Transcript Genetics Power point

Genetics
Def: the study of reproduction and the results of
the combination of chromosomes.
Gregor Mendel – (1822 – 1884)
Austrian Monk who is considered
“Father of Genetics”
Mendel’s laws
1. Law of Segregation - Chromosomes
separate (segregate) into different
gametes during meiosis.
2. Law of Independent Assortment
All Chromosomes segregate independent of each other. None
are connected to each other
Example of Independent Assortment
Mendel talked about traits and called the genes
for those traits alleles.
Allele - the different
genes for a trait
The traits that you got
when sperm and egg
came together was
NOTHING but probability.
A roll of the dice
or a flip of a coin
Mendel also gave us the genetics terms
Dominant and Recessive
Dominant - A trait that will ALWAYS
show up if it is in the genes
Recessive - A trait that will ONLY show up
if there are no dominant genes present
Example: Your Mom gives you the gene for having a Unibrow (recessive) and
your father gives you the gene for having two eye brows (dominant)
Mom
What are you?
Dad
Let’s look at some traits
DOMINANT
Black color
Recessive
lighter color
This dog’s genetics could be two ways
We show it like this:
“B” from one parent, “B” from the other parent
OR
“B” from one parent, “b” from the other parent
“BB” is Homozygous for the trait.
“Bb” is Heterozygous for the trait.
This dog’s genetics CAN ONLY be
shown one way:
“b” from one parent, “b” from the other parent
Recessive traits are ALWAYS
homozygous; thus it would be “bb”
OK, now for a problem:
If I have a
heterozygous black
male and a golden
female that mate, what is
the chances of having
Bb
golden puppies in the 50% black
litter?
50% golden
X
bb
100%
golden
You can make a Punnett square
b
b
B
Bb
Bb
b
bb
bb
50%
What do we do if we want to predict the
offspring with two traits?
• Dihybrid Cross: tool used to predict the
offspring of parents with TWO traits
• Ex:
Definitions to know:
Genotype:
what the genes say
(heterozygous or homozygous).
Phenotype: physical appearance of the
organism (black or golden).
P Generation: the parents in the problem
F1 Generation: the first “filial” – child, first
generation after the parents.
F2 Generation: the second generation after
the parents.
Everything is not always clear cut:
Incomplete Dominance:
One allele can not
completely
dominate the other.
Codominance:
When both dominant
alleles show in the
offspring.
Red
Roan offspring
White
Multiple Allele Traits:
Traits having more than
one allele that can be
found in the population.
Example:
Human Blood Types
Type A, Type B,
Type AB, Type O
Four distinctly different types
Polygenic Traits:
Traits that are controlled
by several genes at the
same time.
Example:
Human hair color
Black, Brown
Blonde & Red
Four major colors blended through more
than a dozen different allele groups.
Genetic Engineering
Definition: manipulating the genes of an organism due to
selective breeding or microbiological processes
Selective Breeding:
selecting certain individuals
to be the parents of the
future generations.
All of these
things are
products of
selective
breeding
Hybridization:
Crossing two
“wild” species to
try to get a hybrid
with the best
traits of the parent
species.
Hybrid Vigor:
Having an offspring species
that is better in many ways
than either of the parent
species
Chromosomes
You have two for each
“pair”.
One from Mom, and
one from Dad
Mom
Dad
But what happens if there are three for a “pair”?
The situation is called Trisomy:
Having three chromosomes for a
pair of chromosomes.
Some Trisomy situations:
Trisomy 21 (Down syndrome)
Trisomy 18 (Edwards syndrome)
Trisomy 13 (Patau syndrome)
Trisomy 8 (Warkany syndrome 2)
Of these, Trisomy 21 and 18 are the most
common. Both cause delayed growth, mental
issues, and physical limitations.
How can a Doctor know if a person has a
specific Trisomy situation?
Karyotyping:
This involves catching the chromosomes when
they are compacted ready for cell division.
Then they must be paired up with their
“match”
When all the chromosomes in the human
genetic makeup are paired, it looks like
this:
For simplicity,
geneticist only use
one half of each of
the Chromosome to
do the matching.
Each half is a
Chromatid
Genetic Manipulation:
Recombinant DNA:
The process of manipulating a gene
by taking genes from one organism
and moving them to another.
Step 1 – Isolation of target gene.
Lets say that there
is a gene in this
corn that is drought
resistant.
enzymes
Researchers use enzymes to
isolate and cut the gene out
(excise) from the original corn.
Target Gene
Step 2 - Copy the gene
Using a machine called a PCR
(polymerase chain reaction), the geneticist
make thousands of copies of the gene
Step 3 – Insertion of gene
Using enzymes again, the
geneticist inserts the gene into
the genetic code of the target
plant.
Step 4 – Testing of results
Field Biologists set out
plots to test the drought
resistance of the new
plants.
Organisms that have the genes
of other organisms are called:
Transgenic organisms
Examples:
Transgenic Yeast cells
Produces human insulin
Drought-resistant Barley
Can live in little water
and some in salty water
environments
Herbicide resistant and Pest
Resistant Corn
Plants that will not die when weeds
around them are sprayed, and some
species that pests do not want to eat
Cloning
Target
sheep
Donor
sheep
n
u
c
l
e
u
s
Process:
Take a cell from your organism
and an egg from a donor female.
Take the nucleus from the donor
egg.
Fuse the two cells by electro-shock.
Introduce the right hormones to
begin division becoming an embryo.
Implant the embryo into the
donor female.
Embryo
The cloned organism is born.
Review for Genetics Test
Define:
1. Genetics
2. Gregor Mendel
3. Allele
4. Dominant
5. Recessive
6. Homozygous pairs
7. Heterozygous pairs
8. Genotype
9. Phenotype
10. P Generation
11. F2 Generation
12. F1 Generation
13. Incomplete Dominance
14. Co-dominance
15. Multiple Allele Trait 16. Polygenic Trait
17. Monosomy
18 Polysomy
19. Hybrid vigor
20 Genetic engineering
21. Hybridization
22. cloning
23. recombinant DNA
Questions:
1. What are the two “laws” that are attributed to Mendel?
2. How do they affect genetics?