Heredity S7L3. Students will recognize how biological traits are passed on to successive generations. S7L3.a Explain the role of genes and chromosomes in the process of inheriting a specific trait. S7L3.b Compare and contrast that organisms reproduce asexually and sexually (bacteria, protists, fungi, plants & animals). S7L3.c Recognize that selective breeding can produce plants or animals with desired traits.

Important Vocabulary Genetics- the study of heredity Heredity- Passing of traits from parent to offspring. Trait- physical characteristic Ex: brown hair, red hair

Offspring Organism that is the result of reproduction

How do you inherit traits? Meiosis Occurs in gametes (sex cells): sperm in males & egg in females results in 4 cells with ½ as many chromosomes New cells are genetically different

Who was Gregor Mendel?

How Mendel's pea plants helped us understand genetics

Who was Gregor Mendel? Discovered the principles of heredity Father of Genetics Austrian monk born in 1822 known for research and teaching after his death (1884) acknowledgment of his discoveries in 1900 Discovered the principles of heredity Performed experiments with pea plants Realized that offspring inherit traits from their parents

What decides what traits get passed down?

Dominant trait Trait that masks or covers the other form of the trait Represented with a capitol letter Examples Round seed –R Tall plant--T purple flower—F

Recessive trait Trait that is masked or covered by a dominant trait Represented with a lower case letter Examples Wrinkled seed—r Short plant—t White flower--f

genes Your traits are determined by your genes. Instructions for an inherited trait

Each parent gives one set of genes to the offspring Offspring has 2 forms of the same gene for every characteristic

allele Tt Different forms of a gene are called alleles. Can be dominant alleles or recessive alleles Example Tt Dominant allele recessive allele

Practice

Monster # 1 has Rr or 1 dominant and 1 recessive allele How many eyes will this monster have???

Monster # 2 has RR or 2 dominant alleles How many eyes will this monster have???

Monster #3 has rr or 2 recessive alleles How many eyes will this monster have?

Baby Boom Genetics Activity http://www2.edc.org/weblabs/BabyBoom/BabyBoomLabMenu.html Choose 2 aliens that will mate to create an offspring Flip the coin to choose the alleles that will combine to create traits Use the “screen clipping” option in Microsoft word to create a 1 page document of the parents and their offspring After your teacher has checked your document you may print.

Exceptions to the rules Incomplete dominance- there is a blending of traits expressed; neither trait is fully expressed

Codominance- both alleles are shown

Genotype Combination of genes for a specific trait Example: TT, Tt, tt ** expressed in letters

Phenotype Physical appearance of the trait Examples: purple flowers, white flowers, yellow seeds, white seeds

Answer the following questions on the back of your Alien Offspring Print out What is the difference between genotype and phenotype? Give an example of when dominant allele masked a recessive allele in your offspring. What recessive traits did your offspring inherit from their parents?

Punnett Squares Tool used to organize all possible combinations of offspring from particular parents

Homozygous genotype Two same alleles for a trait aka—Purebred Examples: TT, tt

Heterozygous genotype 2 different alleles for the same trait aka hybrid Example: Tt