Inheritance Flashcards
What is inheritance?
The acquisition of characteristics or qualities by transmission from parent to offspring
How are traits passed on?
By factors
What is the law of segregation?
When alleles in each parental plant segregate from one another during formation of reproductive cells
How do alleles exists?
In pairs
What is a allele?
Alternative form of a gene
Observed traits are called
Phenotype
What is a Recessive trait?
It doesn’t show up in an individual can still be passed to the next generation
Each single phenotype still exhibits what ratio?
3:1
What is the law of independent assortment?
Traits are inherited independently of each other
Location of a gene
Locus
What are the five basic patterns of inheritance?
Mendelian pedigree patterns
Name them (pedigree)
- X linked recessive
- X linked Dominant
- Autosomal Dominant
- Y linked
- Autosomal Recessive
Characteristics of Autosomal Dominant?
- Affects all generations (multiple)
- Affects male and female
- Can be passed from any gender
- Affected child has affected parent
Example of Autosomal Dominant Diseases
Huntingtons and Achondroplasia
Numerals uses
YOU KNOW THIS
Characteristics of Autosomal Recessive Disease
- Affects any gender
- Parents are usually unaffected
- Parent is a carrier of the disease
Example of Autosomal Recessive Pattern
Cystic fibrosis and sickle cell anemia
X linked Recessive Characteristics
- Affects mainly males
- No male to male transmission
- Mother is normally a asymptomatic carrier
- Parents usually unaffected
Examples of X- linked Recessive Pattern?
Haemophilia A, Red green color blindness
Characteristics of X linked Dominant Pattern
Mating of affected male and normal female: All daughters affected and all sons normal
Mating of affected female and normal male: All offspring’s have a 50% chance of getting the disease
Example of X linked Dominant disease
Incontinentia pigmenti
Complications to Mendelian inheritance
- Skewed X- inactivation
- Incomplete penetration
- Linkage
- Mitochondrial inheritance
- New mutations (mosaicism)
- Late onset disease
- Parental origin (imprinting)
- Lethal alleles
- Variable expression
What is Skewed X-inactivation?
One mechanism by which women may be affected by an x-linked recessive disease while having just one mutant copy of the allele
What is Mitochondrial inheritance?
All offspring of affected of mother are affected. Affected father cannot transmit disease. Mutations in mitochondrial DNA
What causes the Mitochondrial inheritance
Ovum has a lot of mitochondria
Sperm very little cytoplasm
What does linkage violate?
Mendel’s law of independent assortment
What is incomplete penetrance?
Individual inherits the mutant gene but does not express the disease
What is late onset disease?
Mutant allele inherited but disease not present at birth
Examples of late onset
Huntington’s disease, hereditary cancers
What is variable expression?
All patient express the disease but they may express all symptoms or only a few
Example of variable expression?
Marfan’s syndrome
