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