Mendelian Genetics CH 5 SEC 1 AND 2

Mendelian Genetics CH. 5 SEC. 1 AND 2

Inheritance �For a long time, general ideas of inheritance were known… Cows give birth to cows… not horses. Brown dogs usually give birth to brown dogs. � What was really lacking was an understanding of how particular traits were passed down to their offspring.

Gregor Mendel �The basic laws of heredity were first formed during the mid-1800’s by an Austrian botanist monk named Gregor Mendel. Because his work laid the foundation to the study of heredity, Mendel is referred to as “The Father of Genetics. ”

Heredity and Gregor Mendel �Heredity: The passing of traits from parents to offspring. �Mendel discovered the principles of heredity. �Mendel studies pea plants. They were selfpollinating (have both male and female structures, so it can pollinate itself). �Pea plants can also cross-pollinate (pollinate a different flower).

Mendel’ Pea Plants Mendel based his laws on his studies of garden pea plants. Mendel was able to observe differences in multiple traits over many generations because pea plants reproduce rapidly, and have many visible traits such as: Pod color Seed Color Plant Height Green Tall Short Yellow Seed Shape Pod Shape Wrinkled Smooth Pinched Round

Studying Pea Plants �Mendel studied one characteristic at a time. �A characteristic is a feature that has different forms in a population. �The different forms of these characteristics are called traits.

Mendel’s Experiments �Mendel saw some interesting traits appear when plants were crossed. �The first generation offspring are called the F 1 generation. �The second generation offspring are called the F 2 generation. �Dominant traits are observed in the organism’s characteristics if present. �Recessive traits are traits that are hidden if the dominate trait is present. �Recessive traits can only be seen in the organisms if both alleles are recessive.

Mendel’s Observations

Traits and Inheritance �Gene: One set of instructions for an inherited trait. �Each parent gives their offspring one set of genes. �The different forms of a gene are called alleles. • Homozygous: When alleles from both parents are the same. HH or hh Called a purebred • Heterozygous: When alleles from parents are different. Hh • Called a hybrid

Genotype Vs. Phenotype �Phenotype: An organism’s appearance (what you see: hair color, height, eye color etc. ) �Genotype: The genetic make-up of an organism– the alleles that are present for a trait. (Hh or AA)

Karyotype �Photograph of an organism’s chromosomes.

Heredity Concept Map Heredity Use the following terms to complete the concept map below: Alleles parents Heredity Phenotype Genes Offspring genotype Characteristics dominant

Heredity Concept Map Heredity Use the following terms to complete the concept map below: Alleles parents Heredity Phenotype Genes Offspring genotype Characteristics dominant

Question #1 Different forms of a gene are called: #traits #alleles #chromosomes

Question #2 One set of instructions for an inherited trait is called: #gene #allele #trait

Question #4 The genetic make-up of an organism: #phenotype #appearance #genotype

Question #4 Traits that are hidden if the dominate trait is present: #dominant #recessive #gene