dna technology (intro video)
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DNA TECHNOLOGY (intro video)
Chapter 16 karyotyping
splicing and restriction enzymes
gel electrophoresis
cloning
stem cells
gene therapy
microarrays
•STRUCTURE CONTAINING THE DNA WITHIN A CELL
DNA IS IN THE FORM OF CHROMATIN IN THE CELL MOST OF THE TIME (LOOSE FIBERS OF DNA)
USUALLY NOT VISIBLE UNTIL PREPS FOR REPLICATION – THEN BECOMES A REPLICATED CHROMOSOME WITH 2 SISTER CHROMATIDS HELD BY A CENTROMERE
What is a Chromosome?
Chromosome Number in Humans Number of chromosomes in cells? 46 = 23 pairs for humans 23 from mother/23 from father AUTOMSOMAL chromosomes: 1-22 SEX chrom.: 23rd pair (XX = female / XY = male) DIPLOID – pairs of chromosomes/2n 23 pairs – total 46 HAPLOID – no pairs /n 23 single
2 kinds of cells
Somatic or Body cells: 2n Contain diploid # chromosomes 2 sex chromosomes Pairs of chromosomes
Sex Cells: egg or sperm 1n Contain haploid # chromosomes 1 sex chromosomes No pairs of chromosomes
Karyotype
A picture taken through a microscope of a person’s genome ( chromosomes) organized in appearance according to size, shape, and banding appearance. Visible replicated chromosomes
Used for:
Identifying gender
Chromosomal abnormalities
Original photo of nucleus
Male and Female Karyotypes
Male Female
FYI - Chromosome 1
Chromosome 1 contains nearly twice as many genes as the average chromosome and makes up 8% of the human genetic code.
It is packed with 3141 genes and linked to 350 illnesses including cancer, Alzheimer's and Parkinson's disease
The sequence of chromosome 1 took an international team of 150 scientists 10 years to complete.
Nondisjunction
Failure of homologous chromosomes to separate properly during meiosis
Typical Abnormalities: Trisomy
Gamete with an extra chromosome is fertilized by a normal gamete, the zygote will have an extra chromosome
Human-47 Chromosomes instead 46
Extra chromosome #21
Down Syndrome – most common 1. short stature 2. slanting fold of skin of the upper eyelids 3. susceptibility to leukemia and cataracts 4. subnormal mentality 5. shortened lifespan Chances increase with mother’s age. But, 23% of cases are due to father having an
extra #21.
Edward’s Syndrome-2nd most common nondisjunction disorder
trisomy of chromosome 18
mental and motor retardation serious health problems. Ninety percent die in infancy; however, those who live past their first birthday usually are quite healthy thereafter. They have a characteristic hand appearance with clenched hands and overlapping fingers.
Other 3 copies of chromosomes:
Three #18 Three #13 (Patau)
Different symptoms at birth Both die within a few weeks
Nondisjunction
Another example Triploidy
Total lack of separation of homologous chromosomes
Offspring with three sets of chromosomes
Rare in animals, common in plants
Triploidy
Abnormalities in Sex Chromosomes
Remember: normal is XX or XY
Turner Syndrome
Monosomy - 1 X chromosome (not XX or XY)Female sexual characteristics are
present but underdeveloped. Sterile, short stature, low hairline,
abnormal eye features and bone development and a "caved-in" appearance to the chest, heart defects
Super Female – XXX, XXXX, XXXXXXXX – triple X syndrome Appearance: normal Looks like Turner individual Retardation Sterile
XXXX, XXXXX – Tetra X and Penta X severely retarded
Klinefelter’s Syndrome - XXY
Men are usually sterile, have longer arms and legs and are taller than their peers.
Boys with the syndrome are often shy and quiet, and have a higher incidence of speech delay and dyslexia.
Jacob’s Syndrome - XYY
Super male
Taller than average Persistent acne Lower intelligence Criminal Syndrome – early claims incorrect?
What is the diagnosis?
Edward’s Syndrome
What is the diagnosis?
Kleinfelter’s (XXY) Syndrome
What is the diagnosis?
Turner Syndrome
What is the diagnosis?
Down Syndrome
Genetic Engineering -
Manipulation and alteration of genes for practical purposes (use DNA technology)
- identify genes for specific traits
- transfer genes from one organism to another
Terms to Know: Recombinant DNA:
DNA from 2 or more sources
Transgenic organism:
host organism receiving recombinant DNA (example: transgenic bacteria can be put into growth medium to reproduce and make cloned insulin
GENE SPLICING Cutting DNA of a gene to add base pairs. no sharp instruments are involved, restriction enzymes are used (like scissors)
DNA ligase “glues the pieces together!!
Restriction Enzymes
Bacterial enzymes are used to cut DNA molecules Recognize specific sequences of nucleotides Create “sticky ends” that can bind to
complimentary chains of DNA Used to cut DNA samples for DNA fingerprinting
and cloning vectors
DNA Fingerprinting-pattern of bands made from specific fragments from individual DNA
Compare banding fragments of two individuals Compare two species to see how closely related Use a statistical probability of a chance match
between a suspect and biological evidence at a crime scene or in paternity cases
Depends upon the number of times a repeating pattern occurs
Easier to exclude as a parent or convict as criminal
DNA is found in …hair, semen, blood and other cells
DNA Fingerprinting…DNA Fingerprinting…
11stst used in England for a paternity case in 1985 used in England for a paternity case in 1985
11stst used in U.S. to convict criminals in 1987 used in U.S. to convict criminals in 1987
Accuracy
Complete sets of DNA are not compared Only .1% of human genome varies from person to
person (ID people by this DNA) Useful for: person’s paternity, identifying human
remains, tracing human origins, and providing evidence in a criminal case.
98% of genetic makeup doesn’t code for proteins Compare segments that vary the most from person
to person (noncoding segments that repeat over and over)
More uses for DNA Fingerprinting?
Identify endangered and protected species as an aid to wildlife officials (could be used for prosecuting poachers)
Detect bacteria and other organisms that may pollute air, water, soil, and food
Match organ donors with recipients in transplant programs
Determine pedigree for seed or livestock breeds Authenticate consumables such as caviar and wine
The likelihood that any 2 people would share the same DNA profile is…
1 in a quintillion (18 0’s)
How is a DNA fingerprint made?
1) Restriction enzymes are added to the DNA sample to cut it up into smaller pieces or fragments
How is a DNA fingerprint made?
2) Fragments are pulled through a gel (by an electrical charge) and distribute according to the size of the fragment
How is a DNA fingerprint made?
3) An x-ray picture is taken of this distribution and then can be compared to other DNA samples
How is a DNA Fingerprint made?
Different people have different restriction enzyme “cut sites”
Resulting in different band patterns on a gel
Resulting in different sized DNA fragments.
Person 1 Person 2
Uses of….
Video: Can We Live Forever?PBS
53 minutes
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