Genes code for a trait. A version of a gene is called an allele You have two copies of each gene, one from each parent. Autosomal Homologous Chromosome #8 GeneAllele ShoeNikeVans SodaPepsiSprite Eye ColorBrownBlue HeightTallShort From MOM From DAD Brown Eyes Tall Short Blue Eyes

The sry gene controls testicular development and is only found in males. Which chromosome is it most likely found on? A) On any autosomal chromosome (1-22) B) On Chromosome #8 C) On the X Sex Chromosome D) On the Y Sex Chromosome

The sry gene controls testicular development and is only found in males. Which chromosome is it most likely found on? A) On any autosomal chromosome (1-22) B) On Chromosome #8 C) On the X Sex Chromosome D) On the Y Sex Chromosome

Two words to know: Genotype: The genes or combination of alleles shown by two letters. (Tt, TT, tt, Rr, RR, rr, CC, Cc, cc) Phenotype: How an organism looks like (Tall, short, Round, Squared, Colorblind, Not Colorblind) – Phenotype: Physical Features!!! – Genotype: Genes!!

If a boy inherits an allele for brown eyes and another for blue eyes, what will his eye color be? Some alleles are dominant, meaning they block the expression of the other allele. Dominant alleles are CAPITALIZED! The allele that is not dominant is called recessive (lower case letter) Brown Eyes (B) Blue Eyes (b) MOM DAD Dominant Recessive

Homozygous: genotype with two same alleles for a trait (Example: TT, tt) Heterozygous: genotype with two different alleles for a trait (Example: Tt) 2 more words to know

Gene: Eye Color B = Brown eyes b= blue eyes BB = Homozygous Dominant (Genotype) Phenotype? Brown Eye Color Bb = Heterozygous Dominant (Genotype) Phenotype? Brown Eye Color bb = Homozygous Recessive (Genotype) Phenotype? Blue Eye Color

Write Question and Answer: Pg Are the following genotypes Homozygous or Heterozygous TT __Homozygous___ Tt _______________ Aa _______________ DD_______________

2. Is it a genotype or a phenotype? Aa _________________ Eye Color ____________ Nose Shape __________ RR _____________

3. Is the genotype homozygous dominant, homozygous recessive, or heterozygous? AA _____________________ Aa _____________________ Ee _____________________ ee _____________________

4.A rabbit that has the trait for black fur is dominant over white fur. If B= Black fur and b = white fur, what is the phenotype of the following genotypes: BB ____Black fur____ Bb________________ bb _______________

The Famous Punnett Square Used to predict the traits of an offspring. EX: What is the probability or what is the chance that my child will have brown eyes? You need mom and dad’s genotypes to figure this out.

Mom is homozygous dominant for brown eyes. Dad is heterozygous for that gene. Find the possible genotypes and phenotypes of the offspring. (Brown eyes is dominant over blue eyes) BB Bb B B B b Possible Genotype: 2/4 BB or 50% BB 2/4 Bb or 50% Bb Possible Phenotypes: 100% Brown Eyes

Homer is homozygous recessive for the spiky hair allele. Marge is heterozygous for the spiky hair allele. S is spiky hair, s is non-spiky hair. Find the possible genotypes and phenotypes of the offspring. SsSs SsSs ss S s Possible Genotype: 2/4 Ss or 50% Ss 2/4 ss or 50% ss Possible Phenotypes: 50% Spiky Hair 50% Non-spiky hair

What is a Carrier?

Hemophilia is a bleeding disorder. It is a sex- linked recessive trait. Hemophiliacs tend to bleed inside their body, especially in the knees, ankles, and elbows. This bleeding can damage organs and tissues and may be life threatening. A wife is a carrier, the male has hemophilia. What is the probability that a baby girl will have hemophilia? ___/____ or _______% What is the probability that a baby boy will have hemophilia? ___/____ or _______% What is the probability that the next child will NOT have hemophilia? ___/____ or _______%