Lab Report: Developmental Biology and Human Molecular Genetics

Your Name:
SECTION ONE: HUMAN MOLECULAR GENETICS
Pre-Lab Questions
1). What do the letters on the outside of a Punnett square represent? What do the letters on the inside of a Punnett square represent?
The letters outside the Punnett square represents each parental genotype one on the rows and one on the column
The letters on the inside of a Punnett square represent represents the predicted frequency of all of the potential genotypes among the offspring each time reproduction occurs.
2). Suppose you live in a population which expresses curly, straight, or wavy hair. Assume this is a monogenic trait. Curly- and straight-haired individuals are homozygous, while wavy-haired individuals are heterozygous. Based on the Introduction information, what pattern of inheritance most likely causes these phenotypes?
Curly and straight hair represents the dominant traits while having wavy hair is the recessive trait.
3). The following equation can be used to determine the total number of possible genotypes for a gamete using any number of heterozygous genes: 
2g = Number of possible genotypes
where “g” is the number of heterozygous genes. For example:
1 gene: 21 = 2 gamete genotypes
2 genes: 22 = 4 gamete genotypes
3 genes: 23 = 8 gamete genotypes
Consider the following genotype: Ee Ff AA. How many different gamete genotypes can be produced from the Ee Ff AA genotype?
1 Gamete genotypes.
4). Phenotypes, such as eye color, are controlled by multiple genes. This type of inheritance is called polygenic. If eye color was controlled by the number of genes indicated below, how many possible genotypes would there be?
1 gene: 21 = 2 gamete genotypes
Thus, the number of genes (g) = 2g
10 Genes: 1024
15 Genes: 32768
1 Genes: 1048576
5). Compare and contrast monogenic disorders and chromosomal disorders.
Monogenic disorders are disorders caused by variation in a single gene and are usually recognized by their striking familial inheritance patterns. A single gene defect commonly does not cause the chromosome structure or number to be abnormal. An individual can have normal genes, but, he or she can also have extra copies of genes due to a chromosome abnormality. The extra copies can cause the genes to malfunction. An individual can possess normal chromosomes in number and structure, but still express a disease, disorder, or condition due to a mutation in one or more of the genes on the chromosomes. A single gene defect usually does not cause the chromosome structure or number to be abnormal.
6). Describe the basic storage mechanism for DNA using the words histone complex, nucleosome, chromatin, and chromosome.
Chromatin is a matter within a chromosome comprising of DNA and protein. The primary proteins in chromatin are histones. Histones help in packaging the DNA in a compact form that fits in the cell nucleus. Changes in chromatin structure are linked to DNA replication and gene expression.
Exercise 1: Patterns of Inheritance
Post-Lab Questions
 Part 1: Monohybrid Cross
Record Punnett squares for Crosses 1A and 1B here.
* Earlobes: free earlobes (E) and attached earlobes (e)
Ee-male heterozygous
EE-female homozygous

E

e

E

EE

Ee

E

EE

Ee

b. Freckles: freckles (F) and no freckles (f)
Female-no freckles ff
Male; has freckles homozygous FF

F

F

f

Ff

Ff

f

Ff

Ff

What are the resulting phenotype and genotype ratios in Cross 1A? Use your results to support your answer.
Genotypic results: EE, Ee, EE, Ee, thus 2EE:2Ee, which represents genotypic expression chance of 50%
All the genotypic c outcomes gave the dominant expression of the gene, which means all outcomes will have free earlobes (E).
Based on this Punnett square, what percentage of the offspring will have attached earlobes? Use your results to support your answer.
None will have attached earlobes because all, outcomes have the dominant gene of free earlobes (E). Thus, the attached earlobes expression is 0%.
What are the resulting phenotype and genotype ratios in Cross 1B? Use your results to support your answer.
Genotypic rations: Ff, Ff, Ff, Ff, which is 1:1:1;1
Based on this Punnett square, what percentage of the offspring will have freckles? Use your results to support your answer.
There is a 100 % chance of having outcomes with freckles because all genotypic combinations have dominant gene F for freckles.
Record the Punnett square for Cross 2A here.
A male homozygous for free earlobes and heterozygous for freckles
. A female heterozygous for free earlobes and heterozygous for freckles
Male genotype: EE Ff
Female genotype: Ee Ff


