Extensions of Mendelian inheritance 4 Flashcards
Mendelain Inheritance
Refers to inheritance patterns that obey the law of segregation (3:1 ratio) & the law of independent assortment (9:3:3:1 ratio)
______________ alleles usually carry mutant alleles
Recessive
What are the 3 ways dominant mutant alleles exert their effects?
- Gain-of- function
- Dominant- negative mutations
- Haploinsufficiency
Gain-of-function mutations
Change the gene so that it gains a new or abnormal function
Dominant-negative mutations
Change a protien such that the mutant protein acts against the normal protein
Haploinsufficiency
Heterozygote (one with normal allele & mutant allele) exhibits an abnormal or disease phenotype
Ex. Having extra fingers & toes
Traits may skip a generation due to ____________ & vary in their expressivity
Incomplete penetrance
Incomplete Penetrance
When an allele is expected to cause a certain trait but doesn’t
The ____________ may also have an effect on the phenotype
Environment
Norm of reaction
The effect of the environment on a phenotype
Incomplete dominance
Occurs when two alleles produces a phenotype that is a mix of the two alleles (Ex. Crossing red and white flowers and get a pink flower)
Overdominance
When a heterozygote has greater reproductive success than either of the homozygotes
In overdominance _____________ is better than _________ because you have a better advantage of survial
Heterozygous is better than homozygous
Codominance
When two alleles are both dominant and both traits are expressed in a heterozygous person
(Ex. ABO blood type IAIB)
Multiple allele
When there is 2 or more alleles
What is the universal donor blood type?
Blood type O because its geneotype (ii) is recesive and has no antigens so it can be taken up by either type A or type B blood types
What is the universal blood acceptor?
Type AB blood type because its codominant between type A & type B blood type so it can accept A or B blood type
How does gender affect the type of traits a person have?
- Sex-influenced
- Sex-limited
Sex-influenced
When an allele (trait) dominant in one gender but recessive in the other gender (occurs by being heterozygous)
(Ex. Baldness its dominant in men but recessive in females)
Sex-limited
Traits that are only for one gender (Ex. Girls have eggs & guys have sperm)
Lethal Allele
An allele that has the potential to cause death of an organism (usually inherited recessively)
An essential gene
One that must be present for survival
Pleitropy
Occurs when the expression of a single gene has two or more affects on its phenotype (when one gene has many traits)
What an example of pleiotropy?
Cystic fibrosis because it contains a protein called CFTR which transports Cl- ions & when that CFTR gene has mutation the CTFR gene can cause thick mucus in lungs, salty sweat on skin , no enzymes in the pancreas, etc
More than one gene affects a trait but you only have to look at the single gene where the two traits _____________
Are different
Gene Interaction
When two different genes interact to influence the outcome of a trait
A gene interaction can exhibit __________ & ____________
Epistasis & Complementation
Epistasis
When allels of one gene mask the phenotype of alleles of another gene
Complementation
When two recessive parents produce an offspring with a dominant trait
_______________ can result from recessive epistatic because the recessive epistatic is recessive if the offspring has any dominant alleles that aren’t mask by the recessive alleles then the dominant alleles is exxpressed
Complementation
Due to _________________ loss-of-function alleles may have no effect on the phenotype
Gene redundancy
Gene Redundancy
When one gene can compensate for the lost of function in another genes (If one genes losses its function the other gene can make up for both of them)
Paralogs
Copies of genes but they aren’t identical (like homologs) (when one gene is missing a paralog may be able to carry on without it)
