Making A Face - A Genetic Simulation

Converting Genotype Into Phenotype by Simulating Gametogenesis, Fertilization and Embryogenesis

Congratulations, you are going to have a baby!..... Well, you are actually going to simulate having a baby.

After this simulation, you should be able to answer the following questions:

How many chromosome pairs does each human parent have?
How many chromosomes does each parent "donate" to the next generation?
Are some genes and gene characteristics expressed over others.... are dominant and recessive genes responsible for how a baby looks?
What is the difference between Genotype and Phenotype?
Do some traits require more than one gene to be fully expressed?
What are sex-linked traits?
How is there so much variation in the way children look even if they come from the same parents?
What is epistasis?
What is polygenic inheritance?

Why siblings are very different both in genotype and phenotype is the question we want to address in this simulation. This activity should help you answer that question and stimulate other questions as well.

Directions continued from page one.

You have been given a pink set of chromosomes if you are going to represent the wife, and a blue set of chromosomes if you are going to represent the husband. We are asking the question... What would your baby look like if both you and your classmate (who will simulate your spouse) have one dominant gene and one recessive gene for each of the facial features illustrated on the following pages? This, of course, is not the way it really is, but this is a simulation. Each of you will be heterozygous for each trait. To determine the facial appearance of your child, you and your spouse will drop your 23 pair of chromosomes to the floor to simulate gametogenesis (sex cell formation). This "dropping your chromosomes" will determine which one of the pair of chromosomes will enter the successful sex cell. Each parent, mom and dad, donate one and only one of each of their 23 pair of chromosomes. Therefore they both donate 23 chromosomes. Since genes ride in the DNA of the chromosomes, each child will end up with a pair of genes for each trait, one from the dad and one from the mom.

After you drop your own chromosomes and line them up according to size, then you will "mate" with your partner by pushing the chromosomes one at a time toward one another until they are side by side. This represents the establishment of pairs of chromosomes. When you are done you should have twenty three pairs of chromosomes again. The mathematics of sex is..... one of each pair from the mother.....Plus.... one of each pair from the father equals a pair of each kind for the baby! You essentially will supply one gene and your spouse will supply one gene for each characteristic. The resulting two genes that are paired up will produce the genotype. Record the genetic contributions from each parent on the chart provided. Translate the genetic information into the phenotypic information, type of protein (what will your baby look like). You and your spouse will produce one child only. Name the baby. Each of you go home and make a birth announcement which describes in rich and loving detail your wonderful offspring. After this is done, then you will each produce an excellent final draft drawing of your baby 15 years later when he or she is in high school! Do not place the child's name on the front of your paper....only on the back. We want to see if we can match you and your mate's drawings of your child. Don't collaborate with your mate on either one of these assignments.

Making a Baby!

Marriage Ceremony. There will be a short marriage ceremony. The long-term / lifetime commitment of a husband and wife bond is the preferred way to raise children. Place the married names of the parents on the data table that is provided to you. Get away in a secluded spot and get ready to make some sex cells.

Gametogenesis. Hold the chromosomes high in the air above your head. Drop them one at a time to the floor. If they don't twirl then drop them again. When they have all dropped to the floor carefully pick them up without turning them over and find a lab table where you can face each other, then organize them according to size. Your teacher will demonstrate how they should line up. Equal sizes should be across from each other as you face your partner. The sex chromosomes should be organized away from the 22 autosomal chromosomes. Keep in mind that you begin this exercise with the chromosome pair above your head, they twirl down to the floor and finally land.... only one of the pair face up.... this upward facing one of the pair represents the chromosome that ended up in the successful gamete that you have just produced. Yes, those 23 chromosomes that are all neatly lined up represent the contents your sperm or egg. Since you have your sperm and egg produced, it is time to mate!

Mating / Fertilization. Gently push the like-sized chromosomes toward each other at point halfway between you, pair them up according to size and number. This represents the moment when a new human potential is reached. A totally unique human is conceived!

Determination of child's sex. After conception, parents are always interested in determining the sex of their child. In this case the "husband" has pushed either an "X" chromosome or a "y" chromosome toward the middle (which ever dropped facing up) and matched it with the "wife's "X" chromosome. If an "X", then you have a beautiful little girl, if a "y", then a beautiful little boy! Give your child a name and record the name on your data sheet.

Determination of various genotypes. Do the same with all of the chromosomes. Carefully read the genes on the chromosomes and circle the resulting genotypes and phenotypes on the chart that is provided to you.

Making Birth Announcement. Finally, after all of the phenotypes have been determined you need to go home and make a birth announcement which will describe how proud you are of your offspring, and what he or she looks like. Use all of the traits / phenotypes that you have in the data table.

Draw the baby. Time passes, you get older, your baby is growing up! What does your baby look like now that he or she is a teenager? Make a full page drawing of your teenager's face using your best drawing ability. Color is necessary; some of the genes produce pigment!

How to cut the chromosome models out properly.

Step #1

Cut out each pair of chromosomes on the solid line that surrounds each pair.

Step #2

Fold along the dotted line between the pair of chromosomes.

