Transcript A Survey of Human Traits

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:
– Right or Left
• Genotype:
– Right = RR or Rr
– Left = rr
Hitchhiker’s thumb
• Phenotype:
– Present (top) or Absent
(bottom)
• Genotype:
– Present (HH or Hh)
– Absent (hh)
Ear lobes
• Phenotype:
– Unattached (top) or
attached (bottom)
• Genotype:
– Unattached (LL or Ll)
– Attached (ll)
Tongue Rolling
• Phenotype:
– Roller or non-roller
• Genotype:
– Roller (RR or Rr)
– Non-Roller (rr)
Widow’s Peak
• Phenotype:
– Present (see pictures) or
absent
• Genotype:
– Present (WW or Ww)
– Absent (ww)
Dimples
• Phenotype:
– Present (see
pictures) or absent
• Genotype:
– Present (DD or Dd)
– Absent (dd)
Cleft Chin
• Phenotype:
– Present (see
pictures) or absent
• Genotype:
– 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:
– Taster or non-taster
• Genotype:
– 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?