GENETICS PROBLEMS

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.

1. Rr- Ry

2. RrYy- RY, ry

3. rrYy- rY, ry

4. RrYY- RY, rY

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

1. D- The genotype of haploid cells are represented.

2. GG- The genotype of diploid cells are represented.

3. P- The genotype of haploid cells are represented.

4. ee- The genotype of diploid cells are represented.

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.
    This is an example of incomplete dominance because this alleles does not follow the dominant/recessive patterns.

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.

The genotypes of the parents are Bb and Bb and this example is a dominant recessive allele.

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.

Gg is the phenotype with a ratio of 50/50 in being yellow or green.  The type of inheritance is dominant-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?

Yy is the phenotype with a ratio of 50/50 in being White or Yellow.  The type of inheritance is dominant-recessive.

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 phenotype ratio of red, white and pink is 1:1:2.  The inheritance type is dominant recessive.

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 for 50/50 for the child to have normal blood clotting.  This type of inheritance is called 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 phenotype ratio of offspring would be 1:4; A, B, AB, O. The inheritance type is 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.

AaBBCC, AaBBCc, AaBbCc, AAbbcc, aabbCc. This type of inheritance is polygenic.

FLIP-A-COIN LAB

	Allele(s) from Mother	Allele(s) from Father	Genotype	Phenotype
Sex of child:		F	F	Female
Face shape	r	r	rr	Square
Chin Shape (I)	v	V	vV	Very Prominent
Chin Shape (II)	R	r	Rr	Round
Cleft chin	a	a	aa	Present
Skin color	ABCd	aBcD	AaBBCcdD	Dark Brown
Hair type	C	c	Cc	Wavy
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	Close together
Eyes size	e	E	Ee	Medium
Eyes shape	A	a	Aa	Almond
Eyes slant	H	H	HH	Horizontal
Eyelashes	l	l	ll	Short
Eye color	aBC	ABC	aABBCC	Brown
Mouth size	m	M	Mm	Average
Lips	l	L	Ll	Thick
Protruding lower lip	h	H	Hh	Slightly Protruding
Dimples	D	D	DD	Present
Nose size	N	N	NN	Big
Nose shape	r	R	Rr	Rounded
Nostril shape	r	r	rr	Pointed
Earlobe Attachment	F	f	Ff	Free
Freckles on checks	F	F	FF	Present
Hair color	abCd	Abcd	aAbbCcdd	Blonde

VIRTUAL MITOSIS LAB

Part 1. VIRTUAL MITOSIS LAB

Based on your data and observations, what are some of the differences between normal cells and cancer cells?

Normal cells have a significantly greater amount of cells at rest vs. cancer cells.  Normal cells majority are in the interphase stage of preparing for nuclear division.

When studying cell division in tissue samples, scientists often calculate a mitotic index, which is the ratio of dividing cells to the total number of cells in the sample. Which type of tissue would have a higher mitotic index, normal tissue or cancerous tissue? Explain.

Cancerous tissue would have a higher mitotic index because they have a higher percentage of cells dividing than normal tissue.

Different types of normal tissues in the human body have different mitotic indices. From the following list, which normal tissues would you expect to have the highest mitotic index: muscle, skin, kidney, or lung? Explain your answer.

I’d expect that skin tissue would have the highest mitotic index because it is the largest organ in the body.

	Interphase	Prophase	Metaphase	Anaphase	Telophase	% of Cells Dividing	% of Cells at Rest
Normal Lung	19	1	0	0	0	0	100
Cancerous Lung	16	0	2	1	1	10	90
Normal Stomach	18	0	1	0	1	10	90
Cancerous Stomach	14	2	1	1	2	20	80
Normal Ovary	18	0	1	2	0	10	90
Cancerous Ovary	11	2	2	2	2	25	75

Part 2. Your Personal Chromosome.

1. Find the number of the chromosome you have been assigned (see list below).
• 19.
2. Visit DNAi and locate your chromosome on the Web site. On the page go to Genome Mining > Tour > Genome Fishing (0n top) > Pick a (your) Chromosome from This Menu.
3. Find four genes on your chromosome that you like by clicking on various symbols in column “Symbol.” Some genes may be more interesting to your than others.
• BSG.  This gene is a protein coding type that is a plasma membrane protein.
• C3.  This gene is also a protein coding type gene that plays a central role in the activation of the complement system. If you are c3 deficient, you are more susceptible to bacterial infection.
• INSR.  This gene is an insulin receptor that stimulates glucose uptake.
• RETN. This gene belongs to the mouse resistin-like family.  
4. Write a complete sentence or two for each describing its action or product. Decipher or explain any words or phrases that do not make sense to you or would be difficult for the average person to understand.
5. Be sure to cite any sources (with MLA) you use for this.
• NCBI Map Viewer. “Homo Sapiens Annotation”. http://www.ncbi.nlm.nih.gov/gene?cmd=retrieve&dopt=full_report&list_uids=56729 (Assessed April 8, 2014).
6. Pick one gene (I know this is probably a stretch…) of these four that seems the most interesting to you. In a few sentences, explain why it is interesting to you.
• RETN.  This mouse resistin-like gene is most interesting to me because it may be the hormone that links obesity to type II diabetes.