Dominant and Recessive Traits

What are traits?• Physical Traits

– Can be seen by others– Eye color, hair color, height, left handed

• Acquired Traits– Learned skills– Playing a sport, riding a bike, playing a musical

instrument

• Behavioral Traits– Instinctual actions– Nest building and migration

Review Terms Used in Modern Genetics

• Genotype– The particular alleles (genes) an individual carries– They are inherited from your biological parents– Genes control your traits

• Phenotype– An individual’s observable traits

• What people can SEE when they look at you

Review Terms Used in Modern Genetics

• An individual with non-identical alleles of a gene is heterozygous for that gene– Examples: Bb, Tt, Aa

• An individual with identical alleles of a gene is homozygous for that gene– Examples: BB or bb, TT or tt

Terms Used in Modern Genetics

• An allele is dominant if its effect masks the effect of a recessive allele paired with it– Capital letters (A) signify dominant alleles;

lowercase letters (a) signify recessive alleles– Homozygous dominant (AA)– Homozygous recessive (aa)– Heterozygous (Aa)

What traits do you have?

• We will go through the most common traits that people have

• On your sheet, record if you have the mentioned trait or not

• You may have to ask your neighbor for help

Detached (EE, Ee) or attached (ee) Earlobes

Can Tongue Roll (TT, Tt) or Can’t (tt)

Dimples (DD, Dd) No Dimples (dd)

Right (RR, Rr) or Left (rr) handed?

Freckles (FF, Ff) No Freckles (ff)

Curly (HH, Hh) or Straight (hh)

Cleft Chin (CC, Cc) or No Cleft (cc)

Allergies (AA, Aa) or No Allergies (aa)

Hand Clasp Right over Left?

Normal (BB, Bb) Color Blindness (bb)

Can you see the number inside the circle?

If you cannot, you may be colorblind

Widow’s Peak (WW, Ww) or Straight (ww)

Data

• We will now record our class data and graph our results

• Does our data support which genes are dominant and which genes are recessive?

• What about the whole 7th grade?