Chapter 4a: Modification of Mendelian Ratios Flashcards
what are Mendel’s 4 postulates?
- unit factors exist in pairs
- dominance/ recessiveness
- paired unit factors segregate
- independent assortment
2 things that describe a loss-of-function mutation
- premature stop codon
2. misshapen active site
2 things that describe a gain-of-function mutation
- better enzymatic performance
2. gene duplications lead to gene family proliferation
a neutral mutation is AKA
a synonymous mutation
when no dominance exists between alleles that is known as
variation
an intermediate phenotype is?
one that results from a cross between parents with contrasting traits
give an example of an intermediate phenotype
R1R2 gives a pink color
what type of dominance describes a trait where neither allele is dominant?
incomplete or partial dominance
codominance describes
-influence of both alleles that is clearly evident
what are the two forms of glycoproteins that exist
M and N
mating between two heterozygous individuals can produce
children with all 3 blood types (A, B, AB)
inadequate substrate for enzyme that causes h substance to be incompletely formed is due to a rare mutation in the _____ gene.
FUT1
lethal genes represent…
essential genes
essential genes are
- absolutely required for survival
- tolerated if heterozygous
what type of mutations result in homozygous recessive individuals that do not survive?
recessive lethal alleles
lethal alleles are inherited in a
recessive manner
the presence of one copy of this type of allele results in death
dominant lethal allele
Huntington’s disease is an example of a
dominant lethal allele
combining modes of inheritance modifies the 9:3:3:1 ratio because of
product law
epigenesis is defined as
a progression in the complexity of a phenotype as development increases
complex phenotypes come from…
undifferentiated cells
epistasis is when the…
expression of one gene masks/modifies effect of another gene pair
in epistasis a gene masks the
phenotypic effects of another gene
effects of epistasis can be inferred if
- inheritance is discontinuous
- genes are not linked
- complete dominance exists
- all P1 crosses involving homozygotes/ F1 are heterozygous
- F2 is focus of analysis
complementation analyses allows one to determine if
two mutations with a similar phenotype are different alleles of the same locus
two characteristics of complementation analysis
- screens number of individual mutations resulting in the same phenotype
- can predict the total number of genes determining a trait
a complementation group shows..
all mutations present in any single gene
complementation analyses is what type of genetic study?
a special form of test cross
define pleiotropy…
the expression of a single gene that has multiple phenotypic effects
give an example of pleiotropy
marfan syndrome
-affects eyes, aorta, bones, and other tissues that use fibrillin
