Pedigree Charts

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Pedigree Charts

• The family tree of genetics

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Pedigree Charts
I
II
III
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Overview

• What is a pedigree?
• Definition
• Uses
• Constructing a pedigree
• Symbols
• Connecting the symbols
• Interpreting a pedigree

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What is a Pedigree?

• A pedigree is a chart of the genetic history of
  family over several generations.
• Scientists or a genetic counselor would find out
  about your family history and make this chart to
  analyze.

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Constructing a Pedigree

• Female

• Male

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Connecting Pedigree Symbols
Examples of connected symbols

• Fraternal twins
• Identical twins

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Connecting Pedigree Symbols
Examples of connected symbols

• Married Couple
• Siblings

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Example

• What does a pedigree chart look like?

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Symbols in a Pedigree Chart

• Affected
• X-linked
• Autosomal carrier
• Deceased

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Interpreting a Pedigree Chart

• Determine if the pedigree chart shows an
  autosomal or X-linked disease.
• If most of the males in the pedigree are affected
  the disorder is X-linked
• If it is a 50/50 ratio between men and women the
  disorder is autosomal.

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Example of Pedigree Charts

• Is it Autosomal or X-linked?

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Answer

• Autosomal

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Interpreting a Pedigree Chart

• Determine whether the disorder is dominant or
  recessive.
• If the disorder is dominant, one of the parents
  must have the disorder.
• If the disorder is recessive, neither parent has
  to have the disorder because they can be
  heterozygous.

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Example of Pedigree Charts

• Dominant or Recessive?

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Answer

• Dominant

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Example of Pedigree Charts

• Dominant or Recessive?

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Answer

• Recessive

https//www.youtube.com/watch?vIr1t9awmUl4
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Summary

• Pedigrees are family trees that explain your
  genetic history.
• Pedigrees are used to find out the probability of
  a child having a disorder in a particular family.
• To begin to interpret a pedigree, determine if
  the disease or condition is autosomal or X-linked
  and dominant or recessive.

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Pedigree Chart -Cystic Fibrosis
https//www.youtube.com/watch?vWuk0W10EveU
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Human Genetics
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Karyotype
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Chromosome Number
Homologous Chromosomes are the sets of each pair

• Different for different species
• Full set 2NDiploid
• N
• pairs
• 1 pair from mother
• 1 pair from father
• Humans 23 pairs or
• 46 total

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Autosomes Sex Chromosomes
Autosomes 1-22 for all traits except sex
Sex chromosomes Pair 23 XX(female)
or XY(male)
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Down Syndrome 3 of 21
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Klinefelters XXY
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Mutation
A to A G C
A T GC

• Change in DNA code
• Caused by
• Chemical damage
• Errors in Replication
• X-ray damage
• UV damage

X
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Mutation

• Changes in the DNA code
• Changes in the final proteins made
• Changes in the organism

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Mutations

• Chromosome mutations involve changes in the
  structure of a chromosome or the loss or gain of
  a chromosome.
• There are three types of chromosome mutations
• 1. deletion the loss of a piece of a chromosome
  due to breakage.
• 2. inversion a chromosomal segment breaks off,
  flips around backward and then re-attaches.
• 3. translocation a piece of one chromosome
  breaks off and re attaches to a non-homologous
  chromosome.

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Genetic Technology

• Recombinant DNA
• Bacterial Transformation

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1. Mice that glow???
https//www.youtube.com/watch?vk7-ofCWJiUg
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2. Genetic Engineering

• Altering the genetic makeup of an organism
• By Cutting DNA from one organism and inserting
  fragments into a host
• Recombinant DNA
• Alters the allele frequency of a population by
  artificial means

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Recombinant DNA

• Recombine
• Connecting or reconnecting DNA fragments
• DNA of two different organisms
• Example lab of inserting human DNA into bacteria

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Genetic Engineering of Insulin
Human DNA cut out
Human DNA put into bacteria DNA
Many Bacteria Grow human insulin
Bacteria DNA is opened up
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4. Transgenic Organism

• trans across
• genic race
• Contains genes from another organism
• Bacteria
• Virus
• Human

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5. Tobacco Recombinant DNA Process

• Isolated DNA to be inserted into host
• Attach DNA fragment to a vehicle (vector)
• Transfer the vector to the host
• Transgenic organisms

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Restriction Enzymes
Bacterium DNA cut
Human Cut
Restriction Enzymes cut DNA at very specific
sites Separate the base pairs of both
strands Scissors in Recombinant DNA
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Vectors vehicles

• Carry foreign DNA fragments into the host
• Bacteria carried the firefly DNA into the tobacco
  cells
• Biological or
• Mechanical

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Vectors

• Biological
• Virus
• Bacterial plasmid (circular DNA)

• Mechanical
• Micropipette
• Metal bullet coated with DNA

https//www.youtube.com/watch?vnfC689ElUVk
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Recombinant DNA Uses

• Grow human hormones in bacteria cultures
• Artificial sweeteners using bacteria to make
  amino acids
• Study human diseases by inserting human DNA into
  mice
• Replace incorrect DNA sequences

• Replace harmful bacteria on plants
• Nitrogen bacteria in the soil plants to make
  fertilizer
• Improve transport of fruits
• Resist diseases
• Increase protein production

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Genetic engineering and Gene therapy Right or
wrong?

