GeneticsGeneticsDef: 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 LawsMendel’s Laws1. Law of Segregation -
Chromosomes separate (segregate) into different gametes during meiosis.2. Law of Independent
AssortmentAll 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 -Allele - the
different genes for a traitThe traits that you got
when sperm and egg came together was
NOTHINGNOTHING 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 genesRecessive - A trait that will ONLY
show up if there are no dominant genes presentExample: Example: Your Mom gives you the gene for having a Your Mom gives you the gene for having a
Unibrow (recessive) and Unibrow (recessive) and your father gives you the gene your father gives you the gene for having two eye brows (dominant)for having two eye brows (dominant)What are
you?
Mom Dad
Let’s look at some traits
DOMINANT Black color
Recessive lighter color
This dog’s genetics could be two waysWe show it like this:“B” from one parent, “B” from the
other parent
“BB” is Homozygous for the trait.
“B” from one parent, “b” from the other parent
OROR
“Bb” is Heterozygous for the trait.
This dog’s genetics CAN ONLY be shown one way:
“b” from one parent, “b” from the other parentRecessive traits are ALWAYSALWAYS homozygous; thus it would be “bb”
OK, now for a problem:
If I have a heterozygous black male and a golden female that mate,
X what is the chances of having golden puppies in the litter?
B b b b50% black
50% golden100% golden
You can make a Punnett square
b b
B
b
Bb Bb
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:
GenotypeGenotype: what the genes say (heterozygous or
homozygous).PhenotypePhenotype: physical appearance of the organism (black or golden).P GenerationP Generation: the parents in the problemFF11 Generation Generation: the first “filial” – child, first generation after the parents.FF22 Generation 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 White
RoanRoan offspring
Multiple Allele Multiple Allele TraitsTraits::Traits having more than one allele that can be found in the population.
Example:
Human hair color
Black, Brown BlondeBlonde & & RedRed
Human Blood Types
Type A, Type B, Type AB, Type
O
Polygenic TraitsPolygenic Traits::
Traits that are controlled by several genes at the same time.
Four distinctly different types
Four major colors blended through more than a dozen different allele groups.
Example:
Genetic Engineering
Definition: manipulating the genes of an organism due to selective breeding or microbiological processesSelective Breeding:Selective Breeding:
selecting certain selecting certain individuals to be the individuals to be the parents of the future parents of the future generations.generations.
All of these
things are products
of selective breeding
Hybridization:Crossing two Crossing two “wild” species to “wild” species to try to get a try to get a hybrid with the hybrid with the best traits of the best traits of the parent species. parent species.
Hybrid VigorHybrid Vigor:Having an offspring Having an offspring species that is species that is better in many better in many ways than either of ways than either of the parent speciesthe parent species
ChromosomesYou have two for each “pair”.
Mom
One from Mom, and one from Dad
But what happens if there are three for a “pair”?The situation is called
Trisomy: Having three chromosomes for a pair of chromosomes.
Dad
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:
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.
Researchers use enzymes to isolate and cut the gene out (excise) from the original corn.
enzymes
Target Gene
Recombinant DNA:
Step 2 - Copy the geneUsing a machine called a PCR (polymerase chain reaction), the geneticist make thousands of copies of the gene
Step 3 – Insertion of geneUsing enzymes again, the geneticist inserts the gene into the genetic code of the target plant.
Step 4 – Testing of resultsField Biologists set out
plots to test the drought resistance of the new plants.
Organisms that have the genes of other organisms are called: TransgenicTransgenic organismsExamples:
Transgenic Yeast Transgenic Yeast cellscellsProduces human insulin
Drought-resistant Drought-resistant BarleyBarleyCan live in little water
and some in salty water environments
Herbicide resistant and Herbicide resistant and Pest Resistant CornPest Resistant Corn
Plants that will not die when weeds around them are sprayed, and some species that pests do not want to eat
CloningCloningProcess:
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.
The cloned organism is born.
Target sheep
Donor sheep
nucleus
Embryo
Review for Genetics TestReview for Genetics TestDefine:Define:1.1. GeneticsGenetics 2. Gregor Mendel2. Gregor Mendel 3. Allele3. Allele
4. Dominant4. Dominant 5. Recessive5. Recessive 6. Homozygous 6. Homozygous pairspairs
7. Heterozygous pairs7. Heterozygous pairs 8. Genotype8. Genotype 9. 9. PhenotypePhenotype
10. P Generation10. P Generation 11. F11. F22 Generation Generation 12. 12. FF1 1 GenerationGeneration
13. Incomplete Dominance13. Incomplete Dominance 14. Co-dominance14. Co-dominance
15. Multiple Allele Trait15. Multiple Allele Trait 16. Polygenic Trait16. Polygenic Trait 17. 17. MonosomyMonosomy
18 Polysomy18 Polysomy 19. Hybrid vigor19. Hybrid vigor 20 Genetic 20 Genetic engineeringengineering
21. Hybridization21. Hybridization 22. cloning22. cloning 23. recombinant DNA23. recombinant DNA
Questions:Questions:
1.1. What are the two “laws” that are attributed What are the two “laws” that are attributed to Mendel?to Mendel?
2.2. How do they affect genetics?How do they affect genetics?
Top Related