STUDENT WORKSHEET The Genetics of Parenthood Data Sheet Parents and Child's gender Child's name Fill in data table as you determine each trait described in the Guidebook. Do not simply flip the coin for all traits before reading the guide, because some traits have special instructions. Believe it or not, it will make your life easier if you follow directions. In the last column, combine the information and draw what that section of the child's face would look like. # TRAIT ALLELE FROM MOM ALLELE FROM DAD CHILD'S GENOTYPE CHILD'S PHENOTYPE (written) CHILD'S PHENOTYPE (drawn) 1 Face Shape A a A a face & chin 2 Freckles F f F f 3 Dimples D d D d 4 Cleft Chin C c C c 5 Skin Color E e F f G g E e F f G g 6 Hair Color H h I i J j K k H h I i J j K k 7 Red Tints L 1 L 2 L 1 L 2 hair 8 Hair Type M m M m 9 Widow's Peak O o O o 10 Eye Color P p Q q P p Q q eye & eyelashes 11 Eye Distance R r R r 12 Eye Size S s S s 13 Eye Shape T t T t Eye U u U u 14 Slantedness 15 Eye Lashes V v V v 16 Eyebrow Color W w W w eyebrow 17 Eyebrow Thickness X x X x 18 Nose Size Y y Y y 19 Mouth Size Z z Z z mouth 20 Lip Thickness T t T t 21 Ear Size L l L l
STUDENT REFERENCE The Genetics of Parenthood Guidebook Why do people, even closely related people, look slightly different from each other? The reason for these differences in physical characteristics (called phenotype) is the different combination of genes possessed by each individual. To illustrate the tremendous variety possible when you begin to combine genes, you and a classmate will establish the genotypes for a potential offspring. Your baby will receive a random combination of genes that each of you, as genetic parents, will contribute. Each normal human being has 46 chromosomes (23 pairs - diploid) in each body cell. In forming the gametes (egg or sperm), one of each chromosome pair will be given, so these cells have only 23 single chromosomes (haploid). In this way, you contribute half of the genetic information (genotype) for the child; your partner will contribute the other half. Because we don't know your real genotype, we'll assume that you and your partner are heterozygous for every facial trait. Which one of the two available alleles you contribute to your baby is random, like flipping a coin. In this lab, there are 36 gene pairs and 30 traits, but in reality there are thousands of different gene pairs, and so there are millions of possible gene combinations! Procedures Record all your work on each parent's data sheet. First, determine your baby's gender. Remember, this is determined entirely by the father. The mother always contributes an X chromosome to the child. Heads = X chromosome, so the child is a GIRL Tails = Y chromosome, so the child is a BOY Fill in the results on your data sheet. Name the child (first and middle name; last name should be the father's last name). Determine the child's facial characteristics by having each parent flip a coin. Heads = child will inherit the first allele (i.e. B or N1) in a pair Tails = child will inherit the second allele (i.e. b or N2) in a pair On the data sheet, circle the allele that the parent will pass on to the child and write the child's genotype. Using the information in this guide, look up and record the child's phenotype and draw that section of the face where indicated on the data sheet. Some traits follow special conditions, which are explained in the guide. When the data sheet is completed, draw your child's portrait as he/she would look as a teenager. You must include the traits as determined by the coin tossing. Write your child's full name on the portrait.
