Animal Genetics Dominant vs Recessive Traits Intro to

Animal Genetics: Dominant vs. Recessive Traits Intro to Agriculture Science

GOALS: q Explain the difference between dominant and recessive genes. q Use a Punnett Square to predict genotypic and phenotypic ratios of offspring.

What do we already know? review…

Phenotype q Appearance! q Result of Genotype Example: Bw = Black Coat Because B is dominant

Genotype q The genetic makeup! q Alleles from parents q What you can’t see Example: Alleles that code for good milk production.

Alleles q. A pair of genes q That code for the same trait Example: Hair Color Eye Color Height

What do we need to know? vocabulary…

Dominant Genes q Determine what the offspring will look like! q Expressed as capital letters q Mask recessive genes. Example: B=Black w=White Dominant Allele = B

Recessive Genes q Sometimes determine what the offspring will look like. q Expressed as lowercase letters Example: B=Black w=White Recessive allele = w

What is it called when both alleles are the same? q Homozygous

Example AA or aa

? ? AA or aa Identify. . . Dominant & Recessive

Homozygous Dominant Recessive AA or aa

What is it called when both alleles are different? q. Heterozygous

Example Aa

Lets Get to It! Genetic Crosses Punnett Squares Monohybrid Crosses

What the heck are they? q Punnett squares are genetic crosses used by biologists to predict the probability that certain traits will be inherited by offspring.

What do they look like? q Punnett Square:

MONOHYBRID CROSS q. A Punnett Square q. Using one pair of contrasting traits q. Ex: hair color

Example #1: q. Homozygous vs.

Example #1: A White Sow (ww) q crossed with q. A Black Boar (BB)

Homozygous vs. Homozygous (ww) w w Bw Bw B (BB) B

Example #2: q. Homozygous Heterozygous vs.

Example #2: A White Sow (ww) q crossed with q. A Black Boar (Bw)

Homozygous vs. Heterozygous (ww) w w Bw Bw ww ww B (Bw) w

Example #3: q. Heterozygous vs.

Heterozygous vs. Heterozygous (Bw) B w BB Bw Bw ww B (Bw) w

Result…

Try it! cfu…