Quarter 4 - THE MENDELIAN GENETICS GRADE 8.pptx

Quarter 4 - THE MENDELIAN GENETICS GRADE 8.pptx

1. MENDELIAN GENETICS PREPARED BY: MA’AM AIRA MAE

2. What is Genetics? A branch of biology that deals with the transmission and variation of inherited characteristics in particular chromosomes and DNA. A science of the way traits are passed from parent to offspring.

3. Who was Gregor Mendel? He studied the inheritance of traits in pea plants.

4. Who was Gregor Mendel? Mendel stated that the physical traits are inherited as “ particles” Mendel did not know that the “particles” were actually chromosomes and DNA Father of Genetics.

5. Mendel conducted 2 main experiments to determine the laws of inheritance. These experiments were: Monohybrid Cross experiment - the result of a cross between two true-breeding parents that express different traits for only one characteristic Dihybrid Cross experiment - the result of a cross between two true-breeding parents that express different traits for two characteristics.

6. What is Gene? A unit of inheritance. It is always come in pair. What is Allele? Two (2) forms of gene. - Dominant or recessive

7. 2 TYPE OF TRAITS Dominant traits - are traits that appear to mask (or hide) other traits . - OBSERVABLE TRAITS - Always capital letter (R) Recessive traits - are traits that can be hidden in one generation and then appear in the next . - HIDDEN TRAITS - Always small letter (r)

8. PHENOTYPE and GENOTYPE Genotype - An organism’s underlying genetic makeup , consisting of both physically visible and non-expressed alleles (RR, Rr , rr ) - Homozygous and Heterozygous Phenotype - observable traits (physical appearance) expressed by an organism. - e.g. brown eyes, black eyes

9. TYPES OF GENOTYPE HOMOZYGOUS – pair of allele which are identical. - either 2 dominant (RR), or 2 recessive ( rr ). HETEROZYGOUS – pair of alleles which are not identical ( Rr ).

10. What is a Punnett Square? A Punnett square, devised by the British geneticist Reginald Punnett , can be drawn that applies the rules of probability to predict the possible outcomes of monohybrid cross and and their expected frequencies

11. Step-by-Step: How to set up a Punnett Square?

12. Tt

13. Phenotype: 75% Axial Genotype: 25% Homozygous Axial 50% Heterozygous Axial 25% Terminal