Genetic Disorders

Huntington’s Disease: dominant; HH or Hh

Alzheimer’s: dominant; AA or Aa

Sickle-Cell Anemia: recessive; ss

Cystic Fibrosis: recessive; cc

Albinism: recessive; aa

Fragile-X:(x linked dominant) XfXf or XfX for females, XfY for males

Muscular Dystrophy:(x linked recessive(rare for females)) XmXm for females, XmY for males

Hemophilia:(x linked recessive(rare for females)) XhXh for females, XhY for males

Ocular Albinism:(x linked recessive (women usually do not inherit if only on one X) XoXo for women, XoY for males

Color Vision Deficiency:(x linked recessive(rare for females)) XcXc for females, XcY for males

A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

Vocabulary

• Genotype– the genetic constitution of an individual organism.
•  Phenotype– the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.
• Homozygous – having identical alleles at corresponding chromosomal loci
• Heterozygous – having dissimilar alleles at corresponding chromosomal loci
• Dominant – most important, powerful, or influential.
• Recessive -relating to or denoting heritable characteristics controlled by genes that are expressed in offspring only when inherited from both parents, i.e., when not masked by a dominant characteristic inherited from one parent.
• Allele– one of two or more alternative forms of a gene that arise by mutation and are found atthe same place on a chromosome.
• Trait– specific characteristic of an individual
• Gene– sequence of DNA that codes for a protein and thus determines a trait; factor that is passed from parent to offspring
• Punnett Square– diagram that can be used to predict the genotype and phenotype combinations of a genetic cross
• Pedigree– a chart that shows the presence or absence of a trait according to the relationships within a family across several generations
• Inheritance patterns– trace the transmission of genetically coded traits, conditions, or diseases to offspring
• Hybrids– The offspring of crosses between parents with different traits
• Polygenic traits– Traits controlled by two or more genes
• Sex-linked gene– a gene located on a sex chromosome
• Genome– the full set of genetic information an organism carries in its DNA

How to Create A Pedigree

 

circles – female

squares – male

triangle – unknown/unidentified

line through shape – carrier

filled in shape – has disease

line connecting 2 people – had children

line going down from the connecting line – children of the 2 people above

dotted line – same person

How to determine genotype and or phenotypes of parents based on background info or family info (parents or children)

Create a pedigree for the family.

If a trait passes directly from parent to child, it is most likely dominant.

If a trait skips generations or seams to appear randomly, it is most likely recessive.

If the trait is a blend of the parent’s traits, than it is neither dominant nor recessive.

A dominant trait will appear as the phenotype if the person is homozygous dominant or heterozygous

A recessive trait will only appear as the phenotype if the carrier is homozygous recessive.

Works Cited

Works Cited

Bailey, Regina. “What Is Incomplete Dominance in Genetics?” About.com Education. N.p 16 Feb. 2016. Web. 20 Feb. 2016.

“Dihybrid Crosses: Crosses That Involve 2 Traits.” Biology Corner. N.p., n.d. Web. 22 Feb. 2016.  

“Huntington’s Disease.” Genetics Home Reference. US National Library of Medicine, June  2013. Web. 5 Jan. 2016.

Lobo, Ingrid. “Environmental Influences on Gene Expression.” Nature Education. N.p., 2008. Web. 15 Feb. 2016.

Miller, Kenneth R., and Joseph S. Levine. Biology. Upper Saddle River, NJ: Prentice Hall,       2000. Print.

“Rh Factor Blood Test.” – Mayo Clinic. N.p., n.d. Web. 01 Mar. 2016. <http://www.mayoclinic.org/tests-procedures/rh-factor/basics/definition/prc-20013476&gt;.

Scoville, Heather. “Codominance – Evolution Definition.” About.com Education. N.p., 29       June 2015. Web. 16 Feb. 2016.

Punnett Squares

Using the parent’s two alleles for a specific trait, you line one parent’s alleles on the top of a 4 square box the other parent’s on the side. Then, using the alleles, combine them to make 4 different ‘children’ or combinations of alleles. 

To create a two factor cross (Dihybrid cross) 

1: First determine what alleles would be found in all the possible gametes that each parent could produce. (In this example we are crossing RrYy and RrYy. Round/wrinkled and yellow/green. In this case round and yellow are dominant and wrinkles and green are recessive). 

2: Next determine the gametes by using the FOIL method for each of the parent’s alleles. (Front, Outside, Inside, Last) 

3: Then set up a 4 by 4 punnett square, and place the alleles for one parent on top, and one the other parent’s alleles on the left side of the square.

4: Finally write the genotypes of the F1 offspring in each of the boxes.  

 

 1: In the case of a incomplete dominance cross create your punnett square as usual with one parent’s alleles on the top and the other parent’s alleles on the side. ( In this example we are using RR and WW. Red and White.)

2: Then cross the alleles in the boxes. In this case, we create four heterozygous RR offspring. Because the parents alleles are neither dominant or recessive over the other, the flowers will create a combination of each. In this case, the offspring are pink.

  
 

X-Linked Diseases/Traits

Blood Type

 

Blood types including rH factor
Types: A, B, O, AB
Type A: Ao, AA
Type B: Bo, BB
Type O: oo
Type AB: AB

Rh Fator:
Dominant – Rh Positive
Recessive – Rh Negative

“Rhesus (Rh) factor is an inherited protein found on the surface of red blood cells. If your blood has the protein, you’re Rh positive. If your blood lacks the protein, you’re Rh negative.

Rh positive is the most common blood type. Having an Rh negative blood type is not an illness and usually does not affect your health.”
– http://www.mayoclinic.org/tests-procedures/rh-factor/basics/definition/prc-20013476

Common Human Traits

Length of eyelashes:

Long dominant, short recessive

Shape of eyebrows:

Thick dominant, thin recessive

Position of eyebrows:

Separated dominant, joined recessive

Size of nose:

Large: dominant

Medium: heterozygous

Small

Shape of lips:

Thick: dominant

Normal: heterozygous

Thin: recessive

Size of ears:

Large: Homozygous Dominant

Normal: Heterozygous

Small: Homozygous recessive

Size of mouth:

Large: homozygous dominant

Medium: Heterozygous

Small: homozygous recessive

Freckles:

Present dominant, absent recessive

Dimples:

Dimples dominant, no dimples recessive

Shape of face:

Oval dominant, square recessive

Cleft in chin:

No cleft dominant, cleft recessive

Hair:

Curly: homozygous dominant
Wavy: heterozygous
Straight: homozygous recessive

Widows peak:

Widow peak dominant, straight hairline recessive

Spacing of eyes:

Close: dominant

Normal: heterozygous

Far: recessive

Shape of eyes:

Almond dominant, round recessive

Position of eyes:

Straight dominant, slant recessive

Size of eyes:

Large: dominant

Medium: heterozygous

Small: recessive

Gender:

50% male

50% female