Step #3

Glue/tape the folded pair together, press until they are perfectly flat. Watch for undried glue squeezing out from between the chromosomes; they may stick with other chromosomes!

Step #4

Bring your chromosomes to school in an envelope stored in one of your books.... keep your paired chromosomes flat!

Cut these pairs of chromosomes out using these instructions.

Characteristic

Geno -> Pheno

Sex

Female

Male

Sex Chromosomes

Mother's Name

Kid's Name

Father's Name

Face Shape

Round

Square

Chin Shape

J. Leno

Not Leno

Chin Shape

Round

Square

If LL or Ll only

Cleft Chin

Cleft

No Cleft

If LL or Ll only

Skin Color

Very Very Dark Brown

Very Dark Brown

Dark Brown

Medium Brown

Light Brown

Light Light Brown

Very Very Light Brown

Polygenic

AAAAAA

AAAAA / a

AAAA / aa

AAA / aaa

AA / aaaa

A / aaaaa

aaaaaa

Hair Color

Black

Very Dark Brown

Dark Brown

Brown

Light Brown

Honey Blond

Blond

Very Light Blond

VERY light! Platinum

Polygenic

HHHHHHHH

HHHHHHH / h

HHHHHH / hh

HHHHH / hhh

HHHH / hhhh

HHH / hhhhh

HH / hhhhhh

H / hhhhhhh

hhhhhhhh

Eye Color

Dark Brown

Brown

Dark Blue

Light Blue

Pale Blue

FFBB

FFBb

FFbb

FfBB

FfBb

Ffbb

ffBB

ffBb

ffbb

Red Hair	Red	Less Red	No Red
	Pigment	Pigment	Pigment
	GG	Gg	gg

Hair Type	Curly	Wavy	Straight
	WW	Ww	ww

Widow's Peak	Present	Present	Absent
	PP	Pp	pp

Eyebrow Thickness	Thick	Thick	Thin
	TT	Tt	tt

Eyebrow Placement	Apart	Apart	Touching in Middle
	EE	Ee	ee

Eye Distance Apart	Close	Less Close	Far Apart
	OO	Oo	oo

Eye Size	Large	Medium	Small
	II	Ii	ii

Eye Shape	Almond	Almond	Round
	VV	Vv	vv

Eyelashes ("Movie")	Long	Long	short
	MM	Mm	mm

Mouth Size	Wide	Average	Narrow
	QQ	Qq	qq

Lips: Thickness	Thick	Thick	Thin
	JJ	Jj	jj

Dimples	Dimples	Dimples	Absent
	KK	Kk	kk

Nose Size	Big	Medium	Small
	NN	Nn	nn

Nose Shape	Rounded	Rounded	Pointed
	UU	Uu	uu

Earlobe Attachment	Free	Free	Attached
	ZZ	Zz	zz

Hairy Ears	Present	Present	Absent
	DD	Dd	dd

Freckles on Cheeks	Present	Present	Absent
	$$	$ $	$$

Freckels on Forehead	Present	Present	Absent
	@@	@ @	@@

Genotype to Phenotype

Translation Booklet

The contents of this booklet

will help you determine

what your baby will look like.

If your dropping of the genes resulted in two "XX" chromosomes turning face up, then you are the very lucky parents of a little girl.

The Mom contributed one "X" and the Dad the other "X".

Its a Girl!

If your dropping of the genes resulted in an "Xy" combination of chromosomes turning face up, then you are the very lucky parents of a little boy.

The Mom contributed one "X" and the Dad the "Y" chromosome.

Its a Boy!

Chromosome #1 contains the genetic information in a gene we will call "R". This information determines the general shape of the face.

Place your baby's genotype for face shape in the data table.

Chromosome #2 contains the chin shape gene "L." The genotype "ll" prevents the expression of the next two pairs of genes.

Place your baby's genotype for chin shape in the data table.

The control of one set of genes by another is called epistasis.

If you landed the genotype "ll" then skip the next two and start on Skin Color.

Back to Front Page Back to Teacher's Information Page Back to Student's Instructions and Materials Back to Genotype -> Phenotype Classroom Booklet

Chromosome #3 contains the "S" gene. This gene controls the shape of the chin, round or square. These genes are activated only if the dominant "L" on chromosome #2 is present.

Place your baby's genotype for chin shape in the data table.

The control of one set of genes by another is called epistasis.

Chromosome #5 carries the "C" gene. The "C" gene controls the development of the cleft chin phenotype.

Remember these "C" genes are activated only if the dominant "L" on chromosome #2 is present.

Place your baby's genotype for chin shape in the data table.

The control of one set of genes by another is called epistasis.

Skin color is determined by three sets of genes on chromosomes #'s 1, 2,and4. The dominant genetic code, gene "A" translates into a protein called melanin. This dark pigment is like a natural UV blocker. The greater the number of dominant genes one has, the greater the amount of melanin, the darker the skin, and the more UV protection a person has. These genes have been selected-for near the Earth's equator where the intense UV photons can cause a great deal of damage to lighter skin.

Count up the number of dominant and recessive genes and place your baby's genotype for skin color in the data table.

