Genes & TechnologyTechnology to Understand the Human Genome

Chromosomal Mutations

• Large sections of DNA contain 100,000’s of bases and multiple genes.• Chromosomal mutations are large scale

changes to chromosomes.

Types of Chromosomal Mutations• Deletion—remove large section of DNA• Duplication—copy a section of DNA 2

times• Inversion—reverse the order of a section

of DNA• Insertion—move a section of DNA to a

different chromosome• Translocation—different chromosomes

trade sections• All mutations move multiple genes in a

section.

Check your understanding• Match the letter to the

mutation.• Duplication• Deletion• Translocation• Inversion• Insertion

E

Karyotype

• A photomicrograph is taken of the chromosomes during mitosis.• The chromosomes are

cut apart and sorted into homologous pairs.• Criteria for pairing:• Size• Banding• Location of centromere

SKY Spectral Karyotype is a recent improvement.

Normal or not?• Humans have 23 chromosomes in homologous pairs.• Nondisjunction is an error during meiosis• Normal meiosis tetrad divided into 2 pairs, pairs divided into 1’s• Error results in a gamete with 3: trisomy

1: monosomy

Normal 3 1 Trisomy Monosomy

Errors in Chromosome Number• Trisomy results from fusing a gamete with 2 chromosomes

plus a gamete with the normal 1 chromosome = total 3.• Trisomy 21—Down’s Syndrome. Effects many body systems.• Other trisomies are possible, 13, 18, and sex chromosomes.• Karyotype has 47 chromosomes.

• Monosomy results from fusing a gamete with 0 chromosome with the normal 1 chromosome gamete = total 1 • Turner’s Syndrome—single X is the only survivable monosomy.• Karyotype has 45 chromosomes.• Turner’s women can live relatively normal life.• Effects multiple body systems.Actress Linda Hunt, successful person with Turner’s Syndrome.

Make your own karyotype

• Visit the Learn.Genetics website and try the computer model for building a karyotype.• This diagnostic study used for genetic counseling.• Karyotype can be used to:• Diagnose nondysjunction—trisomy or monosomy• Diagnose chromosomal mutations• Diagnose 1000’s of genetic disorders

• Complete the karyotype and make a diagnosis• http://

www.biology.arizona.edu/human_bio/activities/karyotyping/patient_a/patient_a.html

Gel Electrophoresis• Method of analyzing patterns in DNA• Test also called DNA fingerprinting, DNA profile, DNA

barcoding• Sample of DNA from one source• Make many copies• Cut in pieces with an enzyme

• Prepare Gel and bath set up

• Add DNA sample and DNA of known sizes to separate wells• Connect electricity, let the DNA move• Large pieces are slow and small pieces move faster.

Results of Gel Electrophoresis• Bars of stained DNA are visible.• Reference DNA of known size allows estimate of unknown

DNA sizes by comparison.• Compare the patterns.

• Find 2 patterns that are alike.

Check your understanding• Take a look at the DNA fingerprint analysis. • M is the mother, Jennifer Barker. • C is the child, Andrew Barker. • AF is the alleged father, Steven Barker. • Remember, to conclude that the alleged father is truly the father,

every band in the child's fingerprint that does not match in the mother's fingerprint must match in the father's.

• Could this be the true father?

Types of DNA in Genome

• Genome is the total of all DNA

• Autosomal DNA—chromosomes #1 to #22• Crossing over in meiosis introduces genetic diversity.

• X chromosomal DNA—from mother to sons and daughters• Maternal line inheritance

• Y chromosomal DNA—from father to son• Paternal line inheritance

• Mitochondrial DNA—from mother to sons and daughters• Little to no mutation in DNA contained in the mitochondria.

Human Genome• Human Genome Project took 13 years and cost $3 billion.• First completion of decoding the human genome was done by

multi-national teams in 2000.• Less expensive sequencing equipment has increased the rate

of discovery.• The cost for a human genome sequencing has reached $1,000.• Personalized genomic medicine is starting to be practiced.• How to sequence the human genome—Mark Kiel, TedEd• http://www.youtube.com/watch?v=MvuYATh7Y74

Gene Therapy• Inserting a new gene into an existing organism using

a delivery system.• Delivery—harmless virus or stem cells• Conditions that may be treated are genetic in origin

and• Are well understood• Faulty gene identified & working gene available• Cells needing treatment are accessible• Delivery method available• Only somatic cells, no sex cells—no risk to future

Gene Therapy

The technique may be used• to replace a faulty gene • Example: Bubble children• Severe Combined Immune Deficiency first trial in 2000.• 10 children, 7 cured, and 2 developed leukemia• Only treatment resulting in full cure.

• to introduce a new gene whose function is to cure or to favorably modify the clinical course of a condition • Example: gene for improving attack on cancer

• to inactivate a faulty gene

Genetic Engineering• Selective breeding by people to modify animals or crops• Wild maize to modern corn

• GMO—genetically modified organism• Current technique for inserting new gene• Herbicide resistant crops for easier weed control, pest resistant,

or adapted to environmental conditions.• 10% of world crops in 2010 were GM crops.

Resources• Staff, 2014, Human Genome Project, National Human Genome

Research Institute, http://www.genome.gov/10001772• Staff, 2014, Make a Karyotype, Genetic Science Learning Institute,

University of Utah, http://learn.genetics.utah.edu/content/chromosomes/karyotype/

• Staff,2014,Chromosomes and Inheritance, Genetic Science Learning Institute, University of Utah, http://learn.genetics.utah.edu/content/chromosomes/

• Staff, 2012, Gene Therapy, Centre for Gene Therapy, New South Wales, Australia, http://www.genetics.edu.au/Publications-and-Resources/Genetics-Fact-Sheets/FactSheet27

• Staff, 2014, Gel Electrophoresis, Biology Block, http://biologyblock.com/?p=1109