• Genetic engineering is one of the
• fastest growing medical sciences.
• There are 2 types of cell and so 2 types of
• gene therapy
• Somatic cells found in the body
• Germ-line - cells found in sperm and eggs
• (hereditary)

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Somatic Cell Therapy

• This is when a gene is introduced into a
• patient to help them recover from a
• disease.
• It could be used to help those suffering
• from cystic fibrosis.
• Only the patient is affected and so there
• are few ethical concerns.

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Germ Line Therapy

• Changes are made to genes that will
• affect subsequent generations.
• We do not know the consequences of this.
• It will affect what it means to be human.
• We take charge of our own evolution.

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The many uses of Genetic Engineering

• To repair a genetic defect.
• To enhance a natural effect e.g. growth.
• To increase crop resistance to disease or
  climate.
• To test and screen for genetically inherited
  diseases.
• To cure disease by altering the genes.
• To select human genes embryo selection
  (designer babies)

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Embryo Selectionas a form of Genetic Engineering
Designer babies or a cure for genetically
inherited diseases? To select the sex of a child
or to create a healthy baby to cure a sick
sibling?
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• Embryo Selection is a relatively simple process.
  An ovarian biopsy can yield many eggs which can
  be fertilized in vitro with the partners sperm.
  The cells can be grown in culture, and at the
  eight cell stage, one of the cells can be removed
  for diagnosis.

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Embryo Selection

• To the right is a picture of a glass micropipette
  used to remove the cell for diagnosis. The width
  of the pipette opening is one cell wide.

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• How is it done?
• The removal of one cell allows DNA tests to be
  performed on the embryo. The embryo with the
  desired trait can then be selected.
• The final step is implanting the embryo into the
  uterus, and letting the pregnancy continue to
  term.
• This process is called in vitro fertilization.

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Embryo selection is being done for certain select
conditions, like cystic fibrosis, Huntingtons
disease, and sickle cell anaemia.
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Questions raised by embryo selection

• What are the specifics of embryo selection, is
  there a limit?
• What are the benefits and consequences of embryo
  selection?
• What is the difference between embryo selection
  and genetic engineering?

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Questions raised by embryo selection

• Is embryo selection ethical?
• Is it ethical to choose the sex of your baby?
• Is it ethical to choose the characteristics of
  your baby?
• Is it ethical to rid your baby of diseases
  through this process?
• What is done with the embryos that are not
  selected?
• How do you store and dispose of the unused
  embryos?

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What are the specifics of embryo selection, is
there a limit?

• Bioethicists generally find current practices of
  embryo selection not too problematic, because the
  elimination of debilitating diseases justifies
  the intrusion. However, if embryo selection can
  be used to select deleterious traits, why
  couldnt it be used to select for other
  enhancing traits. Here bioethicists begin to
  find the procedure more problematic because it
  takes on eugenic nature.

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What are the benefits and consequences of embryo
selection?

• Benefits
• Many embryos are implanted back into the woman
  (greater chance of pregnancy)
• Child is without disease
• Other embryos can be cultured and frozen so they
  can be used again

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What are the benefits and consequences of embryo
selection?

• Consequences
• Goes against nature
• Very expensive
• Not 100 guaranteed
• Not available to all women

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Is Embryo Selection Ethical?

• Some would say
• Embryo selection is ethical when
• looking for syndromes/diseases which later would
  cause the child to die within the first few
  years,
• would cause severe retardation,
• cases which would be a better choice than
  abortion, and to avoid emotional stress.
• Embryo selection is not ethical when
• choosing specific sex,
• choosing character traits,
• killing discarded embryos.

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Issues for Ethics

• Personhood the morality of discarding an embryo
  when it is considered a person.
• The right to life what is done with spare
  embryos.
• The right to a child.

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Ethical Approaches4. Virtue Ethics

• The virtue of compassion is important when
  considering those suffering from genetic
  diseases.
• But it is also important to consider compassion
  to the embryos, so it could be argued both ways.

https//www.youtube.com/watch?vdKBfxoPnT7g