Genetics and Inheritance lab

Genetics and Inheritance Lab

Part 1. Flip-a-coin

	Allele(s) from Mother	Allele(s) from Father	Genotype	Phenotype
Sex of child:		Girl
Face shape	r	R	rR	Round
Chin Shape (I)	v	V	vV	very prominent
Chin Shape (II)	R	R	RR	Round
Cleft chin	A	a	Aa	Absent
Skin color	AaBbccdd			very light brown
Hair type	c	c	cc	straight
Widow’s Peak	w	W	wW	present
Eyebrows (I)	B	B	BB	bushy
Eyebrows (II)	N	N	NN	not connected
Eyebrow color	H	h	Hh	same color as hair
Eyes distance apart	e	E	eE	average
Eyes size	E	e	Ee	medium
Eyes shape	A	A	AA	almond wide
Eyes slant	h	H	hH	horizontal
Eyelashes	l	L	lL	long
Eye color	aaBbcc			blue
Mouth size	M	m	Mm	average
Lips	l	L	lL	thick
Protruding lower lip	H	H	HH	very protruding
Dimples	d	d	dd	absent
Nose size	n	N	nN	average
Nose shape	r	r	rr	pointed
Nostril shape	r	r	rr	pointed
Earlobe Attachment	F	F	FF	free
Freckles on checks	f	f	ff	absent
Hair color	aaBbccdd			light blond

My child ended up being a daughter of course. Since I already have four of them why wouldn't it be! According to my data sheet the image below represents my daughter at about the age of sixteen.

Part 2. Genetics problem Calculator 

1. For each of the diploid genotypes presented below, determine the genetic make up for all of the possible gametes that would result through the process of meiosis. Remember, each egg or sperm must have one of each letter. That letter can be upper or lower case.

a.    Rr

b.    RrYy

c.    rrYy

d.    RrYY

2. For each of the following, state whether the genotype of a diploid or haploid cell is represented.

a.    D- Haploid

b.    GG- Diploid

c.    P-Haploid

d.    ee-Diploid

3. Yellow guinea pigs crossed with white ones always produce cream colored offspring. Two cream colored guinea pigs when crossed produced yellow, cream and white offspring in the ratio of l yellow: 2 cream: l white. Explain how are these colors inherited?  No calculations needed! Name the type of inheritance this represents.

Cream colored guinea pigs are heterozygous, therefore they contain one allele of yellow and one allele of the white gene. when they reproduce they can either have a white,yellow or cream offspring, depending on which allele they get from each parent. This is incomplete dominance, due to the heterozygous is expressed as an phenotype.

4. In sheep white is due to a dominant gene (B), black to its recessive allele (b). A white ewe mated to a white ram produces a black lamb. What are the genotypes of the parents? You might need to construct Punnet squares experimenting with different crosses to come up with this answer. Name the type of inheritance this represents.

This is homozygous recessive inheritance and both parent would have to be Bb heterozygous.

5. In peas, yellow color (G) is dominant to green color (g). A heterozygous yellow is crossed with a green. What is the expected phenotype ratio of the offspring? Name the type of inheritance this represents.

The expected phenotype ratio would be 50/50 green to yellow. This is both inheritance heterozygous and homozygous recessive.

6. White color (Y) is dominant to yellow color (y) in squash. A heterozygous white fruit plant is crossed with a yellow fruit plant. What is the expected phenotype ratio of the offspring? What is this type of inheritance called?

The expected ratio would again be 50/50 white to yellow squash. This is both heterozygous and homozygous recessive inheritance.

7. In certain flowers, a cross between homozygous red and a homozygous white will always result in a pink flower. A cross is made between two pink flowers. What is the predicted phenotype ratio of the colors red, pink and white appearing in the offspring? What is this type of inheritance called?

The predicted phenotype ratio would be 1:3 (25%) for white or red flowers and 1:1 (50%) for pink flowers. This is incomplete inheritance due to heterozygous genotypes (unlike phenotypes).

8. In humans, the condition for normal blood clotting dominates the condition for non-clotting or hemophilia. Both alleles are linked to the X chromosome. A male hemophiliac marries a woman who is a carrier for this condition. In this respect, a carrier is a woman who has an allele for normal blood clotting and an allele for hemophilia. What are the chances that if they have a male child he will be normal for blood clotting? What is this type of inheritance called?

The chances that their son would be normal for blood-clotting would be 50%, and this would be sex linked inheritance.

9. A person with an allele for type A blood and type O blood marries someone with an allele for type B blood and type O blood. List the types of offspring they could have and the probability for each blood type in the offspring. (A allele = IA, B allele = IB, O allele = i) What is the expected phenotype ratio of the offspring? What is this type of inheritance called?

The expected phenotype of the offspring ratio would be 1:3 (25%) for AB blood type. It would also be 1:3 (25%) for O blood type, 1:3 (25%) for type A blood type , finally 1:3 (25%) would be B type. This is called codominance.

10. Skin color in humans becomes darker by the number of dominant alleles; AABBCC have the darkest skin and aabbcc have the lightest skin. Place these genotypes in sequence according to the color of skin expected for each. Place the darkest skin first. What is this type of inheritance called?

Genotypes: AaBbCc, AAbbcc, aabbCc, AaBBCc, AaBBCC.

The sequence according to skin color form darkest to lightest goes: AaBBCC, AaBBCc, AaBbCc, AAbbcc, aabbCc. This is called polygenic inheritance.

References

Johnson, Michael D. Human Biology: Concepts and Current Issues. Seventh ed. San Francisco: Pearson Benjamin Cummings, 2014. Print.