Genetics and Inheritance

Transcription

1 + Genetics and Inheritance

2 + Intro to Genetics Every living thing plant or animal, microbe or human being has a set of characteristics inherited from its parent or parents. Your DNA holds the genetic code for every TRAIT (physical characteristic) you have.

3 + Remember! DNA RNA Protein

4 + Heredity and Genetics Passing characteristics (traits) from parent to offspring is called heredity. The scientific study of heredity, known as genetics, is the key to understanding what makes each organism unique. Key Question: How can we know, just by looking at our DNA, what we physically look like?

5 + Brainstorm: Why is one flower white and one flower purple? It s because of each flower s unique DNA genetic code!

6 Looking closely at the genetic message Chromosomes carry GENES (most have at least 1,000 genes) CHROMOSOME GENE Gene: a section of a chromosome that codes for a specific trait (ex. hair color) Example: FLOWER COLOR, hair color, etc.

7 Each gene can have different forms/options! Example: purple OR white flowers Allele: different forms of a gene The alleles determine an organism s TRAIT TRAIT: physical appearance (what it looks like!)

8 PUTTING IT ALL TOGETHER Match each statement with its key term (gene, allele, trait) 1)Flower color looks purple TRAIT 2) DNA segment coding for flower color GENE 3) DNA segment coding for purple flower color ALLELE

9 + STOP AND JOT! In your own words, describe the relationship between the terms below. An example may help your description! 1. Chromosome 2. Gene 3. Trait 4. Allele

10 + The Experiments of Mendel Genetics was founded by an Austrian monk named Gregor Mendel. Mendel correctly figured out that parents pass traits on to their offspring. Mendel studied peas

11 + Genetic Crosses When doing genetic crosses, we call the original pair of organisms the P, or parental, generation.

12 + Genetic Crosses Their offspring (kids) are called the F 1, or first filial, generation.

13 + Mendel s Crosses Mendel did experimental crosses for seven different traits Each parent had a different version of each trait One of the traits disappeared in the F 1 generation

14 + Dominant and Recessive Traits Principle of Dominance: Some traits are dominant to other traits When both dominant and recessive alleles are present, we only see the dominant trait. We write dominant alleles with an UPPERCASE letter We write recessive alleles with an lowercase letter

15 + Example Plant Height Tall = Dominant Short = Recessive

16 + Learning Check Seed Color Yellow = Green = Dominant Recessive

17 + F2 Generation Did the recessive alleles go away? NO! They come back in the F 2 Generation Dominant? Tall Recessive? Short

18 + Dominant and Recessive Alleles Every sexually reproducing organism inherits two alleles for every trait One allele from MOM and one from DAD Examples: From Mom From Dad B = curly hair b = straight hair B = freckles b = NO freckles

19 + Check for Understanding 1. How many alleles do you have for a single trait? 2 2. If your mother gave you a dominant allele (E) and your father gave you a recessive allele (e), what gene combination would YOU have? Ee

20 3. If your mother gave you a dominant allele (E) and your father also gave you a dominant allele (E), what gene combination would YOU have? EE 4. Based on these questions, what are the ONLY three possible allele combinations that you could have? EE ee Ee Dominant came from BOTH parents Recessive came from BOTH parents Dominant from one parent and recessive from the other parent

21 + Check for Understanding In Chinchillas, Grey is a recessive fur color. What would the alleles of the grey chinchilla be? ff

22 + Check for Understanding In Chinchillas, Grey is a recessive fur color. If two grey chinchillas had babies, what color would they be? Grey

23 + Check for Understanding In Chinchillas, Beige is a dominant fur color. What would the alleles of the grey chinchilla be? FF or Ff

24 + Check for Understanding In Chinchillas, Beige is a dominant fur color. If two Beige chinchillas had babies, what color would they be? Depends

25 + Check for Understanding What vocabulary word match the following definitions? Gene, Allele or Trait 1. Your physical appearance 2. A specific form of a gene TRAIT ALLELE 3. A part of DNA that codes for a trait GENE 4. The DNA section that codes for a dog s fur color GENE 5. The DNA section that codes for brown fur ALLELE 6. The dog s fur appears brown TRAIT 7. Dominant or Recessive? 1. Aa 2. TT 3. ee 4. Ff 5. bb 6. RR DOM DOM REC DOM REC DOM

26 + Genotype and Phenotype Every organism has a genetic makeup as well as a set of observable characteristics Phenotype physical expression of traits (result of environment and genotype) What you SEE Genotype genetic makeup (inherited) The DNA