TRAITS (HOMOZYGOUS) DOMINANT both heads (HETEROZYGOUS) HYBRID- 1 heads; 1 tails (HOMOZYGOUS) RECESSIVE both tails FACE SHAPE Round (RR) Round (Rr) Square (rr) FRECKLES Present (FF) Present (Ff) Absent (ff) DIMPLES Present (DD) Present (Dd) Absent (dd) CLEFT CHIN SKIN COLOR HAIR COLOR Present (CC) Present (cc) Absent (cc) 6 Dominant Alleles = Black (EE,FF,GG) 5 Dominant Alleles = Very Dark Brown 8 Dominant Alleles = Black (HH,II,JJ,KK) 7 Dominant Alleles = Very Dark Brown 6 Dominant Alleles = Dark Brown 4 Dominant Alleles = Dark Brown 3 Dominant Alleles = Medium Brown 2 Dominant Alleles = Light Brown 5 Dominant Alleles = Brown 4 Dominant Alleles = Light Brown 3 Dominant Alleles = Brown Blonde Mix 1 Dominant Alleles = Light Tan 0 Dominant Alleles = White (ee,ff,gg) 2 Dominant Alleles = Blonde 1 Dominant Alleles = Very Light Blonde 0 Dominant Alleles = Silvery White (hh,ii,jj,kk)
** RED COLOR TINTS IN HAIR Dark Red Tint (L 1 L 1 ) Light Red Tint (L 1 L 2 ) No Red Tint (L 1 L 2 ) HAIR TYPE Curly (MM) Wavy (Mm) Straight (mm) WIDOW S PEAK EYE COLOR Present (OO) Present (Oo) Absent (oo) Black (PPQQ) Dark Brown (PPQq) Brown w/green Tints (PpQQ) Brown (PpQq) Violet (PPqq) Gray Blue (Ppqq) Green (ppqq) Dark Blue (ppqq) Light Blue (ppqq) EYE DISTANCE Close (RR) Average (Rr) Far Apart (rr) EYE SIZE Large (SS) Medium (Ss) Small (ss) EYE SHAPE Almond (TT) Almond (Tt) Round (tt) EYE SLANTEDNESS Horizontal (UU) Horizontal (Uu) Upward Slant (uu) EYE LASHES Long (VV) Long (Vv) Short (vv)
EYEBROW COLOR Darker Than Hair Color (WW) Same As Hair (Ww) Lighter Than Hair (ww) EYEBROW THICKNESS Bushy (XX) Bushy (Xx) Fine (xx) NOSE SIZE Large (YY) Medium (Yy) Small (yy) MOUTH SIZE Long (ZZ) Medium (Zz) Short (zz) LIP THICKNESS Thick (TT) Thick (Tt) Thin (tt) EAR SIZE Large (LL) Medium (Ll) Small (ll)
Problem How are traits inherited? Pre-Lab Discussion Read the entire investigation. Then, work with a partner to answer the following questions. 1. What does a single side of a double-sided coin or disk represent? Each single side of a coin or disk represents one of two possible alleles. 2. What is the probability, in percent, that a single coin toss will result in heads? In tails? The probability that a single coin toss will result in either heads or tails is 50 percent. are the result of the combination of two alleles, or an allele pair. 3. Why is a coin toss a good way to represent allele combinations that occur in nature? The combination of alleles in nature occurs by chance, as does the result of a coin toss. 4. For the traits explored in this lab, do all heterozygous pairs of alleles produce an intermediate phenotype? No; for some of the traits listed, heterozygous pairs produce only the dominant phenotype. 5. Can you accurately determine an organism s genotype by observing its phenotype? Explain your answer. Although knowing an organism s genotype would allow one to predict its phenotype, some phenotypic traits can Analysis and Conclusions 1. Inferring. What are the possible genotypes of the parents of an offspring who has wavy (Hh) hair? HH 2. Predicting. Would you predict that another pair of students in your class would have an offspring genetically identical to yours? Support your answer. Because the genotype of each trait is determined by chance, and because there are so many traits considered, the probability of two genetically identical offspring within a single class is highly unlikely. 3. Drawing Conclusions. Do you think anyone in your class has all the same genetic traits that you have? Explain your answer. No. Each person has a unique combination of many genetic traits passed on to them by their parents. (Identical twins, however, do share all of their genetic traits.) 4. Comparing and Contrasting. How is this coin-toss model similar to the way in which traits are inherited in living things? How is the model different? nations