics• Part of the mitochondrial genome is highly polymorphic,
making it useful for human identification.– The two most variable regions known as HV1 and HV2 are usually
amplified and sequenced to compare the difference between the evidence and reference samples
– Mt DNA varies ~1-2% between unrelated individuals (two individuals differ by an average of 87 nucleotides in the approx 800bp region commonly sequenced by forensic labs)
• Because mtDNA presents technical and interpretational challenges, mtDNA is reserved for cases where nuclear DNA analysis failed due to minimal quality or quantity.– 1000s of copies of the mtDNA genome maybe present in a single
cell. Because of its abundance and small size compared to nuclear chromosomes, mtDNA is often the last typable DNA present in a small, old and badly degraded sample. If no results obtained with other systems, often mtDNA can be typed.
– MtDNA is used to type the dead cells in hair shafts, bones and teeth.
![Page 40: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/40.jpg)
CODIS – Combined DNA Index System
• 13 standardized STRs (p. 379)– Available commercially
• Each STR has a specific frequency within a population– Multiple STRs used to unambiguously identify
a person
![Page 41: DNA basics DNA is a molecule located in the nucleus of a cell Every cell in an organism contains the same DNA Characteristics of DNA varies between individuals](https://reader031.vdocument.in/reader031/viewer/2022032706/56649dff5503460f94ae84ff/html5/thumbnails/41.jpg)