NON-MENDELIAN GENETICS: GENE INTERACTIONS AND MODIFICATIONS OF MENDELIAN RATIOS Flashcards
MENDEL’S LAWS OF INHERITANCE ARE ____________
FOUNDATIONS OF GENETICS
MENDEL’S LAWS OF INHERITANCE ARE FOUNDATIONS OF GENETICS:
- PRINCIPLE OF UNIT FACTORS
- PRINCPLE OF DOMINANCE
- LAW OF SEGREGATION
- LAW OF INDEPENDENT ASSORTMENT
In Mendel’s work on pea plants, each gene came in just__________ versions, or ______, and these alleles had a nice, clear-cut dominance relationship.
two different; alleles
In the real world, genes often come in many (alleles). Alleles aren’t always ____________ to one another, but may instead display codominance or incomplete dominance.
fully dominant or recessive
Non-mendelian genetics involves the ___________ that does not follow Mendel’s laws.
pattern of inheritance
When scientists began exploring more and more test crosses, they observed that there are ________ that do not match up with Mendel’s laws.
several traits
in Mendelian inheritance ______ dominates the other
one gene
in Mendelian, dominant allele _____ on the organisms while
the recessive allele will ______
appear; not appear
in Non-Mendelian, ______ come together and mix
Many genes
in Non-Mendelian, Genes from both parents can _______ in organisms, causing the inheritance to become uncertain or hard to predict
mix or show up
a term that describes the joint role of multiple genes in determining phenotypic variability
GENE INTERACTIONS
GENE INTERACTIONS:
I. Allelic interactions
II. Non-allelic interactions
This occurs when one gene control one trait, such as in various forms of dominance relationship.
Allelic interactions
Allelic interactions:
A. Complete dominance
B. Incomplete dominance
C. No dominance
A condition wherein the allele regarded as dominant completely masks the effect of the allele that is recessive.
Complete dominance
in complete dominance, Heterozygotes are _________ to the homozygous dominant
phenotypically identical
in complete dominance, F2 phenotypic ratio is _____
3:1
incomplete (means) dominance
partial
The dominant character expresses itself but not completely.
INCOMPLETE DOMINANCE
in incomplete dominance, the case is, dominance is ______ and the progeny _____ resemble any of its parents.
absent; does not
in incomplete dominance, Heterozygotes are __________ between the two homozygous types of the parents
phenotypically intermediate
in incomplete dominance, F2 Phenotypic Ratio is _____
1:2:1
No particular gene is dominant
NO DOMINANCE
No particular gene is dominant, such as:
→ Codominance
→ Lethal genes
Codominance means ______
mutual/together
Both the dominant alleles are equally strong & thus expressed in the offspring simultaneously.
Codominance
in Codominance, Heterozygotes exhibit a _____ of the phenotypic
characters of both homozygotes instead of a single intermediate expression.
mixture
in Codominance, Characters with two forms are displayed at ________
the same time
in Codominance, F2 Phenotypic Ratio is _______
1:2:1
These are genes that can cause the death of an organism.
Lethal Genes
Lethal Genes Type:
→ Dominant lethals
→ Recessive lethals
These are the alleles whose presence is required in one copy in an entity for them to turn fatal
Dominant lethals
Example: Huntington’s disease
Dominant lethals
those that are lethal when in homozygous recessive condition
Reccesive lethals
effects of recessive genes are sufficiently drastic to kill the bearers of certain genotypes
Reccesive lethals
examples are sickle cell anemia and albinism
Reccesive lethals
