A Survey of Human Traits

Trait A feature you inherit. (eye color, freckles, body structure, etc.)

Allele Alternate form of a gene for a trait Blue or Brown are alleles for eye color Allele may be dominant or recessive (B or b)

Dominant A trait that covers over another form of that trait. Represented with a capital letter (B)

Recessive A trait that gets covered up by the dominant allele and it seems to disappear. Represented with a lower case letter (b)

Phenotype The outward, physical appearance of an organism as a result of its genotype. (brown hair, left handed, freckles) What is her phenotype? Brown eyes, brown hair, curly hair, no freckles, medium skin tone

Genotype The genetic make-up of an organism Represented by two alleles (one from mom, one from dad) BB, Bb, bb (homozygous or heterozygous)

Survey yourself Look at each trait and determine your phenotype (outward appearance) Next, determine your genotype (what letters/alleles you have for the trait.) You may have dominant, recessive, or hybrid alleles We will work through this together…

Handedness Phenotype: Genotype: Right or Left Right = RR or Rr Left = rr

Hitchhiker’s thumb Phenotype: Genotype: Present (top) or Absent (bottom) Genotype: Present (HH or Hh) Absent (hh)

Ear lobes Phenotype: Genotype: Unattached (top) or attached (bottom) Unattached (LL or Ll) Attached (ll)

Tongue Rolling Phenotype: Genotype: Roller or non-roller Roller (RR or Rr) Non-Roller (rr)

Widow’s Peak Phenotype: Genotype: Present (see pictures) or absent Present (WW or Ww) Absent (ww)

Dimples Phenotype: Genotype: Present (see pictures) or absent Present (DD or Dd) Absent (dd)

Cleft Chin Phenotype: Genotype: Present (see pictures) or absent Present (CC or Cc) Absent (cc)

Interlocking fingers Phenotype: Left thumb on top or right thumb on top Genotype: Left on top (TT or Tt) Right on top (tt)

PTC Taster Phenotype: Genotype: Taster or non-taster Taster (PP or Pp) Non-taster (pp)

Tonight Survey your family members. See who has what phenotypes. Can you figure out where some of your genes came from?