Human Genectics Lab 12
BioLab3
Human Genetics
Lab Report Answer Key
Student Name: Kendall Austin
I.Inheritance of Human Genetic Characteristics
A.Genetic Variation
Define the following terms:
PedigreesA chart used to show the genetic connections between generations
PolygenicA trait may show dominant-recessive inheritance or incomplete dominance
Sex chromosomesDesignated with an X or Y contain the genes that deal with gender
AutosomesCode for other traits besides gender
CarriersIndividuals with one defective copy
Sickle-cell anemiaA genetic disorder which produces abnormal hemoglobin in red blood cells
AlbinismAbsence of skin pigmentations
Phenylketonuria (PKU)Where a missing enzyme leads to the buildup of phenylalanine which can in turn lead to mental retardation
GalactosemiaCaused by a defective gene failing to produce an enzyme necessary in the breakdown of milk
Duchenne muscular dystrophy (DMD),A muscle wasting disease
Hemophilia AA blood-clotting disorder
Red-green color
BlindnessResults in persons who cannot distinguish red from green in dim light
Multiple allelesWhere there are more than two possible alleles
CodominantIf a person inherits two alleles both protein types will be expressed on their red blood cells
EXERCISE 1 Visualizing human genetic variation
For each trait determined by a flip of the coin, record the genes donated by the mother, the genes donated by the father, and the resulting genotype of the baby. Also describe how the trait will appear in the baby (phenotype). Flip a coin as described in the lab manual to determine each trait.
Childs Name:Childs Sex:
TraitAllele from MotherAllele from FatherBabys GenotypeBabys Phenotype
1.Widows peakwwwwStraight
hairline
2.EyebrowsbBBbbushy
3.EyelashesLLLLLong
4.LipsTtTtthick
5.DimplesddddNo dimples
6.Nose shapeRRRRRounded
7.FrecklesffffNo freckles
8.Face shaperrrrround
9.EarlobeFfFfFree
10.Hair typeCCCCcurly
11.Eye sizeCCClarge
12.Mouth lengthLlLlaverage
13.Nose sizelLLlmedium
14.Hair colorBBBBDark brown
15.Eye colorBBBBDark brown
When you have determined all 15 traits for your baby, write a paragraph describing the babys phenotype.
The baby has a straight hairline with bushy eyebrows and dark brown eyes. Their hair is dark brown with long eyelashes and thick lips. No dimples litter their round face as their curly hairs shapes their large eyes. Their ears are free and they have no freckles.
In a random sample of 100 babies, how many children would you expect to have bushy eyebrows?
About 75 percent, since bushy eyebrows are a dominate trait.
How are these babies related to one another?
They all have allele for the shape of their eyebrows
In the case of 100 babies the following phenotypes resulted. What is the ratio?
PhenotypeNumber w/ TraitRatio
Bushy Eyebrows72
Thin Eyebrows28
B.Human Genetic Analysis
EXERCISE 2 Pedigree development
List the F2 phenotypes possible from the pedigree shown below.
Possible Phenotype(s)
Child 1Free (FF)
Child 2Free (Ff)
Child 3Free (Ff)
Child 4Attatched (ff)
What percent have free ear lobes?
If F-is free and f-is attached about 75% have free ear lobes
A pedigree can also be used to trace previous generations. What are the possible parent (P1) phenotypes of the above pedigree?
Possible Phenotype(s)
Paternal FatherFree (Ff)
Paternal MotherAttached (ff)
Maternal FatherFree (FF)
Maternal MotherFree or Attached (Ff)
EXERCISE 3 Autosomal inheritance
Two of the parents of the F1 individuals have genotypes that are shown in the figure below. Predict and fill in the answers for the other parents possible genotypes. What are the potential genotypes of the F2 generation?
RelationshipGenotype(s)
Paternal Grandmother
(Two possibilities)NN
Nn
Maternal Grandmother
(Two possibilities)nn
Nn
Child 1NN
Child 2Nn
Child 3Nn
Child 4nn
What are the possible parental genotypes of the F1 generation? Phenotypes?
GenotypePhenotype
Paternal FathernnSickle-cell anemia
Paternal MotherNNhealthy
Nncarrier
Maternal FatherNNhealthy
Maternal Mother Nncarrier
nnSickle-cell anemia
What percentage of the F1 individuals are normal? Are carriers?
Normal:0%
Carriers:100%
What percentage of F2 individuals are normal? Are carriers? Are affected?
Normal:25%
Carriers:50%
Affected:25%
Describe the symptoms of the genetic disorder you modeled.
