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Heredity, Genetics and DNA. The Unique You. Describe in 5 words the characteristics that best describe your physical appearance. Eye color, height, hair color. What is heredity? Heredity is the passing of traits from parent to offspring. You inherit traits from your parents. What are traits?.
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The Unique You Describe in 5 words the characteristics that best describe your physical appearance. Eye color, height, hair color
What is heredity?Heredity is the passing of traits from parentto offspring. You inherit traits from your parents.
What are traits? Eye Color Hair Color Height Weight Body Structure Facial Features Skin Color
How traits are passed? When organisms reproduce, traits are passed from parent to offspring. These traits are carried in DNA, the genetic material found in a cell’s nucleus. DNA acts like a blueprint.
How are traits passed? Cells contain chromosomes Chromosomes are made of DNA DNA is shaped like a twisted ladder Specific sections of DNA are called genes Genes contain the code for building proteins Proteins build the structures and control the function of the organism
Dominant and Recessive • Each parent has two genes (or letters) for a trait. These letters are called alleles.
Dominant and Recessive • Capital letters are called Dominant alleles. • When these alleles are present, they take over or show. They are the “stronger” alleles
Dominant • B – brown eyes • T – tall • C – curly hair • W – widows peak • F – freckles • D – dark skin
Dominant and Recessive • Lower case letter are recessive alleles and are the “weaker” of the alleles.
Recessive • b – blue eyes • t – short • s – straight hair • w – no widows peak • f – no freckles • d – light skin
Genotype and Phenotype Genotype – the inherited alleles (letters) Phenotype– what the alleles look like when inherited
GenotypePhenotypeff No Freckles Ff Freckles cc Straight Hair Cc Curly Hair tt Short TT Tall bb Blue Eyes Bb Brown Eyes
Homozygous and Heterozygous IF the genes are the same, they are homozygous – “homo” means same IF the genes are different, they are heterozygous – “hetero” means different. Also called hybrid
Homozygous Or Heterozygous • RR • Rr • rr • Tt • tt • BB • Bb
A unique you • Trace your hand • Place your finger print in each of the fingers • Use the hand lens to observe your fingerprints • Are you a loop, arch or whorl? Page 339 • Compare your fingerprints to those around you.
II. Mendel- the story • Personal history 1. Austrian monk 2. Teacher of high school natural science- love of evolution, nature, meteorology 3. “for the fun of it”: crossed peas and mice- saw inheritance patterns
The research 1. pea plants- why? - structure (male and female parts on same plant) - distinctive traits - rapid reproduction - ability to control pollination and fertilization
1. Mendel studied the inheritance of one trait (for example plant's height, color of flowers or color and shape of seeds).
2. Mendel first cross pollinated tall pea plants (identified as TT, height of plants in this variety were about six feet tall) with each other.
Mendel noticed, that only tall plants were produced. He came to a conclusion, that the tall variety of a pea plant, must contain some factor for tallness.
3. Mendel then cross pollinated short pea plants (identified as tt, height of plants in this variety were about one foot tall) with each other.
In every generation of this plant only short plants were produced. Once again he concluded that pea plant must contain some factor for height (in that variety - for shortness).
4. The next step of Mendel's experiment was to crossed tall pea plants (TT) with short pea plants (tt). The resulting plants were labeled Tt and only tall plants were produced.
Here we crossed two peas which contained both tall and short information.
P F1 F2
5. Mendel named every generation: Starting generation – P (parent) generation. The following offspring generation was called F1 - first generation (daughter generation), F2 - second filial generation, and so on.