Variations on a Human Face LabIntroduction:Have you ever wondered why everybody has a different appearance even if they are closelyrelated? It is because of the large variety or characteristics that exist in the human population.This lab will demonstrate this concept. You are to be parent and you are going to make a baby.What would your baby look like if you and your partner spouse both typically have one dominantand one recessive gene for each of the following features of the face?Objective:The student will determine the appearance of their child’s face. By flipping coins the student willdetermine the bits of information that will contribute to the complete appearance of the child’sface.Materials:2 coins (pennies)2 studentsHandout of the TraitsWhite paperColors – Pencils, crayons, or markersProcedure:1. First determine which partner will toss for the male and which will toss for the female. Each of you will get a penny. (You will have the opportunity to make 2 children you will pick which one you would like to draw)2. Have the partner who is representing the male flip the coin, if the coin lands heads up, the offspring is female, if tails, the offspring is male. What is the sex of your offspring?______3. For all coin tosses from now on. Heads will represent the dominant allele and tails will represent the recessive allele. For each trait on the chart you will flip a coin to determine what GENOTYPE your offspring will have. Write the allele that mom and dad both give in the correct area of the chart and the genotype of the child next to each trait given.4. Complete the traits in the chart first. Then complete the polygenic traits.
Polygenic TraitsSome traits are controlled by more than one gene and are called polygenic. Hair, eye color andskin color are examples of polygenic traits. To determine the color of your child’s hair and eyes,you will flip your coins twice, once to represent the A gene, and once to represent the B gene. Example: Flip 1 Head / Head Flip 2 Head / Tail Genotype AA Bb4. Hair Color -- What did you flip? Flip 1 ___________________ Flip 2 _______________ Possible genotypes and hair color. If the genotype is…. The hair color is… AABB black AABb black AAbb red AaBB brown Aabb regular blonde AaBb brown aaBB dark blonde aaBb regular blonde aabb pale yellow blonde5. Eye Color -- What did you flip? Flip 1 ___________________ Flip 2 _______________ If the genotype is…. The eye color is…. AABB dark brown AABb dark brown AAbb brown AaBB brown with green flecks AaBb brown Aabb gray-blue aaBB green aaBb dark blue aabb light blue (hazel)6. Skin Color – skin color is controlled by a lot of different genes that basically add together to determine how dark the skin is and variations in tone. To simulate how skin color might be determined. Flip a single coin 10 times. Each time the coin turns up heads, give your offspring a point. Add your points together. 10 pts would be a very dark child and 1 pt would be a very pale child. How many points does your child have?
DRAW YOUR CHILDNow that you have determined all the traits of your child, draw a picture. Use colors and try tomake the sketch as accurate as possible given the traits your child inherited. Make sure youname your child too!Analysis and Conclusions1. What are the odds that your child will be a boy? _________________ Which parent determines the sex of the child? __________________2. In your cross, both of the parents have wavy hair and round faces. How is it possible that thechild of this cross could have neither of these traits?3. Which traits are codominant or incompletely dominant ? (these traits don’t have a cleardominant or recessive, the heterozygous condition shows a “blending” or a “middle” condition).List at least three.4. Why did you have to flip the coin twice to determine hair and eye color?5. Show the cross of a wavy haired person with a wavy haired person. Use a Punnet square.What percentage of the offspring will have straight hair? ________ What percentage of the offspring will have wavy hair? ________ What percentage of the offspring will have curly hair? ________ *What type of hair did your child have? _____________________________
Biology Parents: ___________________________________________ Variations on a Human Face Lab CHILD #1 CHILD #2 Genotype Genotype Mother’s Mother’s Father’s Father’s Child’s Child’s Genes Genes Genes Genes Possible TraitsShape of FaceCleft in ChinHairWidow’s PeakSpacing of EyesShape of EyesPosition of EyesSize of eyesLength of EyelashesShape of EyebrowsPosition of EyebrowsSize of NoseShape of LipsSize of MouthSize of EarsFrecklesDimplesHair ColorEye ColorSkin Color
Human Variations Trait Dominant Hybrid Recessive (both heads) (one head, one tail) (both tails) Trait Dominant Hybrid Recessive Shape of (both heads) (one head, one (both tails) Eyebrows tail) Bushy (BB) Bushy (Bb) Thin (bb)Shape of Position Face of Not connected (NN) Not connected (Nn) Connected (nn) Eyebrows Round (RR) Round (Rr) Square (rr) Cleft in Size of Chin Nose Absent (CC) Absent (Cc) Present (cc) Large (NN) Medium (Nn) Small (nn) Hair Shape of Lips Thick (TT) Medium (Tt) Thin (tt) Curly (HH) Wavy (Hh) Straight (hh)Widow’s Size of Peak Mouth Large (LL) Medium (Ll) Small (ll) Present (WW) Present (Ww) Absent (ww)Spacing Size ofof Eyes Close (EE) Normal (Ee) Far (ee) Ears Large (LL) Medium (Ll) Small (ll)Shape of Hairy Eyes Almond (AA) Almond (AA) Round (aa) Ears Absent (HH) Absent (Hh) Present (hh) Position Dimples of Eyes Straight (SS) Straight (Ss) Slant (ss) Present (DD) Present (Dd) Absent (dd) Size of Hapsburg eyes Large (LL) Medium (Ll) Small (ll) Lip Protruding (HH) Slight (Hh) Absent (hh)Length of FrecklesEyelashes Long (LL) Long (Ll) Short (ll) Present (FF) Present (Ff) Absent (ff)