GENETICS

1. GENETICS CHP. 5

2. GREGOR MENDEL1822-1884 • KNOWN AS THE FATHER OF GENETICS • EDUCATED IN MATH AND SCIENCE • WANTED TO BE A TEACHER BUT FAILED THE EXAM

3. MORE ABOUT MENDEL • HE WAS A MONK • IN THE MONASTERY HE WAS IN CHARGE OF THE GARDEN • HERE IS WHERE HE STARTED HIS WORK IN GENETICS

4. MENDEL’S EXPERIMENTS • HE USED PEA PLANTS • HE COULD CONTROL FERTILIZATION • WORK WITH ONE TRAIT AT A TIME • EASY TO GROW

5. MORE ON HIS EXPERIMENTS • HE BELIEVED THAT TRAITS WERE DETERMINED BY INDIVIDUAL UNITS • WE CALL THESE UNITS ALLELES • OFFSPRING GET ONE ALLELE FOR EACH TRAIT FROM EACH PARENT • FROM HIS EXPERIMENTS WITH PEAS HE DISCOVERED THE LAWS OF GENETICS

6. ALLELE DIFFERENT FORMS OF ONE TRAIT DOMINANT ALLELE ALLELE THAT IS EXPRESSED IN OFFSPRING REPRESENTED BY A CAPITAL LETTER RECESSIVE ALLELE ALLELE THAT IS NOT EXPRESSED IN THE OFFSPRING REPRESENTED BY A LOWER CASE LETTER GENETICS TERMS

7. PUREBRED AN OFFSPRING THAT HAS THE SAME TWO ALLELES FOR A TRAIT BOTH ALLELES ARE DOMINANT OR RECESSIVE EXAMPLE AA OR aa HYBRID AN OFFSPRING THAT HAS TWO DIFFERENT ALLELES FOR A TRAIT ONE ALLELE IS DOMINANT ONE IS RECESSIVE EXAMPLE Aa MORE GENETICS TERMS

8. LAWS OF GENETICS • LAW OF DOMINANCE STATES THAT WHEN AN INDIVIDUAL IS HYBRID FOR A TRAIT, ONLY ONE ALLELE WILL EXPRESS ITSELF. THE ALLELE THAT EXPRESSES ITSELF IS CALLED DOMINANT. THE TRAIT THAT DOESNOT EXPRESS ITSELF IS CALLED RECESSIVE.

9. LAWS OF GENETICS CONT. • LAW OF SEGREGATION

10. PUNNETT SQUARES • IT IS USED TO SHOW ALL THE WAYS THAT ALLELES CAN COMBINE

11. HOW TO MAKE AND USE PUNNETT SQUARES • SELECT A TRAIT TO BE STUDIED • LIST THE ALLELES FOR THE FEMALE ON THE TOP OF THE SQUARE • LIST THE ALLELES FOR THE MALE ALONG THE SIDE OF THE SQUARE • FILL IN EACH SQUARE WITH ONE MALE ALLELE AND ONE FEMALE ALLELE

12. GENOTYPE IT IS THE ALLELE COMBINATION THAT IS INHERITED IT IS THE LETTERS EX. AA, aa, Aa PHENOTYPE PHYSICAL APPEARANCE OF OFFSPRING DETERMINED BY DOMINANT ALLELE HOMOZYGOUS THIS MEANS THE SAME AS PUREBRED EX. AA, aa HETEROZYGOUS THIS MEANS THE SAME AS HYBRID EX. Aa TERMS FOR PUNNETT SQUARES

13. EXAMPLE PUNNETT SQUARE • This bird has two genes for orange feathers. •   Its genotype is AA • A is a dominant characteristic

14. EXAMPLE PUNNETT SQUARE • This bird has two genes for blue feathers. •   Its genotype is aa • a is a recessive characteristic

15. EXAMPLE PUNNETT SQUARE • This Punnett Square shows how we can diagram the genes. • The orange bird has two dominant A genes. • We put two A s along the top of the square. • The blue bird has two recessive a genes. • We put two a s down along the left side of the square.

16. SEX-LINKED TRAITS • FEMALES HAVE XX AND MALES HAVE XY • Sex-linked traits, therefore, are traits determined by genes found on the X chromosome. If such a gene has a recessive allele it is much more likely to be expressed in males than females because they only have one copy of this gene • EXAMPLES HEMOPHILIA, COLOR-BLINDNESS

17. MUTATIONS • THESE ARE ANY PERMANENT CHANGES IN AN ALLELE • THEY CAN BE CAUSED • NATURALLY BY ALLELES NOT MATCHING UP CORRECTLY • X-RAYS, RADIOACTIVITY, CHEMICALS, DRUGS • THEY CAN BE HARMFUL OR HELPFUL • THEY CAUSE VARIATIONS WITHIN A POPULATION