Download Restriction Fragment Length Polymorphisms

Biotechnology
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Introductory Question
Based on your understanding of
restriction enzymes, speculate why each
of us has a unique DNA fingerprint or
profile.
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Essential Questions
 What are restriction fragment length
polymorphism (RFLP)
 What role do VTNRs play in RFLP and DNA
fingerprinting?
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Each individual has a unique DNA
fingerprint- Why?
 Each individual has unique DNA sequences
within their DNA
 Variation in DNA sequences between
individuals of a population is known as
polymorphism.
 Because of polymorphism, the location of
restriction sites varies between individuals
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Restriction Fragment Length
Polymorphism (RFLP)
 Variation in restriction sites create different size
fragments when cut with a restriction enzyme
 Length variation of restriction fragments between
individuals is known as Restriction Fragment Length
Polymorphism (RFLP)
 Scientists have identified within Human DNA where
restriction fragment length is highly variable
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Unique DNA Sequences
 Many of these variable DNA sequences are in
junk DNA
 DNA that is not transcribed into RNA and translated
into protein.
 This is the non-coding region of DNA
 much more variable than the coding region of DNA
 Does not affect the phenotype of the individual.
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Question????
 Under what conditions, would two
individuals not be polymorphic?
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Discovery of Short Repeated DNA
Sequences
 Sir Alec Jeffreys identified
short nucleotide
sequences that are
repeated multiple times
in non-coding regions of
DNA
 The number of repeats
can range between 10
and 100 times
http://www2.wmin.ac.uk/~redwayk/lectures/images/DN
A_fingerprinting_07.jpg
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Unique Repeated sequences are
in Tandem
 These short sequences that can range between 2 and
300 base pairs are repeated in tandem meaning right
next to each other.
 For example, the sequence CAT in the following DNA
sequence AGCATCATCATGA is repeated 3 times.
 These short sequences are referred to as variable
number tandem repeats (VNTRs); also known as short
tandem repeats (STR)
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Tandem Repeats in Human DNA
 These tandem repeats
are found throughout
the human genome
 These repeats are
found at a specific
chromosomal locus- a
specific location along
the chromosome.
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VTNR identified on different
chromosomes
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http://upload.wikimedia.org/wikipedia/commons/thumb/
7/7a/Codis_profile.jpg
5/8/2017
Individual variation in RFLP
 These hypervariable regions (VTNRs)
vary between individuals and give rise to
variation in restriction fragment length.
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Uses of VTNR analysis
 This analysis is commonly used to create
DNA profiles for
 Identification of tissue left at a crime scene
 Identification of biological father in
paternity suits
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Individual VTNRs
 Examination of a VTNR locus
for an individual commonly
results in a two-band pattern
 These two bands represent
different alleles, one donated
from each parent
 If more than one VTNR locus is
examined, more than two
bands can appear
http://202.114.65.51/fzjx/wsw/website/bioproject/human_bio
/problem_sets/DNA_forensics_1/graphics/05AR.gif
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Thumbs up / Thumbs down
At one VTNR locus, individuals
commonly have 5 bands
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How to identify when two
individuals are related
 When two individuals are related there
should be overlap in the DNA profiles
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DNA profiles in Paternity Suits
 Examine the DNA profiles
for mom, dad, daughters
1 and 2, and sons 1 and 2.
Identify the children that
are biologically related to
mom and dad, to mom, to
dad, or neither.
http://molbiol4masters.masters.grkraj.org/html/Genetic_Engineeri
ng5D-DNA_Profiling_files/image012.gif
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Answer to DNA profile
 D1 and S1 are the
biological children of
mom and dad
 D2- Biological child of
mom from previous
marriage
 S2- adopted
http://molbiol4masters.masters.grkraj.org/html/Genetic_Engi
neering5D-DNA_Profiling_files/image012.gif
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VTNR analysis
 Examination of DNA profiles at a single
VTNR locus for unrelated individuals are
usually different.
 However, because there is a chance that
unrelated individuals may have the same
profile, typically 4-6 different VTNR loci
are examined
http://www.scq.ubc.ca/a-brief-tour-of-dna-fingerprinting/
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Other Uses for Restriction DNA
Fragments
 Isolation of a specific gene that encodes for a specific
protein
 Example: gene that codes for insulin
 Manipulation of the DNA instructions in that isolated
gene
 Changing the gene’s instructions within the organism
 Putting those instructions into another organism that does
not contain that gene.
 Ex. Putting the insulin gene inside bacterium
Answer the following questions
IYOW
1.
Define the following terms
 RFLP
 Junk DNA
 VTNR
2. Explain why each individual has a unique DNA
Fingerprint.
3. Why does each VTNR locus have 2 bands for an
individual?
4. How can restriction fragments be used?
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