The hair color gene, like skin color, is polygenic. The same genetic code is found on chromosome #'s 3, 4, 10 and 18. This code translates into pigment which is incorporated into the hair as it is growing. The greater the number of dominant alleles, the darker the hair. Hair color varies from black to white.

Count up the number of dominant and recessive genes and place your baby's genotype for hair color in the data table.

Chromosomes #'s 11 and 12 contain Eye Color Genes: Darker eyes are produced in the presence of more active alleles. In this situation, the Capital letters (F or B) represent alleles which are active in depositing dark pigment. Lower case letters (f or b) represent alleles which deposit little pigment. To determine the color of the eyes, assume there are two gene pairs involved, one of which codes for depositing pigment in the front of the iris, and the other codes for depositing pigment in the back of the iris. Determine the genotype of the first pair (FF,Ff,ff). and the the second (BB,Bb,bb). If your genotype is in the first column then check your eye color in the second column.

Column #1	Column #2
Genotypes	Protein Phenotypes
FFBB	Dark brown
FFBb	Brown
FFbb	Brown
FfBB	Brown
FfBb	Dark Blue
Ffbb	Dark Blue
ffBB	Light Blue
ffBb	Light Blue
ffbb	Pale blue

Place your baby's genotype for eye color in the data table.

Red Hair: Red hair is another gene for hair color present on a different chromosome.It blends its effect with other hair colors. Redness of the hair seems to be caused by a single gene pair with two alleles, red (G) or no red (g), and displays incomplete dominance. Thus, if a person has two genes for red (GG), the hair will be a more intense red than if they have a single gene (Gg). If a person has no genes for red (gg), then the hair does not show as red at all. Red hair is complicated by the fact that dark pigment, controlled by the many hair color genes, may mask or hide the red color. The darker the brown, the less the red shows through, although more shows with (GG) than with (Gg). As the hair becomes lighter in color, more red shows through. If your child is blond as evidenced by 3 Capitals or less above and (GG) lands facing up, then your child will probably have flaming red hair. Auburn might be (Gg) with the lighter shades of pigmentation.

GG = Heavy Red Pigment

Gg = Medium Red Pigment

rr = No Red Pigment

Chromosome #7 contains the genetic code for hair type. The "W" hair-making DNA codes for amino acids which contain a sulfur atom which causes cross links between amino acids in the hair..... thus curly hair! Straight hair lacks the many sulfur amino acids and does not make as many cross links.

Place your baby's genotype for hair type in the data table.

Chromosome #8 contains the genetic code for Widow's Peak. If your baby has a dominant "P" then he or she will possess that trait. (Notice that there is a line through the recessive small " p ".)

Place your baby's genotype for Widow's Peak in the data table.

Chromosome #9 carries a gene for eyebrow thickness called "T". It works with complete dominance.

Place your baby's genotype for eyebrows in the data table.

Chromosome #10 has the gene for eyebrow placement. "E" separates and lack of "E" causes connected eyebrows.

Place your baby's genotype for eyebrow placement in the data table.

Chromosome #11 has the gene for eye placement. The dominant gene places the eyes close together, the recessive, far apart.

Place your "baby's" genotype for eye placement in the data table.

Chromosome #12 beside carrying one of the pigment genes for eye color also carries the gene "I" for eye size.

Place your "baby's" genotype for eye size in the data table.

Chromosome #13 has the eye shape gene "V." Dominant genes code for almond shape and homozygous recessive is round.

Place your baby's genotype for eye shape in the data table.

Movie star eyelashes are found on chromosome #15. Dominant "M" genes place your kid on the way to stardom!

Place your baby's genotype for eyelashes in the data table.

Chromosome #17's "Q" gene controls the width of the mouth. The dominant gene imparts width.

Place your baby's genotype for mouth width in the data table.

Chromosome #18's gene "J" adjusts the thickness of the lips.

Place your baby's genotype for fullness of lips in the data table.

Chromosome #16 contains genetic information regarding the construction of dimples.

Place your baby's genotype for dimples in the data table.

Chromosome #19 contains genetic information regarding the construction of nose size

Place your baby's genotype for nose size in the data table.

Your baby's nose shape is determined by a gene on chromosome #14. The allele "U" imparts a rounded shape to the nose.

Place your baby's genotype for nose shape in the data table

Chromosome #22 carries the gene for free ears. The gene "Z" causes the earlobe to hang free at the side of the head.

Place your baby's genotype for earlobe attachment in the data table.

Chromosome #20 contains DNA information encoded in a gene called "D". This information, if in its dominant form, causes the ear to grow a large amount of fuzzy hair.

Place your baby's genotype for hairy ears in the data table.

Chromosome #21 contains a gene, "$" which causes uneven pigment to form in the cheek region. If "$" is present then your child will have cheek freckles.

Place your baby's genotype for freckles in the data table.

Finally on chromosome #9 there is data in the form of a gene "@". If your baby has "@" there will be freckles on the forehead! ("@@" underlined, represent the recessive genes)

Place your baby's genotype for freckles in the data table.