Download Unit 04 Part III - Doral Academy Preparatory

Pedigree Charts
The family tree of genetics
Pedigree Charts
I
II
III
Overview
What is a pedigree?
I.
a.
b.
Definition
Uses
Constructing a pedigree
II.
a.
b.
III.
Symbols
Connecting the symbols
Interpreting a pedigree
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.
Constructing a Pedigree
 Female
 Male
Connecting Pedigree Symbols
Examples of connected symbols:
Fraternal
twins
Identical
twins
Connecting Pedigree Symbols
Examples of connected symbols:
Married
Couple
Siblings
Example
 What
like?
does a pedigree chart look
Symbols in a Pedigree Chart
 Affected
 X-linked
 Autosomal
carrier
 Deceased
Interpreting a Pedigree Chart
1.
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.
Example of Pedigree Charts
 Is
it Autosomal or X-linked?
Answer
 Autosomal
Interpreting a Pedigree Chart
2.
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.
Example of Pedigree Charts
 Dominant
or Recessive?
Answer
 Dominant
Example of Pedigree Charts
 Dominant
or Recessive?
Answer
 Recessive
https://www.youtube.com/watch?v=I
r1t9awmUl4
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.
Pedigree Chart -Cystic Fibrosis
https://www.youtube.com/watch?v=Wuk0W10EveU
Human Genetics
Karyotype
Chromosome Number
Different # for
Homologous
different species
Chromosomes
 Full set =
are
the sets of
2N=Diploid

N= pair
each

# pairs
 1 pair from mother
 1 pair from father
 Humans= 23
pairs or
 46 total

Autosomes & Sex
Chromosomes
Autosomes = # 122 for all traits
except sex
Sex chromosomes=
Pair # 23 XX(female) or
XY(male)
Down Syndrome= 3 of #21
Klinefelter’s = XXY
Mutation


1.
2.
3.
4.
Change in DNA
code
Caused by:
Chemical
damage
Errors in
Replication
X-ray damage
UV damage
A
T
G
C
A
to A
G
C
Mutation
Changes
in the
DNA code
= Changes in
the final
proteins made
=Changes in
the organism
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

Genetic
Technology
Recombinant
DNA &
Bacterial Transformation
1. Mice that glow???
https://www.youtube.com/watch?v=k
7-ofCWJiUg
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
Recombinant DNA:
“Recombine”
Connecting
or
reconnecting DNA
fragments
DNA of two different
organisms

Example: lab of inserting human DNA
into bacteria
Genetic Engineering of Insulin
Human DNA cut out
Human DNA put
into bacteria DNA
Bacteria DNA is opened up
Many Bacteria
Grow human
insulin
4. Transgenic Organism:
 “trans”
= across
 “genic” = race
 Contains genes from
another organism
 Bacteria
 Virus
 Human
5. Tobacco Recombinant DNA
Process:
a.
b.
c.
Isolated DNA to be
inserted into host
Attach DNA fragment to a
vehicle (vector)
Transfer the vector to the
host=
Transgenic organisms
Restriction Enzymes:
Human Cut
Restriction Enzymes cut DNA at
very specific sites
Separate the base pairs of both
strands
“Scissors” in Recombinant DNA
Bacterium
DNA cut
Vectors = vehicles
Carry
foreign DNA
fragments into the
host
Bacteria carried the
firefly DNA into the
tobacco cells
Biological or
Vectors:
Biological: Mechanical:
Virus
Micropipett
Bacterial
e
plasmid
Metal bullet
(circular
coated
with
DNA)
DNA
https://www.youtube.com/watch?v=
nfC689ElUVk
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

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)
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.
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.
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)

Embryo Selection
as 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?

Embryo Selection is a relatively simple
process. An ovarian biopsy can yield
many eggs which can be fertilized in
vitro with the partner’s sperm. The
cells can be grown in culture, and at
the eight cell stage, one of the cells
can be removed for diagnosis.
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.

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.
Embryo selection
is being done for
certain select
conditions, like
cystic fibrosis,
Huntington’s
disease, and sickle
cell anaemia.
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?
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?
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
couldn’t it be used to select for other “enhancing” traits.
Here bioethicists begin to find the procedure more
problematic because it takes on eugenic nature.
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
What are the benefits and
consequences of embryo selection?
Consequences
Goes against nature
 Very expensive
 Not 100% guaranteed
 Not available to all women

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.
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.

Ethical Approaches
4. 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?v=
dKBfxoPnT7g