This is a recessive disorder. Which means that it needs to have both of the recessive alleles for a person to be affected (nn). If one only has one recessive allele (Nn) then they are a carrier but do not have the disease themselves. Only the NN are completely healthy.
EXERCISE 4 X-linked inheritance
Two of the parents of the F1 individuals have genotypes that are shown in below. Predict and fill in the other parents genotype.
What are the possible parental genotypes of the F1 generation? Phenotypes?
RelationshipGenotype(s)Phenotype(s)
Paternal GrandmotherXNXnColor blind carrier
XnXnColor blind (less likely)
Maternal GrandfatherXnYColor blind
Child 1XNYnormal
Child 2XnXnColor blind
Child 3XnYColor blind
Child 4XNXnColor blind carrier
What is the percent probability of F2 individuals who are normal? Carriers? Affected?
MalesFemales
Normal:25%10%
Carriers:25%25%
Affected:50%30%
Describe the symptoms of the genetic disorder red-green color blindness.
It is caused by a defect in a gene on the X chromosome. It is a x-linked recessive disorder which means that in order for a person to have this they need to have both the alleles in the recessive form. Which is why it is more common in males. Men only have one X chromosome and if just that one has the defect then they will be color blind. For females, they have two X chromosomes and both of these need to carry the defect for them to be color blind.
C.Inheritance of Blood Groups
EXERCISE 5 Inheritance of blood groups
Is it possible for a child of blood type AB to be produced by two type O parents? Show your work in the Punnett square then explain.
OO
OOOOO
OOOOO
Produce Child of Type AB?No
Explain:
It is not possible because neither of the parents have the A or B allele.
In a case of disputed paternity, the child is type O, the mother is type B. What are the genotypes of the mother and child?
Genotype
MotherBO
ChildOO
Use Punnett squares to determine which of the following blood types could be the father. The first square is shown with answers as an example.
(HINT: Do not forget that a heterozygous versus a homozygous blood type may yield different results.)
IAi
iIAiii
iIAiii
IBi
iIBiii
iIBiii
Could he be the father?yes
Could he be the father?yes
Type ABIAi
IAIAIAIAi
IBIAIBIBi
Type BIBi
IBIBIBIBi
iIBiii
Could he be the father?yes
yes
EXERCISE 6 Blood type problems
Cross 1
What are the possible blood types with heterozygous type A father and heterozygous type B mother?
IAi
IBIAIBIBi
iIAiii
PercentageRatio
Blood Type:A25%
B25%1:1
AB25%
O25%
Cross 2
Is it possible to produce type O baby from type A father and type O mother?
IAi
iIAiIi
iIAiii
Could he be the father?yes
Does this evidence alone prove he is the father?
No, there are a lot of other genetic factors that need to be considered.
II.Bioethics and the Human Genome Project
Define the following terms:
GenomeThe haploid set of chromosomes in a gamete or microorganism
GenomicsThe discipline in genetics that applies to recombinant DNA
EXERCISE 7 Genetics and Society
In the space below, indicate the title of each article as well as a brief discussion (not a summary) of how the topics in the articles you chose may impact either you, your family or society as a whole.
Title:__Whose DNA is it anyway? Can genes be patented?
As a man, Im really kind of simple minded on this subject.
Title: Cloning
I wouldnt mind this. It shows that the world wants more of me ?
Title: Should newborns be genetically profiled?
Although I do not have children, I think it would be dangerous to genetically profile them. Sort of like racism, the child may have a genetic make up that severely differs from the genetics on the outside.
Summary Questions
1.Give examples of human traits that show these patterns of inheritance:
Dominant/Recessive:Cleft chin/no cleft chin
Incomplete Dominance:Wavy hair
Polygenic Inheritance:Skin color
Codominance:Blood types
4.Queen Victoria of England was a carrier of the genetic disorder which causes hemophilia A. The following diagram is a partial pedigree of her family. Use the information below to answer the next series of questions.
How many sons did Queen Victoria have?
4
Of her sons, what percentage were hemophiliacs?
25%
What percentage of her daughters were carriers of the hemophilia gene?
40%
Overall, who does hemophilia affect more, males or females?
males
5.What is The Human Genome Project?
A scientific research project that determines the sequence of chemical base pairs that make up DNA
6.What was the ultimate goal of the HGP?
To provide a complete and accurate sequence of 3 billion DNA base pairs that make up the human genome and to find all of the estimated 20,000 to 25,000 human genes.
7.What do you feel is the most important issue facing our society as a result of the HGP?
Ethical issues involving people seeking to alter or change their DNA.
