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Mendelian Genetics

Mendelian Genetics. Gregor Mendel : Known as “ THE FATHER OF GENETICS”. - laid the foundations for the SCIENCE OF GENETICS through his study of inheritance patterns of traits in pea plants. Mendel’s Experiments:.

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Mendelian Genetics

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  1. Mendelian Genetics

  2. Gregor Mendel: Known as “THE FATHER OF GENETICS”. - laid the foundations for the SCIENCE OF GENETICS through his study of inheritance patterns of traits in pea plants.

  3. Mendel’s Experiments: He prevented self-pollination and used another method called Cross Pollination(the joining of pollen and egg) from 2 different plants creating what is called a Hybrid (an organism that received 2 different forms of a genetic trait from each parent).

  4. What is GENETICS: The study of heredity or inheritance of traits. What is a TRAIT? A specific characteristic that can be passed from parent to offspring. What is HEREDITY (inheritance)? Passing of traits from parent to offspring or from one generation to the next. Genes are the coded instructions that define our traits

  5. How are genes inherited? • Humans have 2 sets of chromosomes for a total of 46 chromosomes. Each parent contributes only 1 set of chromosomes to their child. • When a sperm cell (23 chromosomes) and an egg cell (23 chromosomes) join during fertilization, it results in a zygote (46 chromosomes).

  6. The Principle of Dominance: States that some traits are dominate and others are recessive. So what does this mean?

  7. A recessive trait is a trait that is sometimes “hidden” & is expressed using a lower case letter (b) A dominanttraitis a trait that is visible & expressed using a capital letter (B).

  8. PRINCIPLE OF SEGREGATION: States that each pair of genes segregate or separate during meiosis carrying only a single copy of each gene.

  9. Gene: section of chromosome that codes for a protein which will indicate a genetic trait (ex. height of plant or pea color). • Most organisms have 2 copies of every gene (on each chromosome). • Alleles: A different form of the same gene (ex. tall or short, yellow or green).

  10. HOMOZYGOUS - organisms that have 2 identical alleles for a particular trait and are called true-breeds (purebred). (Genotype would read as HH or hh) HETEROZYGOUS - organisms have 2 different alleles for the same trait and are called hybrids. (Genotype would read Hh)

  11. PHENOTYPE – Refers to the physical appearance of an organism. (Tall or short, yellow or green, short tail or long tail) GENOTYPE – Refers to the genetic make up of an organism. (Tt, Ss)

  12. PRINCIPLE OF PROBABILITY Method used to predict the possible outcome of genetic crosses (like flipping a coin – you have a 50/50 chance of heads or tails)

  13. What is a Punnett Square? • A tool or grid used to predict and compare the genetic variations that will result in a cross of two organisms traits.

  14. Punnett Squares RED HEADS ( r ) vs BLONDES (R) heterozygous Genotypes Rr - 50% rr - 50% Phenotypes Red - 50% Blonde - 50% homozygous recessive

  15. Dihybrid Cross (2 factors): a 16 square grid that is used to predict and compare the genetic variations that will result when crossing 2 traits of two organisms. RY Ry rY ry RY Ry rY ry RRYY RRYy RrYY RrYy RRYy RRyy Rryy RrYy RrYY RrYy rrYY rrYy RrYy Rryy rrYy rryy

  16. PRINCIPLE OF INDEPENDENT ASSORTMENT: - States that traits are inherited independently and accounts for variation among plants and other organisms.

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