Genetics Flashcards
(21 cards)
Character def.
A heritable feature that varies among individuals of a population
Trait def.
Heritable variants of a character in an organism
Phenotype def.
Observable traits in an organism, that arises from the interaction of the organism’s genotype with the environment.
Gene def (genetics)
The basic unit by which genetic information is passed from parents to offspring. It is a DNA sequence usually residing at a specific locus on a particular chromosome. It aids in the development of 1 or more phenotypes by coding for specific proteins or peptides.
Locus def.
A fixed position on a chromosome.
Alleles def.
Alternative versions of genes. Reside on same locus of different chromosomes, can have different nucleotide sequences.
Genotype def.
The genetic makeup or set of alleles for a gene in an organism.
Dominant allele
At heterozygous state, the allele that completely masks expression of other allele and determines the organism’s phenotype.
Recessive allele
The allele that does not exhibit any noticeable effect on phenotype at heterozygous state.
How are pure breeding plants obtained?
self pollinating over many generations, producing only the same variety as the parent plant
Pure lines def.
Uniform lines produced by self fertilization of pure-breeding varieties over many generations.
What plants are produced from habitually self-fertilized seeds?
Wheat, oats, barley, tobacco
Incomplete dominance definition
Phenomenon in which, at heterozygous state, a blend phenotype from both alleles is expressed.
Codominance definition.
Phenomenon in which, at heterozygous state, expression of both alleles contributes equally to the phenotype.
Polyalleleism def.
Occurs when there are multiple alleles for a single genetic locus. phenomenon in which a trait is determined by a combination of more than 2 types of alleles.
Epistasis def.
phenomenon resulting from interactions between genes of different loci, where alteration of phenotypic expression of a gene at one locus occurs due to interference of another gene on a different locus.
Dominant epistasis def.
Phenomenon in which dominant allele of a gene at a specific locus alters phenotypic expression of another gene at a different locus.
Recessive epistasis def.
Phenomenon in which the homozygous recessive genotype of a gene at a particular locus alters the expression of another gene at a different locus.
Polygenic inheritance
inheritance of a phenotype, particularly of quantitative characters like height, skin color and IQ, resulting from cumulative expression of 2 or more genes.
How does gene linkage occur?
It occurs when some genes coding for particular characters are located on the same chromosome close to each other, so they escape from crossing over and independent assortment during meiosis and get inherited together.
Pleiotropy defintion
Phenomenon in which expression of one gene effects the expression of many traits that are unrelated to each other.
