1. LS 13: Genetics

2. Genetics The study of heredity
the branch of biology that deals with heredity and genetic variations

3. Mendel Crossed pea plants
Discovered that certain traits show up in offspring without any blending of parent characteristics
He discovered the genetics of inheritance
The first scientist to recognize that the principles of probability can be used to predict the results of genetic crosses

4. Franklin
Used x-rays to discover the structure of DNA

5. Watson and Crick
Used models and Franklin’s work to discovered the structure of DNA

6. The role of DNA
DNA contains coded instructions that store and pass on genetic information from one generation to the next
DNA replication is necessary for life

7. DNA: What does it look like?
Double helix molecule

8. DNA: What makes it up? Sugars Nitrogenous bases Phosphates
The arrangement of the nitrogenous bases within the double helix forms a chemical code.

9. Chromosomes
Strands of tightly wound DNA

10. Genes
Sections of a chromosome that carry the code for a particular trait

11. Traits
A characteristic that an organism can pass on to its offspring through its genes

12. Alleles The different forms of a gene
Individual alleles control the inheritance of traits
Some alleles are dominant, while other alleles are recessive.

13. Types of alleles Dominant Recessive
an allele whose trait always shows up in the organism when the allele is present
Recessive
an allele that is masked when a dominant allele is present

14. Homozygous an organism that has two identical alleles for a trait
Purebred – an organism that always produces offspring with the same form of a trait as the parent.

15. Heterozygous
Heterozygous – an organism that has two different alleles for a trait.
Hybrids – an organism that has two different alleles for a trait; an organism that is heterozygous for a particular trait.

16. How genes are expressed
Genotypes
Phenotypes

17. Genotypes
an organism’s genetic makeup, or allele combinations

18. Phenotypes The outward expression of a trait. Example Blue eyes
Big nose

19. An example… 1) A genotype of BB is considered homozygous dominant.
2) A genotype Bb is considered heterozygous.
3) A genotype bb is considered homozygous recessive.

20. My mom has brown eyes and so does my dad. So HOW did I get blue eyes?????

21. Codominance
the alleles are neither dominant nor recessive

22. Factor affecting the expression of traits
Heredity
the passing of traits from parents to offspring

23. My dad was a college rugby player and my mom was a college soccer player. So why do I have two left feet?

24. Inherited or not? Inherited Not inherited
Mendelian genetics explain the transmission of most traits can be inherited from generation to generation.
Inherited
Not inherited
Traits that are expressed through genes can be inherited.
Characteristics that are acquired through environmental influences, such as injuries or practiced skills, cannot be inherited

25. Punnett Square
Predicts the possible combinations of inherited factors resulting from single trait crosses
Geneticists use Punnett squares to show all the possible outcomes of a genetic cross and to determine the probability of a particular outcome.

26. Example

27. Genetic engineering
The genetic code is manipulated to obtain a desired product.
The aim is to introduce new characteristics to an organism in order to increase its usefulness, such as…
increasing the yield of a crop species, introducing a novel characteristic, or producing a new protein or enzyme.

28. Genetic engineering applications
Genetic engineering has numerous practical applications in….
Medicine
Agriculture
Biology
Examples are…
the production of human insulin through the use of modified bacteria
the production of new types of experimental mice such as the OncoMouse (cancer mouse) for research, through genetic redesign
Seedless watermelon and other genetically modified fruits and vegetables

29. Dolly the sheep Dolly (5 July 1996 – 14 February 2003)
The first mammal to be cloned from adult cells of another sheep