Chapter 13: Genetic Technology

Chapter 14: The Human Genome

Making a Pedigree

J Pedigree – a graphic representation of genetic inheritance

J Symbols of a Pedigree

J Male

J Female

J Death

J Married

J Children

J Twins

J Affected Individuals

J Carrier

Analyzing a Pedigree

I

III

Recessive Alleles

J Genetic Disorders – the harmful effects produced by mutated genes

J Most genetic disorders are caused by recessive alleles

J Some are common in certain ethnic groups

J Cystic Fibrosis

J Recessive disorder

J Carried on chromosome #7

J Fairly common in white Americans

J 1 in 20 carrier the allele

J 1 in 2000 have the disorder

J A defective protein causes thick mucus to accumulate in the lungs and digestive tract

J Usually don’t survive to adulthood

J New drug therapies and special diets have raised the life expectancy

J Tay-Sachs

J Recessive disorder

J Affects central nervous system

J Lipids build up in brain

J Death in early childhood

J Common in US among Jews

J Phenylketonuria (PKU)

J Recessive disorder

J Carried on chromosome #12

J Failure of brain to develop in infancy

J Phenylalanine is not broken down so it builds up and causes mental retardation

J Common in people whose ancestors came from Norway or Sweden

J Newborns appear normal until they drink milk

J PKU test is given at birth

J Infants are given diets low in phenylalanine until their brains are fully developed

Dominant Alleles

J A single dominant allele inherited from one parent is all that is needed to show the trait

J Huntingtons Disease

J Dominant disorder

J Breakdown of certain areas of the brain

J Uncontrollable movements

J Onset usually occur between 30-50

J Achondroplasia

J Dominant disorder

J dwarfism

Codominant Alleles

J Sickle Cell Anemia

J Recessive disorder

J Most common in black Americans

J 1 in 12 African Americans is heterozygous for the trait

J In homozygous individuals the oxygen carrying protein hemoglobin is defective

J This causes red-blood cells to be sickle shape and reduces there oxygen carrying capacity

J Heterozygous individuals have both normal and sickle shaped red-blood cells because they are codominant

Sex Determination

J 23 pairs of chromosomes

J 22 pairs are autosomes

J 1 pair is sex chromosomes

J Female XX

J Male XY

Sex-Linked Inheritance

J Sex-linked traits – traits controlled by genes on sex chromosomes

J Any allele on the X chromosome of a male will not be masked by a corresponding allele on the Y chromosome

J If a son receives a recessive X chromosome from mom he will express the recessive phenotype because he has no chance of inheriting a dominant allele from his father to mask the recessive allele

J More males have sex-linked disorders

J Red-Green Color Blindness

J Sex linked recessive

J Can’t tell the difference between red and green

J Hemophilia

J Sex linked recessive

J Failure of blood to clot

J Muscular Dystrophy

J Sex linked recessive

J Wasting away of muscles

X-Chromosome Inactivation

J If one X is enough how do cells adjust to extra X in females?

J In females 1 X is randomly switched off

J Turned off X is called a Barr body

J Example: Calico Cat

J In cats the gene for fur color is on the X chromosome

J 1X could have the allele for orange and the other the allele for black

J So depending on which allele is turned off or on gives the different colors

J All cats with 3 colors are female

14-2 Human Heredity

J Karyotype – a chart of chromosome pairs that is valuable in pinpointing unusual chromosome numbers in cells

J A picture is taken of chromosomes in metaphase. Why?

J Because they are coiled up tightly and lined up so they are very visible.

J They are cut out and arranged in pairs according to length and location of the centromere

Chromosomal Disorders

J Disorders caused by nondisjunction

J Down Syndrome – Trisomy 21

J Some degree of mental retardation

J Incidence of down syndrome births is higher in older mothers especially over 40

