Pattern of Inheritance Flashcards
What is gene?
A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA or RNA.
What is allele?
The alternative versions of a gene that produces distinguishable phenotypic effects
What is a locus?
A specific place along the length of a chromosome where a given gene is located.
What is homozygous?
Having 2 identical alleles for a given gene.
What is heterozygous?
Having 2 different alleles for a given gene.
What is genotype?
Set of alleles.
What is phenotype?
Physical traits determined by set of alleles.
What is dominant allele?
Expressed in both homozygous and heterozygous.
What is recessive allele?
Expressed only in homozygous recessive.
What is F1 generation?
The first hybrid offspring in a series of genetic crosses.
What is F2 generation?
Interbreeding of the F1 hybrid generation.
What is Mendel’s law of hereditary?
Law of segregation
Law of Independence Assortment
What is Law of segregation?
During gamete formation, the two alleles at a gene locus segregate from each other, results in each gamete having an equal probability of containing either allele.
Explain how Law of segregation works.
Each homozygous parent in the parental generation forms only 1 kind of gamete.
The heterozygous offspring forms two kinds of gametes.
Self pollination of the F1 offspring forms F2 offspring with a 3:1 phenotypic ratio.
What is law of independent assortment?
The alleles of two or more different genes get sorted into gametes independently of one another.
What is monohybrid cross?
A genetic cross between two individuals with homozygous genotypes.
What is dihybrid cross?
A genetic cross between two individuals with heterozygous genotypes.
What is test cross?
Used to identify whether an organism exhibiting a dominant trait is HM or HT for a specific allele.
How does test cross work?
Always cross with HZ recessive trait
If ratio 1:1, F1 is HT
If 100%, F1 is HZ
What is backcross?
Mating a hybrid with one of its parents (HZ dominant or HT)
What is reciprocal cross?
A cross with phenotype of each sex reversed as compared with original cross.
Autosomal gene - same offspring genotype
X linked gene - different offspring genotype
What is a codominant?
Condition in a heterozygote where both alleles are equally dominant and both exhibit their effect in phenotype in separate, distinguishable ways.
What is incomplete dominance?
Phenotypes of F1 hybrids is between the phenotypes of two parental varieties.
Recessive allele not fully masked by dominant allele.
What is polygenes?
Each individual gene makes a small contribution to organism’s phenotype.
What is epiptasis?
Type of gene interaction in which a gene at one locus alters the phenotypic effects of another gene at another locus.
When is a gene epiptastic?
Its presence suppress another gene’s effect on another locus.
What is the name of suppressed gene?
Hypostatic.
What is multiple allele?
Three or more allele for a particular gene.
What is lethal genes?
Genes which result in the reduction of viability of an individual.
Can be dominant or recessive, but rapidly eliminated.
Not expressed until reproductive age.
What is linked genes?
Genes located on the same chromosome that tend to be inherited together unless crossing over occurs.
What is parental type offspring?
Offspring with phenotype matching one of the parental phenotypes.
What is recombinant type offspring?
Offspring with non-parental phenotypes (new combinations of traits).
How to find recombinant frequency?
Number of recombinants/total offspring x 100%
What is genetic mapping?
Genetic map of chromosomes based on recombination frequencies.
How is distance between genes expressed?
1 centimorgan = 1% recombinant frequency
What is sex linkage?
Sex linked gene/X linked gene is when a gene carried on the X chromosome.
Female - XX
Male - XY
Mothers pass sex linked alleles to who?
Both sons and daughters
Fathers pass sex linkage alleles to who?
Daughters only.
What is gene pool?
Sum of population’s genetic material at a given time.
What is the Hardy-Weinberg equilibrium?
The genetic variation in a population will remain constant from one generation to another with absence of disturbing factors.
What are the conditions of HW equilibrium?
No mutations - no new alleles
Large gene pool - large population
Random mating
No migration - no allele exchanging
No selection - not favoring one genotype
Evolution doesn’t occur when?
Non random mating
Change in genotype frequency
How to calculate allele frequency?
p + q = 1
How to calculate genotype frequency?
p2 + 2pq + q2 = 1