27 + Determining Phenotypes How do you determine traits based on the allele combination? Dominant alleles will always appear as the physical trait. Recessive alleles will only appear if they come from BOTH parents. EE= Dominant trait shown Ee= Dominant trait shown ee= Recessive trait shown

28 + Genotype or Phenotype? Hh G Brown Hair P Blue eyes P Small ears P AA G Kk G

29 + Homozygous and Heterozygous Homozygous: two of the same alleles Homozygous Dominant: AA Homozygous Recessive: aa Heterozygous: two different alleles Aa What phenotype? Dominant

30 1) Homozygous: Definition: Having two copies of the SAME allele EXAMPLES: HOMO MEANS SAME!! AA BB aa bb What type of trait can this code for? Dominant (AA) or Recessive (aa)

31 2) Heterozygous Definition: Having two DIFFERENT alleles HETERO MEANS DIFFERENT!! EXAMPLES: Aa Gg Tt Bb What type of trait can this code for? ONLY DOMINANT

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33 + Heterozygous (He) or Homozygous (Ho) Ho Ho He He AA EE Ii Mm He Ho He Ho Bb ff Jj nn

34 + Check for Understanding 1. If two dominant alleles are inherited (DD), the Dominant trait will be expressed. 2. If one dominant and one recessive allele is inherited (Dd), the Dominant trait will be expressed. 3. If two recessive alleles are inherited (dd), the Recessive trait will be expressed.

35 + Check for Understanding Circle ALL of the allele combinations below that will show the dominant trait. Dd dd DD Bb bb RR Rr

36 + Check for Understanding Label using the correct terms: Homozygous v. Heterozygous EE= Homozygous Dominant Ee= Heterozygous ee= Homozygous Recessive Now add Dominant or Recessive

37 Practice on YOUR OWN! Genotype Heterozygous or Homozygous? Dominant or Recessive? AA Bb Cc dd LL Pp hh HOMOZYGOUS HETEROZYGOUS HETEROZYGOUS HOMOZYGOUS HOMOZYGOUS HETEROZYGOUS HOMOZYGOUS DOM DOM DOM REC DOM DOM REC

38 + Check for Understanding 1. Which of these is an example of a homozygous genotype? A. Rr B. RR C. wrinkled D. round 2. Which of these is an example of a heterozygous genotype? A. Rr B. RR C. wrinkled D. round

39 + Determining PHENOTYPE from GENOTYPE Unattached earlobes are dominant to attached earlobes EE Unattached earlobes Ee Unattached earlobes ee Attached earlobes Brown eyes are recessive to blue eyes. BB Blue eyes Bb Blue eyes bb Brown eyes

40 + Check for Understanding In Chinchillas, Grey is a recessive fur color. Genotype? ff Phenotype? Grey or Homozygous Recessive

41 + Check for Understanding In Chinchillas, Ebony is a dominant fur color. Genotype? FF or Ff Phenotype? Homozygous Dominant or Heterozygous

42 + Challenge! In Chinchillas, White is a dominant fur color Homozygous White (FF) is LETHAL, so there are no Homozygous White Chinchillas. Genotype? Ff Phenotype? Heterozygous

43 + Check for Understanding In humans the trait of having freckles (F) is dominant to not having freckles (f). Which genotype and phenotype are correctly paired? FF no freckles Ff no freckles Ff freckles ff freckles

44 + Check for Understanding In humans, the allele for being a tongue curler is dominant (T) and the allele for not being a tongue curler (t) is recessive. A woman who is homozygous dominant for this trait marries a man who is homozygous recessive. What is the genotype of the mom? TT What is the genotype of the dad? What is the phenotype of the mom? What is the phenotype of the dad? tt Tongue curler Not a tongue curler

45 + Putting it all together: Fill in the blanks with the key terms you ve learned! A trait is a physical appearance. A gene is a sequence of DNA that codes for a specific trait. An allele is a specific form of a gene. A person inherits two genes for each trait. One gene comes from the mother and one gene comes from the. father The genetic makeup of an individual, usually represented by two letters, is called the individual s. genotype How a person looks as a result of this genotype is called a. phenotype When the two alleles are the same (BB or bb), a person is homozygous for that trait. When the two alleles are different (Bb), a person is heterozygous for that trait. These genes can be dominant or, recessive depending on the combination of alleles.