J 3 chromosomes on pair number 21

J Patau Syndrome – Trisomy 13

J Multiple abnormalities

J Condition usually fatal by one year of age

J Edward Syndrome – Trisomy 18

J Varying degrees of mental retardation

J Usually fatal by three months of age

Sex Chromosome Disorders

J Disorders caused by nondisjunction

J Turner Syndrome

J X ____

J Females

J Sterile

J Shorter, stocky

J Triple X

J XXX

J Females

J Usually fertile

J Abnormalities vary

J Klinefelter Syndrome

J XXY

J Males

J Sterile

J May be mentally retarded

J Slight breast development

J Underdeveloped genitalia

J Sparse body hair

J Jacob Syndrome

J XYY

J Males

J Sterile

Environmental Influences

J As an organisms develops many factors can influence how the gene is expressed or if it is expressed at all

J Temperature, nutrition, light, chemicals can all influence gene expression

J Ex. Leaves of different sizes

J Ex. Himalayan rabbit fur color

J Ex. Arctic Fox fur color

Chapter 13: Genetic Engineering

13.2 Manipulating DNA

Molecular Biology

J DNA Fingerprint – a sequence of bands that shows a persons DNA sequence

J How to make a DNA Fingerprint

1. DNA Extraction

J Cell is opened and the DNA is separated from the other cell parts

2. Cutting DNA

J DNA is so long we cut it into smaller fragments

J Restriction Enzymes – cut DNA at a specific sequence of nucleotides

J Types of Restriction Enzymes

J EcoRI - C T T A A G

G A A T T C

J Bam I - C C T A G G

G G A T C C

J Hae III - C C G G

G G C C

3. Separating DNA

J Gel Electrophoresis – a technique for separating DNA

J DNA is negatively charged

J Load DNA into gel

J Apply electric voltage to gel

J DNA will move through gel to positive

J Smaller DNA fragments move faster and further

J How do you end up with different size fragments that are unique to each individual?

J Tandem Repeat – region of a chromosome that contains multiple copies of a DNA sequence

J The origin and significance of tandem repeats is a mystery

J For forensic scientists they offer a means of distinguishing one individual from another through DNA fingerprinting

J 30% of human genome is composed of tandem repeats.

J Tandem repeats seem to act as filler or spacers between the gene regions of DNA

Polymerase Chain Reaction (PCR)

J PCR – the process of making many copies of genes

J Heat DNA to separate two strands

J As it cools DNA polymerase starts making copies

J Repeat this process and end up with millions of copies

13-3 Cell Transformation

J Transformation – one organism is changed by a gene or genes from another organism

J Genetic Engineering – method of cutting DNA from one organism and inserting the DNA into another organism

J Recombinant DNA – DNA made by recombining fragments of DNA from different sources

J Plasmid

J Extra circular DNA found in some bacteria

J Very useful for DNA transfer from one organism into another

J Process of Transformation

1. Cut out gene of interest with restriction enzyme

2. Use same restriction enzyme to cut plasmid

J This creates ends on each that will match up

3. Combine the gene of interest with the plasmid

4. Place the recombinant DNA into a bacteria cell

5. Bacteria will replicate this new DNA and make many copies of the gene of interest

13-4 Applications of Genetic Engineering

J When recombinant DNA is put into a host that organism will use the foreign DNA as if it were its own.

J Transgenic Organisms – contain functional foreign DNA

J Ex. Glowing bacteria

Application of DNA Technology

J Transgenic bacteria in agriculture

J A bacteria on strawberry plants promotes frost damage on leaves. The gene for this protein is removed and frost damage is prevented.

J A bacteria that lives in soil and in the roots of plants can be engineered to increase the rate of conversion of atmospheric nitrogen to nitrates, a natural fertilizer, to help cut back on fertilizer use and cost

J Transgenic bacteria in industry

J Used to clean up oil spills

J Extract valuable minerals from ores

J Transgenic bacteria in medicine

J The production of growth hormone to treat dwarfism

J Human insulin used to treat diabetes

J Transgenic plants

J Have been genetically engineered to resist herbicides, produce internal pesticides or increase their protein production.

J Produce rice with vitamin A

J In 2000 52% of soybeans and 25% of corn grown in US was genetically modified

J Transgenic Animals

J Make animals grow faster and produce leaner meat

J Trying to produce chickens resistant to bacterial infections that cause food poisoning

J Cows produce different human proteins in their milk

Cloning

J Clone – genetically identical offspring produced from a single cell

J In 1997 Scottish scientist Ian Wilmut cloned first mammal, a sheep named Dolly

14-3 Human Molecular Genetics

Human Genome Project

J Human Genome Project

J An international effort to completely map and sequence the human genome

J Started in 1990 and completed in 2000

J How did they do it?