EE

Ff

Ee

EE, Ee

Ff, Ee

Ff

EEFf

Ff, Ff


Record the possible gametes produced in Part 2: Step 1. Free earlobes +freckles, free earlobes+ no freckles, attached earlobes +freckles, attached earlobes+no freckles
What were the resulting phenotype and genotype ratios in Cross 2A?
The ratio is 2:2,
Based on this Punnett square, what percentage of the offspring will have freckles? Use your results to support your answer.
Yes, there is a chance that there will be attached earlobes among offspring due to the availability of w two recessive genes.
Part 2: Dihybrid Cross
Record your results from Part 2: Step 1 here.
Male genotype: EE, Ff - Homozygous Free earlobe and heterozygous for freckle
Female genotype: Ee, Ff-heterozygous for free earlobes and heterozygous for freckles
Record the possible gametes produced in Part 2: Step 1.
Record the possible gametes produced in Part 2: Step 1. Free earlobes +freckles, free earlobes+ no freckles, attached earlobes +freckles, attached earlobes+no freckles.
 

 EE

Ff 

 

 

Ee 

 EEEe

 FfEe

 

 

Ff 

 EEFf

 FfFf

 

 

Record Your Punnett square from Step 2 here.
What is the phenotypic ratio for possible offspring?
Phenotypic ration: 1.EEEe (Free earlobes with no freckles): 1 FfEe (Free earlobe with freckles):1 EEFf (Free earlobes with freckles) 1: FfFf (with freckles or with no freckles, and no free earlobes
Is it possible for the possible offspring to have attached earlobes? Use your results to explain your answer.
Yes, there is a chance that there will be attached earlobes among offspring due to the availability of w two recessive genes.
Part 3: Sex-Linked Inheritance
Record Punnett squares for Crosses 1A and 1B here.
a.
male/female

XH

XH

Xh

XHh

XHh

Xh

XHh

XHh

b.

Xh

Xh

XH

XHh

XHh

XH

XHh

XHh

What are the resulting phenotype and genotype ratios per sex cell from Cross A? Use your results to support your answer.
1:1
Will any of the daughters from Cross A exhibit the symptoms of hemophilia? Use your results to explain your answer.
Yes they will carry the hemophilia chromosome
Will any of the sons from Cross A exhibit symptoms of hemophilia? Use your results to explain your answer.
No, they will not but may carry the chromosome.
What percent of the offspring from Cross A can pass the allele for hemophilia to future offspring? Use your results to support your answer.
50%
What are the resulting phenotype and genotype ratios per sex cell from Cross B? Use your results to support your answer.
1:1
Will any of the daughters from Cross B exhibit the symptoms of hemophilia? Use your results to explain your answer.
They will.
Will any of the sons from Cross B exhibit symptoms of hemophilia. Use your results to explain your answer.
They will not exhibit the symptoms
What percent of the offspring from Cross B can pass the allele for hemophilia to their future offspring? Use your results to support your answer.
50 % due to the presence of
Part 4: Codominance
Record Punnett squares for Crosses 1A and 1B here.

I

A

IA

IA

IA

IB

IB

IB


i

B

i

i

iB

i

ii

iB

What is the ratio of phenotypes that result from Cross 1A? Write your ratios in the order of the phenotypes A, B, AB, and O.
What is the ratio of phenotypes that result from Cross 1B? Write your ratios in the order of the phenotypes A, B, AB, and O.
Type O blood or type B blood.
List the possible genotypes that can be responsible for each blood phenotype. 
Can have type O or type B blood.
Exercise 2: Genetic Disorders
Post-Lab Questions
Part 1: Monogenic Disorders
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