Tuesday, January 4, 2011 Objective: SWBAT understand Mendelian genetics. Bellringer: (on a new BR sheet) –On Monday’s write: NO BR –Tuesday’s: 1. What are some traits that you share within your family? 2. What are some traits that are different between you and your friends?

Think for a second about the most crazy thing you have ever seen…

when something like THIS could be possible… Imagine in the future…

The future is now…

How did the scientists do it?

INTRO TO GENETICS

GENETICS the study of how traits are passed from one generation to the next

TRAIT a characteristic Examples: Plant size, seed color, pod shape

GENES Each feature of the pea plants is controlled by a gene. It may have a gene that controls its color, another for size and another for shape.

GENE the factors that control traits (found in the DNA)

Above you see chromosomes. The circled area is a gene on chromosome #22. The absence of this gene causes velo-cardio- facial syndrome (VCFS) which may cause ADD and mental illness

ALLELES Each gene comes in different forms called alleles, so the gene that controls flower color may come in two alleles: purple and white.

ALLELES different forms of a gene

GREGOR MENDEL The “father” of genetics Lived from Austrian Monk Published his work in 1866, but no one took him seriously until Studied Pea Plants!

MENDEL’S EXPERIMENTS

Mendel experimented with 7 different characteristics

Mendel Got Lucky for 2 Big Reasons 1.First, he had a lot of time…he was a monk. This let him do LOTS of experiments with the peas! 2.Each trait had 2 options. This was key because he could tell if it was one way or the other.

HOMOZYGOUS organism with two identical alleles for the same trait (TT or tt)

HETEROZYGOUS organism with two different alleles for the same trait (Tt)

DOMINANT allele that is expressed when in the presence of a recessive allele (TT or Tt = tall)

RECESSIVE allele that is expressed only when homozygous (tt = short)

PHENOTYPE physical characteristics (Tall, Brown)

GENOTYPE the genetic makeup (TT, TtHh)

GENE = Height ALLELE = Tall, Short Gene is represented by the letter “t” Dominant = T Recessive = t Remember you need 2 copies of every gene!!!

Mendel’s Principles of Inheritance Rule of Unit Factors - Inherited traits are transmitted by genes which occur in alternate forms called alleles; organisms carry 2 alleles for each gene. Principle of Dominance - When 2 forms of the same gene are present the dominant allele is expressed. Law of Segregation - In meiosis two alleles separate so that each gamete receives only one form of the gene. Law of Independent Assortment - Each trait is inherited independent of other traits (by chance).

each trait is inherited independent of other traits (by chance) Independent Assortment

in meiosis two alleles separate so that each gamete (sex cell) receives only one form of the gene from each parent Segregation

Homework Choose 10 vocabulary words from the list of 17 for Section 10.1 (on page 253) For each of the 10 words, give: –The book definition, and… –A definition in your own words (what you think it means)