Parents wrecked genes P1

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Genetics Genetics  is the study of t raits , h eredity , &   variation .

Heredity is::

Heredity is: The transfer of genetic characteristics such as eye color from one generation to the next


Objective : To learn how genes play a role in inherited characteristics Bell work: What is does it mean to inherit? What Do YOU Think?


Genetics… what’s the purpose? To provide you (and other living things) with the traits that make you, well… YOU ! Take a few minutes to read the passage “ My Parents Wrecked My Favorite Genes.” When complete, find the correct term for the definitions on your sheet. You Are Not a Hamster!


Why don’t you look like your pet hamster ?! You get your genes from your mom and dad - that’s why you look like a combination of them and not your pet hamster. That is, unless your parents were hamsters! Father of Genetics Objective : To describe the contributions of Gregor Mendel in the area of genetics


It’s all in your genes… A single gene… one from mom, one from dad… Let’s take this concept and apply it to Gregor Mendel and his famous pea experiments… Depending on how those codes match up, you may have brown , blue , green , or some other variation of eye color. Genes have the DNA code that give you traits . For example, brown eyes are among the many options for eye color.


In 1854, a monk named Gregor Mendel researched how traits were inherited by plants. At the time, it was believed that offspring would inherit a blending of the traits of each parent. Mendel studied inheritance by working with pea plants because they were easy to breed. So who was this Mendel guy anyway?


Give Peas a Chance… Mendel found in his experiments that the different traits could be: Dominant OR Recessive Tall Plant vs. Short Plant Purple Flower vs. White Flower Green pea vs. Yellow pea And there are MANY more traits that pea plants exhibit.

This led to Mendel’s Principle of Dominance::

This led to Mendel’s Principle of Dominance : Only dominant genes are expressed. The re cessive gene , is pushed back.


Help Mendel! Watch this short and sweet video about our favorite monk.


An organisms PHENOTYPE is its physical appearance or visible traits.


An organisms GENOTYPE is its genetic makeup .


Today’s scientists call the factors that control traits… genes .


Scientists call the different forms of a gene ‘ alleles .’


A dominant allele is one whose trait always shows up in the organism when the allele is present . A recessive allele is covered up when the dominant allele is with it. A hybrid has two different alleles


Let’s Put It All Together… Mendel found in his experiments that the different traits could be: Dominant OR Recessive Meaning that the dominant trait was the one that showed up in the population more often, while the recessive trait hid in, or “receded” into, the background. We call those dominant and recessive genes “ alleles .” Depending on how those alleles pair up, you may see the dominant or the recessive trait. Dominant alleles are represented with a capital letter : B Recessive alleles are represented with a lowercase letter : b Two of the same alleles are considered homozygous or purebred : B B, bb Two different alleles are considered heterozygous or hybrid : Bb Putting them together can make several combinations: BB: homozygous dominant – two dominants = DOMINANT Bb: heterozygous dominant – dominant covers up recessive = DOMINANT bb: homozygous recessive – two recessive = RECESSIVE


Let’s Put It All Together… Dominant OR Recessive The letter combination of alleles is called the genotype : For example in the tall versus short plant above, if T = dominant, and t = recessive, what would the genotypes be? T he physical expression is called the phenotype : For example, the phenotype is what we physically “see.” So, in the pea plant example above, what would we “see” for the dominant trait? The recessive trait? TT, Tt tt Tall short

Let’s practice!:

Let’s practice! GG Gg gg Rr RR Aa aa Ss LL rr Identify whether each is homozygous (purebred) or heterozygous (hybrid): GG - Ho Gg - He gg - Ho Rr - He RR - Ho Aa - He aa - Ho Ss - He LL - Ho r r - Ho Did you get them right?

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