Test 3 - Mendelian Genetics And Inheritance Flashcards
What are Mendel’s 3 laws and describe them?
Law of segregation
—Factors for each trait segregate such that each gamete only carries one factor for each trait
—Basically, one allele comes from one parent and another comes from the second
Law of independent assortment
—Each factor that segregates does so independently
Law of dominance
—Some factors are dominant, some are recessive, and the dominant trait will always be expressed when present
What is an allele?
Different forms of a gene
—I.e. flower color is an allele
Relating to the law of independent assortment, the number of combinations therefore depends on what?
Number of alleles
Dominance does not imply superior or normality, but what?
Simply preferred expression
*They are not always the most common in a population, they can be rare
Genetic variability and selection are important, why?
Maintaining genetic adaptability to variable environmental factors
*Resistance to extinction
**Example - Bananas are basically clones and very prone to disease
What is an example of non-Mendelian genetics?
Blood types
- A - dominant
- B - dominant
- AB - dominant
- O - recessive
What is incomplete dominance?
Some alleles will both express, like snapdragons. Red and white snapdragons produce pink snapdragons
What is mosaicism?
Different cells in the body have different genotypes and thus express different phenotypes
—Calico cats
Females have two X’s, and one of their X’s becomes what?
Barr body - Not expressed
Some female cats have both an orange X and a black X, and their paired-yet-different-colored Barr body is not expressed. What is the result?
Calico cats with black and orange fur
A Y-linked trait is passed onto whom?
Males only
Explain X-linked dominant traits.
Father with dominant X will pass it to his daughters (X from Dad, X from Mom), but not his sons (B/c they get his Y).
Mother would give it to 1/2 to all offspring depending on if she is homozygous or heterozygous. Male and/or female.
See slide in pictures if needed
Explain X-linked recessive traits.
Predominate in males
However, homozygous females can be affected.
Carrier mother could pass ailment to a son and also make a daughter a carrier if father is unaffected.
*See slide in pictures if needed
What is extra nuclear inheritance?
Factors passed from cytoplasm
—Mito DNA from ova
What is gene conversion?
Recombination where DNA sequence from one homologous chromosome can replace a sequence on its counterpart
Example: Paternal copy of a gene can be edited in to replace the maternal copy.
