Genetics

1. Genetics Genetics is the scientific study of how physical, biochemical, and behavioural traits are transmitted from parents to their offspring

2. Terminology • Genes- small portions of DNA and protein • Alleles- genes controlling same characteristic example eye colour • Haploid – half the number of chromosomes • Diploid– full set of chromosomes • Somatic/body cells (containing genes in pairs) • Sex cells/gametes (containing unpaired genes) • Homozygous – has similar genes for specific characteristic • Heterozygous- unlike genes for a specific characteristic • Human genome - the entire genetic blueprint of a human beings

3. Father of Genetics Father of Genetics Gregor Mendel developed the principles of heredity while studying seven pairs of inherited characteristics in pea plants. Although the significance of his work was not recognized during his lifetime, it has become the basis for the present-day field of genetics.

4. Stamen -male Carpel female Mendel – Monohybrid crosses Parents YY yy P1 Generation 1 Smooth or dented seeds F1 Yy x Yy Generation 2 Green or yellow seeds F2 YY Yy yy Yy Green or yellow pods Punnet square White or purple flowers

5. Father of Genetics Genetics: Assessment Question: Determines the Genotype and the Phenotype, by means of a Punnet diagramme, the F1 and F2 generations when a homozygote yellow coloured plant (Dominant - Y) is crossed with a white one Resssive - y). male female P1 zygotes: YY x yy Meiosis Gametes: Y Y y y Fertilisation:

6. P2 zygotes: Yy x Yy Meiosis Gametes: Y y Y y Fertilisation: F1: Genotype = Heterozygous 100% Yy Phenotype = 100% Yellow F2 generation: male female

7. F2: Genotype = Homozygous 25% YY Heterozygous 50% Yy Homozygous 25% yy Phenotype = 75% Yellow 25% White

8. 100% 100% 100% C A B 50% 50% 50% 25% 25% 25% Bb bb Bb bb BB Assessment (LO1) The following histograms represent the percentage of various genotypes that occur in the F1 generation in several monohybrid crosses. For each, predict the genotypes of the parents (P1).

9. Inheritance and variation Father Mother Off spring

10. Blond straight hair Dark wavy hair Brown eyes Blue eyes Upturned nose Straight nose Receding chin Projecting chin Unlobed ears Lobed ears Human traits Recessive traits Dominant traits

11. Inherited traits Hitch-hiker’s thumb Mid-digit hair Bent little finger Dimples Widow’s peak Rolled tongue Earlobes: Free and Attached

12. Sex determination Is it a boy or a girl? XX = girl XY = boy Hallo here am I

13. Blood types • The method of classifying human blood on the basis of the inherited properties of red blood cells (erythrocytes) as determined by their possession or lack of the so-called antigens A and B. • Thus, persons may have type A, type B, type O, or type AB blood. The A, B, and O blood groups were first identified by the Austrian immunologist Karl Landsteiner in 1901.

14. Blood – multiple alleles • Four phenotypes A,B,AB and O • Are determined by presence of two out of three possible alleles namely A,B and O

15. Assessment • In the TV series Days of Our Lives, two good friends, namely, Hope and Lexie each gave birth to a son. These babies were deliberately switched in the hospital. • From the following blood types, determine which baby belongs to which parents: • Baby 1 : Type O • Baby 2 : Type A • Hope : Type B • Hope’s Husband : Type AB • Lexie : Type B • Lexie’s Husband : Type B

16. Human Pedigrees Shows the line of ancestors: the line of ancestors of an individual animal or person. Haemophilia Affected male Female carrier • Used to trace diseases like Haemophilia, Muscular dystrophy, Cystic fibrosis