INTRODUCTION TO GENETICS.pptx GREGOR MENDEL

Genetics is the study of how genes and how traits are passed down from one generation to the next. Our genes carry information that affects our health, our appearance, and even our personality!Genes, through the proteins they encode, determine how efficiently foods and chemicals are metabolized, how effectively toxins are detoxified, and how vigorously infections are targeted. Genetic diseases can be categorized into three major groups: single-gene, chromosomal, and multifactorial.

Some of the branches of genetics include behavioural genetics, classical genetics, cytogenetics, molecular genetics, developmental genetics, and population genetics. Molecular genetics, in particular, is a study of heredity and variation at the molecular level.

1. MEIOSIS

2. HUMAN CHROMOSOMES HUMAN HAVE 46 TOTAL NUMBER OF CHROMOSOMES 23-EGG CELL (MOTHER) 23-SPERM CELL (FATHER) AUTOSOMES- THE FIRST 22 PAIRS OF CHROMOSOMES SEX CHROMOSOMES- THE 23 rd PAIR OF CHROMOSOME EGG CELL - CONTAINS X CHROMOSOME SPERM CELL – CONTAINS X OR Y CHROMOSOMES XX - FEMALE XY - MALE

3. STRUCTURES OF CHROMOSOME CHROMOSOME - a structure found inside the nucleus which carry the genes. DNA- a chemical where chromosome is composed of. It is known as the blueprint of life. HISTONES- A special protein responsible for coiling of DNA into a chromosome.

4. HISTONES

5. CHROMOSOMES, GENES AND DNA THE ESTIMATED NUMBER OF GENES IN HUMAN IS 19,000-20,000 PROTEIN CODING GENES AND REPEATEDLY REVISED UP TO 100,000 GENOME SEQUENCE

6. FORMATION OF TWINS IDENTICAL TWINS- also known as “monozygotic” , developed from a single fertilized egg and split into two blastocysts or zygote. FRATERNAL TWINS- also known as “ dizygotic ” , developed from two egg cells fertilized by two different sperm cell forming two blastocysts . Formation of Twins - YouTube.mp4

7. CROSSING OVER ON THE SECOND MITOTIC DIVISION CROSSING OVER- THE EXCHANGE OF A PART OF HOMOLOGOUS OR IDENTICAL CHROMOSOMES DURING MEIOTIC DIVISION.

8. A branch of Science that deals with the study of genes and heredity. GENETICS

9. GREGOR MENDEL The Father of Modern Genetics The Austrian monk who made some experiments using a pea plant ( pisum sativum ) and was able to provide answers to the problems of inheritance. The results from these experiments explains both the blending of parental characteristics of offspring as well as the significant variations in them.

10. MENDEL’S PRINCIPLE INDEPENDENT ASSORTMENT - Traits are inherited independent of each other.

11. PRINCIPLE OF DOMINANCE AND RECESSIVENESS States that one factor (gene) in a pair may mask the expression of the other. When pure parents with opposite traits are mated, the first generation shows only one trait (dominant). The other trait (recessive) is hidden.

12. SEGREGATION States that the pair of factors (genes) is segregated or separated during the formation of the gametes (egg and sperm cell) for it contains only one factor of a pair, the other factor having gone to another gamete. When hybrids are crossed, the opposite traits are separated into different offspring in a ratio of 3:1 (dominant : recessive)

13. Key Terms TRAITS - are observable characteristics determined by specific segments of DNA. GENES - a distinct unit of hereditary material found in chromosomes. These are the determiners of traits or factors of inheritance. NUCLEUS(PART of cell) HEREDITY - the genetic transmission or the passing of traits from parents to offspring.

14. NON-MENDELIAN INHERITANCE A term that refers to any pattern of inheritance in which traits do not segregate in accordance with Mendel’s principle, that is, each parent contributes one of two possible alleles for a trait.

15. INCOMPLETE DOMINANCE This occurs when one allele is unable to express its full phenotype in a heterozygous individual.

16. Key Terms ALLELE - an alternative form of a gene. DOMINANT - a trait or character that appears on an individual. RECESSIVE – a trait or character that seemed to disappear on an individual. GENOTYPE – The genetic make up or the combination of genes of an organism. It is the internal genetic constitution of an individual . The actual set of genes by an organism.

17. Key Terms PHENOTYPE – This refers to the external appearance of an individual as influenced by its genetic make up. The expression or manifestation of an organism’s genotype . HOMOZYGOUS – the alleles for a trait are identical or are the same. HETEROZYGOUS – when the two inherited alleles are different for a particular gene.

18. Reginald C. Punnett presented a diagram to interpret the outcomes of experiment in cross breeding.

19. PUNNETT SQUARE A grid system devised by REGINALD PUNNETT commonly used for determining the probable outcomes of the experiments in cross breeding. FEMALE M A L E

20. MONOHYBRID CROSS The cross involving one pair of genes. ( RRrr ) LEGEND: R- Tall, r- Short Mother: Pure tall Father: Pure short R R r r Rr Rr Rr Rr

21. PHENOTYPE ( EXTERNAL) GENOTYPE (INTERNAL) Pure Homozygous Hybrid Heterozygous

22. Example 1 Legend: F- Fair complexion f- brown complexion Mother: Pure fair -FF Father: Hybrid fair - Ff Phenotype: 2 Pure Fair, 2 Hybrid fair Genotype: 2 Homozygous fair, 2 Heterozygous fair F F Genotypic Ratio: 4:4 F f FF FF Ff Ff

23. Example 3 Legend: C- long tail c- short tail Mother cat- Hybrid long tail Father cat- Hybrid long tail Phenotype: Genotype: Genotypic Ratio:

24. Legend: C- Straight hair c- curly hair (shape) F- Black hair f- Brown hair (color) Mother: Pure Straight black hair Father: Pure Curly brown hair Phenotype: Genotype: Genotypic ratio:

25. DIHYBRID CROSS The cross involving two pairs of genes. ( RRrr x YYyy ) LEGEND: Round = R Wrinkled= r Shape Yellow = Y Green = y Color Phenotype: 1 pure RY, 8 hybrid RY, 3 hybrid RG,3 hybrid WY, 1 pure WG Genotype: 1 homozygous RY, 8 heterozygous RY, 3 heterozygous RG, 3 hetrozygous WY, 1 homozygous WG

26. Legend: B- Black hair b- Brown hair (Color) C- Straight hair c- Curly Hair (STRAND)   Female: 2 Pure Black straight hair 2 Hybrid black curly hair Male: 4 Hybrid black curly hair

27. Answer: Phenotype: 8 Hybrid Black straight hair, 8 Hybrid Black curly hair Genotype:8 Heterozygous Black straight hair, 8 heterozygous black curly hair Genotypic Ratio:8:8 BC BC Bc Bc Bc Bc Bc Bc BBCc BBCc BBcc BBcc BBCc BBCc BBcc BBcc BBCc BBCc BBcc BBcc BBCc BBCc BBcc BBcc8

28. PUNNETT SQUARE

29. Legend: S- round eyes s- chinita eyes (shape) H- Black eyes h- brown eyes ( color) Female: 4 Pure chinita brown eyes Male: 4 Pure Round brown eyes

30. Answer: Phenotype : 16 hybrid round brown eyes Genotype : 16 heterozygous brown eyes Genotypic ratio : 16:16 sh sh sh sh Sh Sh Sh Sh Sshh Sshh Sshh Sshh Sshh Sshh Sshh Sshh Sshh Sshh Sshh Sshh Sshh Sshh Sshh Sshh

31. PUNNETT SQUARE