Bell Ringer: Copy All of Agenda (Leave it out so I can see!) Genetics Review Bell Ringer: Copy All of Agenda (Leave it out so I can see!)

Meiosis Remember that meiosis creates 4 different sex cells (sperm or egg) These sex cells are HAPLOID so they have half the number of chromosomes Thanks to INDEPENDENT ASSORTMENT we are never sure which allele is going to end up in the sex cell

Fertilization When two sex cells come together they form a DIPLOID zygote This zygote is a combination of the mother and father’s alleles. Thus, everyone has TWO alleles for any gene

Mendel Gregor Mendel was the “father of genetics” He studied pea plants and determined that the way they looked was due to unseen “factors” We now know that these factors he was referring to were genes

Genes & alleles Any TRAIT (characteristic about you) is determined by your GENES. GENES are regions of your DNA. Genes come in different kinds. ALLELES are different versions of the same gene. For example, there might be a gene for hair color and the alleles can be black, blonde or brown.

Alleles For simple traits, there are dominant and recessive alleles DOMAINANT alleles always mask the recessive ones The only way for recessive traits to show up is if they are the only alleles present.

Genotype & Phenotype GENOTYPE is the actual alleles someone gets (Example: AA or aa) PHENOTYPE is how those alleles appear in the organism (Example: blonde hair, blue eyes, attached earlobes)

HETEROZYGOUS VS. HOMOzYGOUS HETEROZYGOUS means an individual had two different alleles (one dominant, one recessive) HOMOZYGOUS means that an individual has two of the same allele (AA or aa, both dominant or both recessive)

ALLELEs What is the genotype of a person who is heterozygous for Hitchhiker’s thumb (H) Having a straight thumb is recessive. What is the genotype of someone

Punnett Squares When we want to know the outcome of a particular cross (two parents breeding), we can use a punnett square. PUNNETT SQUARES are ways to predict the potential offspring

Punnett squares Punnett squares model what would happen if two organisms had offspring. Since we don’t know what alleles a mom or dad will give we show all 4 possibilities. We put the parent’s alleles along the sides and top. Then we fill in the boxes so each child has 2 alleles.

Punnett Squares What is wrong with the following punnett square? R r

Vocab Words Morphemes are the smallest unit of meaningful language The following at the vocab words for you to define: Homozygous Heterozygous Genotype Phenotype Haploid Diploid