J First determined markers – a sequence of bases in widely separated regions of DNA

J Cut DNA into random fragments

J Determined sequences of the fragments

J Computers found areas of overlap between the fragments

J One surprise was how few genes humans have

J Fruit fly – 14,000

J Tiny worm – 20,000

J Human – 25,000

J A human diploid cell contains more than 3 billion base pairs

J Only about 2% of the DNA in your chromosomes functions as genes

J The average human gene consists of about 3000 base pairs

J The largest gene in the human genome has more than 2 million base pairs

J Chromosome 22 and 21 were the first 2 human chromosomes sequenced

J Chromosome 22

J Contains approximately 43 million base pairs

J 545 genes

J 1 causes leukemia

J 1 neurofibromatosis

J Chromosome 21

J Approximately 32 million base pairs

J 225 genes

J Lou Gehrigs disease (ALS) – loss of muscle control due to destruction of nerves in the brain and spinal cord

Chapter 14: The Human Genome

Making a Pedigree

J Pedigree –

J Symbols of a Pedigree

J Male

J Female

J Death

J Married

J Children

J Twins

J Affected Individuals

J Carrier

Analyzing a Pedigree

I

III

Recessive Alleles

J Genetic Disorders –

J Most genetic disorders are caused by ______alleles

J Some are common in certain ethnic groups

J Cystic Fibrosis

J Recessive disorder

J Carried on chromosome ______

J Fairly common in ______

J 1 in ______carrier the allele

J 1 in ______have the disorder

J A defective ______causes thick mucus to accumulate in the lungs and digestive tract

J Usually don’t survive to ______

J New drug therapies and special diets have raised the life expectancy

J Tay-Sachs

J Recessive disorder

J ______build up in brain

J Death in early childhood

J Common in US among ______

J Phenylketonuria (PKU)

J Recessive disorder

J Carried on chromosome ______

J ______is not broken down so it builds up and causes mental retardation

J Common in people whose ancestors came from Norway or Sweden

J Newborns appear normal until they drink ______

J PKU test is given at birth

J Infants are given diets low in phenylalanine until their brains are fully developed

Dominant Alleles

J A single dominant allele inherited from one parent is all that is needed to show the trait

J Huntingtons Disease

J Dominant disorder

J Uncontrollable movements

J Onset usually occur between ______-______

J Achondroplasia

J Dominant disorder

Codominant Alleles

J Sickle Cell Anemia

J Recessive disorder

J Most common in ______

J 1 in ______African Americans is ______for the trait

J In homozygous individuals the oxygen carrying protein hemoglobin is defective

J This causes red-blood cells to be sickle shape and reduces there ______carrying capacity

J Heterozygous individuals have both ______and ______shaped red-blood cells because they are codominant

Sex Determination

J ______pairs of chromosomes

J 22 pairs are ______

J 1 pair is ______chromosomes

J Female ______

J Male ______

Sex-Linked Inheritance

J Sex-linked traits –

J Any allele on the X chromosome of a male will not be masked by a corresponding allele on the Y chromosome

J If a son receives a recessive X chromosome from mom he will express the recessive phenotype because he has no chance of inheriting a dominant allele from his father to mask the recessive allele

J More ______have sex-linked disorders

J Red-Green Color Blindness

J Sex linked ______

J Can’t tell the difference between red and green

J Hemophilia

J Sex linked recessive

J Muscular Dystrophy

J Sex linked recessive

X-Chromosome Inactivation

J If one X is enough how do cells adjust to extra X in females?

J In females 1 X is randomly ______

J Turned off X is called a ______

J Example: Calico Cat

J In cats the gene for fur color is on the X chromosome

J 1X could have the allele for ______and the other the allele for ______

J So depending on which allele is turned off or on gives the different colors

J All cats with 3 colors are ______

14-2 Human Heredity

J Karyotype –

J A picture is taken of chromosomes in metaphase. Why?

J They are cut out and arranged in pairs according to length and location of the centromere