Mendelian Genetics Flashcards
Analysis of the inheritance of physical characteristics from parent to offspring
Mendelian Genetics
Monohybrid crosses yield a ___ phenotypic ration and a ___ genotypic ratio
3:1 and 1:2:1
___ prove the Law of Dominance and Law of Segregation
Monohybrid Crosses
___ yield a 9:3:3:1 phenotypic ration and a 1:2:1:2:4:2:1:2:1 genotypic ratio
Dihybrid Crosses
Dihybrid Crosses prove the ____
Law of Independent Assortment
Mating experiment in which the inheritance pattern of a single trait is followed
Monohybrid Cross
Mating experiment in which the inheritance of two traits is followed simultaneously
Dihybrid Cross
A genetic cross in which two parental organisms are genetically identical
Self-Cross
The pair of genetic factors an organism possesses for a certain trait
Genotype
The observable physical manifestation of a certain trait
Phenotype
One of the possible variations of a trait’s expression
Allele
The allele of a gene that is observed in hybrid organisms
Dominant
The allele of a gene that is not observed in hybrid organisms
Recessive
Describes a genotype in which the two alleles are identical
Homozygous
Describes a genotype in which the two alleles are different
Heterozygous
A genetic cross in which an organism of unknown genotype is crossed with an organism known to be homozygous recessive
Test-Cross
A chart that depicts the results of a genetic cross
Punnett Square
Neither allele is truly dominant. Heterozygous organisms exhibit an intermediate phenotype
Incomplete Dominance
Both alleles exhibit dominance, neither is masked. Heterozygous organisms exhibit both alleles simultaneously
Codominance
More than two potential variants/alleles exist in the population. There are more possible genotypes for these traits
Multiple Alleles
Many characteristics are controlled by the combined influence of several genes. The result is a very broad range of phenotypes for the characteristic. E.g. Pigmentation
Polygenic Inheritance
One gene/locus may affect several phenotypes
Pleiotropy
Less than 100% of the individuals who are genetically expected to exhibit a certain phenotype actually exhibit that phenotype
Incomplete Penetrance
The degree to which a trait is expressed varies greatly among individuals bearing the associated genotype
Variable Expressivity
Sex can prevent the expression of some autosomal genes (Ovarian development)
Sex Limited
Sex (Male v Female) can modify the expression of some autosomal genes (Pattern Baldness)
Sex Influenced
Two non-allelic genes interact. One genotype masks (prevents) the expression of a phenotype for the other gene
Epistasis
There may be multiple genetic sources of the same mutant phenotype
Complementation
In some genes, the mother’s phenotype influences how the offspring’s genotype is expressed as a phenotype
Maternal Effect
Way of “marking” a gene for cellular recognition.
Imprinting
Adding ___ to the cytosine nucleotides is one way to mark/imprint a gene
Methyl groups
During gamete formation or early embryonic development, a gene can be inactivated
Epigenectics
The Slipper limpet (a sea mollusk) embryo develops a certain gender in response to the surface upon which the embryo lands. If it lands on sand or on a male, develops as a female. If it lands on a female, it develops as a male
Environmental Determination
Refers to a pair of chromosomes that have different composition
Heteromorphic
Refers to homologous chromosome pairs, not direct determinants of sex
Autosomes
The sex/gender possessing a homologous pair of sex determination chromosomes
Homogametic
The sex/gender possessing a mismatched (hetermorphic) pair of sex determination chromosomes
Heterogametic
In ___ the ratio of X chromosomes to autosomes is the basic determining factor
Drosophila
XX Numerator homodimers are a transcription activator for a gene on the X chromosome called __
Sxl
The ___ is made early in female development. It stimulates the activity of a second gene, called tra
SXL peptide
Expression of __ directs the editing/splicing of a third gene, dsx
Tra
When tra is active, __ is spliced in a different way, ultimately leading to the molecules needed for male structures
Dsx
___ plays a significant role in the development of sex phenotypes in Drosophila
Epistasis
All early embryos have a ___ that includes a medulla and a cortex
Pre-gonad
Can be induced to develop testes
Medulla
Can be induced to develop into ovaries
Cortex
If ___ gene is present, it codes for the ___
SRY, Testis Determination Factor (TDF)
___ boosts androgen gene expression
TDF
TDF also serves boosts the expression of an autosomal gene called ___
MIS
___ destroys ovarian tissue that was beginning to form in the
MIS
___ also suppresses the expression of the Ovarian development genes
MIS
X chromosomes contain a gene called Xic, it codes for an RNA called ___
Xist= X inactivation specific transcript
Methylation is an ___ on the X chromosome
Imprint
Permanently condensed X chromosomes
Barr Bodies
