genetics laboratory 5 Flashcards
(19 cards)
gene
a factor of inheritance for a particular trait or characteristic of an organism
alleles
allele of this gene could include green, yellow, or purple seed colour
dominant allele
where the phenotypic effect is the same in both the heterozygous and homozygous conditions. (represented as uppercase letters)
recessive allele
One that is not expressed phenotypically in the heterozygous condition. (represented as lowercase letters)
heterozygous
where a diploid organism has only particular genes if it has two different alleles for the genes
homozygous
where a diploid organism has only particular genes if it has two identical alleles for the genes
genotype
the genetic makeup of an organism (can be indicated using letters, Rr or GgHH)
phenotype
the physical appearance of an organism for a particular trait (indicated as descriptive words, purple seeds)
genotypic frequencies
0.5Dd, 0.25DD,0.25dd
phenotypic frequencies
0.75 green seeds, 0.25 white seeds
genotypic ratio
1DD:2Dd:1dd
phenotypic ratio
3 green seeds: 1 white seed
monohybrid cross
between two organisms that differ with respect to one characteristic
principle of dominance
when parents differ in one characteristic, their hybrid offspring resemble only one of the parents and are not a blend of the two-parent phenotypes
Mendels first law
when alleles of one gene segregate from one another during the formation of gametes
dihybrid cross
is between two organisms that differ with respect to two characteristics
Mendels second law
alleles of different genes assort independently of one another during gamete formation
test cross
involves crossing an individual of unknown genotype with a homozygous recessive individual
crossing over
genetic exchange can occur between homologous chromosomes during prophase I
